Optical Multiplexer

Abstract

In the optical multiplexer, an optical diffusion element separates a first input beam from a first input port and a second input beam from a second input port into a plurality of wavelength components. A reflection mirror comprises first and second reflection elements. A first output port is provided in a propagation path for a reflected beam of the first input beam from the first reflection element, the reflected beam corresponding to a first wavelength band. A second output port is provided in a propagation path for a reflected beam of the first input beam from the second reflection element, the reflected beam corresponding to a second wavelength band. The second input port is disposed in a position where a third reflected beam, which is a reflected beam of the second input beam, from the second reflection element corresponding to the second wavelength band is optically coupled with the first output port and is outputted from the first output port.

Description

[Technical field]

[0001] The present disclosure relates to optical multiplexers. [Background technology]

[0002] A wavelength division multiplexing (WDM) network is a communication network that uses WDM optical communication technology. In a WDM network, an optical add drop multiplexer (OADM) that enables the addition and drop of optical signals is provided at a branch point.

[0003] As an example of OADM, a tunable OADM that can change the wavelength band to be dropped / added is known. Examples of tunable OADM include an OADM equipped with a tunable filter and an OADM equipped with a wavelength selective switch (WSS). The wavelength selective switch includes, for example, a MEMS mirror and a spatial optical system electrically controlled by a controller, and is configured to be able to transmit an arbitrary wavelength of an optical signal to an arbitrary path (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-156015 A Summary of the Invention [Problem to be solved by the invention]

[0005] An OADM equipped with a tunable filter uses a coupler to drop / add optical signals, and the tunable filter to switch the wavelength band to be dropped / added. With this OADM, an optical signal passes through two couplers and one tunable filter before being output after the drop / add process. Each coupler causes a signal loss of 3 dB, and the tunable filter causes a signal loss of 2 dB.

[0006] Although OADMs equipped with wavelength selective switches have excellent wavelength selectivity, they are expensive and have a high failure rate compared to other OADMs because the optical and electronic components they incorporate are large and complex.

[0007] Therefore, according to one aspect of the present disclosure, it is desirable to provide a new optical multiplexer that is excellent overall in terms of insertion loss, reliability, and cost. [Means for solving the problem]

[0008] According to one aspect of the present disclosure, there is provided an optical multiplexer comprising a first input port, a second input port, an optical dispersive element, a reflective mirror, a first output port, and a second output port.

[0009] The optical dispersion element is provided in a propagation path of the first input light from the first input port and the second input light from the second input port, and is configured to separate each of the first input light and the second input light into a plurality of wavelength components by dispersing the first input light and the second input light in a predetermined wavelength dispersion direction.

[0010] The reflective mirror includes a first reflective element for reflecting a group of wavelength components corresponding to a first wavelength band among the multiple wavelength components separated by the optical dispersion element, and a second reflective element for reflecting a group of wavelength components corresponding to a second wavelength band different from the first wavelength band in a direction different from the group of wavelength components corresponding to the first wavelength band of the corresponding input light.

[0011] The first output port is provided in a propagation path of a first reflected light, which is reflected light by a group of first reflective elements of a wavelength component of the first input light corresponding to a first wavelength band, and is configured to output the first reflected light.

[0012] The second output port is provided in a propagation path of second reflected light, which is reflected light by a group of second reflective elements of wavelength components corresponding to a second wavelength band of the first input light, and is configured to output the second reflected light.

[0013] The reflective mirror is configured to reflect incident light in a direction different from the incident direction, with the first and second reflective elements arranged such that the first and second reflected lights propagate apart in a direction perpendicular to the wavelength dispersion direction.

[0014] The second input port is located at a position away from the first input port in a direction perpendicular to the wavelength dispersion direction, and at a position where a third reflected light, which is reflected light of a wavelength component of the second input light corresponding to the second wavelength band by a group of second reflective elements, is optically coupled to the first output port and output from the first output port.

[0015] This optical multiplexer can spatially separate a group of wavelength components in a first wavelength band and a group of wavelength components in a second wavelength band contained in a first input light and output them from a first output port and a second output port without using a coupler. Then, without using a coupler, a group of wavelength components in a second wavelength band contained in a second input light can be output from the first output port in addition to the group of wavelength components in the first wavelength band contained in the first input light. This optical multiplexer can be realized with a relatively simple structure.

[0016] Therefore, according to one aspect of the present disclosure, it is possible to provide an optical multiplexer that is excellent overall in terms of insertion loss, reliability, and cost.

[0017] According to another aspect of the present disclosure, an optical multiplexer may include a mirror array, a drive element, and a controller. The mirror array may include a plurality of reflective mirrors, each configured as the above-mentioned reflective mirror with a first reflective element and a second reflective element.

[0018] The driving element may be configured to displace the mirror array. The controller may be configured to control the arrangement of the mirror array through the driving element. Each of the plurality of reflective mirrors may be a reflective mirror in which a first reflective element and a second reflective element are arranged to have a different combination of the first wavelength band and the second wavelength band.

[0019] The controller may be configured to control the arrangement of the mirror array so that the first input light and the second input light dispersed by the light dispersing element are selectively incident on a designated one of the multiple reflecting mirrors.

[0020] A configuration including such a movable mirror array can provide a tunable optical multiplexer capable of switching the wavelength band of the signal components to be dropped (ie, dropped) / inserted (ie, added).

[0021] According to another aspect of the present disclosure, an optical multiplexer may include a mirror array, an optical deflector, and a controller. The mirror array may include a plurality of reflecting mirrors, each of which is configured as the above-mentioned reflecting mirror including a first reflecting element and a second reflecting element. The optical deflector may be provided between the mirror array and the optical dispersion element, and may be configured to change the propagation direction of the first input light and the second input light dispersed by the optical dispersion element to the mirror array.

[0022] The controller may be configured to control the propagation direction by controlling the optical deflector. Each of the plurality of reflecting mirrors may be a reflecting mirror in which a first reflecting element and a second reflecting element are arranged so as to have a different combination of the first wavelength band and the second wavelength band.

[0023] The controller can control the optical deflector so that the first input light and the second input light dispersed by the optical dispersion element are selectively incident on a designated one of the multiple reflecting mirrors.

[0024] The optical deflector may be a movable mirror, in which case the controller may control the propagation direction by controlling the angle of the reflective surface of the movable mirror.

[0025] Even with a configuration using such an optical deflector, it is possible to provide a wavelength-tunable optical multiplexer that can switch the wavelength band of the signal components to be dropped / added. [Brief description of the drawings]

[0026] [Figure 1] FIG. 2 is a diagram illustrating the operation of an OADM. [Diagram 2] 1 is a block diagram illustrating a configuration of an optical multiplexer according to a first embodiment. [Diagram 3] 3A and 3B are diagrams illustrating the internal configuration of the optical multiplexer of the first embodiment as viewed in a direction parallel to the chromatic dispersion direction. [Figure 4] 2 is a diagram illustrating an internal configuration of the optical multiplexer according to the first embodiment as viewed in a direction perpendicular to the wavelength dispersion direction. FIG. [Diagram 5] 5A and 5B are diagrams showing the arrangement of a first reflective element and a second reflective element. [Figure 6] 11 is a diagram illustrating the internal configuration of an optical multiplexer according to a second embodiment, as viewed in a direction parallel to the wavelength dispersion direction. FIG. [Figure 7] 4A to 4C are diagrams illustrating examples of combinations of a first wavelength band and a second wavelength band realized by a mirror array. [Figure 8] FIG. 8A is a block diagram showing the configuration of an optical multiplexer according to the third embodiment, and FIG. 8B is a diagram showing the internal configuration of the optical multiplexer according to the third embodiment as viewed in a direction parallel to the chromatic dispersion direction. [Figure 9] FIG. 9A is a block diagram showing the configuration of an optical multiplexer according to the fourth embodiment, and FIG. 9B is a diagram showing the internal configuration of the optical multiplexer according to the fourth embodiment as viewed in a direction parallel to the chromatic dispersion direction. [Figure 10] FIG. 13 is a diagram illustrating the internal configuration of an optical multiplexer according to a fifth embodiment, as viewed in a direction parallel to the wavelength dispersion direction. [Explanation of symbols]

[0027] 100, 200, 300, 400, 500... Optical multiplexer, 110... Optical system, 130, 530... Transmission diffraction grating, 150, 510... Lens, 170, 270, 370, 570... Reflection mirror, 171, 371... First reflection element, 172, 372... Second reflection element, 260, 560... Mirror array, 280, 580... Driving source, 290, 590... Controller, 373... Third reflection element, 374...fourth reflective element, 540...movable mirror, P_IN...first input port, P_IN1, P_IN2...main input ports, P_AD...second input port, P_AD1, P_AD2, P_AD3...add input ports, P_TH...first output port, P_TH1, P_TH2...thru output ports, P_DR...second output port, P_DR1, P_DR2, P_DR3...drop output ports. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Exemplary embodiments of the present disclosure will now be described with reference to the drawings.

[0029] Optical multiplexers 100, 200, 300, 400, 500 according to exemplary embodiments of the present disclosure are optical multiplexers suitable for use as OADMs 10 in WDM networks.

[0030] The OADM 10 is provided at a branch point of the WDM network and performs branching and adding of optical signals. In the WDM network illustrated in FIG. 1, a first communication node N1, a second communication node N2, and a third communication node N3 are connected via the OADM 10.

[0031] Optical communication is carried out between the first communication node N1 and the third communication node N3 via a first channel corresponding to a first wavelength band, and optical communication is carried out between the first communication node N1 and the second communication node N2 via a second channel corresponding to a second wavelength band.

[0032] In the process of transmitting an optical signal from the first communication node N1 to the third communication node N3, the OADM 10 drops the second channel signal component contained in the optical signal and transmits it to the second communication node N2, and passes through the first channel signal component and transmits it to the third communication node N3.

[0033] The OADM 10 adds the second channel signal component from the second communication node N2 to the optical signal from the first communication node N1 from which the second channel signal component has been dropped, and transmits the result to the third communication node N3.

[0034] [First embodiment] A first embodiment optical multiplexer 100 suitable for use as the above-mentioned OADM 10 has a first input port P_IN, a second input port P_AD, a first output port P_TH, and a second output port P_DR, as shown in FIG. 2.

[0035] The optical multiplexer 100 outputs the signal components in the first wavelength band of the optical signal input from the first input port P_IN from the first output port P_TH, and outputs the signal components in the second wavelength band from the second output port P_DR. The optical multiplexer 100 further outputs the signal components in the second wavelength band of the optical signal input from the second input port P_AD from the first output port P_TH.

[0036] In the following, the optical signal input from the first input port P_IN is referred to as an in signal, the optical signal input from the second input port P_AD is referred to as an add signal, the in signal output from the first output port P_TH is referred to as a through signal, and the optical signal output from the second output port P_DR is referred to as a drop signal.

[0037] The optical multiplexer 100 includes an optical system 110 shown in Figures 3A, 3B, and 4. The optical system 110 includes a transmission type diffraction grating 130 as an optical dispersion element, a lens 150, and a reflecting mirror 170.

[0038] As shown in FIGS. 3A and 3B, the transmissive diffraction grating 130 is provided in the propagation path of the optical signals (ie, the IN signal and the ADD signal) input from the first input port P_IN and the second input port P_AD.

[0039] The transmissive diffraction grating 130 is configured to separate the optical signals (i.e., the IN signal and the ADD signal, respectively) input from the first input port P_IN and the second input port P_AD into a plurality of wavelength components by dispersing the optical signals in a predetermined direction. When the optical signals pass through the transmissive diffraction grating 130, they are spatially separated into a plurality of wavelength components in the Z direction shown in Figures 3A and 3B.

[0040] 3A and 3B show the internal configuration of the optical multiplexer 100 as viewed in a direction parallel to the Z direction, which is the chromatic dispersion direction. In particular, FIG. 3A conceptually illustrates the propagation of an IN signal input from the first input port P_IN with a solid arrow, and conceptually illustrates a portion of the propagation of an ADD signal input from the second input port P_AD with a dashed arrow for reference. FIG. 3B conceptually illustrates the propagation of an ADD signal input from the second input port P_AD with a solid arrow, and conceptually illustrates a portion of the propagation of an IN signal input from the first input port P_IN with a dashed arrow for reference.

[0041] 3A and 3B, the first input port P_IN and the second input port P_AD are arranged at a predetermined distance in the X direction perpendicular to the Z direction, which is the wavelength dispersion direction. As a result, the IN signal from the first input port P_IN and the ADD signal from the second input port P_AD are incident on the transmission diffraction grating 130 in a state of being spatially separated in the X direction.

[0042] The transmissive diffraction grating 130 spatially separates, in the Z direction, the multiple wavelength components contained in each of the IN signal and ADD signal that are incident in a state spatially separated in the X direction, as shown in FIG.

[0043] Fig. 4 shows the internal configuration of the optical multiplexer 100 as viewed from a direction parallel to the X direction perpendicular to the wavelength dispersion direction. The multiple arrows extending from the transmission grating 130 shown in Fig. 4 conceptually indicate that the optical signal incident on the transmission grating 130 is wavelength-dispersed in the Z direction and propagates to the lens 150. That is, the IN signal and ADD signal transmitted through the transmission grating 130 propagate to the lens 150 with multiple wavelength components spatially separated in the Z direction.

[0044] Lens 150 is designed and positioned to focus the wavelength-dispersed IN and ADD signals onto the reflective surface of reflecting mirror 170 .

[0045] 5A, the reflecting mirror 170 includes a first reflecting element 171 and a second reflecting element 172 arranged in the Z direction. The first reflecting element 171 and the second reflecting element 172 are arranged in the Z direction such that, of the wavelength-dispersed IN signal and ADD signal that transmit through the lens 150 and propagate to the reflecting mirror 170, a first signal component that is a group of wavelength components corresponding to a first wavelength band is incident on the first reflecting element 171, and a second signal component that is a group of wavelength components corresponding to a second wavelength band is incident on the second reflecting element 172.

[0046] The first reflective element 171 and the second reflective element 172 have reflective surfaces that are inclined with respect to the X direction as shown in Fig. 5B. Specifically, the first reflective element 171 has a reflective surface that is inclined with respect to the X direction at an angle different from that of the reflective surface of the second reflective element 172.

[0047] A first signal component of the in signal is reflected at a reflection angle corresponding to the angle of incidence on the reflective surface of the first reflective element 171, and a second signal component is reflected at a reflection angle corresponding to the angle of incidence on the reflective surface of the second reflective element 172. The angles of incidence and reflection have non-zero angles with respect to the normal to the reflective surface.

[0048] As described above, the inclination angle of the reflecting surface of the first reflecting element 171 with respect to the X direction is different from the inclination angle of the reflecting surface of the second reflecting element 172 with respect to the X direction. Therefore, the incidence angle and reflection angle of the first signal component with respect to the reflecting surface of the first reflecting element 171 are different from the incidence angle and reflection angle of the second signal component with respect to the reflecting surface of the second reflecting element 172.

[0049] As a result, the first signal component of the IN signal that is incident on and reflected by the reflecting surface of the first reflecting element 171 is reflected in a direction different from the incident direction and different from the reflection direction of the second signal component of the IN signal that is incident on and reflected by the reflecting surface of the second reflecting element 172, and propagates in a state spatially separated from the second signal component of the IN signal in the X direction.

[0050] Specifically, the reflective surface of the first reflective element 171 is angled such that the propagation path of a first signal component of the IN signal that reflects off the first reflective element 171 is optically coupled to the first output port P_TH. The reflective surface of the second reflective element 172 is angled such that the propagation path of a second signal component of the IN signal that reflects off the second reflective element 172 is optically coupled to the second output port P_DR.

[0051] The first output port P_TH is provided on the propagation path of reflected light of a first signal component of the IN signal by a first reflecting element 171, and the second output port P_DR is provided on the propagation path of reflected light of a second signal component of the IN signal by a second reflecting element 172.

[0052] With this optical design, a first signal component of the IN signal that reflects off the first reflective element 171 propagates towards and is output from the first output port P_TH, and a second signal component of the IN signal that reflects off the second reflective element 172 propagates in a direction towards and is output from the second output port P_DR.

[0053] Furthermore, due to the characteristic relative position in the X direction of the second input port P_AD with respect to the first input port P_IN, the second signal component of the add signal reflected by the second reflecting element 172 propagates toward the first output port P_TH rather than the second output port P_DR, and is output from the first output port P_TH.

[0054] That is, in this embodiment, the relative position of the second input port P_AD in the X direction with respect to the first input port P_IN is adjusted so that the propagation path of the second signal component of the add signal reflected by the second reflecting element 172 is optically coupled to the first output port P_TH.

[0055] The optical multiplexer 100 is designed so that the incident angle and reflection angle of the IN signal and the ADD signal with respect to the reflecting surface of the second reflecting element 172 are adjusted by adjusting the relative positions, so that the second signal component of the IN signal propagates to the second output port P_DR, while the second signal component of the ADD signal propagates to the first output port P_TH. In other words, the optical multiplexer 100 is designed so that the first signal component of the ADD signal is not optically coupled to any of the output ports.

[0056] According to the optical multiplexer 100 of the present embodiment described above, the reflecting mirror 170 spatially separates the in signal, which has been wavelength-dispersed in the Z direction by the transmissive diffraction grating 130, in the X direction into a first signal component corresponding to a first wavelength band and a second signal component corresponding to a second wavelength band, by the first reflecting element 171 and the second reflecting element 172.

[0057] Therefore, the optical multiplexer 100 can split the IN signal to generate a THROUGH signal and a DROP signal without a coupler. That is, the optical multiplexer 100 can spatially separate the first and second signal components included in the IN signal without using a coupler, and output the first signal component as a THROUGH signal from the first output port P_TH and output the second signal component as a DROP signal from the second output port P_DR.

[0058] Furthermore, the second input port P_AD is located at a position separated from the first input port P_IN in the X direction, and is positioned at a position where the reflected light of the second signal component of the add signal corresponding to the second wavelength band by the second reflecting element 172 is optically coupled to the first output port P_TH and output from the first output port P_TH.

[0059] Therefore, the optical multiplexer 100 can add an add signal in the second wavelength band to a through signal in the first wavelength band without a coupler and output the result from the first output port P_TH. Furthermore, as shown in Figures 3A, 3B, and 4, the optical system 110 of the optical multiplexer 100 is very simple. Therefore, according to this embodiment, it is possible to provide an optical multiplexer 100 that is excellent overall in terms of insertion loss, reliability, and cost.

[0060] As a modified example, in order to configure the optical multiplexer 100 of the first embodiment as a wavelength-tunable optical multiplexer, the reflecting mirror 170 may be configured with an array of MEMS mirrors arranged in the wavelength dispersion direction. When the reflecting mirror 170 is configured with a MEMS mirror array, the arrangement of the first reflecting element 171 and the second reflecting element 172 realized by the MEMS mirror array can be switched by controlling the MEMS mirror array, and the first wavelength band used for the through signal and the second wavelength band used for the add / drop signal can be changed.

[0061] [Second embodiment] An optical multiplexer 200 of the second embodiment shown in Fig. 6 is an optical multiplexer in which the reflecting mirror 170 in the optical multiplexer 100 of the first embodiment is replaced with a mirror array 260, and further includes a driving source 280 for displacing the mirror array 260 in the X direction, and a controller 290 for controlling the driving source 280. Like Fig. 3A, Fig. 6 is a diagram illustrating the internal configuration of the optical multiplexer 200 of the second embodiment from a viewpoint parallel to the Z direction, which is the wavelength dispersion direction.

[0062] In the following, configurations of the optical multiplexer 200 of the second embodiment that are different from the optical multiplexer 100 of the first embodiment will be selectively described, and descriptions of the same configurations will be omitted as appropriate. Among the components of the optical multiplexer 200, the same components as those of the optical multiplexer 100 of the first embodiment will be given the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0063] The mirror array 260 of the optical multiplexer 200 in this embodiment is configured with a plurality of reflecting mirrors 270 arranged in the X direction. Each of the reflecting mirrors 270 is configured similarly to the reflecting mirror 170 in the first embodiment. That is, the reflecting mirror 270 includes a first reflecting element 171 and a second reflecting element 172 arranged in the Z direction, similar to the reflecting mirror 170 in the first embodiment (see FIGS. 5A and 5B).

[0064] The first input port P_IN, the second input port P_AD, the first output port P_TH, the second output port P_DR, the transmission grating 130, and the lens 150 in the optical multiplexer 200 are arranged in the same manner as in the optical multiplexer 100 of the first embodiment.

[0065] The lens 150 is disposed so as to focus the IN signal and the ADD signal on one of the multiple reflecting mirrors 270 (hereinafter referred to as a selected mirror) that are disposed in the normal position as in the first embodiment.

[0066] The displacement of mirror array 260 in the X direction changes a selected mirror among the multiple reflecting mirrors 270 that is to be placed at the correct position corresponding to the focal point of lens 150. Controller 290 controls the placement of mirror array 260 in the X direction through control of drive source 280 so that one externally designated reflecting mirror 270 among the multiple reflecting mirrors 270 is placed at the above-mentioned correct position.

[0067] Here, a detailed configuration of the mirror array 260 will be described with reference to Fig. 7. Each of the multiple reflecting mirrors 270 arranged in the X direction in the mirror array 260 is configured such that the first reflecting elements 171 and the second reflecting elements 172 are arranged so as to have different combinations of a first wavelength band which is a transmission channel for a through signal and a second wavelength band which is a transmission channel for a drop / add signal.

[0068] According to the example shown in FIG. 7, six reflecting mirrors 270 are arranged in the mirror array 260, and when the first (#1) reflecting mirror 270 is arranged in the normal position as the selected mirror, signal components in, for example, 20% of the wavelength band on the short wavelength side (i.e., high frequency side) of the total wavelength band of the IN signal that can be reflected by the selected mirror are propagated to the second output port P_DR as signal components in the second wavelength band, and the wavelength components in the remaining 80% of the wavelength band are propagated to the first output port P_TH as signal components in the first wavelength band.

[0069] For C=2, 3, or 4, when the Cth (#C) reflecting mirror 270 is placed in the normal position as a selected mirror, signal components in a wavelength band, for example 20×C% on the short wavelength side of the total wavelength band of the IN signal, propagate to the second output port P_DR as signal components in the second wavelength band, and the remaining wavelength components in the (100-20×C)% wavelength band propagate to the first output port P_TH as signal components in the first wavelength band.

[0070] When the fifth (#5) reflecting mirror 270 is placed in the normal position as a selective mirror, the first reflecting element 171 does not exist, and the entire wavelength band of the IN signal propagates to the second output port P_DR as a signal component of the second wavelength band. When the sixth (#6) reflecting mirror 270 is placed in the normal position as a selective mirror, the second reflecting element 172 does not exist, and the entire wavelength band of the IN signal propagates to the first output port P_TH as a signal component of the first wavelength band.

[0071] According to this optical multiplexer 200, it is possible to switch the wavelength selection pattern of the transmission channel of the through signal and the transmission channel of the drop / add signal with a degree of freedom corresponding to the number of reflecting mirrors 270 prepared in advance.

[0072] Although the optical multiplexer 200 is inferior to an optical multiplexer including a WSS in terms of the degree of freedom in wavelength selection, the internal structure including the movable elements is simpler than that of an optical multiplexer including a WSS, and therefore the failure rate is low and highly reliable operation can be achieved for a long period of time. Therefore, according to this embodiment, it is possible to provide a wavelength-tunable optical multiplexer that is comprehensively superior in terms of insertion loss, reliability, and cost.

[0073] [Third embodiment] The third embodiment optical multiplexer 300 shown in Figures 8A and 8B is configured by providing, in the optical multiplexer 100 of the first embodiment, multiple add input ports P_AD1, P_AD2, and P_AD3 instead of the second input port P_AD, multiple drop output ports P_DR1, P_DR2, and P_DR3 instead of the second output port P_DR, and providing a reflecting mirror 370 having first to fourth reflecting elements 371 to 374 instead of the reflecting mirror 170.

[0074] Fig. 8A shows that the optical multiplexer 300 is a 4-input 4-output optical multiplexer including a first input port P_IN, a first output port P_TH, three add input ports P_AD1, P_AD2, and P_AD3, and three drop output ports P_DR1, P_DR2, and P_DR3. Fig. 8B is a diagram illustrating the internal configuration of the optical multiplexer 300 of the third embodiment from a viewpoint parallel to the Z direction, which is the chromatic dispersion direction, similar to Figs. 3A and 3B.

[0075] In the following, configurations of the optical multiplexer 300 of the third embodiment that are different from the optical multiplexer 100 of the first embodiment will be selectively described, and descriptions of the same configurations will be omitted as appropriate. Among the components of the optical multiplexer 300, the same components as those of the optical multiplexer 100 of the first embodiment will be given the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0076] In the reflecting mirror 370, the first reflecting element 371, the second reflecting element 372, the third reflecting element 373, and the fourth reflecting element 374 are arranged in the Z direction as shown in FIG. 8B.

[0077] The first reflective element 371, the second reflective element 372, the third reflective element 373, and the fourth reflective element 374 are arranged in the Z direction so that, of the in signal and the add signal that have been wavelength-dispersed by the transmission type diffraction grating 130 and transmitted through the lens 150, a first signal component corresponding to a first wavelength band is incident on the first reflective element 371, a second signal component corresponding to a second wavelength band is incident on the second reflective element 372, a third signal component corresponding to a third wavelength band is input to the third reflective element 373, and a fourth signal component corresponding to a fourth wavelength band is input to the fourth reflective element 374.

[0078] The add signals described in this embodiment are a first add signal using a second wavelength band, a second add signal using a third wavelength band, and a third add signal using a fourth wavelength band. The first add signal is input from a first add input port P_AD1, the second add signal is input from a second add input port P_AD2, and the third add signal is input from a third add input port P_AD3.

[0079] The first reflecting element 371 has a reflecting surface inclined with respect to the X direction such that a propagation path of a first signal component of the IN signal reflected by the first reflecting element 371 is optically coupled to the first output port P_TH. The second reflecting element 372 has a reflecting surface inclined with respect to the X direction such that a propagation path of a second signal component of the IN signal reflected by the second reflecting element 372 is optically coupled to the first drop output port P_DR1.

[0080] The third reflecting element 373 has a reflecting surface inclined with respect to the X direction such that the propagation path of the third signal component of the IN signal reflected by the third reflecting element 373 is optically coupled to the second drop output port P_DR2. The fourth reflecting element 374 has a reflecting surface inclined with respect to the X direction such that the propagation path of the fourth signal component of the IN signal reflected by the fourth reflecting element 374 is optically coupled to the third drop output port P_DR3.

[0081] The first output port P_TH is provided on a propagation path of light reflected by a first reflecting element 371 of a first signal component of the IN signal. The first drop output port P_DR1 is provided on a propagation path of light reflected by a second reflecting element 372 of a second signal component of the IN signal. The second drop output port P_DR2 is provided on a propagation path of light reflected by a third reflecting element 373 of a third signal component of the IN signal. The third drop output port P_DR3 is provided on a propagation path of light reflected by a fourth reflecting element 374 of a fourth signal component of the IN signal.

[0082] With this optical configuration, the first signal component of the IN signal reflected by the reflecting mirror 370 is output from the first output port P_TH, the second signal component of the IN signal is output from the first drop output port P_DR1, the third signal component of the IN signal is output from the second drop output port P_DR2, and the fourth signal component of the IN signal is output from the third drop output port P_DR3.

[0083] Further, the second signal component of the first add signal reflected from the second reflecting element 372, the third signal component of the second add signal reflected from the third reflecting element 373, and the fourth signal component of the third add signal reflected from the fourth reflecting element 374 propagate toward and are output from the first output port P_TH.

[0084] According to this embodiment, the first add input port P_AD1 is positioned away from the first input port P_IN in the X-direction so that the propagation path of the second signal component of the first add signal reflected by the second reflective element 372 is optically coupled to the first output port P_TH.

[0085] The second add input port P_AD2 is positioned such that a propagation path of a third signal component of the second add signal that reflects off the third reflective element 373 is optically coupled to the first output port P_TH. The third add input port P_AD3 is positioned such that a propagation path of a fourth signal component of the third add signal that reflects off the fourth reflective element 374 is optically coupled to the first output port P_TH.

[0086] In this way, the optical multiplexer 300 branches the in signal into a through signal in a first wavelength band, a first drop signal in a second wavelength band, a second drop signal in a third wavelength band, and a third drop signal in a fourth wavelength band without using a coupler. Furthermore, the optical multiplexer 300 adds a first add signal in a second wavelength band, a second add signal in a third wavelength band, and a third add signal in a fourth wavelength band to the through signal in the first wavelength band, and outputs the results from the first output port P_TH.

[0087] Therefore, the optical multiplexer 300 can form a multi-branching point and realize optical communication by being used as the OADM 10 in a WDM network. As a modified example, the optical multiplexer 300 may have four or more add input ports and drop output ports. These add input ports and drop output ports can also be positioned and arranged in the X direction according to the above-mentioned technical concept. That is, the optical multiplexer 300 may be configured as an M-input N-output optical multiplexer having M input ports, which is four or more, and N output ports, which is four or more.

[0088] [Fourth embodiment] The optical multiplexer 400 of the fourth embodiment shown in Figures 9A and 9B is configured by providing, in the optical multiplexer 100 of the first embodiment, multiple main input ports P_IN1, P_IN2 instead of the first input port P_IN, multiple through output ports P_TH1, P_TH2 instead of the first output port P_TH, multiple add input ports P_AD1, P_AD2 instead of the second input port P_AD, and multiple drop output ports P_DR1, P_DR2 instead of the second output port P_DR.

[0089] Fig. 9A shows that the optical multiplexer 400 is a 4-input 4-output optical multiplexer having two main input ports P_IN1 and P_IN2, two through output ports P_TH1 and P_TH2, two add input ports P_AD1 and P_AD2, and two drop output ports P_DR1 and P_DR2. Fig. 9B, like Figs. 3A and 3B, explains the internal configuration of the optical multiplexer 400 of the fourth embodiment from a viewpoint parallel to the Z direction, which is the chromatic dispersion direction.

[0090] In the following, configurations of the optical multiplexer 400 of the fourth embodiment that are different from the optical multiplexer 100 of the first embodiment will be selectively described, and descriptions of the same configurations will be omitted as appropriate. Among the components of the optical multiplexer 400, the same components as those of the optical multiplexer 100 of the first embodiment will be given the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0091] In the optical multiplexer 400 of this embodiment, a first IN signal is input from the first main input port P_IN1. A second IN signal is input from the second main input port P_IN2. A first ADD signal is input from the first ADD input port P_AD1, and a second ADD signal is input from the second ADD input port P_AD2.

[0092] The second main input port P_IN2 is disposed a predetermined distance away from the first main input port P_IN1 in the X direction perpendicular to the chromatic dispersion direction.

[0093] The first IN signal from the first main input port P_IN1, the first ADD signal from the first ADD input port P_AD1, the second IN signal from the second main input port P_IN2, and the second ADD signal from the second ADD input port P_AD2 are wavelength-dispersed in the Z direction by the transmission diffraction grating 130, and then pass through the lens 150 and enter the reflecting mirror 170.

[0094] A first signal component, which is a group of wavelength components in a first wavelength band of the wavelength-dispersed first in signal, second in signal, first add signal, and second add signal, is incident on a first reflecting element 171 of a reflecting mirror 170 and is reflected by the reflecting surface of the first reflecting element 171.

[0095] A second signal component, which is a group of wavelength components in a second wavelength band of the wavelength-dispersed first in signal, second in signal, first add signal, and second add signal, is incident on the second reflective element 172 of the reflecting mirror 170 and is reflected by the reflective surface of the second reflective element 172.

[0096] The first through output port P_TH1 is disposed at a position where it is optically coupled to a propagation path of a first signal component of the first in signal reflected by the first reflecting element 171. The second through output port P_TH2 is disposed at a position where it is optically coupled to a propagation path of a first signal component of the second in signal reflected by the first reflecting element 171.

[0097] The first drop output port P_DR1 is disposed at a position to optically couple to a propagation path of a second signal component of the first IN signal reflected by the second reflecting element 172. The second drop output port P_DR2 is disposed at a position to optically couple to a propagation path of a second signal component of the second IN signal reflected by the second reflecting element 172.

[0098] With this arrangement, the first signal component of the first in signal is output as a first through signal from the first through output port P_TH1, and the second signal component of the first in signal is output as a first drop signal from the first drop output port P_DR1.

[0099] In addition, the first signal component of the second in signal is output as a second through signal from the second through output port P_TH2, and the second signal component of the second in signal is output as a second drop signal from the second drop output port P_DR2.

[0100] More specifically, the second signal component of the first add signal reflected by the second reflecting element 172 propagates toward the first through output port P_TH1 and is output from the first through output port P_TH1. The second signal component of the second add signal reflected by the second reflecting element 172 propagates toward the second through output port P_TH2 and is output from the second through output port P_TH2.

[0101] For this purpose, the first add input port P_AD1 is disposed away from the first main input port P_IN1 in the X direction such that a propagation path of the second signal component of the first add signal reflected by the second reflecting element 172 is optically coupled to the first through output port P_TH1. The second add input port P_AD2 is disposed away from the second main input port P_IN2 in the X direction such that a propagation path of the second signal component of the second add signal reflected by the second reflecting element 172 is optically coupled to the second through output port P_TH2. In other words, the optical multiplexer 400 is designed such that the first signal components of the first and second add signals are not optically coupled to any of the output ports.

[0102] In this way, the optical multiplexer 400 realizes the functions of two of the optical multiplexers 100 by using the transmission type diffraction grating 130 , the lens 150 , and the reflecting mirror 170 that are common to the optical multiplexer 100 .

[0103] Therefore, by using the optical multiplexer 400 as the OADM 10 in a WDM network, it is possible to form multiple branching points and realize optical communication. In addition, the optical multiplexer 400 may have three or more sets of a main input port, a through output port, an add input port, and a drop output port. These sets of a main input port, a through output port, an add input port, and a drop output port can also be positioned according to the above-mentioned technical concept.

[0104] [Fifth embodiment] An optical multiplexer 500 of the fifth embodiment shown in FIG. 10 corresponds to a modified example of the optical multiplexer 200 of the second embodiment, and functions as a wavelength-tunable optical multiplexer by controlling the propagation path of an optical signal by a movable mirror 540.

[0105] As shown in FIG. 10, the optical multiplexer 500 of this embodiment includes a first input port P_IN, a first output port P_TH, a second input port P_AD, and a second output port P_DR, a lens 510, a transmissive diffraction grating 530, a movable mirror 540, a mirror array 560, a driving source 580, and a controller 590.

[0106] The IN signal from the first input port P_IN and the ADD signal from the second input port P_AD propagate through the lens 510 to the transmission grating 530, where they are wavelength-dispersed in the Z direction. The wavelength-dispersed IN signal and ADD signal are reflected by the movable mirror 540, pass through the transmission grating 530 and the lens 510 again, and enter the mirror array 560.

[0107] The mirror array 560 is configured in such a way that a plurality of reflecting mirrors 570 are arranged in the X direction, similar to the mirror array 260 of the second embodiment. Each of the reflecting mirrors 570 is configured in the same way as the reflecting mirror 170 of the first embodiment.

[0108] That is, each of the multiple reflecting mirrors 570 is configured such that the first reflecting element 171 and the second reflecting element 172 are arranged such that the combinations of the first wavelength band, which is the transmission channel for the through signal, and the second wavelength band, which is the transmission channel for the drop / add signal, are different from each other.

[0109] According to this embodiment, the movable mirror 540 functions as an optical deflector to change or control the propagation direction of the optical signal. The IN signal and ADD signal reflected by the movable mirror 540 are incident on the mirror array 560 at a position in the X direction according to the angle of the reflecting surface of the movable mirror 540.

[0110] Driving source 580 is capable of rotating movable mirror 540, and is configured to be able to change the angle of the reflecting surface of movable mirror 540 with respect to the X direction by the rotation. Driving source 580 is controlled by controller 590.

[0111] The controller 590 controls the angle of the reflective surface of the movable mirror 540 via the drive source 580 so that the in signal and the add signal are incident on a selected mirror, which is one of the multiple reflective mirrors 570 included in the mirror array 560 that is specified from outside.

[0112] The first signal components of the IN signal and the ADD signal corresponding to the first wavelength band are reflected by the first reflecting element 171 of the selection mirror. The propagation path of the reflected light of the first signal component of the IN signal by the first reflecting element 171 is optically coupled to the first output port P_TH.

[0113] The first signal component of the in signal reflected by the first reflective element 171 passes through the lens 510 and the transmission grating 530, is reflected by the movable mirror 540, and propagates again through the transmission grating 530 and the lens 510 to the first output port P_TH, and is output from the first output port P_TH.

[0114] The second signal components of the IN signal and the ADD signal corresponding to the second wavelength band are reflected by the second reflecting element 172 of the selective mirror. The propagation path of the reflected light of the second signal component of the IN signal by the second reflecting element 172 is optically coupled to the second output port P_DR.

[0115] The second signal component of the in signal reflected by the second reflective element 172 passes through the lens 510 and the transmission grating 530, is reflected by the movable mirror 540, and propagates again through the transmission grating 530 and the lens 510 to the second output port P_DR, and is output from the second output port P_DR.

[0116] The propagation path of the reflected light of the second signal component of the add signal by the second reflecting element 172 is optically coupled to the first output port P_TH. As in the other embodiments, this optical coupling is realized by adjusting the relative position of the second input port P_AD with respect to the first input port P_IN in the X direction.

[0117] The second signal component of the add signal reflected by the second reflective element 172 passes through the lens 510 and the transmissive diffraction grating 530, is reflected by the movable mirror 540, and propagates again through the transmissive diffraction grating 530 and the lens 510 to the first output port P_TH, and is output from the first output port P_TH.

[0118] According to this embodiment, the IN signal and ADD signal can be input to one of the multiple reflective mirrors 570 in the mirror array 560 by controlling the reflective surface of the movable mirror 540, without displacing the mirror array 260 in the X direction as in the second embodiment.

[0119] According to this embodiment, since the internal structure of the optical multiplexer 500 for achieving wavelength tunability is simple, the failure rate can be reduced and the reliability of stable operation can be improved compared to optical multiplexers including WSS.

[0120] Although the exemplary embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described exemplary embodiments and can adopt various aspects.

[0121] For example, the technical concept of the mirror array 260 of the second embodiment may be applied to the optical multiplexer 300 of the third embodiment or the optical multiplexer of the fourth embodiment, so that the optical multiplexers 300 and 400 may be configured as tunable optical multiplexers.

[0122] The function of one component in the above embodiments may be distributed among multiple components. The functions of multiple components may be integrated into one component. Part of the configuration of the above embodiments may be omitted. At least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments. All aspects included in the technical idea identified from the wording of the claims are embodiments of the present disclosure.

Claims

1. A first input port; A second input port; and an optical dispersion element provided in a propagation path of a first input light from the first input port and a second input light from the second input port, and configured to separate each of the first input light and the second input light into a plurality of wavelength components by dispersing the first input light and the second input light in a predetermined wavelength dispersion direction; a reflecting mirror including: a first reflecting element for reflecting a group of wavelength components corresponding to a first wavelength band among the plurality of wavelength components separated by the optical dispersion element; and a second reflecting element for reflecting a group of wavelength components corresponding to a second wavelength band different from the first wavelength band in a direction different from that of the group of wavelength components corresponding to the first wavelength band of a corresponding input light; a first output port provided in a propagation path of a first reflected light, the first reflected light being a wavelength component of the first input light that corresponds to the first wavelength band, reflected by a group of the first reflecting elements, and configured to output the first reflected light; a second output port provided in a propagation path of second reflected light, which is light of a wavelength component of the first input light corresponding to the second wavelength band reflected by a group of the second reflecting elements, and configured to output the second reflected light; Equipped with the reflecting mirror is configured to reflect incident light in a direction different from the incident direction, and the first reflecting element and the second reflecting element are arranged such that the first reflected light and the second reflected light propagate apart in a direction perpendicular to the wavelength dispersion direction; the second input port is disposed at a position spaced apart from the first input port in a direction perpendicular to the chromatic dispersion direction, and at a position where a third reflected light, which is a reflected light of a wavelength component of the second input light corresponding to the second wavelength band by a group of the second reflecting elements, is optically coupled to the first output port and output from the first output port; a mirror array including a plurality of reflective mirrors, each of the reflective mirrors including the first reflective element and the second reflective element; a drive element for displacing the mirror array; a controller configured to control the positioning of the mirror array through the drive elements; Equipped with each of the plurality of reflecting mirrors is a reflecting mirror in which the first reflecting element and the second reflecting element are arranged so that the combinations of the first wavelength band and the second wavelength band are different from each other; The controller is an optical multiplexer that controls the arrangement of the mirror array so that the first input light and the second input light dispersed by the optical dispersion element are selectively incident on a specified one of the plurality of reflecting mirrors.

2. A first input port; A second input port; and an optical dispersion element provided in a propagation path of a first input light from the first input port and a second input light from the second input port, and configured to separate each of the first input light and the second input light into a plurality of wavelength components by dispersing the first input light and the second input light in a predetermined wavelength dispersion direction; a reflecting mirror including: a first reflecting element for reflecting a group of wavelength components corresponding to a first wavelength band among the plurality of wavelength components separated by the optical dispersion element; and a second reflecting element for reflecting a group of wavelength components corresponding to a second wavelength band different from the first wavelength band in a direction different from that of the group of wavelength components corresponding to the first wavelength band of a corresponding input light; a first output port provided in a propagation path of a first reflected light, the first reflected light being a wavelength component of the first input light that corresponds to the first wavelength band, reflected by a group of the first reflecting elements, and configured to output the first reflected light; a second output port provided in a propagation path of second reflected light, which is light of a wavelength component of the first input light corresponding to the second wavelength band reflected by a group of the second reflecting elements, and configured to output the second reflected light; Equipped with the reflecting mirror is configured to reflect incident light in a direction different from the incident direction, and the first reflecting element and the second reflecting element are arranged such that the first reflected light and the second reflected light propagate apart in a direction perpendicular to the wavelength dispersion direction; the second input port is disposed at a position spaced apart from the first input port in a direction perpendicular to the chromatic dispersion direction, and at a position where a third reflected light, which is a reflected light of a wavelength component of the second input light corresponding to the second wavelength band by a group of the second reflecting elements, is optically coupled to the first output port and output from the first output port; a mirror array including a plurality of reflective mirrors, each of the reflective mirrors including the first reflective element and the second reflective element; an optical deflector provided between the mirror array and the optical dispersion element, the optical deflector being configured to change a propagation direction of the first input light and the second input light dispersed by the optical dispersion element to the mirror array; a controller that controls the propagation direction by controlling the optical deflector; Equipped with each of the plurality of reflecting mirrors is a reflecting mirror in which the first reflecting element and the second reflecting element are arranged so that the combinations of the first wavelength band and the second wavelength band are different from each other; The controller is an optical multiplexer that controls the optical deflector so that the first input light and the second input light dispersed by the optical dispersion element are selectively incident on a specified one of the plurality of reflecting mirrors.

3. the optical deflector is a movable mirror, The controller controls the angle of the reflecting surface of the movable mirror to 3. An optical multiplexer according to claim 2, which controls the propagation direction.

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