Photonic circuits with improved data transmission reliability

Abstract

This provides a photonic circuit with improved data transmission reliability. [Solution] According to the present invention, by providing multiple communication channels via a single optical waveguide using wavelength division multiplexing, and transmitting optical signals at different transmission speeds, a main channel containing image signals transmitted at a relatively high transmission speed and an auxiliary channel used for transmitting auxiliary signals for setting the main channel and having a relatively low transmission speed, can be combined and transmitted via the same optical waveguide. This avoids sensitivity problems in high-speed serial links where signal peaks are attenuated and signal widths are widened due to distortion of the transmitted signal, inter-symbolic interference (ISI), delay dispersion, and impedance mismatch, making detection difficult on the receiving side.

Description

Technical Field

[0003] , , , ,

[0004]

[0001] The present invention relates to a photonic circuit, and relates to an auxiliary data for setting a channel for transmitting image data and transmitting the image data between at least one or more display sources and at least one or more display sinks by using an optical signal, and a photonic circuit for distributing or routing the auxiliary data.

Background Art

[0002] As a method for realizing data routing or distribution between a plurality of inputs and outputs, in a method for realizing data routing by using an electrical signal such as an Ethernet switch, there are problems such as heat generation due to conduction of the electrical signal and relatively large energy consumption associated therewith. In recent years, research has been conducted on a photonic circuit for transmitting or routing data by using an optical signal instead of an electrical signal as a medium for information transmission.

Summary of the Invention

Problems to be Solved by the Invention

[0003] One embodiment of the present invention can transmit optical signals in different wavelength bands through a single optical waveguide by wavelength division multiplexing, and while avoiding the problem that it becomes difficult to detect or recognize a signal due to signal attenuation in a high-speed serial link, a wavelength separation band sufficient to suppress cross-talk between different optical signals is ensured, so that the reliability of data transmission can be improved. The photonic circuit includes.

Means for Solving the Problems

[0004] In order to solve the above problems and other problems, the photonic circuit of the present invention an optical fiber for transmitting an optical signal, A coupling with the optical fiber, comprising an input port forming the transmitting end, an output port forming the receiving end opposite to the transmitting end, and an optical waveguide network connecting the input port and the output port, A coupler switch for controlling optical power transmission or optical coupling between adjacent first and second optical waveguides constituting the optical waveguide network, comprising an electrical input for controlling the coupling efficiency between the first and second optical waveguides to realize different optical power transmission states: a through or bar state in which substantially no optical power crossing occurs between the first and second optical waveguides; a splitting, dividing or partial coupling state corresponding to partial optical power retention and partial crossing between the first and second optical waveguides; and a drop or cross state corresponding to total optical power crossing between the first and second optical waveguides. The first optical waveguide includes a pair of 1-1 optical waveguides and 1-2 optical waveguides, and the second optical waveguide includes a pair of 2-1 optical waveguides and 2-2 optical waveguides. Of the aforementioned optical waveguides 1-1, 1-2, 2-1, and 2-2, at least one single optical waveguide has an optical gain or optical loss profile having a full-width at half maximum (FWHM) that is attenuated to half the peak value of the central wavelength band toward both sides from a central wavelength band λ0 forming a single peak, The single optical waveguide transmits optical signals from different wavelength bands that are separated from each other, interposed by a wavelength separation band with a resolution that allows for the separation of different wavelength bands forming different communication channels, in order to prevent crosstalk between them within the wavelength range that forms the full width at half maximum (FWHM).

[0005] For example, the resolution for separating different wavelength bands that form the different communication channels corresponds to the resolution of a wavelength-selective filter for separating optical signals of different wavelength bands transmitted from the single optical waveguide, or the resolution of the wavelength-selective filter plus a margin tolerance.

[0006] For example, the single optical waveguide transmits optical signals of different wavelength bands, forming a high-speed channel and a low-speed channel with different transmission speeds.

[0007] For example, different optical signals transmitted together through the single optical waveguide form a high-speed channel with a relatively high transmission speed and a low-speed channel with a relatively low transmission speed. In the optical gain or optical loss profile of the optical waveguide, The wavelength band of the optical signal assigned to the high-speed channel is relatively close to the central wavelength band having a peak value and has a low attenuation rate. The wavelength band of the optical signal assigned to the low-speed channel is relatively far from the central wavelength band having a peak value and has a high attenuation rate.

[0008] For example, the single optical waveguide is Within the wavelength range that forms the full width at half maximum (FWHM), three different optical signals in different wavelength bands, separated from each other by a wavelength separation band, are transmitted together.

[0009] For example, three distinct optical signals transmitted together through the single optical waveguide form a first and second high-speed channel having a relatively high transmission speed, and a low-speed channel having a relatively low transmission speed, respectively. In the optical gain or optical loss profile of the optical waveguide, The wavelength band of the optical signal assigned to the second high-speed channel is closest to the central wavelength band having the peak value and has the lowest attenuation rate. The wavelength band of the optical signal assigned to the low-speed channel is furthest from the central wavelength band having the peak value and has the highest attenuation rate. The wavelength band of the optical signal assigned to the first high-speed channel is farther from the central wavelength band having a peak value than the wavelength band of the optical signal assigned to the second high-speed channel, but closer than the wavelength band of the optical signal assigned to the low-speed channel, and adjacent to it, with an intermediate attenuation rate.

[0010] For example, the wavelength band of the optical signal assigned to the first high-speed channel, the wavelength band of the optical signal assigned to the second high-speed channel, and the wavelength band of the optical signal assigned to the low-speed channel are assigned to positions asymmetrical to each other with respect to the central wavelength band having the peak value. The wavelength band of the optical signal assigned to the second high-speed channel and the wavelength band of the optical signal assigned to the low-speed channel are assigned to a wavelength range of one of the left half-region and the right half-region, centered on the central wavelength band having the peak value. The wavelength band of the optical signal assigned to the first high-speed channel is assigned to the wavelength range of the other region of the left half-region and the right half-region, centered on the central wavelength band having the peak value.

[0011] For example, the single optical waveguide transmits both an image signal, which includes image data, as first and second high-speed channels having relatively high transmission speeds, and an auxiliary signal, which includes auxiliary data, as a low-speed channel having relatively low transmission speeds.

[0012] For example, the 1-1 optical waveguide and the 1-2 optical waveguide each transmit two high-speed channels having relatively high transmission speeds and one low-speed channel having relatively low transmission speeds, thereby forming a total of six communication channels between the same display source and the same display sink, including four high-speed channels for image signals and two low-speed channels for auxiliary signals. The 2-1 optical waveguide and the 2-2 optical waveguide each transmit two high-speed channels having relatively high transmission speeds and one low-speed channel having relatively low transmission speeds, thereby forming a total of six communication channels between another identical display source and another identical display sink, including four high-speed channels for another image signal and two low-speed channels for another auxiliary signal.

[0013] For example, the 1-1 optical waveguide and the 1-2 optical waveguide each transmit two high-speed channels having relatively high transmission speeds and one low-speed channel having relatively low transmission speeds, thereby forming a total of six communication channels from the same display source, including four high-speed channels for image signals and two low-speed channels for auxiliary signals. The 2-1 optical waveguide and the 2-2 optical waveguide each transmit two high-speed channels with relatively high transmission speeds and one low-speed channel with relatively low transmission speeds, thereby forming a total of six communication channels, including four high-speed channels for image signals and two low-speed channels for auxiliary signals, all destined for the same display sink.

[0014] For example, the optical waveguide network is a 2Nx2N optical waveguide network that maps 2N input ports and 2N output ports to each other. The 2N input ports are connected in a 2:1 ratio to the display sources so that image signals and auxiliary signals output from the N display sources are input to the 2N input ports. The 2N output ports are connected to the display sinks in a 2:1 ratio so that image signals and auxiliary signals are output to the N display sinks. In order to achieve different optical power transmission between the adjacent first optical waveguide and second optical waveguide, which constitute an optical waveguide network between the input port and the output port, the coupler switch routes or distributes pairs of image signals and auxiliary signals input via input ports connected to the same display source toward output ports connected to the same display sink, in accordance with the control signal applied to the coupler switch.

[0015] For example, the optical power transmission that crosses between the 1-1 optical waveguide and the 2-1 optical waveguide, and the optical power transmission that crosses between the 1-2 optical waveguide and the 2-2 optical waveguide are both controlled by the same coupler switch.

[0016] For example, the optical waveguide network connects input ports and output ports formed on the first and second sides of the base substrate on which the optical waveguide network is formed, which are opposite to each other. The first and second optical waveguides are, The system includes a coupling section that extends parallel to the output port from the input port at a relatively close distance, and a phase shift section that extends parallel to the output port at a relatively far distance.

[0017] For example, in the phase shift section, an external electric field is applied to at least one of the first and second optical waveguides, and a coupler switch is formed to set a voltage that induces a phase difference or phase mismatch between the first and second optical waveguides.

[0018] For example, the optical power transmission or optical coupling efficiency that intersects between the first and second optical waveguides in the coupling section is formed to differ depending on the phase difference or phase mismatch between the first and second optical waveguides caused by the voltage set by the coupler switch in the phase shift section.

[0019] For example, the coupled switch receives first and second coupler control bits for applying three different levels of voltage between the first and second optical waveguides to cause different degrees of phase difference or phase mismatch between the first and second optical waveguides, in order to achieve different optical power transmissions including non-crossing through, partial remaining and partial crossing, and full crossing between the first and second optical waveguides.

[0020] For example, according to the voltage set by the coupled switch, i) When a zero voltage is set by the coupled switch, a drop or cross optical power transmission corresponding to full crossing of optical power is realized between the first and second optical waveguides from the input port to the output port. ii) When a maximum voltage is set by the coupled switch, a through or bar optical power transmission with substantially no crossing of optical power is realized between the first and second optical waveguides from the input port to the output port. iii) When a voltage between the zero voltage and the maximum voltage is set by the coupled switch, a dividing optical power transmission corresponding to partial remaining and partial crossing of optical power is realized between the first and second optical waveguides from the input port to the output port.

[0021] For example, at bit 0 of the first and second coupler control bits, while achieving phase matching between the first and second optical waveguides from the input port to the output port, a drop or cross optical power transmission corresponding to full crossing of optical power is realized. In bit 1 of the first coupler control bit and bit 0 of the second coupler control bit, a phase mismatch is created between the first and second optical waveguides from the input port to the output port, blocking a portion of the optical power transmission, while realizing optical power transmission in a dividing or partial coupling state corresponding to partial retention and partial crossing of optical power. In bit 1 of the first and second coupler control bits, a phase mismatch is created between the first and second optical waveguides from the input port to the output port, thereby blocking the transmission of all optical power, while achieving a through or bar state in which there is virtually no optical power transmission.

[0022] For example, the optical waveguide network is an NxN optical waveguide network that maps N input ports and N output ports to each other. The 1-1 optical waveguide and the 2-1 optical waveguide are optical waveguides that extend adjacent to each other between two distinct input ports out of the N input ports and two distinct output ports out of the N output ports. The first- and second-2 optical waveguides are optical waveguides that extend adjacent to each other between two other distinct input ports out of the N input ports and two other distinct output ports out of the N output ports. The flow of optical power intersecting between the 1-1 optical waveguide and the 2-1 optical waveguide, and the flow of optical power intersecting between the 1-2 optical waveguide and the 2-2 optical waveguide, are both controlled by the same coupler switch.

[0023] For example, the optical waveguide network connects input ports and output ports formed on the first and second sides of the base substrate on which the optical waveguide network is formed, which intersect at one corner so as to be in contact with each other. To control the optical power transmission or optical coupling efficiency at the intersection between the first optical waveguide connected to the input port and the second optical waveguide connected to the output port, a coupler switch is provided which includes a movable coupler that enables forward / backward movement along the approaching direction toward the intersection of the first and second optical waveguides or the backward direction toward the intersection of the first and second optical waveguides.

[0024] For example, the movable coupler is i) At the first position furthest from the intersection of the first and second optical waveguides, through or bar optical power transmission is achieved between the first waveguide connected to the input port and the second waveguide connected to the output port, in which substantially no crossing of optical power occurs. ii) At the third position closest to the intersection of the first and second optical waveguides, optical power transmission equivalent to a drop or cross of total optical power crossing is realized between the first waveguide connected to the input port and the second waveguide connected to the output port. iii) At a second position between the first position furthest from the intersection of the first and second optical waveguides and the third position closest to it, optical power transmission is realized in a splitting, dividing, or partial coupling state corresponding to partial retention and partial crossing of optical power.

[0025] For example, the coupler switch receives first and second coupler control bits for applying three distinct levels of control voltage so that the movable coupler is set from a first position furthest from the intersection of the first and second optical waveguides to a third position closest to it.

[0026] For example, in bit 0 of the first and second coupler control bits, the movable coupler is set to the first position furthest from the intersection of the first and second optical waveguides. In bit 1 of the first coupler control bit and bit 0 of the second coupler control bit, the movable coupler is set to a second position from the intersection of the first and second optical waveguides. In bit 1 of the first and second coupler control bits, the movable coupler is set to the third position closest to the intersection of the first and second optical waveguides.

[0027] For example, the movable coupler is A first coupling rib extending parallel to the first optical waveguide is provided to form an evanescent coupling with the first optical waveguide, The device includes a second coupling rib extending parallel to the second optical waveguide so as to form an evanescent coupling with the second optical waveguide.

[0028] For example, the evanescent field leaking between the first optical waveguide and the movable coupler has an amplitude that decreases from the first optical waveguide toward the movable coupler. The evanescent field leaking between the second optical waveguide and the movable coupler has an amplitude that decreases from the movable coupler toward the second optical waveguide. [Effects of the Invention]

[0029] According to the present invention, by providing multiple communication channels via a single optical waveguide using wavelength division multiplexing, and transmitting optical signals at different transmission speeds, it is possible to avoid detection sensitivity problems in high-speed serial links where signal peaks are attenuated and signal widths are broadened due to signal distortion, inter-symbolic interference (ISI), delay dispersion, and impedance mismatch, making detection difficult at the receiving end. In other words, for high-speed channels, wavelength bands adjacent to the central wavelength band that forms a single peak in the optical gain or optical loss profile of the optical waveguide are assigned, while for low-speed channels, where the effect of signal attenuation in the high-speed serial link is relatively small, wavelength bands relatively far from the central wavelength band that forms a single peak are assigned. This allows for the provision of multiple communication channels of different wavelength bands via a single optical waveguide, while avoiding problems such as difficulty in detecting or recognizing signals due to signal attenuation in the high-speed serial link, and ensuring sufficient wavelength separation bandwidth to prevent crosstalk between different communication channels.Furthermore, in one embodiment of the present invention, a total of six communication channels, including four main channels (high-speed channels) containing image signals and two auxiliary channels (low-speed channels) containing auxiliary signals for setting the main channels, are distributed between a display source and a display sink to two high-speed channels and one low-speed channel, respectively, to different optical waveguides for transmitting two high-speed channels and one low-speed channel. Based on the central wavelength band that forms a single peak in the optical gain or optical loss profile of the optical waveguide, wavelength bands relatively adjacent to the central wavelength band and wavelength bands relatively far from the central wavelength band are assigned to the two high-speed channels, respectively. On the other hand, for the low-speed channel, wavelength bands are assigned to the region of the left and right halves of the region on both sides of the central wavelength band that are relatively adjacent to the central wavelength band (high-speed channels), based on the central wavelength band. This avoids the problem of difficulty in detecting or recognizing signals due to signal attenuation in high-speed serial links, while ensuring sufficient wavelength separation bandwidth to suppress crosstalk between communication channels of different wavelength bands. [Brief explanation of the drawing]

[0030] [Figure 1] This figure illustrates a configuration in the first type of the present invention, which includes an optical waveguide network WN connecting a plurality of input ports INP and a plurality of output ports OUTP, and a coupler switch CS for realizing different optical power transmissions between adjacent optical waveguides W that form the optical waveguide network WN to realize a mapping set between the plurality of input ports INP and a plurality of output ports OUTP. [Figure 2] Figure 1 is a diagram illustrating the configuration of a coupler switch CS, which includes a phase shift section PS (phase shifter) and a coupling section CP (tunable coupler). [Figure 3A]This diagram illustrates the ratios Out1 and Out2 (see Figure 2) of optical powers crossing between the first optical waveguide W1 and the second optical waveguide W2 due to the phase difference or phase mismatch Δφ caused between the first optical waveguide W1 and the second optical waveguide W2, based on the magnitude of the voltage set by the coupler switch CS or the set voltage, for different optical coupling efficiencies k. [Figure 3B] This diagram illustrates the ratios Out1 and Out2 (see Figure 2) of optical powers crossing between the first optical waveguide W1 and the second optical waveguide W2 due to the phase difference or phase mismatch Δφ caused between the first optical waveguide W1 and the second optical waveguide W2, based on the magnitude of the voltage set by the coupler switch CS or the set voltage, for different optical coupling efficiencies k. [Figure 3C] This diagram illustrates the ratios Out1 and Out2 (see Figure 2) of optical powers crossing between the first optical waveguide W1 and the second optical waveguide W2 due to the phase difference or phase mismatch Δφ caused between the first optical waveguide W1 and the second optical waveguide W2, based on the magnitude of the voltage set by the coupler switch CS or the set voltage, for different optical coupling efficiencies k. [Figure 4]This figure illustrates a configuration in the second type of the present invention, which includes an optical waveguide network WN connecting a plurality of input ports INP and a plurality of output ports OUTP, and a coupler switch CS for realizing different optical power transmissions between adjacent optical waveguides W that form the optical waveguide network WN in order to realize a mapping set between the plurality of input ports INP and a plurality of output ports OUTP. [Figure 5A] Figure 4 illustrates the operation of the coupler switch CS, which enables the transmission of different optical power between adjacent optical waveguides W constituting the optical waveguide network WN, according to the different first position P1 and third position P3 set on the movable coupler MOC of the coupler switch CS shown in Figure 4. The figure illustrates a through or bar state in which no optical power crossing occurs between adjacent first optical waveguides W1 and second optical waveguides W2 at the first position P1 of the movable coupler MOC, or the OFF state of the coupler switch CS. [Figure 5B] Figure 4 illustrates the operation of the coupler switch CS, which realizes different optical power transmission between adjacent optical waveguides W constituting the optical waveguide network WN, according to the different first position P1 and third position P3 set on the movable coupler MOC of the coupler switch CS shown in Figure 4. The figure illustrates a drop or cross state in which a total crossover of optical power occurs between adjacent first optical waveguides W1 and second optical waveguides W2 at the third position P3 of the movable coupler MOC, or the ON state of the coupler switch CS. [Figure 6]Figure 4 illustrates the operation of the coupler switch CS, which enables the transmission of different optical power between adjacent optical waveguides W that constitute the optical waveguide network WN, according to the different second position P2 and third position P3 set on the movable coupler MOC of the coupler switch CS shown in Figure 4. The figure illustrates a dividing or partial coupling state in which some optical power remains and some crossing occurs between adjacent first optical waveguides W1 and second optical waveguides W2 at the second position P2 of the movable coupler MOC, and a drop or cross state in which all optical power crossing occurs between adjacent first optical waveguides W1 and second optical waveguides W2 at the third position P3 of the movable coupler MOC. [Figure 7] (a) to (c) are diagrams illustrating the operation of the coupler switch CS shown in Figure 4, which realizes different optical power transmission between adjacent optical waveguides W that constitute the optical waveguide network WN, depending on the different first positions P1 to third positions P3 set on the movable coupler MOC of the coupler switch CS, and illustrate a through or bar state in which no optical power crossing occurs between adjacent first optical waveguides W1 and second optical waveguides W2 at the first position P1 of the movable coupler MOC; a dividing or partial coupling state in which some optical power remains and some crossing occurs between adjacent first optical waveguides W1 and second optical waveguides W2 at the second position P2 of the movable coupler MOC; and a drop or cross state in which all optical power crossing occurs between adjacent first optical waveguides W1 and second optical waveguides W2 at the third position P3 of the movable coupler MOC. [Figure 8A] This diagram illustrates three distinct states set by a coupler switch CS, relating to optical power transmission that crosses between adjacent first optical waveguides W1 and second optical waveguides W2 that constitute an optical waveguide network WN, and also illustrates a bar state in which there is no optical power transmission that crosses between the first optical waveguide W1 and second optical waveguide W2. [Figure 8B]This diagram illustrates three distinct states set by a coupler switch CS, relating to the transmission of optical power that crosses between adjacent first optical waveguides W1 and second optical waveguides W2 that constitute an optical waveguide network WN. The diagram illustrates a partially coupled state in which some optical power remains and some crossing occurs between the first optical waveguide W1 and second optical waveguide W2. [Figure 8C] This diagram illustrates three distinct states set by a coupler switch CS, relating to three distinct states concerning optical power transmission that intersect between mutually adjacent first optical waveguides W1 and second optical waveguides W2 that constitute an optical waveguide network WN, and further illustrates the cross state in which all optical power crossing occurs between the first optical waveguide W1 and second optical waveguide W2. [Figure 9A] This diagram illustrates the lattice coupling between the optical fiber F through which the optical signal is transmitted and the input port INP (lattice coupler). It illustrates vertical fiber coupling, where the optical fibers F are arranged with different orientations relative to the input port INP. [Figure 9B] This diagram illustrates the lattice coupling between the optical fiber F through which the optical signal is transmitted and the input port INP (lattice coupler). It illustrates horizontal fiber coupling in which the optical fibers F are arranged with different orientations relative to the input port INP. [Figure 10] Figure 9B illustrates the grid coupling between the optical fiber F and the input port INP in the horizontal fiber coupling shown. [Figure 11] This diagram illustrates the configuration of an input port INP, or a grid coupler for input port INP, which enables coupling between the core of an optical fiber F with a relatively wide cross-sectional area and an optical waveguide W with a relatively narrow cross-sectional area. [Figure 12] This is a cross-sectional view illustrating the configuration of a silicon-based photonic circuit, comprising a base substrate (S,Si), a lower oxide film BOX (SiO2) on the base substrate (S,Si), an optical waveguide (Si) on the lower oxide film (SiO2), and cladding CL (SiO2) that embeds the optical waveguide (Si). [Figure 13] This figure illustrates a structure in which, in the first type of the present invention, a pair of 1-1 optical waveguides W1-1 and 1-2 optical waveguides W1-2 forming a first optical waveguide W1 connected to the same display source, and a pair of 2-1 optical waveguides W2-1 and 2-2 optical waveguides W2-2 forming a second optical waveguide W2 connected to the same display sink, are configured as a stack with each other arranged vertically, and the figure illustrates a coupler switch CS that is configured or interlocked together to set the same state (bar, partial coupling, cross state) regarding optical power transmission that crosses between the 1-1 optical waveguide W1-1 and the 2-1 optical waveguide W2-1, and between the 1-2 optical waveguide W1-2 and the 2-2 optical waveguide W2-2. [Figure 14] This figure illustrates a structure in the second type of the present invention in which a pair of 1-1 optical waveguides W1-1 and 1-2 optical waveguides W1-2 forming a first optical waveguide W1 connected to the same display source, and a pair of 2-1 optical waveguides W2-1 and 2-2 optical waveguides W2-2 forming a second optical waveguide W2 connected to the same display sink, are configured as an interleave type with the two optical waveguides arranged horizontally to each other. The figure illustrates coupler switches CSa, CSb, and CSc that are configured or interlocked together to set the same state (bar, partial coupling, cross state) regarding optical power transmission that crosses between the 1-1 optical waveguide W1-1 and the 2-1 optical waveguide W2-1, and between the 1-2 optical waveguide W1-2 and the 2-2 optical waveguide W2-2. [Figure 15] This diagram illustrates the four main channels (Channel 0, 1, 2, Clock Channel, Lane 0, 1, 2, 3) with high transmission speeds that are set between the display source and the display sink in HDMI® transmission. [Figure 16]This diagram illustrates the two auxiliary channels (SDA, SCL, and AUX Channel) with low transmission speeds that are set up between the display source and the display sink in DisplayPort transmission. [Figure 17] This figure illustrates how, in one embodiment of the present invention, optical signals of different wavelength bands are assigned to five channels allocated to an optical waveguide W. [Figure 18] This figure illustrates an embodiment of the present invention in which, as three channels assigned to an optical waveguide W, two channels with high transmission speeds and one channel with a low transmission speed, optical signals of different wavelength bands are assigned according to their respective transmission speeds. [Figure 19] This figure illustrates an embodiment of the present invention in which, as four channels assigned to an optical waveguide W, two channels with high transmission speeds and two channels with low transmission speeds are assigned optical signals of different wavelength bands according to their respective transmission speeds. [Figure 20] This figure illustrates an embodiment of the present invention in which, as three channels assigned to an optical waveguide W, one channel with a high transmission speed and two channels with low transmission speeds, optical signals of different wavelength bands are assigned according to their respective transmission speeds. [Figure 21] This figure shows the optical loss or attenuation of an optical fiber F (silica-based optical fiber) according to its wavelength. [Figure 22] This diagram illustrates edge coupling between an optical fiber F through which an optical signal is transmitted and an input port INP (edge ​​coupler), and illustrates edge coupling which is different from lattice coupling or surface coupling shown in Figures 9A and 9B. [Figure 23] This figure illustrates an embodiment of a communication protocol to which the optical waveguide network WN of the present invention may be applied, specifically illustrating USB communication. [Figure 24]This figure illustrates an embodiment of a communication protocol to which the optical waveguide network WN of the present invention may be applied, and describes Thunderbolt communication. [Modes for carrying out the invention]

[0031] A photonic circuit according to a preferred embodiment of the present invention will be described below with reference to the attached drawings.

[0032] Figure 1 illustrates a configuration in the first type of the present invention, which includes an optical waveguide network WN connecting a plurality of input ports INP and a plurality of output ports OUTP, and a coupler switch CS for realizing different optical power transmissions between adjacent optical waveguides W that form the optical waveguide network WN in order to realize a mapping set between the plurality of input ports INP and a plurality of output ports OUTP.

[0033] Figure 2 is a diagram illustrating the configuration of the coupler switch CS shown in Figure 1, and illustrates the configuration of the coupler switch CS including a phase shift section PS (phase shifter) and a coupling section CP (tunable coupler).

[0034] Figures 3A to 3C are diagrams illustrating the ratios Out1 and Out2 (see Figure 2) of optical powers crossing between the first optical waveguide W1 and the second optical waveguide W2 due to the phase difference or phase mismatch Δφ caused between the first optical waveguide W1 and the second optical waveguide W2, based on the magnitude or voltage set by the coupler switch CS, for different optical coupling efficiencies k.

[0035] Figure 4 illustrates a configuration in the second type of the present invention, which includes an optical waveguide network WN connecting a plurality of input ports INP and a plurality of output ports OUTP, and a coupler switch CS for realizing different optical power transmissions between adjacent optical waveguides W that form the optical waveguide network WN in order to realize a mapping set between the plurality of input ports INP and a plurality of output ports OUTP.

[0036] Figures 5A and 5B illustrate the operation of the coupler switch CS shown in Figure 4, which enables the transmission of different optical power between adjacent optical waveguides W that constitute the optical waveguide network WN, depending on the different first position P1 and third position P3 set on the movable coupler MOC of the coupler switch CS. The first figure illustrates a through or bar state, or the OFF state of the coupler switch CS, where no optical power crossing occurs between adjacent first optical waveguides W1 and second optical waveguides W2 at the first position P1 of the movable coupler MOC, and the second figure illustrates a drop or cross state, or the ON state of the coupler switch CS, where all optical power crossing occurs between adjacent first optical waveguides W1 and second optical waveguides W2 at the third position P3 of the movable coupler MOC.

[0037] Figure 6 is a diagram illustrating the operation of the coupler switch CS shown in Figure 4, which realizes phase-shifted optical power transmission between adjacent optical waveguides W that constitute the optical waveguide network WN, depending on the phase-shifted second position P2 and third position P3 set on the movable coupler MOC of the coupler switch CS. The diagram illustrates a dividing or partial coupling state in which some optical power remains and some crossing occurs between adjacent first optical waveguides W1 and second optical waveguides W2 at the second position P2 of the movable coupler MOC, and a drop or cross state in which all optical power crossing occurs between adjacent first optical waveguides W1 and second optical waveguides W2 at the third position P3 of the movable coupler MOC.

[0038] Figures 7(a) to 7(c) illustrate the operation of the coupler switch CS shown in Figure 4, which realizes different optical power transmission between adjacent optical waveguides W that constitute the optical waveguide network WN, depending on the different first positions P1 to 3rd positions P3 set on the movable coupler MOC of the coupler switch CS. The figures illustrate a through or bar state in which no optical power crossing occurs between adjacent first optical waveguides W1 and second optical waveguides W2 at the first position P1 of the movable coupler MOC; a dividing or partial coupling state in which some optical power remains and some crossing occurs between adjacent first optical waveguides W1 and second optical waveguides W2 at the second position P2 of the movable coupler MOC; and a drop or cross state in which all optical power crossing occurs between adjacent first optical waveguides W1 and second optical waveguides W2 at the third position P3 of the movable coupler MOC.

[0039] Figures 8A to 8C are three distinct states set by the coupler switch CS, illustrating three distinct states relating to optical power transmission crossing between adjacent first optical waveguides W1 and second optical waveguides W2 that constitute the optical waveguide network WN. These figures illustrate a bar state in which there is no optical power transmission crossing between the first optical waveguide W1 and second optical waveguide W2, a partially coupled state in which some optical power remains and some crossing occurs between the first optical waveguide W1 and second optical waveguide W2, and a cross state in which all optical power crossing occurs between the first optical waveguide W1 and second optical waveguide W2.

[0040] Figures 9A and 9B illustrate the lattice coupling between the optical fiber F through which the optical signal is transmitted and the input port INP (lattice coupler). They illustrate vertical fiber coupling and horizontal fiber coupling, respectively, where the optical fibers F are arranged with different orientations relative to the input port INP.

[0041] Figure 10 illustrates the grid coupling between the optical fiber F and the input port INP in the horizontal fiber coupling shown in Figure 9B.

[0042] Figure 11 illustrates the configuration of an input port INP, or a grid coupler for input port INP, which enables coupling between the core of an optical fiber F with a relatively large cross-sectional area and an optical waveguide W with a relatively small cross-sectional area.

[0043] Figure 12 is a cross-sectional view illustrating the configuration of a silicon-based photonic circuit, consisting of a base substrate (S,Si), a lower oxide film BOX (SiO2) on the base substrate (S,Si), an optical waveguide (Si) on the lower oxide film (SiO2), and cladding CL (SiO2) that embeds the optical waveguide (Si).

[0044] A photonic circuit according to one embodiment of the present invention is Optical fiber F for transmitting optical signals, A coupling (lattice coupling) is formed with the optical fiber F, comprising an input port INP forming the transmitting end, an output port OUTP forming the receiving end opposite to the transmitting end, and an optical waveguide network WN connecting the input port INP and the output port OUTP. A coupler switch CS for controlling optical power transmission or optical coupling that crosses between adjacent first optical waveguides W1 and second optical waveguides W2 forming the optical waveguide network WN, comprising an electrical input to control the coupling efficiency between the first optical waveguides W1 and second optical waveguides W2, thereby realizing different optical power transmission states: a through or bar state in which there is substantially no crossing of optical power between the first optical waveguides W1 and second optical waveguides W2; a splitting, dividing or partial coupling state corresponding to partial retention and partial crossing of optical power between the first optical waveguides W1 and second optical waveguides W2; and a drop or cross state corresponding to total crossing of optical power between the first optical waveguides W1 and second optical waveguides W2. The first optical waveguide W1 includes a pair of 1-1 optical waveguide W1-1 and 1-2 optical waveguide W1-2, and the second optical waveguide W2 includes a pair of 2-1 optical waveguide W2-1 and 2-2 optical waveguide W2-2, The flow of optical power intersecting between the 1-1 optical waveguide and the 2-1 optical waveguide, and the flow of optical power intersecting between the 1-2 optical waveguide and the 2-2 optical waveguide, are both controlled by the same coupler switch CS.

[0045] In one embodiment of the present invention, an input port INP into which an optical signal is input from an optical fiber F, an output port OUTP to which an optical signal is output, an optical waveguide network WN connecting the input port INP and the output port OUTP according to a set mapping, and a coupler switch CS for realizing the set mapping between the input port INP and the output port OUTP by controlling the optical power transmission or optical coupling efficiency between different optical waveguides W forming the optical waveguide network WN are integrally formed on a base substrate S (for example, a silicon substrate) that forms a common support base.

[0046] In one embodiment of the present invention, the input port INP includes a lattice coupler that forms a lattice coupling with the optical fiber F. In various embodiments of the present invention, depending on the type of lattice coupling due to the arrangement between the input port INP and the optical fiber F, the optical fiber F may form a vertical fiber coupling with the base substrate S on which the input port INP is formed (see Figure 9A), or a horizontal fiber coupling with the base substrate S on which the input port INP is formed (see Figure 9B). For example, in the vertical fiber coupling (see Figure 9A), the optical fiber F is positioned in a downward inclined position toward the base substrate S, and in the horizontal fiber coupling (see Figure 9B), the optical fiber F is positioned parallel to the base substrate S, but an inclined surface FS is formed at the end of the optical fiber F to induce downward total internal reflection toward the base substrate S. Referring to Figure 11, in one embodiment of the present invention, the input port INP or the lattice coupler of the input port INP that forms a lattice coupling with the optical fiber F achieves optical coupling between a core with a diameter of approximately 10.4 μm and an optical waveguide W having a cross-section of 0.45 μm × 0.22 μm, thereby achieving coupling with relatively low optical loss while focusing the optical signal propagating along the core of the optical fiber F, which has a relatively large cross-sectional area, onto the optical waveguide W, which has a relatively small cross-sectional area. For example, the optical fiber F is a single-mode optical fiber F for transmitting optical signals in the 1550 nm wavelength band, and the diameter including the core and the cladding CL surrounding the core is formed to be approximately 125 μm, and the diameter of the core where the propagation of the optical signal is concentrated is formed to be approximately 10.4 μm.

[0047] Referring to Figures 10 and 12, in one embodiment of the present invention, the structure of the optical waveguide W forming the optical waveguide network WN has a lower oxide film BOX (SiO2) formed on a silicon substrate as a base substrate S, and a structure in which the core of the optical waveguide W (e.g., Si) and cladding CL (e.g., SiO2) surrounding the core (e.g., Si) are formed, and the propagation of optical signals can be concentrated to the core (Si) of the optical waveguide W due to the refractive index difference between the core (Si) of the optical waveguide W and the cladding CL (SiO2) surrounding the core (Si). For example, in one embodiment of the present invention, the input port INP or the lattice coupler of the input port INP that provides coupling of optical signals between the optical fiber F and the optical waveguide W is formed with a cross-section of approximately 12 μm × 20 μm, which is wider than the cross-section of the core of the optical fiber F (10.4 μm diameter) (see Figure 11).

[0048] Referring to Figures 1 and 4, in one embodiment of the present invention, the input port INP and output port OUTP are arranged in multiple arrays along the first side S1 and second side S2 of a base substrate S (e.g., a silicon substrate). For example, each optical fiber F forms a one-to-one lattice coupling with each input port INP, corresponding to an array of input ports INP arranged along the first side S1 of the base substrate S. For example, the optical signal transmitted through each optical fiber F is transmitted through the input port INP that forms a lattice coupling with each optical fiber F and the respective optical waveguide W connected to each input port INP.

[0049] Referring to Figures 1 and 4, in one embodiment of the present invention, the optical waveguide network WN sets up connections between N input ports INP and N output ports OUTP according to a mapping set up between N input ports INP and N output ports OUTP, and to achieve this, the photonic circuit according to one embodiment of the present invention may include a coupler switch CS for controlling the optical coupling efficiency between adjacent optical waveguides W so as to realize different optical power flows or different optical power transmissions between adjacent optical waveguides W forming the optical waveguide network WN.

[0050] In one embodiment of the present invention, the coupler switch CS can receive electrical control signals (first coupler control bit b1 and second coupler control bit b2, described later) as input to realize different optical power flows or different optical power transmissions between the first optical waveguide W1 and the second optical waveguide W2, whose intersecting optical power flows are controlled via the coupler switch CS. In one embodiment of the present invention, the different optical power transmissions or different optical power flows realized between adjacent first optical waveguides W1 and second optical waveguides W2 that constitute the optical waveguide network WN can be represented as three distinct states as follows. i) A through (see Figure 7A) or bar state (see Figure 8A) in which there is no substantially intersecting optical power transmission between the first optical waveguide W1 and the second optical waveguide W2; ii) Splitting (see Figure 7B) or partial coupling state (see Figure 8B) corresponding to partial retention and partial crossover of optical power between the first optical waveguide W1 and the second optical waveguide W2; iii) A drop (see Figure 7C) or cross state (see Figure 8C) corresponding to the total crossover of optical power between the first optical waveguide W1 and the second optical waveguide W2.

[0051] In one embodiment of the present invention, optical power transmission or flow intersecting between different optical waveguides W can be defined as three states, i) ii) iii), as described above. i) The through (see Figure 7A) or bar state (see Figure 8A) where there is substantially no crossing optical power transmission between the first optical waveguide W1 and the second optical waveguide W2 means a state in which there is substantially no optical power transmission between the adjacent first optical waveguide W1 and the second optical waveguide W2, the optical coupling efficiency is at its lowest (for example, a state in which the optical coupling efficiency is substantially close to zero), or a state in which there is substantially no optical coupling between the first optical waveguide W1 and the second optical waveguide W2. For example, this means a state in which an optical signal transmitted through the first optical waveguide W1 is not transmitted to the second optical waveguide W2, or if it is transmitted to the second optical waveguide W2, it is transmitted with negligible optical power, and an optical signal that was transmitted through the first optical waveguide W1 is transmitted as is through the first optical waveguide W1. ii) The splitting (see Figure 7B) or partial coupling (see Figure 8B) state between the first optical waveguide W1 and the second optical waveguide W2, which corresponds to partial retention and partial crossing of optical power, is a state in which optical power transmission is partially performed between the adjacent first optical waveguide W1 and the second optical waveguide W2, and the optical coupling efficiency is at an intermediate level. For example, between the first optical waveguide W1 through which an optical signal is transmitted and the second optical waveguide W2 adjacent to the first optical waveguide W1, a portion of the optical signal transmitted through the first optical waveguide W1 is transmitted to the second optical waveguide W2, while the remaining portion of the optical signal transmitted through the first optical waveguide W1 continues to be transmitted through the first optical waveguide W1. Furthermore, iii) the drop (see Figure 7C) or cross state (see Figure 8C) corresponding to the total crossover of optical power between the first optical waveguide W1 and the second optical waveguide W2 is a state in which the optical coupling efficiency is at its maximum between the adjacent first optical waveguide W1 and the second optical waveguide W2 (for example, a state in which the optical coupling efficiency is close to 100%), and the optical signal that was transmitted through the first optical waveguide W1 is transmitted to the second optical waveguide W2 with the total optical power, while the optical signal input to the first optical waveguide W1 is output via the second optical waveguide W2 on the output side.

[0052] In one embodiment of the present invention, the optical power transmission or optical coupling efficiency that intersects between adjacent first optical waveguides W1 and second optical waveguides W2 may be understood in terms of the transmission length or coupling length related to the optical coupling efficiency. For example, all of the optical signal or optical power of the first optical waveguide W1 can be transmitted to the second optical waveguide W2 through a transmission length or coupling length that is inversely proportional to the optical coupling efficiency between adjacent first optical waveguides W1 and second optical waveguides W2. As described later, a coupler switch CS is formed on at least one of the optical waveguides W1 and W2, which is used to apply an external electric field to set a voltage that induces a phase difference or phase mismatch between the first optical waveguide W1 and the second optical waveguide W2. For example, when no voltage is set from the coupler switch CS to induce a phase difference or phase mismatch between the first optical waveguide W1 and the second optical waveguide W2, for example, when zero voltage is set from the coupler switch CS, the entire optical power can be transmitted between the first optical waveguide W1 and the second optical waveguide W2 through the transmission length or coupling length related to the optical coupling efficiency between the first optical waveguide W1 and the second optical waveguide W2. When a voltage is set from the coupler switch CS to induce a phase difference or phase mismatch between the first optical waveguide W1 and the second optical waveguide W2, not all of the optical power is transmitted between the first optical waveguide W1 and the second optical waveguide W2, and the optical power that crosses between the first optical waveguide W1 and the second optical waveguide W2 (for example, the optical power transmission ratio that crosses between the first optical waveguide W1 and the second optical waveguide W2) can be expressed as a function of the phase difference or phase mismatch between the first optical waveguide W1 and the second optical waveguide W2.

[0053] Figures 3A to 3C are diagrams for illustrating the ratios Out1 and Out2 (see Figure 2) of optical power crossing between the first optical waveguide W1 and the second optical waveguide W2 due to the phase difference or phase mismatch Δφ caused between the first optical waveguide W1 and the second optical waveguide W2, based on the magnitude or voltage set by the coupler switch CS, for different optical coupling efficiencies k. Referring to Figures 3A to 3C, it can be confirmed that as the voltage set by the coupler switch increases, the phase difference or phase mismatch Δφ between the first optical waveguide W1 and the second optical waveguide W2 increases, and consequently, the ratio of the optical powers (outputs Out1 and Out2, see Figure 2) of the first optical waveguide W1 and the second optical waveguide W2 changes. Furthermore, it can be confirmed that as the voltage set by the coupler switch CS increases, and as the phase difference or phase mismatch Δφ between the first optical waveguide W1 and the second optical waveguide W2 increases from the set voltage, the ratio of the optical powers crossing between the first optical waveguide W1 and the second optical waveguide W2 (relative ratio of Out1 and Out2, see Figure 2) decreases.

[0054] Referring to Figures 1 and 4, the photonic circuit of the present invention may include different first and second types of embodiments, depending on the configuration of a coupler switch CS for realizing different optical power transmissions (for example, the ratio of optical power transmitted between adjacent first optical waveguides W1 and second optical waveguides W2) that constitute the optical waveguide network WN, in order to realize a mapping set between the multiple input ports INP and the multiple output ports OUTP.

[0055] Referring to Figures 1 and 2, in a first type of embodiment of the present invention, the plurality of input ports INP and the plurality of output ports OUTP are formed on the opposing first side S1 and second side S2 of the base substrate S on which the optical waveguide network WN is formed, and the plurality of input ports INP and the plurality of output ports OUTP may be arranged along the opposing first side S1 and second side S2 of the base substrate S. Then, in order to realize mapping between the plurality of input ports INP and the plurality of output ports OUTP while forming the optical waveguide network WN, the first optical waveguide W1 and the second optical waveguide W2, whose intersecting optical power transmission is changed via a coupler switch CS, may include a coupling section CP (tunable coupler) that extends parallel to each other at a relatively close position and a phase shift section PS (phase shifter) that extends parallel to each other at a relatively far position, while extending from the input port INP to the output port OUTP. For example, in one embodiment of the present invention, the plurality of optical waveguides W forming the optical waveguide network WN extend generally parallel from an input port INP formed on the first side S1 of the base substrate S to an output port OUTP formed on the second side S2 facing the first side S1 of the base substrate S, and include a coupling section CP extending parallel at a relatively close position and a phase shift section PS extending parallel at a relatively distant position between adjacent optical waveguides W. However, in various embodiments of the present invention, the coupling section CP and the phase shift section PS may not be separated between adjacent optical waveguides W forming the optical waveguide network WN. For example, they may not be separated into a coupling section CP at a relatively close position and a phase shift section PS at a relatively distant position. Furthermore, in the optical waveguide network WN, the coupling section CP, where optical power intersects in accordance with the leakage electric field of the evanescent field, and the phase shift section PS, which causes a phase difference or phase mismatch between adjacent optical waveguides W, may be formed over substantially the same section.For the sake of understanding, this specification describes adjacent optical waveguides forming an optical waveguide network WN (e.g., a first optical waveguide W1 and a second optical waveguide W2) as including a coupling section CP where optical powers intersect in response to the leakage electric field of the evanescent field at relatively close locations, and a phase shift section PS where adjacent optical waveguides (first optical waveguide W1 and second optical waveguide W2) at relatively distant locations cause a phase difference or phase mismatch; however, the technical configurations of the present invention are not limited to those exemplified.

[0056] In one embodiment of the present invention, a coupler switch CS is formed on at least one of the adjacent first optical waveguides W1 and second optical waveguides W2, which is an optical waveguide W, to which an external electric field is applied to set a voltage that causes a phase difference or phase mismatch between the first optical waveguide W1 and the second optical waveguide W2. For example, in one embodiment of the present invention, the coupler switch CS applies an external electric field on either one of the first optical waveguides W1 and the second optical waveguide W2, or applies external electric fields of opposite polarity to both sides of the first optical waveguide W1 and the second optical waveguide W2. In one embodiment of the present invention, the speed of light of the optical signal traveling through the optical waveguide W changes due to the influence of the external electric field, and a phase difference or phase mismatch may occur between the adjacent first optical waveguide W1 and second optical waveguide W2 depending on, for example, a change in the wavelength of the optical signal or a change in the refractive index of the optical waveguide W.

[0057] As shown in Figures 3A to 3C, the optical power transfer crossing between the first optical waveguide W1 and the second optical waveguide W2 (the optical power transfer ratio crossing between the first optical waveguide W1 and the second optical waveguide W2) changes depending on the phase difference or phase mismatch Δφ between the first optical waveguide W1 and the second optical waveguide W2. For example, depending on the voltage set from the coupler switch CS to cause a phase difference or phase mismatch Δφ between the first optical waveguide W1 and the second optical waveguide W2, the optical power transfer between the two may be: i) through (see Figure 7A) or bar state (see Figure 8A) where there is virtually no optical power transfer between the first optical waveguide W1 and the second optical waveguide W2; or ii) splitting, dividing (see Figure 7B) or partial coupling state where there is some remaining and some crossing between the first optical waveguide W1 and the second optical waveguide W2. (See Figure 8B), iii) Different phase optical power transmission is achieved between the first optical waveguide W1 and the second optical waveguide W2, with a drop (See Figure 7C) or cross state (See Figure 8C) corresponding to the total crossing of optical power. For example, in one embodiment of the present invention, a coupler switch CS that receives an electrical control signal to achieve different phase optical power transmission between adjacent first optical waveguides W1 and second optical waveguides W2 receives a control signal that includes a first coupler control bit b1 and a second coupler control bit b2 (See Figure 1) which can be set to three different levels of voltage to form three different phase states (bar, partial coupling, cross state, see Figures 8A to 8C) or three different phase states. For example, in one embodiment of the present invention, a control unit (not shown) is provided that outputs a control signal to the coupler switch CS including a first coupler control bit b1 and a second coupler control bit b2 in order to realize a mapping set up between a plurality of input ports INP and a plurality of output ports OUTP. The control unit (not shown) generates and outputs a control signal to each coupler switch CS that realizes the mapping that sets up the connection between each input port INP and output port OUTP, according to the user's settings or in response to the start of automatic setting after detecting the connection status.

[0058] In one embodiment of the present invention, three distinct states (bar, partial coupling, and cross states, see Figures 8A to 8C) relating to optical power transmission crossing between the first optical waveguide W1 and the second optical waveguide W2 are set according to the voltage set by the coupler switch CS. i) By setting a zero voltage from the coupler switch CS, optical power transmission in a drop or cross state corresponding to the total crossing of optical power is realized between the first optical waveguide W1 and the second optical waveguide W2 from the input port INP to the output port OUTP (there is no phase difference or phase mismatch between the first optical waveguide W1 and the second optical waveguide W2), ii) By setting the maximum voltage from the coupler switch CS, through or bar state optical power transmission is achieved between the first optical waveguide W1 and the second optical waveguide W2 from the input port INP to the output port OUTP, with virtually no crossing of optical power (a phase difference or phase mismatch that can block all of the optical power crossing between the first optical waveguide W1 and the second optical waveguide W2). iii) By setting a voltage between zero voltage and maximum voltage from the coupler switch CS, optical power transmission in a splitting, dividing, or partial coupling state corresponding to partial retention and partial crossing of optical power is realized between the first optical waveguide W1 and the second optical waveguide W2 from the input port INP to the output port OUTP (a phase difference or phase mismatch that can block a portion of the optical power crossing between the first optical waveguide W1 and the second optical waveguide W2).

[0059] For example, in one embodiment of the present invention, according to the first coupler control bit b1 and the second coupler control bit b2 received by the coupler switch CS, or according to the first coupler control bit b1 and the second coupler control bit b2 output from the control unit toward the coupler switch CS, i) In bit 0 of the first coupler control bit b1 and the second coupler control bit b2, while achieving phase matching between the first optical waveguide W1 and the second optical waveguide W2 from the input port INP to the output port OUTP, optical power transmission is realized in a drop or cross state corresponding to the total cross of optical power (there is no phase difference or phase mismatch between the first optical waveguide W1 and the second optical waveguide W2), ii) In bit 1 of the first coupler control bit b1 and bit 0 of the second coupler control bit b2, a phase mismatch is created between the first optical waveguide W1 and the second optical waveguide W2, which are moving from the input port INP to the output port OUTP, thereby realizing optical power transmission in a splitting, dividing, or partial coupling state corresponding to partial retention and partial crossing of optical power (a phase difference or phase mismatch that can block a portion of the optical power crossing between the first optical waveguide W1 and the second optical waveguide W2), In bit 1 of the first coupler control bit b1 and the second coupler control bit b2, it is possible to achieve through or bar state optical power transmission where there is substantially no crossing of optical power between the first optical waveguide W1 and the second optical waveguide W2, while creating a phase mismatch that blocks the transmission of all optical power between the first optical waveguide W1 and the second optical waveguide W2 from the input port INP to the output port OUTP (a phase difference or phase mismatch that can block all of the crossing optical power between the first optical waveguide W1 and the second optical waveguide W2).

[0060] Referring to Figures 4 to 7, in the second embodiment of the present invention, the plurality of input ports INP and the plurality of output ports OUTP are formed on the first and second sides S1 and S2 that intersect and touch each other at one corner of the base substrate S on which the optical waveguide network WN is formed, and the plurality of input ports INP and the plurality of output ports OUTP are arranged along the intersecting first and second sides S1 and S2 of the base substrate S. Furthermore, with respect to a first optical waveguide W1 and a second optical waveguide W2, whose intersecting optical power transmission is changed via a coupler switch CS to achieve mapping between a plurality of input ports INP and a plurality of output ports OUTP while forming the optical waveguide network WN, a coupler switch CS including a movable coupler MOC that performs forward / backward movement in an approaching / backward direction along a direction approaching toward the intersection of the first optical waveguide W1 and the second optical waveguide W2 or a direction receding away from the intersection of the first optical waveguide W1 and the second optical waveguide W2 may be formed adjacent to the intersection of the first optical waveguide W1 connected to the input port INP and the second optical waveguide W2 connected to the output port OUTP, in order to control the intersecting optical power transmission or optical coupling efficiency between the first optical waveguide W1 connected to the input port INP and the second optical waveguide W2 connected to the output port OUTP.

[0061] In one embodiment of the present invention, the movable coupler MOC sets three different states relating to optical power transmission crossing between the first optical waveguide W1 and the second optical waveguide W2, at first to third positions P1, P2, and P3, which are at different distances from the intersection between the first optical waveguide W1 connected to the input port INP and the second optical waveguide W2 connected to the output port OUTP, depending on the distance from the intersection between the first optical waveguide W1 and the second optical waveguide W2. These states include a first position P1, which is the furthest from the intersection of the first optical waveguide W1 and the second optical waveguide W2; a third position P3, which is the closest to the intersection of the first optical waveguide W1 and the second optical waveguide W2; and a second position P2, which is between the first position P1 and the third position P3 from the intersection of the first optical waveguide W1 and the second optical waveguide W2.

[0062] More specifically, the movable coupler MOC is, i) At the first position P1 furthest from the intersection of the first optical waveguide W1 and the second optical waveguide W2, through or bar state optical power transmission is achieved between the first waveguide W1 connected to the input port INP and the second waveguide W2 connected to the output port OUTP, with substantially no crossing of optical power. ii) At the third position P3 closest to the intersection of the first optical waveguide W1 and the second optical waveguide W2, optical power transmission in a drop or cross state corresponding to the total cross of optical power is realized between the first waveguide W1 connected to the input port INP and the second waveguide W2 connected to the output port OUTP. iii) At the second position P2 between the first position P1, which is furthest from the intersection of the first optical waveguide W1 and the second optical waveguide W2, and the third position P3, which is closest, optical power transmission is realized in a splitting, dividing, or partial coupling state, corresponding to partial retention and partial crossing of optical power.

[0063] In one embodiment of the present invention, the movable coupler MOC can be positioned at three different levels depending on its distance from the intersection of the first optical waveguide W1 and the second optical waveguide W2, from the first position P1 furthest from the intersection of the first optical waveguide W1 and the second optical waveguide W2 to the third position P3 closest to the intersection, so that the coupler switch CS can receive a control signal including a first coupler control bit b1 and a second coupler control bit b2 for applying three different levels of control signals or control voltages. For example, in one embodiment of the present invention, a control unit (not shown) may be provided that outputs a control signal including a first coupler control bit b1 and a second coupler control bit b2 to the coupler switch CS in order to realize a mapping set between a plurality of input ports INP and a plurality of output ports OUTP, and the control unit (not shown) generates and outputs a control signal to each coupler switch CS that realizes a mapping for setting the connection between each input port INP and output port OUTP, according to the user setting or according to the start of automatic setting when the connection state is detected.

[0064] In one embodiment of the present invention, three distinct states (bar, partial coupling, cross state) relating to optical power transmission crossing between the first optical waveguide W1 and the second optical waveguide W2 are set according to the first to third positions P1, P2, P3 set by the coupler switch CS. For example, the first to third positions P1, P2, P3 of the movable coupler MOC set by the coupler switch CS are set as follows, according to a control signal including a first coupler control bit b1 and a second coupler control bit b2 received by the coupler switch CS, or according to a control signal including a first coupler control bit b1 and a second coupler control bit b2 output from a control unit (not shown) to the coupler switch CS. i) In bit 0 of the first coupler control bit b1 and the second coupler control bit b2, the movable coupler MOC is set to the first position P1 furthest from the intersection of the first optical waveguide W1 and the second optical waveguide W2, ii) In bit 1 of the first coupler control bit b1 and bit 0 of the second coupler control bit b2, the movable coupler MOC is set to a second position P2 from the intersection of the first optical waveguide W1 and the second optical waveguide W2. iii) In bit 1 of the first coupler control bit b1 and the second coupler control bit b2, the movable coupler MOC is set to the third position P3 closest to the intersection of the first optical waveguide W1 and the second optical waveguide W2.

[0065] In one embodiment of the present invention, the movable coupler MOC includes a first coupling rib M1 extending parallel to the first optical waveguide W1 to form an evanescent coupling with the first optical waveguide W1 connected to the input port INP, and a second coupling rib M2 extending parallel to the second optical waveguide W2 to form an evanescent coupling with the second optical waveguide W2. For example, as the movable coupler MOC approaches the intersection where the first optical waveguide W1 connected to the input port INP and the second optical waveguide W2 connected to the output port OUTP intersect each other (for example, as it approaches from a first position P1 in a bar state to a second position P2 in a partially coupled state or a third position P3 in a cross state), it induces evanescent coupling between the first optical waveguide W1 and the first coupling rib M1, which extend parallel to each other. More specifically, based on the electric field (evanescent field) leaking to the first coupling rib M1 of the movable coupler MOC, which has an amplitude or intensity that decreases exponentially with respect to the distance from the surface of the first optical waveguide W1, a crossing optical power transmission or flow is formed to the first coupling rib M1 of the movable coupler MOC. Similarly, as the movable coupler MOC approaches the intersection where the first optical waveguide W1 connected to the input port INP and the second optical waveguide W2 connected to the output port OUTP intersect (for example, as it approaches from a first position P1 in a bar state to a second position P2 in a partially coupled state or a third position P3 in a cross state), it induces evanescent coupling between the second optical waveguide W2 and the second coupling rib M2, which extend parallel to each other. More specifically, based on an electric field (evanescent field) leaking into the second optical waveguide W2 with an amplitude or intensity that decreases exponentially with respect to the distance from the surface of the second coupling rib M2, a crossing optical power transmission or flow to the second optical waveguide W2 is formed. For example, in one embodiment of the present invention, the movable coupler MOC forms an evanescent coupling with the first optical waveguide W1 connected to an input port INP into which an optical signal is input, and a portion or all of the optical power of the optical signal in the first optical waveguide W1 is transmitted from the first optical waveguide W1 to the first coupling rib M1 of the movable coupler MOC.Furthermore, the movable coupler MOC forms an evanescent coupling with the second optical waveguide W2 connected to the output port OUTP to which the optical signal is output, and part or all of the optical power of the optical signal propagating along the second coupling rib M2 can be transmitted from the second coupling rib M2 to the second optical waveguide W2 connected to the output port OUTP. Thus, in one embodiment of the present invention, the optical power transmission between the first optical waveguide W1 and the second optical waveguide W2 includes the transmission of optical power from the first optical waveguide W1 connected to the input port INP to which the optical signal is input, to the first coupling rib M1 of the movable coupler MOC by evanescent coupling, and the transmission of optical power from the second coupling rib M2 of the movable coupler MOC to the second optical waveguide W2 by evanescent coupling.

[0066] In one embodiment of the present invention, the electric field (evanescent field) leaking between the first optical waveguide W1 and the movable coupler MOC, which form an evanescent coupling, decreases from the first optical waveguide W1 toward the movable coupler MOC (for example, the first coupling rib M1 of the movable coupler MOC), and has an amplitude or intensity that decreases exponentially, for example. Similarly, the electric field (evanescent field) leaking between the second optical waveguide W2 and the movable coupler MOC decreases from the movable coupler MOC toward the second optical waveguide W2, and has an amplitude or intensity that decreases exponentially, for example. Thus, in one embodiment of the present invention, there are three distinct states (bar, partial coupling, cross) between the first optical waveguide W1 connected to the input port INP and the second optical waveguide W2 connected to the output port OUTP. In realizing optical power transmission by state, the reciprocating movement of the movable coupler MOC, which forms an evanescent coupling between the first optical waveguide W1 connected to the input port INP and the second optical waveguide W2 connected to the output port OUTP, allows the position of the movable coupler MOC to be set to different first positions P1 to third positions P3 depending on the distance from the intersection of the first optical waveguide W1 and the second optical waveguide W2. As a result, the intensity of the electric field leaking between the first optical waveguide W1 and the second optical waveguide W2 and the movable coupler MOC decreases according to the distance to the first optical waveguide W1 and the second optical waveguide W2. For example, depending on the exponentially decreasing intensity of the leaking electric field, the optical power transmission (optical power transmission efficiency between the first optical waveguide W1 and the second optical waveguide W2 and the movable coupler MOC) can be set with a difference.

[0067] Figures 15 and 16 illustrate the four main channels (Channel 0, 1, 2, Clock Channel, Lane 0, 1, 2, 3) with high transmission speeds and the two auxiliary channels (SDA, SCL, AUX Channel) with low transmission speeds that are set up between the display source and the display sink in HDMI transmission and DisplayPort transmission, respectively.

[0068] In the present invention, an embodiment of the present invention, including a first type embodiment (see Figure 1) and a second type embodiment (see Figure 4), is provided, which includes an optical waveguide network WN connecting a plurality of input ports INP and a plurality of output ports OUTP, and a coupler switch CS for realizing optical power transmission in three different states (bar, partial coupling, cross state) between adjacent first optical waveguides W1 and second optical waveguides W2 that form the optical waveguide network WN to realize a mapping set between the plurality of input ports INP and the plurality of output ports OUTP. This allows image signals and auxiliary signals transmitted through the plurality of input ports INP to be output to display sources connected to the plurality of output ports OUTP, and a sequence of image frames relating to the image signal can be reproduced through the display sources. For example, in the present invention, at least one or more display sources are connected to the input ports INP, and at least one or more display sinks are connected to the output ports OUTP. In this specification, the connection of at least one or more display sources to the input port INP means that the display sources are connected to the transmitting end of the optical fiber F that is connected to the input port INP and forms a grating coupling with the input port INP, for example, and does not exclusively mean that the display sources are directly connected to the input port INP. Similarly, the connection of at least one or more display sinks to the output port OUTP does not exclusively mean that the display sinks are directly connected to the output port OUTP, but rather comprehensively means that the display sinks are connected to the output port OUTP via a transmission line such as an optical fiber F or a conductive line connected to the output port OUTP.Furthermore, throughout this specification, the connection of a display source to an input port INP or a display sink to an output port OUTP may comprehensively mean that at least one or more display sources are connected to at least one or more input ports INP, or at least one or more display sinks are connected to at least one or more output ports OUTP.

[0069] In one embodiment of the present invention, a one-to-one or one-to-many connection relationship is formed between a display source that generates and transmits an image signal and a display sink that receives the image signal from the display source and reproduces a sequence of image frames relating to the received image signal. For example, even when a one-to-one connection relationship is formed between the display source and the display sink, multiple communication channels may be formed between these display sources and the display sink to transmit different data. For example, in one embodiment of the present invention, the communication channel formed between the display source and the display sink includes a main channel (or main link) transmitted at a relatively high transmission rate for transmitting the image signal, and an auxiliary channel transmitted at a relatively low transmission rate for transmitting auxiliary signals to set the main channel (or main link) between the display source and the display sink. For example, referring to Figure 15, in HDMI transmission, the main channel includes three channels (Channel 0, 1, 2) for transmitting image data such as R, G, B or Y, Cb, Cr, and one main channel (Clock Channel) for the pixel clock, for a total of four main channels. Furthermore, the auxiliary channels include a clock line SCL and a data line SDA for synchronization between the display source and the display sink, and include a total of two auxiliary channels. For example, referring to Figure 16, in display port transmission, the main channels include four main channels (Lane 0, 1, 2, 3) for transmitting image signals, an auxiliary channel from the display source to the display sink and an auxiliary channel from the display sink to the display source, and two auxiliary channels (AUX channels) for supporting bidirectional communication. Thus, in one embodiment of the present invention, a total of six communication channels can be set between the display source and the display sink for different data communications (four main channels for transmitting image signals and two auxiliary channels for transmitting auxiliary signals).These six distinct communication channels are transmitted not through six optical waveguides W, but through a smaller number of optical waveguides W, for example, two optical waveguides W, via wavelength division multiplexing. That is, in one embodiment of the present invention, each optical waveguide W forming the optical waveguide network WN connecting the input port INP and the output port OUTP can provide multiple communication channels.

[0070] Figure 17 illustrates that, in one embodiment of the present invention, optical signals of different wavelength bands are assigned to five channels allocated to an optical waveguide W.

[0071] Figure 18 illustrates an embodiment of the present invention in which, as three channels assigned to the optical waveguide W, two channels with high transmission speeds and one channel with a low transmission speed, optical signals of different wavelength bands are assigned according to their respective transmission speeds.

[0072] In one embodiment of the present invention, an optical waveguide W forming an optical waveguide network WN connecting an input port INP and an output port OUTP may have an optical gain or optical loss profile having a full-width at half maximum (FWHM) attenuated to half the peak value of the central wavelength band λ0 (-3dB) toward both sides from a central wavelength band λ0 that forms a single peak, depending on the specific structure and scale of the optical waveguide W. Furthermore, the optical waveguide W may simultaneously transmit optical signals from different wavelength bands that are spaced apart from each other via a wavelength separation band B that considers the resolution for separating different wavelength bands that form different communication channels, so as to prevent crosstalk between different communication channels within the wavelength range that forms the full-width at half maximum (FWHM). In this specification, the central wavelength band λ0 means the wavelength band that forms a single peak in the optical gain or optical loss profile, depending on the specific structure and scale of the optical waveguide W. In one embodiment of the present invention, the attenuation of an optical signal transmitted through an optical waveguide W can be suppressed by assigning the wavelength band of the optical signal transmitted through the optical waveguide W to a wavelength range that forms a full width at half maximum (FWHM) attenuated to half the peak value of the central wavelength band λ0 (-3dB) toward both sides from the central wavelength band λ0 which forms a single peak, thereby suppressing attenuation of the optical signal (suppressing the amplitude or intensity of the optical signal from being attenuated to less than half the peak value of the central wavelength band λ0).

[0073] In one embodiment of the present invention, communication channels in different wavelength bands transmitted through the same optical waveguide W by wavelength division multiplexing can be separated into different communication channels by applying a wavelength selective filter. In this case, in order to prevent crosstalk between different communication channels, the resolution for separating the different wavelength bands that form the different communication channels may correspond to the resolution of the wavelength selective filter for separating optical signals in different wavelength bands transmitted from the same optical waveguide W, or the resolution of the wavelength selective filter plus a margin tolerance. For example, in one embodiment of the present invention, the wavelength selective filter for separating optical signals in different wavelength bands that form different communication channels has a resolution of 5 nm. Also, in one embodiment of the present invention, different communication channels transmitted through the same optical waveguide W may be formed as optical signals in different wavelength bands that are separated from each other by a 10 nm wavelength separation band B, which is obtained by adding a margin tolerance to the resolution of the wavelength selective filter (e.g., 5 nm) within the wavelength range of the full width at half maximum (FWHM) of the optical gain or optical loss of the optical waveguide W. For example, in one embodiment of the present invention, different communication channels transmitted over the same optical waveguide W are formed as five different optical signals in different wavelength bands spaced apart from each other by a 10 nm wavelength separation band B, within a wavelength range of 50 nm corresponding to the full width at half maximum (FWHM) of the optical gain or loss of the optical waveguide W (see Figure 17). For example, by assigning a communication channel in the central wavelength band λ0, two communication channels on one side of the central wavelength band λ0 with a 10 nm wavelength separation band B in between, and two communication channels on the other side of the central wavelength band λ0 with a 10 nm wavelength separation band B in between, a total of five communication channels or optical signals in five different wavelength bands can be transmitted over the same optical waveguide W (see Figure 17).

[0074] In one embodiment of the present invention, different optical signals (different communication channels) transmitted together over the same optical waveguide W may include optical signals having different transmission speeds. For example, in one embodiment of the present invention, a main channel (image signal) transmitted at a relatively high transmission speed and an auxiliary channel (auxiliary signal) transmitted at a relatively low transmission speed are combined and transmitted over the same optical waveguide W. In one embodiment of the present invention, the main channel (image signal) transmitted at a relatively high transmission speed is relatively vulnerable to sensitivity problems compared to the auxiliary channel (auxiliary signal) transmitted at a relatively low transmission speed. These problems include signal peak attenuation due to distortion of the transmission signal, inter-symbol interference (ISI), delay dispersion, and impedance mismatch, as well as a widening of the signal width, making detection difficult at the receiving end. Therefore, the main channel (image signal) transmitted at a relatively high transmission speed can be formed as an optical signal in a wavelength band close to the central wavelength band λ0, which has relatively low signal attenuation, within the full width at half maximum (FWHM) of the optical waveguide W (a wavelength band relatively close to the central wavelength band λ0 and with a low attenuation rate is assigned to the main channel having a high transmission speed). On the other hand, the auxiliary channel (auxiliary signal) transmitted at a relatively low transmission speed can be formed as an optical signal in a wavelength band that is relatively far away from the central wavelength band λ0, where signal attenuation is relatively large (a wavelength band that is relatively far away from the central wavelength band λ0 and has a high attenuation rate is assigned to the auxiliary channel having a low transmission speed).

[0075] In one embodiment of the present invention, six communication channels (four main channels (image signals) with high transmission speeds and two auxiliary channels (auxiliary signals) with low transmission speeds) set up between a display source and a display sink can be transmitted through at least two optical waveguides W in order to assign optical signals of different wavelength bands separated from each other by a wavelength separation band B, within the wavelength range of the full width at half maximum (FWHM) relating to the optical gain or optical loss of the optical waveguide W. For example, if all six different communication channels are transmitted through one optical waveguide W, crosstalk may occur between these different communication channels. Thus, in one embodiment of the present invention, the six communication channels set up between a display source and a display sink are distributed and transmitted through two different optical waveguides W, and by combining communication channels having different transmission speeds, it is possible to avoid problems in high-speed transmission (problems in high-speed serial links), such as signal peaks being attenuated and signal widths being widened, making detection (recognition) difficult at the receiving end. For example, the six communication channels set up between the display source and the display sink (four main channels with high transmission speeds and two auxiliary channels with low transmission speeds) are each equally divided into two communication channels, each containing two main channels (image signals) transmitted at high transmission speeds and one auxiliary channel (auxiliary signal) transmitted at low transmission speeds, and the three divided communication channels are each assigned to different optical waveguides W. In this way, a total of six communication channels can be set up between the display source and the display sink via two different optical waveguides W to which each of the three communication channels is assigned. Referring to Figure 18, in one embodiment of the present invention, the three communication channels assigned to each optical waveguide W may be within the wavelength range of the full width at half maximum (FWHM) of the optical gain or loss of the optical waveguide W (suppressing attenuation to less than half of the peak value of the central wavelength band λ0 that forms a single peak in the optical gain or loss profile, for example, to -3 dB), and may be formed as different wavelength bands separated from each other by a sufficient wavelength separation band B.For example, the first and second high-speed channels, which are transmitted at high transmission speeds, are assigned to wavelength bands close to the central wavelength band λ0, where attenuation is relatively small, while the low-speed channels, which are transmitted at relatively low transmission speeds, are assigned to wavelength bands far from the central wavelength band λ0, where attenuation is relatively large. Thus, in one embodiment of the present invention, by assigning the first and second high-speed channels, which are transmitted at high transmission speeds, to wavelength bands close to the central wavelength band λ0, the problem of difficulty in detecting or recognizing signals in high-speed channels (high-speed serial links) is avoided (the problem of difficulty in detecting or recognizing signals caused by signal attenuation and dispersion in high-speed channels is resolved), while attenuation is reduced for low-speed channels, which are assigned to wavelength bands far from the central wavelength band λ0 and where relatively large attenuation is expected, for example, a wavelength separation band B sufficient to suppress crosstalk with the first and second high-speed channels is interposed, while still being assigned to wavelength bands as close as possible to the central wavelength band λ0. In order to assign wavelength bands, wavelength bands are assigned to the first and second high-speed channels at asymmetrical positions on both the left and right halves of the region with respect to the central wavelength band λ0, and to the low-speed channels, wavelength bands are assigned to the right half of the region to which the second high-speed channel is assigned, which is relatively biased toward the central wavelength band λ0. For example, this allows for the assignment of wavelength bands close to the central wavelength band λ0 to the second high-speed channel while interposing a sufficient wavelength separation band B to suppress crosstalk with the second high-speed channel. As a result, the low-speed channels assigned from the second high-speed channel via the wavelength separation band B are also assigned wavelength bands relatively close to the central wavelength band λ0. In various embodiments of the present invention, for the first and second high-speed channels, wavelength bands biased toward the central wavelength band λ0 can be assigned to either the left half or the right half of the region with respect to the central wavelength band λ0 (for example, the right half), and wavelength bands biased toward the opposite side of the central wavelength band λ0 can be assigned to the other region (the left half).Furthermore, in the left and right halves of the region to which different wavelength bands are assigned for the first and second high-speed channels, the wavelength band of the low-speed channel can be assigned to the region (right half) to which wavelength bands that are relatively biased toward the central wavelength band λ0 are assigned.

[0076] Thus, in one embodiment of the present invention, the six communication channels set between the display source and the display sink are equally allocated to two different optical waveguides W, and each optical waveguide W may be allocated three communication channels. More specifically, for the two main channels (image signals) with high transmission speeds allocated to each optical waveguide W, two wavelength bands that are relatively close to the central wavelength band λ0, which forms a single peak in the optical gain or optical loss profile, and have low attenuation may be allocated. For the one auxiliary channel (auxiliary signal) with low transmission speed allocated to each optical waveguide W, one wavelength band that is relatively far from the central wavelength band λ0 and has high attenuation may be allocated. Furthermore, wavelength bands in either the left half-region or the right half-region to which wavelength bands relatively close to the central wavelength band λ0 are allocated may be allocated.

[0077] Figure 13 is a diagram illustrating a structure in the first type of the present invention in which a pair of 1-1 optical waveguides W1-1 and 1-2 optical waveguides W1-2 forming a first optical waveguide W1 connected to the same display source, and a pair of 2-1 optical waveguides W2-1 and 2-2 optical waveguides W2-2 forming a second optical waveguide W2 connected to the same display sink, are configured as a stack with each other arranged vertically. The diagram illustrates a coupler switch CS that is configured or interlocked to set the same state (bar, partial coupling, cross state) for optical power transmission that crosses between the 1-1 optical waveguide W1-1 and the 2-1 optical waveguide W2-1, and between the 1-2 optical waveguide W1-2 and the 2-2 optical waveguide W2-2.

[0078] Figure 14 is a diagram illustrating a structure in the second type of the present invention in which a pair of 1-1 optical waveguides W1-1 and 1-2 optical waveguides W1-2 forming a first optical waveguide W1 connected to the same display source, and a pair of 2-1 optical waveguides W2-1 and 2-2 optical waveguides W2-2 forming a second optical waveguide W2 connected to the same display sink, are configured as an interleave type with the two optical waveguides arranged horizontally to each other. The diagram illustrates coupler switches CSa, CSb, and CSc that are configured or interlocked together to set the same state (bar, partial coupling, cross state) regarding optical power transmission that crosses between the 1-1 optical waveguide W1-1 and the 2-1 optical waveguide W2-1, and between the 1-2 optical waveguide W1-2 and the 2-2 optical waveguide W2-2.

[0079] In one embodiment of the present invention, including the first type of embodiment (see Figure 13) and the second type of embodiment (see Figure 14), an optical waveguide network WN connecting a plurality of input ports INP and a plurality of output ports OUTP can set up connection states such as one-to-many or many-to-many between a plurality of display sources and a plurality of display sinks. For example, if only a one-to-one connection between the same display source and the same display sink is considered separately, the six communication channels set up between the same display source and the same display sink can be formed by two distinct optical waveguides W. For example, the six communication channels set up between the same display source and the same display sink are set up via two distinct optical waveguides W connecting two input ports INP connected to the same display source and two output ports OUTP connected to the same display sink.

[0080] In one embodiment of the present invention, in order to realize a mapping set up between a plurality of input ports INP and a plurality of output ports OUTP, optical power transmission is realized from a coupler switch CS in three different states (bar, partial coupling, cross state) in a first optical waveguide W1 and a second optical waveguide W2, the first optical waveguide W1 may include a pair of 1-1 optical waveguide W1-1 and 1-2 optical waveguide W1-2, and the second optical waveguide W2 may include a pair of 2-1 optical waveguide W2-1 and 2-2 optical waveguide W2-2. For example, the pair of 1-1 optical waveguide W1-1 and 1-2 optical waveguide W1-2 forming the first optical waveguide W1 forms six communication channels set up between the same display source and the same display sink. Similarly, the pair of the second-first optical waveguide W2-1 and the second-second optical waveguide W2-2 that form the second optical waveguide W2 form six communication channels set between the same display source and the same display sink. Furthermore, in one embodiment of the present invention, the flow of optical power intersecting between the first-first optical waveguide W1-1 and the second-first optical waveguide W2-1, and the flow of optical power intersecting between the first-second optical waveguide W1-2 and the second-second optical waveguide W2-2, can be controlled together by the same coupler switch CS. For example, the connection state between the first-first optical waveguide W1-1 and the second-first optical waveguide W2-1, and the connection state between the first-second optical waveguide W1-2 and the second-second optical waveguide W2-2, can be set identically from the same coupler switch CS. For example, in one embodiment of the present invention, when the same display source to which a pair of 1-1 optical waveguide W1-1 and 1-2 optical waveguide W1-2 forming the first optical waveguide W1 are connected, and the same display sink to which a pair of 2-1 optical waveguide W2-1 and 2-2 optical waveguide W2-2 forming the second optical waveguide W2 are connected, are mapped to be connected to each other, the connection between 1-1 optical waveguide W1-1 and 2-1 optical waveguide W2-1 and the connection between 1-2 optical waveguide W1-2 and 2-2 optical waveguide W2-2 can be made from the same coupler switch CS in the same state, such as partial coupling state or cross state, rather than bar state.On the other hand, if the same display source to which the pair of 1-1 optical waveguide W1-1 and 1-2 optical waveguide W1-2 forming the first optical waveguide W1 are connected, and the same display sink to which the pair of 2-1 optical waveguide W2-1 and 2-2 optical waveguide W2-2 forming the second optical waveguide W2 are connected are mapped as non-connected to each other, then the connections between 1-1 optical waveguide W1-1 and 2-1 optical waveguide W2-1, and between 1-2 optical waveguide W1-2 and 2-2 optical waveguide W2-2, can be configured so that they are not connected from the same coupler switch CS in the same state, which is a bar state, rather than a partial coupling state or a cross state. For example, referring to Figure 14, a coupler switch CSa can be provided that is configured or interlocked with the pair of optical waveguides W1-1 and W2-2 of the first optical waveguide W1 connected to the same display source, and the pair of optical waveguides W2-1 and W2-2 of the second optical waveguide connected to the same display sink, so that the same state (bar, partial coupling, cross state) is set in the optical power transmission that crosses between the first optical waveguide W1-1 and W2-1 and between the first optical waveguide W1-2 and W2-2. The remaining coupler switches CSb and CSc can also be configured or interlocked with the pair of optical waveguides W2-1 and W2-2 of the second optical waveguide connected to the same display sink, so that the same state is set in the optical power transmission between adjacent pairs of optical waveguides of different phases.

[0081] Thus, in one embodiment of the present invention, setting the optical power transmission or optical coupling efficiency for the first optical waveguide W1 and the second optical waveguide W2 from the coupler switch CS as one of three distinct states (bar, partial coupling, cross state) means that the optical power transmission and optical coupling efficiency are set from the same coupler switch CS as one of the same state among the three distinct states (bar, partial coupling, cross state) between the 1-1 optical waveguide W1-1 forming the first optical waveguide W1 and the 2-1 optical waveguide W2-1 forming the second optical waveguide W2, and between the 1-2 optical waveguide W1-2 forming the first optical waveguide W1 and the 2-2 optical waveguide W2-2 forming the second optical waveguide W2.

[0082] In this case, the pair of optical waveguides W1-1 and W1-2, which form the first optical waveguide W1 connected to the same display source, can be formed in close proximity to each other. For example, in one embodiment of the present invention, the pair of optical waveguides W1-1 and W1-2, which are connected to the same display source, can be formed vertically stacked (see Figure 13) or horizontally interleaved (see Figure 14), and can be formed in close proximity to each other.

[0083] In a first type of embodiment of the present invention (see Figure 13), a pair of first-1 optical waveguides W1-1 and first-2 optical waveguides W1-2 connected to the same display source are formed as a stack perpendicular to each other, and a pair of second-1 optical waveguides W2-1 and second-2 optical waveguides W2-2 connected to the same display sink may be formed as a stack perpendicular to each other. In this manner, pairs of the first-first optical waveguide W1-1 and the first-second optical waveguide W1-2 are formed in close proximity to each other, and pairs of the second-first optical waveguide W2-1 and the second-second optical waveguide W2-2 are formed in close proximity to each other. Furthermore, optical power transmission between the first-first optical waveguide W1-1 forming the first optical waveguide W1 and the second-first optical waveguide W2-1 forming the second optical waveguide W2, and between the first-second optical waveguide W1-2 forming the first optical waveguide W1 and the second-second optical waveguide W2-2 forming the second optical waveguide W2, can be set from the same coupler switch CS to the same state (one of the states of bar, partial coupling, or cross state). However, as mentioned above, in the first type of embodiment (see Figure 13), the pair of 1-1 optical waveguides W1-1 and 1-2 optical waveguides W1-2 connected to the same display source, and the pair of 2-1 optical waveguides W2-1 and 2-2 optical waveguides W2-2 connected to the same display sink, may be formed as a stack perpendicular to each other, or as an interleave horizontally to each other.

[0084] In a second type of embodiment of the present invention (see Figure 14), a pair of first-1 optical waveguides W1-1 and first-2 optical waveguides W1-2 connected to the same display source are formed horizontally interleaved with respect to each other, and a pair of second-1 optical waveguides W2-1 and second-2 optical waveguides W2-2 connected to the same display sink may be formed horizontally interleaved with respect to each other. In this manner, pairs of the first-first optical waveguide W1-1 and the first-second optical waveguide W1-2 are formed in close proximity to each other, and pairs of the second-first optical waveguide W2-1 and the second-second optical waveguide W2-2 are formed in close proximity to each other. Furthermore, optical power transmission between the first-first optical waveguide W1-1 forming the first optical waveguide W1 and the second-first optical waveguide W2-1 forming the second optical waveguide W2, and between the first-second optical waveguide W1-2 forming the first optical waveguide W1 and the second-second optical waveguide W2-2 forming the second optical waveguide W2, can be set from the same coupler switch CS to the same state (one of the states of bar, partial coupling, or cross state). However, as mentioned above, in the second type of embodiment (see Figure 14), the pair of 1-1 optical waveguides W1-1 and 1-2 optical waveguides W1-2 connected to the same display source, and the pair of 2-1 optical waveguides W2-1 and 2-2 optical waveguides W2-2 connected to the same display sink, may be formed as a stack perpendicular to each other, or as an interleave horizontally to each other.

[0085] In one embodiment of the present invention, a pair of first-first optical waveguides W1-1 and first-second optical waveguides W1-2 connected to the same display source is equally allocated six communication channels with the same display source at one end, and a total of three communication channels, including two main channels (image signals) with high transmission speeds and one auxiliary channel (auxiliary signal) with low transmission speeds, can be assigned to each pair of first-first optical waveguides W1-1 and first-second optical waveguides W1-2. Similarly, a pair of second-first optical waveguides W2-1 and second-second optical waveguides W2-2 connected to the same display sink is equally allocated six communication channels with the same display sink at one end, and a total of three communication channels, including two main channels (image signals) with high transmission speeds and one auxiliary channel (auxiliary signal) with low transmission speeds, can be assigned to each pair of second-first optical waveguides W2-1 and second-second optical waveguides W2-2.

[0086] In one embodiment of the present invention, the fact that the connection between the first-first optical waveguide W1-1 forming the first optical waveguide W1 and the second-first optical waveguide W2-1 forming the second optical waveguide W2, and the connection between the first-second optical waveguide W1-2 forming the first optical waveguide W1 and the second-second optical waveguide W2-2 forming the second optical waveguide W2, are set to the same state (bar, partial coupling, cross state) from the same coupler switch CS, may include, for example, the connection between the first-first optical waveguide W1-1 and the first-second optical waveguide W1-2, and the connection between the second-first optical waveguide W2-1 and the second-second optical waveguide W2-2, being set to the same state from a single coupler switch CS formed as a physically identical entity. Furthermore, even if the first-first optical waveguide W1-1 and the first-second optical waveguide W1-2, and the second-first optical waveguide W2-1 and the second-second optical waveguide W2-2 are set to the same state by coupler switches CS formed as physically separated and distinct entities, it may be included that these coupler switches CS formed as distinct entities are electrically connected to each other so that the same control signal (a control signal including a first coupler control bit b1 and a second coupler control bit b2) is received by these physically separated and distinct entities.

[0087] In one embodiment of the present invention, an optical waveguide network WN connecting a plurality of input ports INP and a plurality of output ports OUTP forms four main channels for image signals and two auxiliary channels for auxiliary signals to mediate the transmission of image signals and auxiliary signals between a display source connected to the input ports INP and a display sink connected to the output ports OUTP. As mentioned above, a total of six channels may be formed via two optical waveguides W, each allocated with two main channels and one auxiliary channel. Furthermore, as shown in Figure 18, different wavelength bands may be assigned to the main channels with high transmission speeds and the auxiliary channels with low transmission speeds, respectively, taking into account signal attenuation.

[0088] In various embodiments of the present invention, the optical waveguide network WN provides six channels for image signals and auxiliary signals, and each optical waveguide W can be assigned a combination of channels with different transmission speeds (a combination of a channel with a relatively high transmission speed and a channel with a relatively low transmission speed), taking into consideration the problem of difficulty in detecting signals due to the effects of signal attenuation, for example, signal attenuation and dispersion in channels with high transmission speeds (high-speed serial links). For example, within the wavelength range of the full width at half maximum (FWHM) in the optical gain or optical loss profile of the optical waveguide W, channels with relatively high transmission speeds can be assigned wavelength bands adjacent to the central wavelength band λ0 that forms a single peak, and channels with relatively low transmission speeds can be assigned wavelength bands relatively far from the central wavelength band λ0 that forms a single peak. This allows multiple communication channels to be transmitted together over a single optical waveguide W while suppressing crosstalk between different wavelength bands through wavelength division multiplexing, while avoiding the problem of difficulty in detecting signals due to signal attenuation in high-speed serial links.

[0089] Figure 19 illustrates an embodiment of the present invention in which, as four channels assigned to the optical waveguide W, two channels with high transmission speeds and two channels with low transmission speeds are assigned optical signals of different wavelength bands according to their respective transmission speeds.

[0090] Figure 20 illustrates an embodiment of the present invention in which, as three channels assigned to the optical waveguide W, one channel with a high transmission speed and two channels with low transmission speeds are assigned optical signals of different wavelength bands according to their respective transmission speeds.

[0091] Figure 21 shows a profile indicating the optical loss or attenuation of optical fiber F (silica-based optical fiber) according to wavelength.

[0092] As shown in Figure 19, in an embodiment in which four different communication channels are formed via a single optical waveguide W, it is possible to combine two channels with relatively high transmission speeds and two channels with low transmission speeds. In this case, for the two channels with high transmission speeds, wavelength bands relatively close to the central wavelength band λ0 may be assigned in the left and right halves of the region centered on the central wavelength band λ0, and wavelength bands at symmetrical positions with respect to the central wavelength band λ0 may be assigned. On the other hand, for the two channels with low transmission speeds, wavelength bands relatively far from the central wavelength band λ0 may be assigned in the left and right halves of the region centered on the central wavelength band λ0, and wavelength bands at symmetrical positions with respect to the central wavelength band λ0 may be assigned.

[0093] As shown in Figure 20, in an embodiment in which three distinct communication channels are formed via a single optical waveguide W, a central wavelength band λ0 forming a single peak can be assigned to one channel having a high transmission speed, and wavelength bands at symmetrical positions in the left and right halves of the region around a single peak can be assigned to two channels having relatively low transmission speeds. For example, in an embodiment in which an odd number of distinct communication channels, such as three or five, are formed via a single optical waveguide W (see Figures 17 and 20), the central wavelength band λ0 with the least signal attenuation is assigned to one channel having a high transmission speed.

[0094] In one embodiment of the present invention, the central wavelength band λ0 that forms a single peak in the optical gain or optical loss profile of the optical waveguide W may be set as a wavelength band that forms a window with relatively small optical loss, by referring to the profile of the optical loss of the optical fiber F connected to the input port INP of the optical waveguide network WN formed by the optical waveguide W (see Figure 21). For example, it may be set as a wavelength band such as 850 nm, 1310 nm, or 1550 nm. In one embodiment of the present invention, the optical loss of the optical fiber F can be suppressed for optical signals of wavelength bands selected from each other via a wavelength separation band B, within a wavelength range of approximately 50 nm that forms the full width at half maximum (FWHM) from the central wavelength band λ0 that is set as a wavelength band that forms a window with relatively small optical loss.

[0095] In one embodiment of the present invention, in the profile of the optical gain or optical loss of an optical waveguide W, assigning wavelength bands separated from each other by a wavelength separation band B within the wavelength range that forms the full width at half maximum (FWHM) to different communication channels may mean assigning different wavelength bands via a minimum wavelength separation band B (e.g., 10 nm) that can suppress crosstalk between communication channels (optical signals) of different wavelength bands. That is, rather than meaning that the wavelength separation band B interposed between the different wavelength bands assigned to each different communication channel is limited to a certain extent, it means assigning different wavelength bands via a minimum wavelength separation band B (e.g., 10 nm) that can suppress crosstalk between them.

[0096] A photonic circuit according to another aspect of the present invention is: Optical fiber F for transmitting optical signals, Forming a connection with the optical fiber F, the network comprises an input port INP forming the transmitting end, an output port OUTP forming the receiving end opposite to the transmitting end, and an optical waveguide network WN connecting the input port INP and the output port OUTP. A coupler switch CS for controlling optical power transmission or optical coupling that crosses between adjacent first optical waveguides W1 and second optical waveguides W2 forming the optical waveguide network WN, comprising an electrical input to control the coupling efficiency between the first optical waveguides W1 and second optical waveguides W2, thereby realizing different optical power transmission states: a through or bar state in which there is substantially no crossing of optical power between the first optical waveguides W1 and second optical waveguides W2; a splitting, dividing or partial coupling state corresponding to partial retention and partial crossing of optical power between the first optical waveguides W1 and second optical waveguides W2; and a drop or cross state corresponding to total crossing of optical power between the first optical waveguides W1 and second optical waveguides W2. The first optical waveguide W1 includes a pair of 1-1 optical waveguide W1-1 and 1-2 optical waveguide W1-2, and the second optical waveguide W2 includes a pair of 2-1 optical waveguide W2-1 and 2-2 optical waveguide W2-2, Of the aforementioned optical waveguides W1-1, W1-2, W2-1, and W2-2, at least one single optical waveguide W has an optical gain or optical loss profile having a full width at half maximum (FWHM) that is attenuated to half the peak value of the central wavelength band toward both sides from a central wavelength band λ0 forming a single peak. The single optical waveguide W transmits optical signals from different wavelength bands that are separated from each other, interposed by a wavelength separation band B, which has a resolution for separating different wavelength bands that form different communication channels, within the wavelength range that forms the full width at half maximum (FWHM) in order to prevent crosstalk between them.

[0097] For example, in one embodiment of the present invention, the optical waveguide network WN can connect a plurality of input ports INP and a plurality of output ports OUTP, in which each optical waveguide W forming the optical waveguide network WN, i.e., the 1-1 optical waveguide W1-1 and 1-2 optical waveguides W1-2 forming the first optical waveguide W1, and the 2-1 optical waveguide W2-1 and 2-2 optical waveguides W2-2 forming the second optical waveguide W2, each optical waveguide W (corresponding to a single optical waveguide in the claims) includes two high-speed channels (image signal transmission) having a high transmission speed and one low-speed channel (auxiliary signal transmission) having a low transmission speed, and each optical waveguide W can form three different communication channels. Referring to Figure 13, the first optical waveguide W1-1 and the first optical waveguide W1-2 forming the first optical waveguide W1 can each transmit two high-speed channels with relatively high transmission speeds and one low-speed channel with relatively low transmission speeds. Thus, the first optical waveguide W1-1 and the first optical waveguide W2-1 together can form a total of six communication channels, including four high-speed channels for image signals and two low-speed channels for auxiliary signals, between the same display source and the same display sink. Furthermore, referring to Figure 13 (Type 1), the 2-1 optical waveguide W2-1 and the 2-2 optical waveguide W2-2 can each transmit two high-speed channels with relatively high transmission speeds and one low-speed channel with relatively low transmission speeds. Thus, the 2-1 optical waveguide W2-1 and the 2-2 optical waveguide W2-2 can together form a total of six communication channels, including four high-speed channels for different image signals and two low-speed channels for different auxiliary signals, between another identical display source and another identical display sink.

[0098] Referring to Figure 14 (Type 2), the 1-1 optical waveguide W1-1 and the 1-2 optical waveguide W2-1 can each transmit two high-speed channels with relatively high transmission speeds and one auxiliary channel with a relatively low transmission speed. Thus, the 1-1 optical waveguide W1-1 and the 1-2 optical waveguide W1-2 can both form a total of six communication channels from the same display source, including four high-speed channels for image signals and two low-speed channels for auxiliary signals. Referring to Figure 14 (Type 2), the 2-1 optical waveguide W2-1 and the 2-2 optical waveguide W2-2 can each transmit two high-speed channels with relatively high transmission speeds and one low-speed channel with relatively low transmission speeds. Thus, the 2-1 optical waveguide W2-1 and the 2-2 optical waveguide W2-2 together can form a total of six communication channels, including four high-speed channels for image signals and two low-speed channels for auxiliary signals, all headed toward the same display sink.

[0099] Referring to Figure 13 (Type 1) and Figure 14 (Type 2), in one embodiment of the present invention, the optical waveguide network is a 2Nx2N optical waveguide network that maps 2N input ports and 2N output ports to each other. The 2N input ports INP are connected in a 2:1 ratio to the display sources such that image signals and auxiliary signals output from N display sources are input to the 2N input ports INP. The 2N output ports OUTP are connected to the N display sinks in a 2:1 ratio so that image signals and auxiliary signals are output to the N display sinks. To achieve different optical power transmissions between adjacent first optical waveguides W1 and second optical waveguides W2, which form an optical waveguide network WN between the input port INP and the output port OUTP, the optical waveguide network WN routes or distributes pairs of image signals and auxiliary signals input via the input port INP, which is connected to the same display source, toward the output port OUTP, which is connected to the same display sink, in response to a control signal applied to the coupler switch CS. For this purpose, the optical power transmissions that intersect between the first-1 optical waveguide W1-1 and the second-1 optical waveguide W2-1, and the optical power transmissions that intersect between the first-2 optical waveguide W1-2 and the second-2 optical waveguide W2-2 can be controlled together by the same coupler switch CS.

[0100] Referring to Figure 13 (Type 1), the optical waveguide network WN is an NxN optical waveguide network WN that maps N input ports INP and N output ports OUTP to each other, and the 1-1 optical waveguide W1-1 and the 2-1 optical waveguide W2-1 are optical waveguides W that extend adjacent to each other between two distinct input ports INP out of the N input ports INP and two distinct output ports OUTP out of the N output ports OUTP. The first-2 optical waveguides W2-1 and the second-2 optical waveguides W2-2 are optical waveguides W that are adjacent to each other and connected between two other distinct input ports INP out of N input ports INP and two other distinct output ports OUTP out of N output ports OUTP. The flow of optical power intersecting between the first-first optical waveguide W1-1 and the second-first optical waveguide W2-1, and the flow of optical power intersecting between the first-second optical waveguide W1-2 and the second-second optical waveguide W2-2, are both controlled by the same coupler switch CS.

[0101] Referring to Figure 13 (Type 1), the pair of 1-1 optical waveguides W1-1 and 1-2 optical waveguides W1-2 connect an input port INP connected to the same display source and an output port OUTP connected to the same display sink. Similarly, the pair of 2-1 optical waveguides W2-1 and 2-2 optical waveguides W2-2 may connect an input port INP connected to a different identical display source and an output port OUTP connected to a different identical display sink. For example, the 1-1 optical waveguides W1-1 and 1-2 optical waveguides W1-2 may transmit an image signal including image data and an auxiliary signal including auxiliary data between the same display source and the same display sink, while the 2-1 optical waveguides W2-1 and 2-2 optical waveguides W2-2 may transmit an image signal including different image data and an auxiliary signal including different auxiliary data between a different identical display source and a different identical display sink.

[0102] Referring to Figure 14 (Type 2), the optical waveguide network WN is an NxN optical waveguide network that maps N input ports INP and N output ports OUTP to each other. The present invention may include N first-first optical waveguides W1-1 and first-second optical waveguides W1-2 (collectively, first optical waveguide W1) connected to the input port INP, and N second-first optical waveguides W2-1 and second-second optical waveguides W2-2 (collectively, second optical waveguide W2) connected to the output port OUTP. That is, in one embodiment of the present invention, the optical waveguide W connected to the input port INP may be defined as the first optical waveguide W1, and the optical waveguide W connected to the output port OUTP may be defined as the second optical waveguide W2. In this case, the flow of optical power intersecting between the first-first optical waveguide W1-1 and the second-first optical waveguide W2-1, and the flow of optical power intersecting between the first-second optical waveguide W1-2 and the second-second optical waveguide W2-2 are both controlled by the same coupler switch CS.

[0103] Referring to Figure 14 (Type 2), the pair of 1-1 optical waveguides W1-1 and 1-2 optical waveguides W1-2, and the pair of 2-1 optical waveguides W2-1 and 2-2 optical waveguides W2-2 can connect an input port INP to which the same display source is connected, and an output port OUTP to which the same display sink is connected. For example, the 1-1 optical waveguides W1-1 and 1-2 optical waveguides W1-2 transmit an image signal containing image data and an auxiliary signal containing auxiliary data from the same display source, while the 2-1 optical waveguides W2-1 and 2-2 optical waveguides W2-2 transmit an image signal containing image data and an auxiliary signal containing auxiliary data directed to the same display sink.

[0104] Figure 22 is a diagram illustrating edge coupling between an optical fiber F through which an optical signal is transmitted and an input port INP (edge ​​coupler), and is a diagram illustrating edge coupling, which is different from the grid coupling or surface coupling shown in Figures 9A and 9B.

[0105] In one embodiment of the present invention, the input port INP may include an edge coupler that forms an in-plane coupling with the optical fiber F. In various embodiments of the present invention, the optical fiber F may be arranged on the base substrate S on which the input port INP is formed, depending on the type of optical coupler depending on the arrangement between the input port INP and the optical fiber F. For example, the optical fiber F may be positioned at a level outside the base substrate S on which the input port INP is formed (out-of-plane coupling, surface coupling, or grating coupling), and depending on the orientation of the optical fiber F with respect to the base substrate S, the optical fiber F may be positioned in a downward orientation toward the base substrate S and form a vertical fiber coupling with the base substrate S on which the input port INP is formed (see Figure 9A), or the optical fiber F may be positioned in a orientation parallel to the base substrate S and form a horizontal fiber coupling with the base substrate S on which the input port INP is formed (see Figure 9B), or the optical fiber F may be positioned facing the facet of the optical waveguide of the base substrate S (butt-coupled) and form an in-plane coupling. The optical signal from the optical fiber F can be guided along the optical waveguide W (Si waveguide) of the base substrate S. For example, as shown in Figure 11, in edge coupling to achieve optical coupling between a core with a diameter of approximately 10.4 μm and an optical waveguide W having a cross-section of 0.45 μm × 0.22 μm, if the optical fiber F and the optical waveguide of the base substrate S are directly butt coupled, an optical coupling loss of about 30 dB may occur. Therefore, in order to improve the optical coupling efficiency between the optical fiber F and the optical waveguide W of the base substrate S, the core of the optical fiber F (the central region of the optical fiber F, which includes the core containing the central axis and the cladding surrounding the core, and has a relatively high refractive index) and the optical waveguide W (Si waveguide) of the base substrate S that forms the optical coupling with the optical fiber F can be optically aligned.Furthermore, a mode-matching structure, such as an inverted taper structure or an optical lens structure, can be introduced between the optical fiber F and the optical waveguide W of the base substrate S to reduce optical mismatch and enable mode matching.

[0106] Figures 23 and 24 illustrate different communication protocol embodiments to which the optical waveguide network WN of the present invention may be applied, illustrating USB communication and Thunderbolt communication, respectively.

[0107] In this specification, one example of a type of signal distribution or mapping performed by an optical waveguide network WN connecting multiple input ports INP and multiple output ports OUTP is described as a one-to-one or one-to-many connection between an HDMI or DisplayPort display source and a display sink. However, the optical waveguide network WN according to one embodiment of the present invention is not limited to the transmission of HDMI or DisplayPort signals including image signals or image signals and auxiliary signals, but can also be applied to a variety of communication protocols such as USB and Thunderbolt. For example, as shown in Figure 23, it is possible to support super(full) speed transmission lanes (super speed TX1+, TX1-, differential pair 1), super(full) speed reception lanes (super speed RX2+, RX2-, differential pair 2), and high speed transmission lanes (high speed D+, D-, differential pair), and the technical features of the present invention described above can be applied substantially identically or similarly to USB communication capable of multi-channel signal transmission (for example, alternative mode -DP Alt Mode- supported by USB-C type), or to Thunderbolt communication capable of multi-channel signal transmission by supporting two transmission lanes and two reception lanes, or generally three transmission lanes and one reception lane, as shown in Figure 24.

[0108] Although the present invention has been described with reference to the embodiments illustrated in the accompanying drawings, these are merely illustrative, and those skilled in the art will understand that a variety of modifications and equivalent other embodiments are possible therefrom. [Explanation of symbols]

[0109] W: Optical waveguide W1: 1st optical waveguide W2: Second optical waveguide WN: Optical Waveguide Network S: Base board S1, S2: First and second surfaces of the base board CS: Coupler switch INP: Input Port OUTP: Output port b1, b2: 1st and 2nd coupler control bits PS: Phase shift interval CP: Joint interval MOC: Movable Coupler F: Optical fiber P1, P2, P3: First to third positions of the movable coupler CL: Cladding

Claims

1. Optical fibers for transmitting optical signals, A coupling with the optical fiber, comprising an input port forming the transmitting end, an output port forming the receiving end opposite to the transmitting end, and an optical waveguide network connecting the input port and the output port, A coupler switch for controlling optical power transmission or optical coupling between adjacent first and second optical waveguides constituting the optical waveguide network, comprising an electrical input for controlling the coupling efficiency between the first and second optical waveguides to realize different optical power transmissions such as a through or bar state in which substantially no optical power crossing occurs between the first and second optical waveguides, a splitting, dividing or partial coupling state corresponding to partial optical power retention and partial crossing between the first and second optical waveguides, and a drop or cross state corresponding to total optical power crossing between the first and second optical waveguides, The first optical waveguide includes a pair of 1-1 optical waveguides and 1-2 optical waveguides, and the second optical waveguide includes a pair of 2-1 optical waveguides and 2-2 optical waveguides. Of the 1-1 optical waveguide, 1-2 optical waveguide, 2-1 optical waveguide, and 2-2 optical waveguide, at least one single optical waveguide has an optical gain or optical loss profile having a full-width at half maximum (FWHM) that is attenuated to half the peak value of the central wavelength band toward both sides from a central wavelength band λ0 forming a single peak, The aforementioned single optical waveguide is a photonic circuit characterized in that, within the wavelength range forming the full width at half maximum (FWHM), it transmits together optical signals in wavelength bands that are spaced apart from each other, by interposing a wavelength separation band that has a resolution for separating different wavelength bands that form different communication channels, in order to prevent crosstalk between them.

2. The photonic circuit according to claim 1, characterized in that the resolution for separating different wavelength bands that form different communication channels corresponds to the resolution of a wavelength-selective filter for separating optical signals of different wavelength bands transmitted from a single optical waveguide, or the resolution of the wavelength-selective filter plus a margin tolerance.

3. The photonic circuit according to claim 1, characterized in that the single optical waveguide transmits optical signals of different wavelength bands that form a high-speed channel and a low-speed channel having different transmission speeds.

4. The different optical signals transmitted together through the single optical waveguide form a high-speed channel with a relatively high transmission speed and a low-speed channel with a relatively low transmission speed. In the optical gain or optical loss profile of the optical waveguide, The wavelength band of the optical signal assigned to the high-speed channel is relatively close to the central wavelength band having a peak value and has a low attenuation rate. The photonic circuit according to claim 3, characterized in that the wavelength band of the optical signal assigned to the low-speed channel is relatively far away from the central wavelength band having a peak value and has a high attenuation rate.

5. The single optical waveguide is The photonic circuit according to claim 1, characterized in that, within the wavelength range that forms the full width at half maximum (FWHM), three different optical signals in different wavelength bands that are separated from each other by a wavelength separation band are transmitted together.

6. The three distinct optical signals transmitted together through the single optical waveguide each form a first and second high-speed channel having a relatively high transmission speed and a low-speed channel having a relatively low transmission speed. In the optical gain or optical loss profile of the optical waveguide, The wavelength band of the optical signal assigned to the second high-speed channel is closest to the central wavelength band having the peak value and has the lowest attenuation rate. The wavelength band of the optical signal assigned to the low-speed channel is furthest from the central wavelength band having the peak value and has the highest attenuation rate. The photonic circuit according to claim 5, characterized in that the wavelength band of the optical signal assigned to the first high-speed channel is farther from the central wavelength band having a peak value than the wavelength band of the optical signal assigned to the second high-speed channel, but closer than the wavelength band of the optical signal assigned to the low-speed channel and adjacent to it, having an intermediate attenuation rate.

7. The wavelength band of the optical signal assigned to the first high-speed channel, the wavelength band of the optical signal assigned to the second high-speed channel, and the wavelength band of the optical signal assigned to the low-speed channel are assigned to positions asymmetrical to each other with respect to the central wavelength band having the peak value. The wavelength band of the optical signal assigned to the second high-speed channel and the wavelength band of the optical signal assigned to the low-speed channel are assigned to a wavelength range of one of the left half-region and the right half-region, centered on the central wavelength band having the peak value. The photonic circuit according to claim 6, characterized in that the wavelength band of the optical signal assigned to the first high-speed channel is assigned to the wavelength range of the other region of the left half region and the right half region, centered on the central wavelength band having the peak value.

8. The photonic circuit according to claim 7, characterized in that the single optical waveguide transmits both an image signal including image data as forming first and second high-speed channels having a relatively high transmission speed, and an auxiliary signal including auxiliary data as forming a low-speed channel having a relatively low transmission speed.

9. The 1-1 optical waveguide and the 1-2 optical waveguide each transmit two high-speed channels having relatively high transmission speeds and one low-speed channel having relatively low transmission speeds, thereby forming a total of six communication channels between the same display source and the same display sink, including four high-speed channels for image signals and two low-speed channels for auxiliary signals. The photonic circuit according to claim 8, characterized in that the second-first optical waveguide and the second-second optical waveguide each transmit two high-speed channels having a relatively high transmission speed and one low-speed channel having a relatively low transmission speed, thereby forming a total of six communication channels between another identical display source and another identical display sink, including four high-speed channels for another image signal and two low-speed channels for another auxiliary signal.

10. The 1-1 optical waveguide and the 1-2 optical waveguide each transmit two high-speed channels having relatively high transmission speeds and one low-speed channel having relatively low transmission speeds, thereby forming a total of six communication channels from the same display source, including four high-speed channels for image signals and two low-speed channels for auxiliary signals. The photonic circuit according to claim 8, characterized in that the second-first optical waveguide and the second-second optical waveguide each transmit two high-speed channels having a relatively high transmission speed and one low-speed channel having a relatively low transmission speed, thereby forming a total of six communication channels, including four high-speed channels for image signals destined for the same display sink and two low-speed channels for auxiliary signals.

11. The aforementioned optical waveguide network is a 2N x 2N optical waveguide network that maps 2N input ports and 2N output ports to each other. The 2N input ports are connected in a 2:1 ratio to the display sources so that image signals and auxiliary signals output from the N display sources are input to the 2N input ports. The 2N output ports are connected to the N display sinks in a 2:1 ratio so that image signals and auxiliary signals are output to the N display sinks. The photonic circuit according to claim 1, characterized in that, in response to a control signal applied to the coupler switch, pairs of image signals and auxiliary signals input via input ports connected to the same display source are routed or distributed toward output ports connected to the same display sink, so as to realize different optical power transmission between adjacent first and second optical waveguides that constitute an optical waveguide network between the input port and the output port.

12. The photonic circuit according to claim 1, characterized in that the optical power transmission that crosses between the first-1 optical waveguide and the second-1 optical waveguide and the optical power transmission that crosses between the first-2 optical waveguide and the second-2 optical waveguide are both controlled by the same coupler switch.

13. The optical waveguide network connects input ports and output ports formed on the first and second sides of the base substrate on which the optical waveguide network is formed, which are opposite to each other. The first and second optical waveguides are, The photonic circuit according to claim 12, characterized in that it includes a coupling section that extends from the input port toward the output port and runs parallel to each other at a relatively close distance, and a phase shift section that runs parallel to each other at a relatively far distance.

14. The photonic circuit according to claim 13, characterized in that, in the phase shift section, an external electric field is applied to at least one of the first and second optical waveguides, and the coupler switch is formed for setting a voltage that induces a phase difference or phase mismatch between the first and second optical waveguides.

15. The photonic circuit according to claim 14, characterized in that the optical power transmission or optical coupling efficiency intersecting between the first and second optical waveguides in the coupling section is formed to differ in accordance with the phase difference or phase mismatch between the first and second optical waveguides caused by the voltage set by the coupler switch in the phase shift section.

16. The photonic circuit according to claim 14, wherein the coupler switch receives first and second coupler control bits for applying three different levels of voltage that cause different degrees of phase difference or phase mismatch between the first and second optical waveguides in order to achieve different optical power transmissions between the first and second optical waveguides, namely through, partial remaining and partial crossing, and full crossing.

17. According to the voltage set by the coupler switch, i) By setting a zero voltage using the coupler switch, a drop or cross of optical power transmission corresponding to the total cross of optical power is realized between the first and second optical waveguides from the input port to the output port. ii) By setting the maximum voltage using the coupler switch, through or bar optical power transmission is achieved between the first and second optical waveguides from the input port to the output port, in which substantially no crossing of optical power occurs. iii) The photonic circuit according to 16, characterized in that the coupler switch sets a voltage between zero voltage and maximum voltage, thereby realizing optical power transmission of a divided state corresponding to partial retention and partial crossover of optical power between the first and second optical waveguides moving from the input port to the output port.

18. In bit 0 of the first and second coupler control bits, while achieving phase matching between the first and second optical waveguides from the input port to the output port, optical power transmission of a drop or cross corresponding to the total cross of optical power is realized. In bit 1 of the first coupler control bit and bit 0 of the second coupler control bit, a phase mismatch is created between the first and second optical waveguides from the input port to the output port, blocking a portion of the optical power transmission. This enables optical power transmission in a divided or partially coupled state, corresponding to partial retention and partial crossing of the optical power. The photonic circuit according to claim 16, characterized in that bit 1 of the first and second coupler control bits achieves a through or bar state in which there is substantially no optical power transmission, while creating a phase mismatch that blocks the total transmission of optical power between the first and second optical waveguides from the input port to the output port.

19. The optical waveguide network is an NxN optical waveguide network that maps N input ports and N output ports to each other. The first-1 optical waveguide and the second-1 optical waveguide are optical waveguides that extend adjacent to each other between two distinct input ports out of the N input ports and two distinct output ports out of the N output ports. The first- and second-2 optical waveguides are optical waveguides that extend adjacent to each other between two other distinct input ports out of the N input ports and two other distinct output ports out of the N output ports. The photonic circuit according to claim 12, characterized in that the flow of optical power intersecting between the first-1 optical waveguide and the second-1 optical waveguide and the flow of optical power intersecting between the first-2 optical waveguide and the second-2 optical waveguide are both controlled by the same coupler switch.

20. The optical waveguide network connects input ports and output ports, respectively, which are formed on the first and second sides of the base substrate on which the optical waveguide network is formed, where they intersect and touch each other at one corner. The photonic circuit according to claim 12, further comprising a coupler switch including a movable coupler that enables forward / backward movement in an approaching direction toward the intersection of the first and second optical waveguides or a backward direction toward the intersection of the first and second optical waveguides, in order to control the optical power transmission or optical coupling efficiency that intersects between the first optical waveguide connected to the input port and the second optical waveguide connected to the output port.

21. The aforementioned movable coupler is i) At the first position furthest from the intersection of the first and second optical waveguides, through or bar optical power transmission is achieved between the first waveguide connected to the input port and the second waveguide connected to the output port, with substantially no crossing of optical power. ii) At the third position closest to the intersection of the first and second optical waveguides, optical power transmission of a drop or cross equivalent to the total cross of optical power is realized between the first waveguide connected to the input port and the second waveguide connected to the output port. iii) The photonic circuit according to claim 20, characterized in that at a second position between the first position furthest from the intersection of the first and second optical waveguides and the third position closest to it, optical power transmission is realized in a splitting, dividing, or partial coupling state corresponding to partial retention and partial crossing of optical power.

22. The photonic circuit according to claim 21, wherein the coupler switch receives first and second coupler control bits for applying three different levels of control voltage, such that the movable coupler is set from a first position furthest from the intersection of the first and second optical waveguides to a third position closest to it.

23. In bit 0 of the first and second coupler control bits, the movable coupler is set to the first position furthest from the intersection of the first and second optical waveguides. In bit 1 of the first coupler control bit and bit 0 of the second coupler control bit, the movable coupler is set to a second position from the intersection of the first and second optical waveguides. The photonic circuit according to claim 22, characterized in that, in bit 1 of the first and second coupler control bits, the movable coupler is set to a third position closest to the intersection of the first and second optical waveguides.

24. The aforementioned movable coupler is A first coupling rib extending parallel to the first optical waveguide is provided to form an evanescent coupling with the first optical waveguide, The photonic circuit according to claim 20, further comprising a second coupling rib extending parallel to the second optical waveguide so as to form an evanescent coupling with the second optical waveguide.

25. The evanescent field leaking between the first optical waveguide and the movable coupler has an amplitude that decreases from the first optical waveguide toward the movable coupler. The photonic circuit according to claim 20, characterized in that the evanescent field leaking between the second optical waveguide and the movable coupler has an amplitude that decreases from the movable coupler toward the second optical waveguide.

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