Photonic switch with multi-wavelength routing capability

Abstract

The invention relates to a photonic switch with multi-wavelength routing capability. Various embodiments disclosed herein describe photonic switches. The controllable photonic switch may be configured to have asymmetry and different doping levels that simultaneously route light of two different wavelengths through a wavelength dependent phase shifter. In some examples, the controllable photonic switch includes a waveguide having an asymmetric cross-sectional shape. In other examples, the controllable photonic switch selectively routes light of different wavelengths to different outputs of the controllable photonic switch.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 540,991, filed on September 28, 2023, under 35 U.S.C. §119(e), the contents of which are incorporated herein by reference as if fully disclosed herein. Technical Field

[0003] The present disclosure generally relates to photonic switches and phase shifters for use in these photonic switches that simultaneously and independently route light of different wavelengths. More specifically, the photonic switches can independently route multiple wavelengths of light via phase shifters having different wavelength dependencies. Background Art

[0004] Controllable photonic switches are often used in photonic integrated circuits to selectively route light to different optical paths within the photonic integrated circuit. In some examples, the photonic switch may incorporate a phase shifter that selectively modulates the phase of light carried by the waveguide of the photonic switch and thereby adjusts how much light is received at each output of the photonic switch. The phase shift may be further adjusted to account for the wavelength of light received by the photonic switch, but existing photonic switches are only capable of tuning for a single wavelength at a time. Therefore, it may be desirable to provide a controllable photonic switch that is capable of adjusting the routing of multiple wavelengths of light received by the controllable photonic switch. Summary of the invention

[0005] Described herein are photonic integrated circuits and optical devices such as controllable photonic switches that may be incorporated as part of a photonic integrated circuit, the controllable photonic switch including one or more phase shifters.

[0006] Some embodiments relate to a photonic integrated circuit comprising: a substrate having a top surface; a waveguide supported on the top surface of the substrate, wherein a section of the waveguide has a cross-sectional shape that is asymmetric in a direction parallel to the top surface and includes a first doped region and a second doped region that form a diode. A phase shifter comprises: a diode; a first conductive trace electrically connected to the first doped region; a second conductive trace electrically connected to the second doped region; and a control circuit configured to drive current through the diode via the first conductive trace and the second conductive trace to introduce a wavelength-dependent phase shift to light traveling through the section of the waveguide. In some variations, the diode is a PN diode. In some variations, the waveguide is a rib waveguide.

[0007] In some variations, the cross-sectional shape of a section of the waveguide includes a first segment having a first height, a second segment having a second height, and a third segment having a third height. Additionally or alternatively, the second segment is positioned between the first segment and the third segment, and the third height is greater than the first height and less than the second height.

[0008] In some variations, the interface between the first doped region and the second doped region is positioned in the first segment. In some of these variations, the cross-sectional area of ​​the second doped region is greater than the cross-sectional area of ​​the first doped region. Additionally or alternatively, the interface between the first doped region and the second doped region is positioned in the second segment. In some variations, the cross-sectional area of ​​the second doped region is equal to the cross-sectional area of ​​the first doped region. In some of these variations, the interface between the first doped region and the second doped region is positioned in the third segment. Additionally or alternatively, the cross-sectional area of ​​the first doped region is greater than the cross-sectional area of ​​the second doped region. In some variations, the first conductive trace is electrically connected to the first segment. Additionally or alternatively, the second conductive trace is electrically connected to the third segment.

[0009] Other embodiments relate to a photonic integrated circuit, the photonic integrated circuit comprising a controllable switch, the controllable switch comprising a first coupler having a first input, a second input, a first output, and a second output. The second coupler comprises a third input, a fourth input, a third output, and a fourth output. The first pin connects the first output of the first coupler to the third input of the second coupler. The second pin connects the second output of the first coupler to the fourth input of the second coupler. The controllable switch comprises a first phase shifter having a first wavelength dependency and a second phase shifter having a second wavelength dependency different from the first wavelength dependency. The first phase shifter and the second phase shifter are each positioned between the first coupler and the second coupler, and the controllable switch is configured to simultaneously receive light of a first wavelength and light of a second wavelength via the first coupler. The first phase shifter and the second phase shifter can be controlled to independently route light of a first wavelength to a first selection of a third output and a fourth output, and to route light of a second wavelength to a second selection of a third output and a fourth output.

[0010] In some variations, the photonic integrated circuit includes a light source unit including one or more light sources configured to generate light of a first wavelength and light of a second wavelength. In some of these variations, a controller is configured to control a first phase shifter to apply a first phase shift to the light of the first wavelength and a second phase shift to the light of the second wavelength according to a first wavelength dependency. The controller may simultaneously control a second phase shifter to apply a third phase shift to the light of the first wavelength and a fourth phase shift to the light of the second wavelength according to a second wavelength dependency. The first phase shift and the third phase shift route the light of the first wavelength from the first coupler to a first selection of a third output terminal and a fourth output terminal. In some variations, the second phase shift and the fourth phase shift route the light of the second wavelength from the first coupler to a second selection of a third output terminal and a fourth output terminal.

[0011] In some variations, the first phase shifter is positioned to change the phase of light traveling through the first pin. Additionally or alternatively, the second phase shifter is positioned to change the phase of light traveling through the second pin. In some variations, the first choice of the third output terminal and the fourth output terminal is the third output terminal. In some of these examples, the second choice of the third output terminal and the fourth output terminal is the fourth output terminal. In other variations, the first choice of the third output terminal and the fourth output terminal is the third output terminal and the fourth output terminal. In some of these variations, the second choice of the third output terminal and the fourth output terminal is the third output terminal and the fourth output terminal.

[0012] In other embodiments, a method of operating a controllable switch having a set of inputs and a set of outputs, and comprising a first coupler, a second coupler, and a plurality of phase shifters positioned between the first coupler and the second coupler. The method comprises receiving light of a first wavelength at a first input of the set of inputs. The method comprises simultaneously receiving light of a second wavelength at a second input of the set of inputs. The method comprises applying a plurality of wavelength-dependent phase shifts between the first coupler and the second coupler using a plurality of phase shifters to independently route light of the first wavelength to a first target selection of the set of outputs and route light of the second wavelength to a second target selection of the set of outputs. The plurality of wavelength-dependent phase shifts are selected using the first input and the second input, the first wavelength and the second wavelength, the first target selection, and the second target selection.

[0013] In addition to the illustrative aspects and embodiments described, further aspects and embodiments will become apparent by reference to the drawings and by study of the following descriptions. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present disclosure will be readily understood through the following detailed description in conjunction with the accompanying drawings, in which like reference numerals represent like structural elements, and in which:

[0015] Figure 1 A schematic diagram of an optical system including a photonic integrated circuit is shown.

[0016] Figure 2A Schematic diagram showing variations of photonic switches suitable for use with the photonic integrated circuits described herein. Figure 2B A schematic diagram of another variation of a photonic switch suitable for use with the photonic integrated circuits described herein is shown.

[0017] Figure 3 Graphs illustrating a comparison of different phase shifts provided by phase shifters having different wavelength dependencies are shown.

[0018] FIG. 4A to FIG. 4E A schematic diagram illustrating the operation of a variation of a 1x2 controllable photonic switch having a single input and two outputs is shown.

[0019] FIG. 5A to FIG. 5E A schematic diagram illustrating the operation of a variation of a 2x2 controllable photonic switch having two inputs and two outputs is shown.

[0020] Fig. 6A and Figure 6B A cross-sectional side view of an example of a waveguide having a symmetrical cross-sectional shape is shown.

[0021] Fig. 7A and Figure 7B A cross-sectional side view of an example of a waveguide having an asymmetric cross-sectional shape is shown.

[0022] FIG. 8A to FIG. 8D A cross-sectional side view of a variation of a carrier-based phase shifter such as described herein is shown, the carrier-based phase shifter including a waveguide having an asymmetric cross-sectional shape.

[0023] 9A to 9D A cross-sectional side view of another variation of a carrier-based phase shifter such as described herein is shown, the carrier-based phase shifter including a waveguide having an asymmetric cross-sectional shape.

[0024] FIG. 10A to FIG. 10D A cross-sectional side view of yet another variation of a carrier-based phase shifter such as described herein is shown, the carrier-based phase shifter including a waveguide having an asymmetric cross-sectional shape.

[0025] Fig.11 A method of operating a controllable switch having a set of inputs and a set of outputs and comprising a first coupler, a second coupler, and a plurality of phase shifters positioned between the first coupler and the second coupler is described.

[0026] It should be understood that the proportions and sizes (relative or absolute) of the various features and elements (and sets and subsets thereof), and the boundaries, spacings, and positional relationships presented therebetween, are provided in the accompanying drawings solely to facilitate understanding of the various embodiments described herein, and therefore may not necessarily be presented or shown to scale and are not intended to indicate any preference or requirement for the illustrated embodiments to exclude the embodiments described in conjunction therewith.

[0027] Directional terms, such as "top", "bottom", "upper", "lower", "front", "rear", "above", "below", "above", "below", "left", "right", "vertical", "horizontal", etc., are used with reference to the orientation of some components in some of the figures described below, and are not intended to be limiting. Since components in various embodiments can be positioned in a plurality of different orientations, directional terms are used for illustrative purposes to demonstrate the relative orientation between components of the systems and devices described herein. Directional terms are intended to be interpreted broadly and therefore should not be interpreted to exclude components oriented in different ways. In addition, as used herein, the phrase "at least one of" following a series of items that separate any of the items in the items with the terms "and" or "or" is to modify the list as a whole, rather than modifying each member of the list. The phrase "at least one of" does not require selection of at least one of each of the listed items; rather, the phrase allows for the meaning of including at least one of any of the items in the items and / or at least one of any combination of the items and / or at least one of each of the items in the items. For example, the phrase "at least one of A, B, and C" or "at least one of A, B, or C" each refers to only A, only B, or only C; any combination of A, B, and C; and / or one or more of each of A, B, and C. Similarly, it should be understood that the order in which elements are presented for either a combined or separate list provided herein should not be construed to limit the present disclosure to only the order provided. DETAILED DESCRIPTION

[0028] Reference will now be made in detail to the representative embodiments illustrated in the accompanying drawings. It should be understood that the following description is not intended to limit the embodiments to a preferred embodiment. On the contrary, it is intended to cover substitutions, modifications and equivalents that may be included in the essence and scope of the described embodiments defined by the appended claims.

[0029] The following disclosure relates to photonic switches and phase shifters for use in photonic integrated circuits. In some instances, the photonic switches described herein are configured to simultaneously and independently route two or more arbitrary wavelengths of light. Specifically, each wavelength of light can be received from one or more input end waveguides of the photonic switch and can be selectively routed between different output end waveguides of the photonic switch. The photonic switch described herein is configured to include phase shifters with different wavelength dependencies, wherein the phase shifters can be controlled together to separately route different wavelengths of light received by the photonic switch.

[0030] Additionally, examples of phase shifters are described herein and are configured with a diode formed in a section of a waveguide having an asymmetric cross-sectional shape. Such phase shifters can be controlled by a control circuit to drive a current through the diode, thereby introducing a wavelength-dependent phase shift into light traveling through the section of the waveguide. The design of the diode can be selected to achieve a specific wavelength dependency, and one or more of these phase shifters designed with different wavelength dependencies can be incorporated into the photonic switches described herein.

[0031] The following references Figures 1 to 11 However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these drawings is for illustrative purposes only and should not be construed as limiting.

[0032] Figure 1 A schematic diagram of an optical system 100 including a photonic integrated circuit 101 and a controller 106 is shown, the photonic integrated circuit including a light source unit 102 and a photonic switch 104. The light source unit 102 is configured to generate light of multiple wavelengths simultaneously. The light source unit 102 can be optically coupled to the photonic switch 104 through a set of waveguides 108a to 108b, and can simultaneously guide light of multiple wavelengths to the photonic switch 104. The photonic switch 104 is configured to independently route different simultaneously received wavelengths between a first output end 110a and a second output end 110b of the photonic switch 104, as described in more detail herein. Therefore, light of different wavelengths can be independently routed to different parts of the photonic integrated circuit 101 as needed.

[0033] The light source unit 102 includes a group of light sources 102a to 102n, each of which can be selectively operated to emit light of a corresponding group of wavelengths. Each light source can be any component capable of generating light of one or more specific wavelengths, such as a light emitting diode or a laser. The laser may include a semiconductor laser, such as a laser diode (e.g., a distributed Bragg reflector laser, a distributed feedback laser, an external cavity laser), a quantum cascade laser, etc. A given light source may be single frequency (fixed wavelength) or may be tunable to selectively generate one of a plurality of wavelengths (i.e., the light source can be controlled to output different wavelengths at different times). The group of light sources may include any suitable combination of light sources, and may work together to generate light of any wavelength in a plurality of different wavelengths.

[0034] The light source unit 102 is capable of generating a plurality of different wavelengths simultaneously (e.g., operating a plurality of light sources in the set of light sources 102a to 102n to generate light of different wavelengths), but it should be understood that in other instances, the light source unit 102 may be operated to generate light of a single wavelength at a time. In these instances, the photonic switch 104 may also be operated to route the light of the single wavelength to a desired selection of outputs 110a to 110b. The light source unit 102 may be integrated into a photonic integrated circuit 101 including the photonic switch 104, or may be separate from the photonic integrated circuit 101 and couple light into the photonic integrated circuit 101. In addition, the optical system 100 may include additional components (not shown) between the light source of the light source unit 102 and the photonic switch 104, so that light initially generated by the light source unit 102 may be altered before it reaches the photonic switch 104.

[0035] The controller 106 may be used to control the operation of the light source unit 102 (e.g., to simultaneously generate light of multiple wavelengths) and may further control the operation of the photonic switch 104. For example, the controller 106 may control multiple phase shifters (not shown) of the photonic switch 104. The controller 106 may include any combination of hardware, firmware, and / or software (e.g., one or more processors connected to corresponding drive circuits for each of the phase shifters of the light source unit 102 and the photonic switch). The design of the controller for controlling the operation of the light source and the phase shifters will be readily understood by those of ordinary skill in the art.

[0036] In general, the photonic switch 104 includes at least two phase shifters, each of which has a different wavelength dependency. Each phase shifter can be controlled to apply a wavelength-dependent phase shift to light traveling through a waveguide of the photonic switch 104. The collective phase shift applied to light of a given wavelength will control how the wavelength is routed between the output ends 110a, 110b of the photonic switch 104. For example, when the photonic switch simultaneously receives light of a first wavelength and light of a second wavelength at one or more of its input ends through the waveguides 108a to 108b, the controller 106 can control the first phase shifter in the photonic switch 104 to apply a first phase shift to the light of the first wavelength according to the first wavelength dependency and a second phase shift to the light of the second wavelength. The controller 106 can also simultaneously control the second phase shifter in the photonic switch 104 to apply a third phase shift to the light of the first wavelength and a fourth phase shift to the light of the second wavelength according to a different second wavelength dependency. The first phase shift and the third phase shift may control how light of the first wavelength is routed between the output ends 110a, 110b, while the second phase shift and the fourth phase shift may control how light of the second wavelength is routed between the output ends 110a, 110b. These phase shifts may be selected by the controller 106 to allow independently controllable routing of the first wavelength and the second wavelength (e.g., changing the selection of the output ends 110a, 110b for light of the first wavelength may not affect how light of the second wavelength is routed, and vice versa).

[0037] The photonic switch described herein includes a first coupler and a second coupler optically connected by a pair of intermediate waveguides (also referred to herein as "pins"). The first coupler has a set of input terminals used as input terminals of the photonic switch, and the second coupler has a set of output terminals used as output terminals of the photonic switch. The first coupler has a set of output terminals, which are optically connected to a set of input terminals of the second coupler via the pair of intermediate waveguides. In addition, the photonic switch includes at least two phase shifters, each of which is configured to provide a phase shift to the light in the corresponding intermediate waveguide. The phase shifter can be positioned to provide a phase change to the light in the same intermediate waveguide, or can be positioned to provide a phase change to the light in different intermediate waveguides.

[0038] For example, Figure 2A Schematic diagram of a photonic switch 200 suitable for use with the photonic integrated circuits described herein is shown. The photonic switch 200 has a set of input terminals (which are Figure 2AThe variation shown in FIG. 1 includes a first input port 202 and an optional second input port 204) and a set of output ports (including a first output port 214 and a second output port 216). The photonic switch is configured to simultaneously receive light of a first wavelength and light of a second wavelength at one or more input ports in the set of input ports, and can be controlled (e.g., using a controller) to independently route different wavelengths to corresponding selections of the set of input ports. It should be understood that the input and output ports of the photonic switch and the input and output ports of the coupler included in the photonic switch can be configured as corresponding sections of waveguides.

[0039] The photonic switch 200 includes a first coupler 206 optically connected to a second coupler 212 via a pair of intermediate waveguides. Specifically, a first waveguide 207 connects a first output end of the first coupler 206 to a first input end of the second coupler 212, and a second waveguide 209 connects a second output end of the first coupler 206 to a second input end of the second coupler 212. The first coupler 206 includes a set of input ends (each of which serves as a corresponding input end of the photonic switch 200), such that light is received by the photonic switch 200 via the first coupler 206. Similarly, the second coupler 212 includes a set of output ends, each of which serves as an output end of the photonic switch, such that light leaves the photonic switch 200 via the second coupler.

[0040] The photon switch 200 includes a first phase shifter 208 and a second phase shifter 210, the first phase shifter and the second phase shifter being located at Figure 2A The first phase shifter 208 and the second phase shifter 210 can be controlled to route light received by the photonic switch 200 between the output ports 214 and 216. The photonic switch 200 can simultaneously receive light of a first wavelength and light of a second wavelength at the set of input ports. Light of each wavelength can be received by any input port of the photonic switch 200 (for example, the photonic switch 200 can receive two wavelengths at a single input port or can receive different wavelengths at different input ports). In some examples, the photonic switch 200 has only a single input port (for example, the input port 202) that receives light of a first wavelength and light of a second wavelength.

[0041] The photonic switch 200 is operably connected to a controller configured to control both the first phase shifter 208 and the second phase shifter 210. Specifically, the controller may control the first phase shifter 208 and the second phase shifter 210 to provide respective phase shifts determined at least in part by: i) a first wavelength and a second wavelength; ii) an input of the photonic switch that receives the first wavelength; iii) an input of the photonic switch that receives the second wavelength; iv) a first selection of an output to which the first wavelength is to be routed; and v) a second selection of an output to which the second wavelength is to be routed.

[0042] For example, the photonic switch 200 may be incorporated into Figure 1 104). In these examples, as part of the operation of the optical system 100, the controller 106 can control the light source unit 102 to generate light of the first wavelength and the second wavelength so that the light is directed to the photonic switch 200. In some examples, the photonic switch 200 can always receive the light at the same input (e.g., light of the first wavelength is always directed to the first selection of inputs, and light of the second wavelength is always directed to the second selection of inputs). In other examples, the selection of inputs can change dynamically based on the operation of the optical system 100. Thus, when operating the photonic switch 200, the controller 106 will have information specifying: i) the first wavelength and the second wavelength currently being routed to the photonic switch 200; ii) the input of the photonic switch 200 that is receiving light of the first wavelength; and iii) the input of the photonic switch 200 that is receiving light of the second wavelength. Additionally, the controller 106 will also have information specifying: iv) a first target selection of an output to which the first wavelength is to be routed; and v) a second target selection of an output to which the second wavelength is to be routed.

[0043] Using this information, the controller 106 can determine control signals to be applied to the first phase shifter 208 and the second phase shifter 210 so that light of the first wavelength will be routed by the photonic switch 200 to the first destination selection of the output terminal, and light of the second wavelength will be routed by the photonic switch 200 to the second destination selection of the output terminal. Specifically, the first phase shifter 208 will provide a first phase shift to any light of the first wavelength passing through the first waveguide 207, and will provide a second phase shift to any light of the second wavelength passing through the first waveguide 207. Because the first phase shifter 208 has a first wavelength dependency, the first phase shift will be different from the second phase shift (e.g., the first phase shifter will phase shift the first wavelength and the second wavelength by different amounts). Similarly, the second phase shifter 210 will provide a third phase shift to any light of the first wavelength passing through the first waveguide 207, and will provide a fourth phase shift to any light of the second wavelength passing through the first waveguide 207. Because the first phase shifter 208 has a second wavelength dependency, the third phase shift will be different from the fourth phase shift (e.g., the second phase shifter will phase shift the first wavelength and the second wavelength by different amounts). The controller 106 may select these phase shifts to achieve a desired routing of the first wavelength and the second wavelength, for example, with respect to Figures 3 to 5E Described in more detail.

[0044] The first phase shifter 208 and the second phase shifter 210 can be any suitable phase shifters capable of providing phase shifts with different wavelength dependencies. Examples of suitable phase shifters that can be designed to have wavelength dependency include, for example, thermo-optical phase shifters, carrier-based phase shifters, and optomechanical phase shifters. In some examples, the first phase shifter 208 and the second phase shifter 210 can be the same type of phase shifter (e.g., both are carrier-based phase shifters, but have different wavelength dependencies) or can be different types of phase shifters (e.g., one is a carrier-based phase shifter and the other is a thermo-optical phase shifter).

[0045] Figure 2B Schematic diagram of another variation of a photonic switch 201 suitable for use with the photonic integrated circuits described herein is shown. The photonic switch 201 is configured and labeled as Figure 2A The photonic switch 200 is the same as the photonic switch 200 except that the first phase shifter 208 and the second phase shifter 210 are positioned to adjust the phase of light in different waveguides. Specifically, the first phase shifter 208 is located on the first waveguide 207, and the second phase shifter 210 is located on the second waveguide 209. FIG. 4A to FIG. 5E An example of the described photonic switch is shown similar to Figure 2B The photonic switch 201 is configured as shown, but it should be understood that the same operating principles can be applied to Figure 2A Photonic switch 200.

[0046] Figure 3A graph 300 comparing phase shifts provided by two phase shifters having different wavelength dependencies is shown. Specifically, dashed line 302 represents a first wavelength dependency of the phase shift provided by a first phase shifter over a wavelength range of light. Solid line 304 represents a second wavelength dependency of the phase shift provided by a second phase shifter over the same wavelength range of light. Figure 3 An arbitrary wavelength range spanning 1 micron is shown in , but it will be appreciated that the phase shifters described herein may be designed to have wavelength dependence over any suitable wavelength range to be received by the photonic switches described herein.

[0047] Specifically, the first wavelength correlation 302 and the second wavelength correlation 304 are Figure 3 is shown as being normalized relative to a first wavelength (e.g., wavelength N). Figure 3 In the example shown, when the first phase shifter is used to shift the phase of light in the waveguide, light at a wavelength of N microns will be phase shifted by a first amount, and light at a wavelength of N+1 microns will be phase shifted by a second amount, the second amount being approximately 1.8 times the first amount. Similarly, when the second phase shifter is used to shift the phase of light in the waveguide, light at a wavelength of N microns will be phase shifted by a third amount, and light at a wavelength of N+1 microns will be phase shifted by a fourth amount, the fourth amount being approximately 0.6 times the third amount. Thus, when the first phase shifter and the second phase shifter are used as part of a photonic switch to simultaneously route light at wavelengths N and N+1 microns, the phase shifts can be selected such that the first amount, the second amount, the third amount, and the fourth amount achieve the desired routing of the light.

[0048] FIG. 4A to FIG. 4E and FIG. 5A to FIG. 5E Describes different ways in which the photonic switches described herein can simultaneously and independently route light of different wavelengths. For example, FIG. 4A to FIG. 4E An example of how light can be routed when two wavelengths of light are simultaneously received at a single input of a controllable photonic switch 401 is shown. FIG. 4A to FIG. 4E 4 is a 1x2 controllable photonic switch 401 having a single input 402 and two outputs (a first output 414 and a second output 416). FIG. 4A to FIG. 4E The described principles can also be applied to a 2x2 controllable photonic switch with two inputs and two outputs (such as the one described in this paper). Figure 2A and Figure 2B described), wherein a single input port simultaneously receives light of a first wavelength and a second wavelength.

[0049] exist Figure 4A In the embodiment, the controllable photon switch 401 includes a first coupler 406 (eg, a 1x2 coupler, such as Figure 4AAs shown in FIG. 4 , a first coupler (or 2×2 coupler) has a first input 402, a first output 411, and a second output 413 used as inputs to a controllable photonic switch 401. The controllable photonic switch 401 also includes a second coupler 412 (e.g., a 2×2 coupler) having a first input 421, a second input 423, a first output 414, and a second output 416. The couplers described herein may include any suitable coupler capable of splitting light received at one or more inputs between two outputs, including but not limited to a multimode interferometer coupler, an adiabatic coupler, a co-directional coupler, and the like. The first output 414 and the second output 416 of the second coupler 412 are used as outputs of the controllable photonic switch. The controllable photonic switch includes a first pin 403 connecting a first output terminal 411 of a first coupler 406 to a first input terminal 421 of a second coupler 412, and a second pin connecting a second output terminal 413 of the first coupler 406 to a second input terminal 423 of the second coupler 412. It should be understood that the input terminal 402, the first output terminal 414, the second output terminal 416, the first pin 403, and the second pin 405 can all be waveguides.

[0050] The controllable photonic switch 401 includes a first phase shifter 408 positioned and controllable to shift a photon traveling through one of the first pin 403 or the second pin 405 (eg, Figure 4A The second phase shifter 410 is positioned and controllable to selectively provide a first wavelength-dependent phase shift to light traveling through the first pin 403 or the second pin 405 (e.g., as shown in FIG. 4 ). Figure 4A The first phase shifter 408 and the second phase shifter 410 can be controlled (e.g., by the controller 106 as previously described) to selectively route light received by the first input end 402 of the first coupler 406 between the first output end 414 and the second output end 416 of the second coupler.

[0051] Specifically, depending on the wavelength-dependent phase shifts provided by the first phase shifter 408 and the second phase shifter 410, the controllable photonic switch 401 can independently route the light of the first wavelength and the light of the second wavelength simultaneously received at the first input end 402 of the first coupler 406. Specifically, the controller can determine a first selection of output ends for the light of the first wavelength and a second selection of output ends for the light of the second wavelength. For example, the first selection of output ends can include: i) only the first output end 414 of the second coupler 412; ii) only the second output end 416 of the second coupler 412; or iii) a split between the first output end 414 and the second output end 416 of the second coupler 412 (e.g., according to a first target split ratio that can also be selected by the controller). Similarly, the second selection of output ends can include: i) only the first output end 414 of the second coupler 412; ii) only the second output end 416 of the second coupler 412; or iii) a split between the first output end 414 and the second output end 416 of the second coupler 412 (e.g., according to a second target split ratio that can also be selected by the controller).

[0052] When light received at the input 402 of the 1x2 controllable switch 401 is split between the first pin 403 and the second pin 405 according to a predetermined split ratio by the first coupler 406. Similarly, light received by each input of the second coupler 412 is split between the first output 414 and the second output 416 according to a second corresponding predetermined split ratio. The relative amount of light coupled into the first output 414 and the second output 416 depends on at least: 1) the relative amount of light in the first pin 403 and the second pin 405 when the light enters the second coupler 412; 2) the phase difference between the light in the first pin 403 and the second pin 405 when the light enters the second coupler 412; and 3) the wavelength of the light. Therefore, the phase difference between the light in the first pin 403 and the second pin 405 can be independently adjusted for different wavelengths to independently route these different wavelengths.

[0053] In order to independently adjust the phase difference between the first pin 403 and the second pin 405 for different wavelengths, the first phase shifter 408 and the second phase shifter 410 can each apply a wavelength-dependent phase shift to the corresponding pin. Figure 4A In the variation shown in FIG. 4 , the first phase shifter 408 will apply a first phase shift to light of a first wavelength traveling through the first pin 403, and will apply a second phase shift to light of a second wavelength traveling through the first pin 403. The values ​​of the first phase shift and the second phase shift will be related according to the first wavelength dependence of the first phase shifter 408 (e.g., such as with respect to Figure 3405 ). Similarly, the second phase shifter 410 will apply a third phase shift to light of the first wavelength traveling through the second pin 405, and a fourth phase shift to light of the second wavelength traveling through the second pin 405. The values ​​of the third phase shift and the fourth phase shift will be related according to the second wavelength dependency of the second phase shifter 410. Thus, the first phase shift and the third phase shift together at least partially control (e.g., together with any other phase shifts applied to light of the first wavelength as part of the operation of the photonic switch 401) the phase difference between the first pin 403 and the second pin 405 of the light of the first wavelength as it enters the second coupler 412. Similarly, the second phase shift and the fourth phase shift together at least partially control (e.g., together with any other phase shifts applied to light of the second wavelength as part of the operation of the photonic switch 401) the phase difference between the first pin 403 and the second pin 405 of the light of the second wavelength as it enters the second coupler 412.

[0054] Thus, the values ​​of the first phase shift, the second phase shift, the third phase shift, and the fourth phase shift may be selected to route the first wavelength and the second wavelength independently to the first selection and the second selection of outputs, respectively. Figure 4A In the example of , the values ​​of the first phase shift and the third phase shift can be selected so that the light of the first wavelength (represented by arrow 407) has a phase difference of π between the first pin 403 and the second pin 405 when it enters the second coupler 412, which causes the light of the first wavelength 407 to be routed only to the first output end 414. Similarly, the values ​​of the second phase shift and the fourth phase shift can be selected so that the light of the second wavelength (represented by arrow 409) has a phase difference of π between the first pin 403 and the second pin 405 when it enters the second coupler 412, which causes the light of the second wavelength 409 to be routed only to the first output end 414. In this way, both the first wavelength 407 and the second wavelength 409 are routed to the first output end 414 at the same time.

[0055] In contrast, in order to simultaneously route the first wavelength light 407 and the second wavelength light 409 only to the second output port 416, such as Figure 4B As shown, the first phase shift and the third phase shift may be selected so that the light 407 of the first wavelength has a phase difference of 0 between the first pin 403 and the second pin 405 when it enters the second coupler 412. The values ​​of the second phase shift and the fourth phase shift may be selected so that the light 409 of the second wavelength has a phase difference of 0 between the first pin 403 and the second pin 405 when it enters the second coupler 412.

[0056] In other examples, the photonic switch 401 can be configured to route the first wavelength of light and the second wavelength of light to different output ends. For example, the first phase shift and the third phase shift can be selected so that when the first wavelength of light 407 and the second wavelength of light 409 enter the second coupler, the first wavelength of light has a phase difference of π between the first pin 403 and the second pin 405, and the second wavelength of light has a phase difference of 0 between the first pin and the second pin. In these examples, the first wavelength of light 407 will only be routed to the first output end 414, and the second wavelength of light 409 will only be routed to the second output end 416, such as Figure 4C shown.

[0057] In yet other examples, the photonic switch 401 may be controlled to split one or both of the wavelengths between the first output and the second output. Figure 4D As shown, the first phase shift and the third phase shift can be selected so that the light 407 of the first wavelength has a first phase difference when it enters the second coupler 412, and the first phase difference is selected to split the light 407 of the first wavelength between the first output end 414 and the second output end 416 according to the first target split ratio. Similarly, the second phase shift and the fourth phase shift can be selected so that the light 409 of the second wavelength has a second phase difference when it enters the second coupler 412, and the second phase difference is selected to split the light of the second wavelength between the first output end 414 and the second output end 416 according to the second target split ratio. In this way, the first output end 414 and the second output end 416 each simultaneously receive corresponding portions of the light 407 of the first wavelength and the light 409 of the second wavelength. The first phase difference and the second phase difference can be selected so that the first target split ratio and the second target split ratio are the same, or so that the first target split ratio and the second target split ratio are different.

[0058] In another example, if Figure 4E As shown, the first phase shift and the third phase shift may be selected so that the light 407 of the first wavelength has a first phase difference when it enters the second coupler 412, and the first phase difference is selected to split the light of the first wavelength between the first output end 414 and the second output end 416 according to the first target split ratio. The second phase shift and the fourth phase shift may be selected so that the light 409 of the second wavelength has a second phase difference when it enters the second coupler 412, and the second phase difference is selected to route the light to only one of the first output end 414 or the second output end 416 (e.g., as shown in FIG. 1 ). Figure 4E (See FIG. 4 for a schematic diagram of a first embodiment of the present invention.) In this manner, light of a first wavelength may be split between the output ports, while light of a second wavelength is routed to a single output port.

[0059] The controllable photonic switch 401 can dynamically adjust the operation of the first phase shifter 408 and the second phase shifter 410 as the first wavelength and the second wavelength and / or the target output ends selected for these wavelengths change. Therefore, some configurations of the controllable photonic switch 401 can have significant flexibility in routing multiple different wavelength pairs to different selections of the target output ends at different times. This may require that the first phase shifter 408 and the second phase shifter 410 can be controlled to provide a range of different phase shifts. In other examples, the controllable photonic switch 401 can be designed to work in a more limited set of environments (e.g., a limited number of wavelength pairs and a limited set of target output ends), in which case the design of the first phase shifter 408 and / or the second phase shifter 410 can be simplified. For example, in some variations, one or both of the phase shifters 408, 410 can be configured as a binary switch that can be controlled by a controller to be "disconnected" by placing a movable structure (not shown) in a first position or "connected" by placing the movable structure in a second position. In these examples, the phase shifters may be capable of applying a first set of wavelength-dependent phase shifts when the binary switch is off, and a second set of wavelength-dependent phase shifts when the binary switch is on. Switching these phase shifters between the off and on states can change how the photonic switch 401 routes light between its outputs.

[0060] When the photon switch includes multiple input terminals, the same as above can be applied. FIG. 4A to FIG. 4E Principles similar to those described above can be used to simultaneously and independently route light received by different inputs of a photonic switch. For example, FIG. 5A to FIG. 5E The operation of a variation of a 2x2 controllable photonic switch 501 having two inputs (a first input 502 and a second input 504) and two outputs (a first output 514 and a second output 516) is shown.

[0061] exist Figure 5A, the controllable photon switch 501 includes a first coupler 506 (e.g., a 2x2 coupler) and a second coupler 512 (e.g., a 2x2 coupler), each of which has two input ends and two output ends. The first input end and the second input end of the first coupler 506 are used as the first input end 502 and the second input end 504 of the controllable photon switch 501. The first pin 503 connects the first output end of the first coupler 506 to the first input end of the second coupler 512, and the second pin 505 connects the first output end of the first coupler 506 to the first input end of the second coupler 512. The first output end and the second output end of the second coupler 512 are used as the first output end 514 and the second output end 516 of the controllable photon switch 501. It should be understood that the first input end 502, the second input end 504, the first output end 514, the second output end 516, the first pin 503 and the second pin 505 can all be waveguides.

[0062] The controllable photonic switch 501 includes a first phase shifter 508 positioned and controllable to selectively provide a first wavelength-dependent phase shift to light traveling through one of the first pin 503 or the second pin 505. A second phase shifter 510 is positioned and controllable to selectively provide a second wavelength-dependent phase shift to light traveling through one of the first pin 503 or the second pin 505. The first phase shifter 508 and the second phase shifter 510 can be controlled (e.g., by the controller 106 as previously described) to selectively route light received by the photonic switch 501.

[0063] The light received by the first input terminal 502 and the second input terminal 504 of the 2x2 controllable switch 501 is split between the first pin 503 and the second pin 505 according to a first predetermined split ratio by the first coupler 506. Similarly, the light received by each input terminal of the second coupler 512 is split between the first output terminal 514 and the second output terminal 516 according to a corresponding second predetermined split ratio. FIG. 4A to FIG. 4E As with the photonic switch 401 of FIG. 4 , the relative amount of light coupled into the first output 514 and the second output 516 depends on at least: 1) the relative amount of light in the first pin 503 and the second pin 505 when the light enters the second coupler 512; 2) the phase difference between the light in the first pin 503 and the second pin 505 when the light enters the second coupler 512; and 3) the wavelength of the light. Therefore, the phase difference between the light in the first pin 503 and the second pin 505 can be independently adjusted for different wavelengths to independently route these different wavelengths.

[0064] In order to independently adjust the phase difference between the first pin 503 and the second pin 505 for different wavelengths, the first phase shifter 508 and the second phase shifter 510 can each apply a wavelength-dependent phase shift to the corresponding pin. These phase shifters 508, 510 can be as described herein with respect to FIG. 4A to FIG. 4E Operation in any of the described manners (e.g., such that the first phase shifter 508 applies a first phase shift and a third phase shift to a pair of wavelengths, and the second phase shifter 510 applies a second phase shift and a fourth phase shift to the pair of wavelengths), except that the selection of a target phase difference for a given wavelength may depend on which input of the photonic switch 501 receives light of that wavelength.

[0065] For example, in Figure 5A , light of a first wavelength (indicated by arrow 507) can enter the photonic switch 501 along the first input port 502, and light of a second wavelength (indicated by arrow 509) can enter the photonic switch 501 along the second input port 504. Figure 5A , the values ​​of the first phase shift and the third phase shift may be selected such that the light 507 of the first wavelength has a phase difference of π between the first pin 503 and the second pin 505 when it enters the second coupler 512, which results in the light 507 of the first wavelength being routed only to the first output end 514. The values ​​of the second phase shift and the fourth phase shift may be selected such that the light 509 of the second wavelength has a phase difference of 0 between the first pin 503 and the second pin 505 when it enters the second coupler 512, which also results in the light 509 of the second wavelength being routed only to the first output end 514. In this way, both the first wavelength 507 and the second wavelength 509 are routed to the first output end 514 simultaneously.

[0066] In contrast, in order to simultaneously route the first wavelength light 507 and the second wavelength light 509 only to the second output port 516, such as Figure 5B As shown, the first phase shift and the third phase shift may be selected so that the light 507 of the first wavelength has a phase difference of 0 between the first pin 503 and the second pin 505 when it enters the second coupler 512. The values ​​of the second phase shift and the fourth phase shift may be selected so that the light 509 of the second wavelength has a phase difference of π between the first pin 503 and the second pin 505 when it enters the second coupler 512.

[0067] In other examples, the photonic switch 501 can be configured to route the first wavelength of light and the second wavelength of light to different output ends. For example, the first phase shift and the third phase shift can be selected so that when the first wavelength of light 507 and the second wavelength of light 509 enter the second coupler, the first wavelength of light has a phase difference of π between the first pin 503 and the second pin 505, and the second wavelength of light has a phase difference of π between the first pin and the second pin. In these examples, the first wavelength of light 507 will only be routed to the first output end 514, and the second wavelength of light 509 will only be routed to the second output end 516, such as Figure 5C shown.

[0068] In yet other examples, the photonic switch 501 may be controlled to split one or both of the wavelengths between the first output and the second output. Figure 5D As shown, the first phase shift and the third phase shift can be selected so that the light 507 of the first wavelength has a first phase difference when it enters the second coupler 512, and the first phase difference is selected to split the light of the first wavelength between the first output end 514 and the second output end 516 according to the first target split ratio. Similarly, the second phase shift and the fourth phase shift can be selected so that the light 509 of the second wavelength has a second phase difference when it enters the second coupler 512, and the second phase difference is selected to split the light of the second wavelength between the first output end 514 and the second output end 516 according to the second target split ratio. In this way, the first output end 514 and the second output end 516 each simultaneously receive corresponding parts of the light 507 of the first wavelength and the light 509 of the second wavelength. The first phase difference and the second phase difference can be selected so that the first target split ratio and the second target split ratio are the same, or so that the first target split ratio and the second target split ratio are different.

[0069] In another example, if Figure 5E As shown, the first phase shift and the third phase shift may be selected so that the light 507 of the first wavelength has a first phase difference when it enters the second coupler 512, and the first phase difference is selected to split the light of the first wavelength between the first output end 514 and the second output end 516 according to the first target split ratio. The second phase shift and the fourth phase shift may be selected so that the light 509 of the second wavelength has a second phase difference when it enters the second coupler 512, and the second phase difference is selected to route the light to only one of the first output end 514 or the second output end 516 (e.g., as Figure 5E (See FIG. 5A for routing to only the second output port 516). In this manner, light of a first wavelength may be split between the output ports, while light of a second wavelength is routed to a single output port.

[0070] In some examples, phase shifters as described herein can be formed from portions of a waveguide having an asymmetric cross-sectional shape. These phase shifters can be designed to have a specific wavelength dependency and can be incorporated into the embodiments described herein with respect to Figures 1 to 5E In the photonic switch described herein. Specifically, the use of an asymmetric cross-sectional shape can affect how the light mode is contained in the waveguide, which can affect the wavelength dependence of the resulting phase shifter. For example, FIG. 6A to FIG. 6B An example of a waveguide having a symmetrical cross-sectional shape is shown. Specifically, Fig. 6A A portion of a photonic integrated circuit 600 is shown that includes a ridge waveguide 602 having a symmetrical cross-sectional shape. The bottom side of the waveguide 602 may be positioned on a cladding layer (not shown), which in turn may be supported on a top surface of a substrate (not shown) (directly or via one or more intermediate layers). Additionally, one or more other surfaces of the waveguide 602 may be covered by a cladding layer (e.g., cladding layer 604). Figure 6B A waveguide 602 is shown carrying two optical modes, specifically a first optical mode of light of a first wavelength 606 and a second optical mode of light of a second wavelength 608 that is longer than the first wavelength 606. In these examples, both the first optical mode and the second optical mode are fundamental modes. The shorter first wavelength 606 is better confined within the waveguide 602, and due to the symmetrical cross-sectional shape of the waveguide 602, both wavelengths 606, 608 have symmetrical mode shapes.

[0071] FIG. 7A to FIG. 7B An example of a waveguide having an asymmetric cross-sectional shape is shown. For example, Fig. 7A A photonic integrated circuit 700 is shown including a ridge waveguide 702 having an asymmetric cross-sectional shape. FIG. 6A to FIG. 6B As with waveguide 602, one or more surfaces of waveguide 702 may be positioned against a cladding (e.g., cladding 704) to help confine light within waveguide 702. FIG. 7A to FIG. 7B In the illustrated variation, the waveguide 702 includes a strip portion 721 positioned between a first shoulder 705 and a second shoulder 707. Specifically, the strip portion 721 forms a first portion of the waveguide 702 having a first height 723, the first shoulder 705 forms a second portion of the waveguide 702 having a second height 709, and the second shoulder 707 forms a third portion of the waveguide 702 having a third height 711. FIG. 7A to FIG. 7B In the illustrated variation, first height 723 is greater than second height 709 , and second height 709 is greater than third height 711 .

[0072] Figure 7BA waveguide 702 is shown carrying two optical modes, specifically a first optical mode of light 706 at a first wavelength and a second optical mode of light 708 at a second wavelength that is longer than the first wavelength 706. Due to the asymmetric shape of the waveguide 702, the modes of both the first wavelength 706 and the longer wavelength 708 are asymmetric. Because the first wavelength 706 is better confined within the strip portion 721 of the waveguide 702, a greater proportion of the mode of the second wavelength 708 will extend into the first shoulder 705. This is achieved in a custom-made combination. FIG. 7A to FIG. 7B The waveguide 702 is useful when the phase shifter has wavelength dependence.

[0073] FIG. 8A to FIG. 8D An example of a carrier-based phase shifter 800 is shown that includes a segment of a waveguide 801 having an asymmetric cross-sectional shape. The phase shifter 800 may be formed as part of a photonic integrated circuit as shown herein. Fig. 8A As shown, a section of a waveguide 801 is configured to form a diode. The waveguide 801 has a first doped region 802 and a second doped region 804 that form a diode. For example, the first doped region 802 may be doped with a first material to form a P-doped region, and the second doped region 804 may be doped with a second material to form an N-doped region. Fig. 8A In the variation shown, the first doped region 802 and the second doped region 804 form a PN diode. It should be understood that one or more portions of the waveguide 801 (eg, such as the undoped region 806 located outside the diode) may remain undoped.

[0074] To operate the phase shifter 800, a first conductive trace 810 is located on and electrically connected to a portion of the first doped region 802, and a second conductive trace 808 is located on and electrically connected to a portion of the second doped region 804. A controller described herein can drive current through the photonic integrated circuit via the first conductive trace 810 and the second conductive trace 808 to introduce a wavelength-dependent phase shift to light traveling through the waveguide 801.

[0075] The waveguide 801 may have an asymmetric cross-sectional shape, such as Fig. 8A 801 is asymmetric in a direction 841 parallel to a top surface of a substrate (not shown) on which the waveguide 801 is supported. In these variations, the waveguide 801 is configured as an asymmetric ridge waveguide having a strip portion 821 positioned between a first shoulder 805 and a second shoulder 807. Specifically, the strip portion 821 forms a first portion of the waveguide 801 having a first height 823, the first shoulder 805 forms a second portion of the waveguide 801 having a second height 809, and the second shoulder 807 forms a third portion of the waveguide 801 having a third height 811. Fig. 8AIn the illustrated variation, first height 823 is greater than second height 809, and second height 809 is greater than third height 811. In these variations, first conductive trace 810 may be connected to first shoulder 805, and second conductive trace 808 may be connected to second shoulder 807, such that current driven through the diode flows through strip portion 821.

[0076] The asymmetric shape of waveguide 801 may have wavelength-dependent confinement of light, such as described herein with respect to Figure 7B as described. Figure 8B A waveguide 801 is shown carrying two light modes, specifically a first optical mode of light 812 at a first wavelength and a second optical mode of light 814 at a second wavelength that is longer than the first wavelength 812. These modes may represent two wavelengths of light received by a photonic switch as described herein. When the phase shifter 800 is operated to drive a current through the diode, the first wavelength 812 and the second wavelength 814 will receive different phase shifts.

[0077] Specifically, in FIG. 8A to FIG. 8C In the configuration shown, the phase shifter 800 will apply a greater phase shift to longer wavelength light 814 than to shorter wavelength light 812. When a current is driven through a diode (e.g., between the first conductive trace 810 and the second conductive trace 808), such as Figure 8C As shown, a depletion region 816 will form at the interface between the first doped region 802 and the second doped region 804. This depletion will locally change the refractive index of the waveguide 801, and this in turn can change the phase of light traveling through the depletion region 816.

[0078] For example, Fig.8D A first wavelength of light 812 and a second wavelength of light 814 are shown traveling through the waveguide 801 when the diode is operated to generate a depletion region 816. FIG. 8A to FIG. 8D In the illustrated variation, the interface between the first doped region and the second doped region is positioned in the first shoulder 805. Thus, the depletion region 816 can be formed at least partially in the first shoulder 805. In some of these variations, the depletion region 816 is positioned in both the first shoulder 805 and the strip portion 821. Because the mode of the second wavelength of light 814 extends further into the first shoulder 805 than the mode of the first wavelength of light 812, a greater percentage of the second wavelength of light 814 will interact in the depletion region 816. Thus, the second wavelength of light 814 will experience a greater phase shift than the first wavelength of light 812. Thus, a controller (e.g., controller 106) can drive current through the photonic integrated circuit via the first conductive trace 810 and the second conductive trace 808 to introduce a wavelength-dependent phase shift to the light traveling through the waveguide 800.

[0079] In other variations, the interface between the first doped region and the second doped region is positioned in the strip portion 821, but is positioned sufficiently close to the first shoulder 805 so that a greater percentage of the second wavelength of light 814 will interact in the depletion region 816. In these examples, the phase shifter 800 can still provide a wavelength-dependent phase shift, but with FIG. 8A to FIG. 8D The configuration shown in can have a weaker wavelength dependence than that shown in FIG.

[0080] 9A to 9D Another example of a carrier-based phase shifter 900 is shown, which includes a segment of waveguide 801 having an asymmetric cross-sectional shape. Phase shifter 900 is configured and labeled as Fig. 8A The phase shifter 800 is the same except that 9A to 9D In the configuration shown, the phase shifter 900 can apply an equal phase shift to longer wavelength light 814 as compared to shorter wavelength light.

[0081] exist 9A to 9D In the variation shown, the interface between the first doped region 802 and the second doped region 804 is positioned in the strip portion 821. Thus, the depletion region 816 can be formed in the strip portion 821. Depending on the placement of the interface and the size of the resulting depletion region, the modes of the first wavelength of light 812 and the second wavelength of light 814 can interact equally in the strip portion 821 in the depletion region 816, resulting in equal phase shifts for the two wavelengths of light being the same.

[0082] FIG. 10A to FIG. 10D Another example of a carrier-based phase shifter 1000 is shown, which includes a section of waveguide 801 having an asymmetric cross-sectional shape. Phase shifter 1000 is configured and labeled as Fig. 8A The phase shifter 800 is the same except that FIG. 10A to FIG. 10D In the configuration shown, the phase shifter 1000 will apply a greater phase shift to the shorter wavelength light 812 than to the longer wavelength light 814 .

[0083] exist FIG. 10A to FIG. 10D In the variations shown, the interface between the first doped region 802 and the second doped region 804 is positioned in the second shoulder 807. Thus, the depletion region 816 can be at least partially formed in the second shoulder 807. In some of these variations, the depletion region 816 is positioned in both the second shoulder 807 and the strip portion 821. Because the second wavelength of light 814 extends further into the first shoulder 805 than the first wavelength of light 814, a greater percentage of the first wavelength of light 812 will interact in the depletion region 816. Thus, the first wavelength of light 812 will experience a greater phase shift than the second wavelength of light 814.

[0084] In other variations, the interface between the first doped region and the second doped region is positioned in the strip portion 821, but is positioned sufficiently close to the second shoulder 807 so that a greater percentage of the first wavelength of light 812 will interact in the depletion region 816. In these examples, the phase shifter 800 can still provide a wavelength-dependent phase shift, but with FIG. 10A to FIG. 10D The configuration shown in can have a weaker wavelength dependence than that shown in FIG.

[0085] Fig.11 A method 1100 of operating a controllable switch is described, the controllable switch having a set of inputs and a set of outputs, and including a first coupler, a second coupler, and a plurality of phase shifters positioned between the first coupler and the second coupler. The method 1100 can be performed by any controllable switch described herein. Initially, the method 1100 includes receiving a first wavelength and a second wavelength simultaneously at a set of inputs at step 1102. The light of the first wavelength is different from the light of the second wavelength. At step 1104, the controllable switch applies a plurality of wavelength-dependent phase shifts between the first coupler and the second coupler using a plurality of phase shifters. The light of the first wavelength and the light of the second wavelength are routed to a first target selection of the set of outputs, and the light of the second wavelength is routed to a second target selection of the set of outputs. The plurality of wavelength-dependent phase shifts are selected using the first input and the second input, the first wavelength and the second wavelength, and the first target selection and the second target selection. The controllable switch includes a waveguide supported on a substrate. In some variations, one of the two phase shifters is formed so that a corresponding section of the waveguide has an asymmetric cross-sectional shape in a direction parallel to the top surface of the substrate. A section of the waveguide includes a first doped region and a second doped region forming a diode. The cross-sectional area of ​​the first doped region is equal to the cross-sectional area of ​​the second doped region. In some variations, the cross-sectional area of ​​the first doped region is greater than the cross-sectional area of ​​the second doped region.

[0086] The above description uses specific nomenclature to provide a thorough understanding of the embodiments for explanation. However, it will be apparent to those skilled in the art that, after reading this specification, the embodiments can be practiced without specific details. Therefore, for the purpose of illustration and description, the foregoing description of the specific embodiments described herein is presented. They are not intended to be exhaustive or to limit the embodiments to the precise form disclosed. It will be apparent to those of ordinary skill in the art that, after reading this specification, many modifications and variations are possible in view of the above teachings.

[0087] Implementation examples are described in the following numbered clauses:

[0088] 1. A photonic integrated circuit, comprising:

[0089] A controllable switch, the controllable switch comprising:

[0090] a first coupler having a first input end, a second input end, a first output end, and a second output end;

[0091] a second coupler having a third input, a fourth input, a third output, and a fourth output;

[0092] a first pin connecting the first output terminal of the first coupler to the third input terminal of the second coupler;

[0093] a second pin connecting the second output of the first coupler to the fourth input of the second coupler; and a first phase shifter and a second phase shifter, the first phase shifter having a first wavelength dependency and the second phase shifter having a second wavelength dependency different from the first wavelength dependency, wherein:

[0094] The first phase shifter and the second phase shifter are each positioned between the first coupler and the second coupler,

[0095] The controllable switch is configured to simultaneously receive light of a first wavelength and light of a second wavelength via the first coupler; and the first phase shifter and the second phase shifter are controllable to independently route light of the first wavelength to a first selection of the third output terminal and the fourth output terminal, and to route light of the second wavelength to a second selection of the third output terminal and the fourth output terminal.

[0096] 2. The photonic integrated circuit of clause 1, further comprising:

[0097] A light source unit includes one or more light sources configured to generate light of the first wavelength and light of the second wavelength.

[0098] 3. A photonic integrated circuit according to clause 1 or clause 2, further comprising:

[0099] A controller, the controller being configured to:

[0100] controlling the first phase shifter to apply a first phase shift to light of the first wavelength and a second phase shift to light of the second wavelength according to the first wavelength dependency; and

[0101] The second phase shifter is simultaneously controlled to apply a third phase shift to the light of the first wavelength and a fourth phase shift to the light of the second wavelength according to the second wavelength dependency, wherein:

[0102] The first phase shift and the third phase shift route light of the first wavelength from the first coupler to the first selection of the third output and the fourth output; and

[0103] The second phase shift and the fourth phase shift route light at the second wavelength from the first coupler to the second selection of the third output and the fourth output.

[0104] 4. A photonic integrated circuit according to any of clauses 1 to 3, wherein the first phase shifter is positioned to change the phase of light travelling through the first pin.

[0105] 5. A photonic integrated circuit according to any of clauses 1 to 4, wherein the second phase shifter is positioned to change the phase of light travelling through the second pin.

[0106] 6. A photonic integrated circuit according to any of clauses 1 to 5, wherein the first selection of the third output and the fourth output is the third output.

[0107] 7. A photonic integrated circuit according to any of clauses 1 to 6, wherein the second selection of the third output and the fourth output is the fourth output.

[0108] 8. A photonic integrated circuit according to any of clauses 1 to 7, wherein the first selection of the third output and the fourth output is the third output and the fourth output.

[0109] 9. A photonic integrated circuit according to any of clauses 1 to 8, wherein the second selection of the third output and the fourth output is the third output and the fourth output.

[0110] 10. A photonic integrated circuit, comprising:

[0111] a substrate having a top surface;

[0112] a waveguide supported on the top surface of the substrate, wherein a section of the waveguide has an asymmetric cross-sectional shape in a direction parallel to the top surface and includes a first doped region and a second doped region forming a diode; and

[0113] A phase shifter, the phase shifter comprising:

[0114] the diode;

[0115] a first conductive trace electrically connected to the first doped region;

[0116] a second conductive trace electrically connected to the second doped region; and

[0117] A control circuit is configured to drive current through the diode via the first and second conductive traces to introduce a wavelength-dependent phase shift to light traveling through the segment of the waveguide.

[0118] 11. A photonic integrated circuit according to clause 10, wherein:

[0119] the cross-sectional shape of the section of the waveguide comprises a first segment having a first height, a second segment having a second height, and a third segment having a third height;

[0120] The second section is positioned between the first section and the third section; and

[0121] The third height is greater than the first height and less than the second height.

[0122] 12. A photonic integrated circuit according to any one of clause 10 or clause 11, wherein an interface between the first doped region and the second doped region is located in the first section.

[0123] 13. A photonic integrated circuit according to any of clauses 10 to 12, wherein the cross-sectional area of ​​the second doped region is greater than the cross-sectional area of ​​the first doped region.

[0124] 14. A photonic integrated circuit according to any one of clause 10 or clause 11, wherein an interface between the first doped region and the second doped region is located in the second section.

[0125] 15. A photonic integrated circuit according to any of clauses 10, 11 or 14, wherein a cross-sectional area of ​​the second doped region is equal to a cross-sectional area of ​​the first doped region.

[0126] 16. The photonic integrated circuit of any one of clause 10 or clause 11, wherein an interface between the first doped region and the second doped region is located in the third section.

[0127] 17. A photonic integrated circuit according to any of clauses 10, 11 or 16, wherein a cross-sectional area of ​​the first doped region is greater than a cross-sectional area of ​​the second doped region.

[0128] 18. A photonic integrated circuit according to any of clauses 10 to 17, wherein a first electrically conductive trace is electrically connected to the first segment.

[0129] 19. A photonic integrated circuit according to any of clauses 10 to 18, wherein a second electrically conductive trace is electrically connected to the third segment.

[0130] 20. A photonic integrated circuit according to any of clauses 10 to 19, wherein the diode is a PN diode.

[0131] 21. A photonic integrated circuit according to any of clauses 10 to 20, wherein the waveguide is a ridge waveguide.

[0132] 22. A method of operating a controllable switch having a set of input terminals and a set of output terminals and comprising a first coupler, a second coupler, and a plurality of phase shifters positioned between the first coupler and the second coupler, the method comprising:

[0133] receiving light of a first wavelength at a first input end of the set of input ends;

[0134] simultaneously receiving light of a second wavelength at a second input end of the set of input ends;

[0135] The plurality of phase shifters are used to apply a plurality of wavelength-dependent phase shifts between the first coupler and the second coupler to independently route light of the first wavelength to a first destination selection of the set of output ports and light of the second wavelength to the set of output ports.

[0136] Second destination selection for the group output; where:

[0137] The plurality of wavelength-dependent phase shifts are selected using the first input and the second input, the first wavelength and the second wavelength, the first target selection, and the second target selection.

Claims

1. A photonic integrated circuit, comprising: A controllable switch, the controllable switch comprising: a first coupler having a first input end, a second input end, a first output end, and a second output end; a second coupler having a third input, a fourth input, a third output, and a fourth output; a first pin connecting the first output terminal of the first coupler to the third input terminal of the second coupler; a second pin connecting the second output terminal of the first coupler to the fourth input terminal of the second coupler; and a first phase shifter and a second phase shifter, the first phase shifter having a first wavelength dependency and the second phase shifter having a second wavelength dependency different from the first wavelength dependency, wherein: The first phase shifter and the second phase shifter are each positioned between the first coupler and the second coupler, The controllable switch is configured to simultaneously receive light of a first wavelength and light of a second wavelength via the first coupler; and the first phase shifter and the second phase shifter are controllable to independently route light of the first wavelength to a first selection of the third output terminal and the fourth output terminal, and to route light of the second wavelength to a second selection of the third output terminal and the fourth output terminal.

2. The photonic integrated circuit according to claim 1, further comprising: A light source unit includes one or more light sources configured to generate light of the first wavelength and light of the second wavelength.

3. The photonic integrated circuit according to claim 1 or claim 2, further comprising: A controller, the controller being configured to: controlling the first phase shifter to apply a first phase shift to light of the first wavelength and a second phase shift to light of the second wavelength according to the first wavelength dependency; as well as The second phase shifter is simultaneously controlled to apply a third phase shift to the light of the first wavelength and a fourth phase shift to the light of the second wavelength according to the second wavelength dependency, wherein: The first phase shift and the third phase shift route light of the first wavelength from the first coupler to the first selection of the third output and the fourth output; and The second phase shift and the fourth phase shift route light at the second wavelength from the first coupler to the second selection of the third output and the fourth output.

4. A photonic integrated circuit as claimed in claim 1 or claim 2, wherein the first phase shifter is positioned to change the phase of light travelling through the first pin.

5. A photonic integrated circuit as claimed in claim 1 or claim 2, wherein the second phase shifter is positioned to change the phase of light travelling through the second pin.

6. A photonic integrated circuit according to claim 1 or claim 2, wherein the first selection of the third output terminal and the fourth output terminal is the third output terminal.

7. A photonic integrated circuit according to claim 1 or claim 2, wherein the second selection of the third output terminal and the fourth output terminal is the fourth output terminal.

8. A photonic integrated circuit according to claim 1 or claim 2, wherein the first selection of the third output terminal and the fourth output terminal is the third output terminal and the fourth output terminal.

9. A photonic integrated circuit according to claim 1 or claim 2, wherein the second selection of the third output terminal and the fourth output terminal is the third output terminal and the fourth output terminal.

10. A photonic integrated circuit, comprising: a substrate having a top surface; a waveguide supported on the top surface of the substrate, wherein a section of the waveguide has a cross-sectional shape that is asymmetric in a direction parallel to the top surface and includes a first doped region and a second doped region that form a diode; as well as A phase shifter, the phase shifter comprising: the diode; a first conductive trace electrically connected to the first doped region; a second conductive trace electrically connected to the second doped region; and A control circuit is configured to drive current through the diode via the first and second conductive traces to introduce a wavelength-dependent phase shift to light traveling through the segment of the waveguide.

11. The photonic integrated circuit of claim 10, wherein: the cross-sectional shape of the section of the waveguide comprises a first segment having a first height, a second segment having a second height, and a third segment having a third height; The second section is positioned between the first section and the third section; and The third height is greater than the first height and less than the second height.

12. A photonic integrated circuit according to claim 10 or claim 11, wherein an interface between the first doped region and the second doped region is located in the first section.

13. The photonic integrated circuit of claim 10 or claim 11, wherein the cross-sectional area of ​​the second doped region is greater than the cross-sectional area of ​​the first doped region.

14. A photonic integrated circuit according to claim 10 or claim 11, wherein an interface between the first doped region and the second doped region is located in the second section.

15. The photonic integrated circuit of claim 10 or claim 11, wherein the cross-sectional area of ​​the second doped region is equal to the cross-sectional area of ​​the first doped region.

16. A photonic integrated circuit according to claim 10 or claim 11, wherein an interface between the first doped region and the second doped region is located in the third section.

17. The photonic integrated circuit of claim 10 or claim 11, wherein the cross-sectional area of ​​the first doped region is greater than the cross-sectional area of ​​the second doped region.

18. A photonic integrated circuit as claimed in claim 10 or claim 11, wherein a first conductive trace is electrically connected to the first segment.

19. A photonic integrated circuit as claimed in claim 10 or claim 11, wherein a second conductive trace is electrically connected to the third segment.

20. A method of operating a controllable switch having a set of input terminals and a set of output terminals and comprising a first coupler, a second coupler, and a plurality of phase shifters positioned between the first coupler and the second coupler, the method comprising: receiving light of a first wavelength at a first input end of the set of input ends; simultaneously receiving light of a second wavelength at a second input end of the set of input ends; applying a plurality of wavelength-dependent phase shifts between the first coupler and the second coupler using the plurality of phase shifters to independently route light of the first wavelength to a first destination selection of the set of outputs and light of the second wavelength to a second destination selection of the set of outputs; wherein: The plurality of wavelength-dependent phase shifts are selected using the first input and the second input, the first wavelength and the second wavelength, the first target selection, and the second target selection.

Images