Array waveguide grating

Abstract

The invention relates to the field of integrated optics, and particularly provides an array waveguide grating, and the array waveguide grating comprises a first array waveguide which comprises a group of first transmission waveguides which are arranged at intervals, and each first transmission waveguide comprises a first sub-waveguide and a second sub-waveguide which are arranged at intervals in a signal transmission direction; the second array waveguide comprises a group of second transmission waveguides which are arranged at intervals, the first transmission waveguides and the second transmission waveguides are arranged in a one-to-one correspondence manner, and the thermo-optical coefficient of the second transmission waveguides is greater than that of the first transmission waveguides; the phase shifter array comprises a plurality of phase shifters, and the phase shifters and the second transmission waveguides are arranged in a one-to-one correspondence mode; optical signals are coupled and transmitted to the corresponding second transmission waveguides through the first sub-waveguides, phase modulation is carried out on the optical signals through the phase shifters, and the optical signals subjected to phase modulation are coupled and transmitted to the corresponding second sub-waveguides. The scheme can effectively reduce the insertion loss of the transmission waveguide and effectively improve the modulation efficiency.

Description

Technical Field

[0001] The present application relates to the field of integrated optics technology, and specifically provides an arrayed waveguide grating. Background Art

[0002] Arrayed waveguide gratings (AWGs) are wavelength division multiplexers / demultiplexers with excellent overall performance. They are widely used in many optical communication systems, such as dense wavelength division multiplexer (DWDM) systems, optical sensors, and spectrometers. Currently, the waveguide core of AWGs is typically made of silicon nitride, due to its advantages such as low loss, high thermal stability, and ease of integration. However, silicon nitride has poor thermal tuning performance, which limits the phase tuning range of the waveguide core to its propagating optical signal, making it unable to meet the requirements for wide phase tuning in certain applications.

[0003] Compared with silicon nitride, silicon has better thermal tuning performance. Related technologies have documented combining a silicon nitride waveguide layer with a silicon waveguide layer to achieve indirect modulation of the silicon nitride waveguide by thermally tuning the silicon waveguide layer. However, with this arrangement, an active coupling region is formed in the overlapping area of ​​the silicon waveguide layer and the silicon nitride waveguide layer. At this time, as the length of the active coupling region increases, the optical signal will produce periodic power exchange between the silicon waveguide and the silicon nitride waveguide, which can easily cause the output power of the silicon nitride waveguide to oscillate. When applied to an arrayed waveguide grating, it will bring about large insertion loss. Moreover, the coupling strength between the silicon waveguide and the silicon nitride waveguide will change with the thermally tuned modulation voltage, and the equivalent modulation length in the silicon waveguide will also change with the voltage value, which is not conducive to the application of the arrayed waveguide grating to achieve stable phase control. Summary of the Invention

[0004] The present application aims to solve the above technical problems, namely, to solve the problem that when the existing phase control is performed by combining materials with good thermal tuning performance, it is easy to cause large insertion loss to the arrayed waveguide grating and it is difficult to achieve stable phase control.

[0005] In a first aspect, the present application provides an arrayed waveguide grating, which includes a first arrayed waveguide, a second arrayed waveguide, and a phase shifter array, wherein:

[0006] The first arrayed waveguide includes a group of first transmission waveguides arranged at intervals, each of the first transmission waveguides includes a first sub-waveguide and a second sub-waveguide arranged at intervals in the signal transmission direction; The second arrayed waveguide includes a group of second transmission waveguides arranged at intervals, the first transmission waveguides and the second transmission waveguides are arranged in a one-to-one correspondence, and the thermo-optic coefficient of the second transmission waveguide is greater than the thermo-optic coefficient of the first transmission waveguide;

[0007] The phase shifter array includes a plurality of phase shifters, and the phase shifters are arranged in a one-to-one correspondence with the second transmission waveguides;

[0008] The optical signal is coupled and transmitted from the first sub-waveguide to the corresponding second transmission waveguide, and is phase-modulated by the phase shifter. The phase-modulated optical signal is then coupled and transmitted to the corresponding second sub-waveguide.

[0009] In some embodiments, along the thickness direction of the second transmission waveguide, the second transmission waveguide is located between the first transmission waveguide and the phase shifter, wherein a lower cladding layer is provided between the second transmission waveguide and the first transmission waveguide, and an upper cladding layer is provided between the second transmission waveguide and the phase shifter.

[0010] In some embodiments, the orthographic projection of the second transmission waveguide on the plane where the first arrayed waveguide is located coincides with the spacing region between the corresponding first sub-waveguide and the second sub-waveguide, a portion of the first sub-waveguide, and a portion of the second sub-waveguide.

[0011] In some embodiments, the first sub-waveguide includes a first strip waveguide region and a first tapered waveguide region, the second sub-waveguide includes a second tapered waveguide region and a second strip waveguide region, and the first tapered waveguide region is spaced apart from the second tapered waveguide region by the spacing region;

[0012] The second transmission waveguide includes a third tapered waveguide region, a third strip waveguide region and a fourth tapered waveguide region. The orthographic projection of the third tapered waveguide region on the plane where the first arrayed waveguide is located partially overlaps with the corresponding first tapered waveguide region, the orthographic projection of the third strip waveguide region on the plane where the first arrayed waveguide is located overlaps with the spacing region, and the orthographic projection of the fourth tapered waveguide region on the plane where the first arrayed waveguide is located partially overlaps with the corresponding second tapered waveguide region.

[0013] In some embodiments, the orthographic projections of the phase shifter and the corresponding second transmission waveguide on the plane where the first arrayed waveguide is located at least partially overlap.

[0014] In some embodiments, the plurality of phase shifters are aligned and spaced apart in a direction perpendicular to the signal transmission direction;

[0015] Alternatively, the phase shifter array includes multiple phase shifter sub-arrays, each phase shifter sub-array includes multiple phase shifters; the multiple phase shifter sub-arrays are arranged at intervals in the signal transmission direction; in each phase shifter sub-array, the multiple phase shifters are aligned in a direction perpendicular to the signal transmission direction, and a preset number of first transmission waveguides are spaced between any two adjacent phase shifters.

[0016] In some embodiments, in the set of first transmission waveguides, the lengths of the respective first transmission waveguides are in an arithmetic progression;

[0017] In the signal transmission direction, the lengths of the second transmission waveguides corresponding to each first transmission waveguide are the same or in an arithmetic progression;

[0018] The phases modulated by the phase shifters corresponding to the group of second transmission waveguides are in an arithmetic progression.

[0019] In some embodiments, the phase shifter includes metal electrodes. When the lengths of the second transmission waveguides corresponding to each first transmission waveguide are the same, the resistances of all metal electrodes in the phase shifter array are in an arithmetic progression and operate at the same current.

[0020] In some embodiments, all metal electrodes in the phase shifter array are connected in series;

[0021] Alternatively, the phase shifter array includes a first phase shifter sub-array and a second phase shifter sub-array, wherein the first phase shifter sub-array includes a plurality of metal electrodes arranged corresponding to the first transmission waveguides located in odd-numbered rows, and the plurality of metal electrodes arranged corresponding to the first transmission waveguides located in odd-numbered rows are connected in series; and the second phase shifter sub-array includes a plurality of metal electrodes arranged corresponding to the first transmission waveguides located in even-numbered rows, and the plurality of metal electrodes arranged corresponding to the first transmission waveguides located in even-numbered rows and resistors are connected in series.

[0022] In some embodiments, the arrayed waveguide grating further comprises: an input waveguide, a first slab waveguide, a second slab waveguide, and an output waveguide;

[0023] The first slab waveguide is used to transmit and distribute the optical signal provided by the input waveguide and provide it to the first arrayed waveguide; the second slab waveguide is used to focus the optical signals of different wavelengths after phase modulation by the second arrayed waveguide and the phase shifter array, and output them to the corresponding output waveguides respectively.

[0024] The present application provides an arrayed waveguide grating, which splits a first transmission waveguide with a relatively small thermo-optical coefficient into a first sub-waveguide and a second sub-waveguide spaced apart along the signal direction. In the signal transmission direction, the optical signal can be coupled from the first sub-waveguide to the second transmission waveguide with a relatively large thermo-optical coefficient. After being phase-adjusted by a phase shifter, the phase-modulated optical signal can be coupled to the second sub-waveguide. Through the above process, highly efficient phase tuning is achieved. In addition, by splitting the first transmission waveguide and designing interlayer coupling, the length of the active coupling region between the first transmission waveguide and the second transmission waveguide can be effectively reduced, thereby avoiding power oscillations caused by mutual coupling of optical signals in the first transmission waveguide and the second transmission waveguide. This effectively reduces the insertion loss of the transmission waveguide and the influence of voltage changes during thermal tuning, thereby facilitating stable phase regulation.

[0025] On the other hand, by optimizing the arrangement of the first transmission waveguide, the second transmission waveguide and the phase shifter, the influence between adjacent phase shifters can be greatly reduced. At the same time, the distribution of multi-stage phase shifters can reduce the driving voltage, thereby effectively improving the modulation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The preferred embodiments of the present application are described below with reference to the accompanying drawings, in which:

[0027] Figure 1A This is a schematic diagram of a partial structure of an arrayed waveguide grating provided in an embodiment of the present application;

[0028] Figure 1B Schematic diagram of the structure of an arrayed waveguide grating provided in an embodiment of the present application;

[0029] Figure 2 Schematic diagram of the positional relationship between a phase shifter and a first transmission waveguide and a second transmission waveguide in an arrayed waveguide grating provided in an embodiment of the present application;

[0030] Figure 3 1 is a schematic structural diagram of a group of first transmission waveguides in an arrayed waveguide grating provided in an embodiment of the present application;

[0031] Figure 4 is a structural schematic diagram of an arrayed waveguide grating provided by another embodiment of the present application;

[0032] Figure 5 1 is a schematic structural diagram of an arrayed waveguide grating provided in yet another embodiment of the present application;

[0033] Figure 6 is based on Figure 2 A schematic diagram of the positional relationship between the phase shifter and the first transmission waveguide and the second transmission waveguide in the arrayed waveguide grating is provided;

[0034] Figure 7Schematic diagram of a partial structure of an arrayed waveguide grating provided in an embodiment of the present application;

[0035] Figure 8 This is a schematic diagram of connecting multiple metal electrodes corresponding to a group of first transmission waveguides in the arrayed waveguide grating provided in an embodiment of the present application;

[0036] Figure 9 This is a schematic diagram of the connection of multiple metal electrodes in an arrayed waveguide grating provided in an embodiment of the present application;

[0037] Figure 10 This is a schematic diagram of the connection of multiple metal electrodes in an arrayed waveguide grating provided by another embodiment of the present application. DETAILED DESCRIPTION

[0038] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0039] Unless otherwise defined, technical or scientific terms used in this disclosure should have the same general meaning as those generally understood by persons skilled in the art in the art to which this disclosure pertains. The terms "first," "second," and similar terms used in this disclosure do not denote any order, quantity, or importance, but are merely used to distinguish different components.

[0040] Figure 1A and Figure 1B They are respectively a structural schematic diagram and a top view of an arrayed waveguide grating provided in an embodiment of the present application, wherein Figure 1A The phase shifter array is omitted; Figure 2 This is a schematic diagram of the positional relationship between a phase shifter and a first transmission waveguide and a second transmission waveguide in an arrayed waveguide grating provided in an embodiment of the present application.

[0041] See also Figure 1A 、 Figure 1B and Figure 2The embodiment of the present application provides an arrayed waveguide grating including a first arrayed waveguide 100, a second arrayed waveguide 200, and a phase shifter array 300. The first arrayed waveguide 100 includes a group of first transmission waveguides spaced apart, each of which includes a first sub-waveguide 101 and a second sub-waveguide 102 spaced apart in the signal transmission direction; the second arrayed waveguide 200 includes a group of second transmission waveguides 201 spaced apart, the first transmission waveguides corresponding to the second transmission waveguides 210 being arranged in a one-to-one correspondence, and the thermo-optic coefficient of the second transmission waveguides is greater than that of the first transmission waveguides; and the phase shifter array 300 includes a plurality of phase shifters 301, each of which corresponding to the second transmission waveguides 201.

[0042] See also Figure 2 As shown, along the thickness direction of the second transmission waveguide 201, the second transmission waveguide 201 is located between the first transmission waveguide and the phase shifter 301, wherein the direction of the arrow indicates the optical signal transmission path. The optical signal is coupled and transmitted by the first sub-waveguide 101 to the corresponding second transmission waveguide 201, and is phase-modulated by the phase shifter 301. The phase-modulated optical signal is then coupled and transmitted to the corresponding second sub-waveguide 102. In some embodiments, a lower cladding layer may be provided between the second transmission waveguide and the first transmission waveguide, and an upper cladding layer may be provided between the second transmission waveguide and the phase shifter. For details, see below. Figure 6 Description.

[0043] In this application, by configuring the first transmission waveguide to be separated into a first sub-waveguide 101 and a second sub-waveguide 102, an optical signal can be coupled from the end of the first sub-waveguide 101 near the separation region to the second transmission waveguide 201 using evanescent wave coupling or other methods. After the optical signal transmitted in the second transmission waveguide 201 is phase-adjusted by the phase shifter 301, it is then coupled from the end of the second sub-waveguide 102 near the separation region to the second sub-waveguide 102 using evanescent wave coupling or other methods. This configuration greatly improves the efficiency of the phase shifter in tuning the phase of the optical signal in the arrayed waveguide without introducing additional losses. Furthermore, the segmented phase shifter configuration avoids mutual influence between phase shifters, reduces driving voltage, and facilitates stable phase control.

[0044] In some embodiments, as Figure 1A and Figure 1B As shown, the arrayed waveguide grating may further include an input waveguide 400 , a first slab waveguide 500 , a second slab waveguide 600 and an output waveguide 700 .

[0045] The input waveguide 400 is used to input a multi-wavelength mixed optical signal from the outside, for example, a multi-wavelength mixed optical signal with wavelengths of λ1, λ2, ..., λn-1, λn, where n is a positive integer greater than 1.

[0046] The first slab waveguide 500 is used to transmit and distribute the optical signal provided by the input waveguide 400 , and provide the optical signal to the first arrayed waveguide 100 .

[0047] The second slab waveguide 600 is used to focus optical signals of different wavelengths transmitted through the second arrayed waveguide 200 and phase-modulated by the phase shifter 300, and output them to corresponding output waveguides 700. Specifically, the second slab waveguide 600 can focus the optical signals output by the multiple second sub-waveguides 102 in the first arrayed waveguide 100. Because optical signals of different wavelengths have different phases, they are focused to different output ports through interference, thus achieving demultiplexing.

[0048] The output waveguide 700 is used to output optical signals of different wavelengths through different output ports.

[0049] For example, multi-wavelength optical signals are input through multiple ports of the second slab waveguide 600 and output from the ports of the first slab waveguide 500 after passing through the first arrayed waveguide 100. The arrayed waveguide grating can also realize the demultiplexing function.

[0050] In some embodiments, the first slab waveguide 500 may adopt a Rowland circle structure or other non-Rowland circle structures such as a parabolic structure or other focusing curved surface structures. The second slab waveguide 600 may adopt a Rowland circle structure to improve the accuracy of wavelength focusing.

[0051] In some embodiments, see Figure 3 As shown, Figure 3 : This is a schematic diagram of the structure of a group of first transmission waveguides in an arrayed waveguide grating provided in an embodiment of the present application. A group of first transmission waveguides may include a plurality of first transmission waveguides whose lengths are in an arithmetic progression. The length difference between any two adjacent first transmission waveguides is equal. Accordingly, the phase difference between any two adjacent first transmission waveguides can be expressed as The length of the first transmission waveguide refers to the sum of the lengths of the first sub-waveguide 101 and the second sub-waveguide 102 included in the first transmission waveguide.

[0052] In some embodiments, as Figure 3 As shown, the spacing distance between the first sub-waveguide 101 and the second sub-waveguide 102 in each first transmission waveguide in the signal transmission direction may be the same.

[0053] The spacing region between the first sub-waveguide 101 and the second sub-waveguide 102 can be flexibly set at any position of the same first transmission waveguide as needed. In some embodiments, the spacing regions corresponding to the first sub-waveguides 101 and the second sub-waveguides 102 in different first transmission waveguides can be aligned in a direction perpendicular to the signal transmission direction; in other embodiments, the spacing regions corresponding to the first sub-waveguides 101 and the second sub-waveguides 102 in different first transmission waveguides can be spaced apart in the signal transmission direction; in other embodiments, the spacing regions corresponding to the first sub-waveguides 101 and the second sub-waveguides 102 of some first transmission waveguides can be aligned in a direction perpendicular to the signal transmission direction, and the spacing regions corresponding to the first sub-waveguides 101 and the second sub-waveguides 102 of any two adjacent first transmission waveguides are spaced apart in the signal transmission direction.

[0054] In the description of this application, the "alignment" of the spacing regions refers to the alignment of the center points of the spacing regions with a specific direction (e.g., perpendicular to the signal transmission direction), or the alignment of the endpoints on one side of the spacing regions with a specific direction. The term "alignment" mentioned later in this document has the same meaning and will not be explained separately.

[0055] As an example, Figure 3 As shown, the spacing areas corresponding to the first transmission waveguides in odd rows and the spacing areas corresponding to the first transmission waveguides in even rows are respectively aligned in a direction perpendicular to the signal transmission direction, and the spacing areas corresponding to the first transmission waveguides in odd rows and the spacing areas corresponding to the first transmission waveguides in even rows are spaced apart in the signal transmission direction.

[0056] In the embodiment of the present application, the phase shifter 301 can adjust the phase of the optical signal through thermal tuning or optoelectronic tuning. The multiple phase shifters 301 in the phase shifter array 300 are arranged in a one-to-one correspondence with the multiple second transmission waveguides 201. Thus, each second transmission waveguide 201 can introduce an additional phase difference to the corresponding first transmission waveguide, enabling tuning over a wide phase range. The aforementioned thermal tuning method utilizes temperature changes to precisely control the phase of the optical signal, while optoelectronic tuning uses an external electric field to control the phase of the optical signal.

[0057] In order to ensure that the phases between different signal transmission channels are in an arithmetic progression after passing through the entire signal transmission channel, the adjustment phases of multiple second transmission waveguides 201 are also required to be in an arithmetic progression, wherein the corresponding first sub-waveguide 101, second transmission waveguide 201 and second sub-waveguide 102 can serve as a complete signal transmission channel.

[0058] As an example, Figure 3As shown, from the inside to the outside, the length of the first transmission waveguide gradually increases and the length of a group of first transmission waveguides is an arithmetic progression. Correspondingly, the phase of the first transmission waveguide also gradually increases and the phase difference between two adjacent first transmission waveguides can be expressed as Accordingly, it is necessary to set the adjustment phases of the plurality of second transmission waveguides 201 to gradually increase from the inner to the outer periphery, and the phase difference between two adjacent second transmission waveguides 201 is the same, which can be expressed as This ensures that the overall phase of different signal transmission channels is an arithmetic progression, and the phase difference between two adjacent signal transmission channels is in, Different values ​​can be achieved by providing different thermal tuning voltages or currents.

[0059] In some embodiments, the spacing regions corresponding to the first sub-waveguide 101 and the second sub-waveguide 102 in different first transmission waveguides are aligned in a direction perpendicular to the signal transmission direction. Accordingly, Figure 1A As shown, a plurality of second transmission waveguides 201 are aligned and spaced apart in a direction perpendicular to the signal transmission direction; accordingly, see Figure 1B As shown, a plurality of phase shifters 301 are aligned and spaced apart in a direction perpendicular to the signal transmission direction.

[0060] In other embodiments, the spacing regions corresponding to the first sub-waveguides 101 and the second sub-waveguides 102 of some first transmission waveguides are aligned in a direction perpendicular to the signal transmission direction, and the spacing regions corresponding to the first sub-waveguides 101 and the second sub-waveguides 102 of any two adjacent first transmission waveguides are spaced apart in the signal transmission direction, such as Figure 3 As shown, the second transmission waveguide 201 and the phase shifter 301 are arranged in a one-to-one correspondence with the spacing area. Accordingly, some of the phase shifters 301 in the plurality of phase shifters 301 are aligned in a direction perpendicular to the signal transmission direction, and any two adjacent phase shifters 301 are spaced apart in the signal transmission direction, as shown in FIG. Figure 4 or Figure 5 shown.

[0061] In some embodiments, as Figure 4 and Figure 5 As shown, the phase shifter array 300 may include multiple phase shifter sub-arrays, each of which is spaced apart in the signal transmission direction. The phase shifter sub-array includes multiple phase shifters 301 (the phase shifter sub-arrays are marked with dashed lines in the figure). In each phase shifter sub-array, the multiple phase shifters 301 are aligned perpendicular to the signal transmission direction, and a preset number of transmission waveguides are spaced between any two adjacent phase shifters 301. By arranging multiple phase shifter sub-arrays for phase modulation, resistance is reduced, subsequent heating is avoided, and modulation efficiency is effectively improved.

[0062] In some embodiments, as Figure 4 and Figure 5 As shown, among the multiple phase shifter sub-arrays, the preset numbers corresponding to different phase shifter sub-arrays are the same, and the different phase shifter sub-arrays are arranged at intervals in the signal transmission direction.

[0063] By arranging at least some of the phase shifters 301 at intervals in the signal transmission direction, thermal crosstalk between different phase shifters 301 can be effectively avoided, thereby facilitating ensuring the temperature accuracy of phase tuning.

[0064] The number of phase shifter sub-arrays and the preset number can be flexibly set according to the requirements. In some embodiments, see Figure 4 As shown, Figure 4 The exemplary embodiment shows a case where two phase shifter sub-arrays (310, 320) are provided, and the preset number is 1, that is, in each phase shifter sub-array, the multiple phase shifters 301 are aligned in a direction perpendicular to the signal transmission direction and a first transmission waveguide is spaced between any two phase shifters 301 in the multiple phase shifters 301. In other embodiments, see Figure 5 As shown, three phase shifter sub-arrays (330, 340, 350) are provided, and the preset number is set to 2.

[0065] Figure 6 is based on Figure 2 The schematic diagram of the positional relationship between the phase shifter and the first transmission waveguide and the second transmission waveguide in the arrayed waveguide grating is provided. In some embodiments, as Figure 6 As shown, the arrayed waveguide grating may further include a lower cladding 800 disposed on the side of the second transmission waveguide 201 proximal to the first transmission waveguide, and an upper cladding 900 disposed on the side of the second transmission waveguide 201 facing away from the first transmission waveguide. In addition to confining light to propagate forward within the second transmission waveguide 201, the lower cladding 800 also serves to isolate the second transmission waveguide 201 from the corresponding first transmission waveguide. In other embodiments, a cladding may also be disposed outside the first transmission waveguide to confine light to propagate forward within the first transmission waveguide and to isolate the first transmission waveguide from the second transmission waveguide.

[0066] The orthographic projection of the second transmission waveguide 201 on the plane where the first arrayed waveguide 100 is located coincides with the spacing region between the corresponding first sub-waveguide 101 and the second sub-waveguide 102 , a portion of the first sub-waveguide 101 , and a portion of the second sub-waveguide 102 .

[0067] like Figure 6 and Figure 7As shown, the phase shifter 301 may include a metal electrode 3011 , and the metal electrode 3011 is used to heat the corresponding second transmission waveguide 201 to adjust the phase of the optical signal.

[0068] The metal electrode 3011 may be specifically disposed on the upper cladding layer 900. In some embodiments, the orthographic projections of the metal electrode 3011 and the corresponding second transmission waveguide 201 on the plane where the first arrayed waveguide 100 is located at least partially overlap.

[0069] In the embodiment of the present application, the phase shifter can adjust the phase of the optical signal by thermal tuning by applying a voltage or current to the metal electrode 3011. The heat generated by the application of the voltage or current to the metal electrode 3011 is transmitted to the second transmission waveguide 201 through the upper cladding layer 900, thereby changing the effective refractive index of the second transmission waveguide 201. According to the following phase expression, it can be seen that the effective refractive index is related to the adjusted phase, thereby achieving phase adjustment:

[0070] in, is the phase adjusted by the phase shifter 301 , n is the effective refractive index of the second transmission waveguide 201 , L is the length of the second transmission waveguide 201 , and λ is the wavelength of the optical signal.

[0071] The thermo-optic coefficient is a key parameter used to characterize the temperature-dependent change in the effective refractive index of the second transmission waveguide 201. It can be expressed as dn / dT, where dn represents the change in effective refractive index and dT represents the change in temperature. Selecting a second transmission waveguide 201 with a larger thermo-optic coefficient facilitates achieving a larger effective refractive index adjustment by applying a smaller voltage or current to adjust the temperature. This, in turn, introduces an additional, larger phase change to the first transmission waveguide, thereby expanding the overall phase tuning range of the arrayed waveguide grating.

[0072] In some embodiments, both the lower cladding layer 800 and the upper cladding layer 900 may be made of silicon dioxide.

[0073] In some embodiments, the first transmission waveguide may be made of silicon nitride, and the second transmission waveguide 201 may be made of silicon or other materials having a thermo-optical coefficient greater than that of silicon nitride.

[0074] In some embodiments, the metal electrode 3011 may be made of titanium nitride.

[0075] The thickness of the lower cladding layer 800 , the second transmission waveguide 201 , the upper cladding layer 900 and the metal electrode 3011 in a direction perpendicular to the plane where the first arrayed waveguide 100 is located can be flexibly set according to requirements.

[0076] In some embodiments, in order to further reduce the coupling loss between the first transmission waveguide and the second transmission waveguide 201 and improve the coupling effect, the first sub-waveguide 101 and the second sub-waveguide 102 and the corresponding second transmission waveguide 201 may be provided with a tapered waveguide region.

[0077] For details, see Figure 7 As shown, Figure 7 It is a schematic diagram of the local structure of the arrayed waveguide grating provided in an embodiment of the present application, wherein the first sub-waveguide 101 includes a first strip waveguide region and a first tapered waveguide region (for ease of understanding and comparison, the length of each part along the signal transmission direction is identified as the corresponding part below). Therefore, the first strip waveguide region is identified as S1, and the first tapered waveguide region is identified as S2; accordingly, the second sub-waveguide 102 includes a second tapered waveguide region S3 and a second strip waveguide region S4, and the first tapered waveguide region S2 is spaced apart from the second tapered waveguide region S3 by a spacing region, and the first tapered waveguide region S2, the spacing region, and the second tapered waveguide region S3 are sequentially arranged between the first strip waveguide region S1 and the second strip waveguide region S4.

[0078] The second transmission waveguide 201 includes a third tapered waveguide region S5, a third strip waveguide region S6 and a fourth tapered waveguide region S7 connected in sequence. The orthographic projection of the third tapered waveguide region S5 on the plane where the first arrayed waveguide 100 is located partially overlaps with the corresponding first tapered waveguide region S2, the orthographic projection of the third strip waveguide region S6 on the plane where the first arrayed waveguide 100 is located overlaps with the spacing area, and the orthographic projection of the fourth tapered waveguide region S7 on the plane where the first arrayed waveguide 100 is located partially overlaps with the corresponding second tapered waveguide region S3.

[0079] In the embodiment of the present application, the widths of the first tapered waveguide region S2 and the fourth tapered waveguide region S7 gradually decrease along the signal transmission direction, and the widths of the second tapered waveguide region S3 and the third tapered waveguide region S5 gradually increase along the signal transmission direction, where the width refers to the dimension in the direction perpendicular to the signal transmission direction.

[0080] In some embodiments, as Figure 7 As shown, in the signal transmission direction, the size of the spacing region can be larger than the size of the third strip waveguide region S6 of the second transmission waveguide 201. Accordingly, the orthographic projection of the third tapered waveguide region S5 on the plane where the first arrayed waveguide 100 is located can overlap with a portion of the first tapered waveguide region S2 and a portion of the spacing region, and the orthographic projection of the fourth tapered waveguide region S7 on the plane where the first arrayed waveguide 100 is located can overlap with a portion of the second tapered waveguide region S3 and a portion of the spacing region.

[0081] In some embodiments, as Figure 7As shown, the metal electrode 3011 partially overlaps with the third strip-shaped waveguide region S6 of the second transmission waveguide 201 on the orthographic projection of the plane where the first arrayed waveguide 100 is located.

[0082] As an example, the length of the first and second tapered waveguide regions S2 and S3 in the signal transmission direction can be 30 μm, the length of the third and fourth tapered waveguide regions S5 and S7 can be 20 μm, the length of the overlapping region between the first and third tapered waveguide regions S2 and S5 in the signal transmission direction can be 18 μm, the length of the overlapping region between the second and fourth tapered waveguide regions S3 and S7 in the signal transmission direction can also be 18 μm, and the length S8 of the metal electrode 3011 can be 100 μm. Furthermore, the minimum width of the first and second tapered waveguide regions S2 and S3 is 0.4 μm, and the minimum width of the third and fourth tapered waveguide regions S5 and S7 is 0.2 μm. It should be noted that the scales shown in the drawings are for illustration only and do not represent actual proportions.

[0083] Based on the above description, it can be seen that the phases modulated by the phase shifters 301 corresponding to a group of second transmission waveguides 201 need to be in an arithmetic progression, that is, the phase differences between any two adjacent second transmission waveguides 201 must be equal.

[0084] Based on the above phase expression, it can be known that the phase difference between any two adjacent second transmission waveguides 201 satisfies the following expression:

[0085] Wherein, i represents the i-th second transmission waveguide 201 , and i is a positive integer greater than or equal to 1.

[0086] To ensure that the phases modulated by the multiple phase shifters 301 are in an arithmetic progression, that is, the phase difference between any two adjacent second transmission waveguides 201 must be equal, in some embodiments, in the signal transmission direction, the lengths of the second transmission waveguides 201 corresponding to each first transmission waveguide are the same (e.g. Figure 1A shown) or in an arithmetic progression.

[0087] When the length of the second transmission waveguide 201 corresponding to each first transmission waveguide is an arithmetic progression, the resistance of all metal electrodes 3011 in the phase shifter array 300 can be the same and they can operate at the same current.

[0088] When the lengths of the second transmission waveguides 201 corresponding to each first transmission waveguide are the same, the resistances of all the metal electrodes 3011 in the phase shifter array 300 are in an arithmetic progression and operate under the same current.

[0089] In some embodiments, in order to make the resistances of all metal electrodes 3011 form an arithmetic progression, all metal electrodes 3011 in the phase shifter array 300 may be configured to use the same material and cross-sectional area, and to have lengths that form an arithmetic progression.

[0090] The lengths of the plurality of second transmission waveguides 201 are set to be equal, that is, L i =L (i-1) ,but

[0091] When the phase shifter 301 uses thermal tuning to adjust the phase, the electric power generated by applying current to the metal electrode 3011 can be expressed as ΔP=I 2 r, I represents the current flowing through the metal electrode 3011, r represents the resistance of the metal electrode 3011, and P represents the electrical power. The electrical power P is converted into a temperature change ΔT through Joule heating, which can be specifically expressed as ΔT = P·R th =I 2 Δr·R th , R th is the thermal resistance coefficient (unit: °C / W), and △r represents the resistance difference between adjacent metal electrodes 3011.

[0092] When the multiple phase shifters 301 all use metal electrodes 3011 of the same material, the thermo-optic coefficient is a constant value. When the same current is provided to the multiple metal electrodes 3011, r = ρl / s, where ρ represents the resistivity of the metal electrode 3011, l represents the length of the metal electrode 3011, and s represents the cross-sectional area of ​​the metal electrode 3011. By using multiple metal electrodes 3011 of the same material and cross-sectional area and providing the same current to the multiple metal electrodes 3011, and setting the lengths of the multiple metal electrodes 3011 in an arithmetic progression, it is possible to ensure that the Δn of any two adjacent second transmission waveguides 201 is equal, thereby ensuring that the phase difference between any two adjacent second transmission waveguides 201 is equal. equal.

[0093] To ensure that the current passing through each metal electrode 3011 is the same, in a first implementation, each metal electrode 3011 is powered separately and the same current is provided to each metal electrode 3011; in a second implementation, all metal electrodes 3011 corresponding to a group of first transmission waveguides are connected in series. Figure 8 As shown, the multiple metal electrodes 3011 are connected end to end in sequence, and the metal electrodes 3011 at both ends are used to be electrically connected to an external circuit, which can reduce wiring.

[0094] In a third implementation, the multiple metal electrodes 3011 corresponding to a group of first transmission waveguides are divided into multiple groups. The multiple metal electrodes 3011 in each group are connected in series, and the metal electrodes 3011 in different groups all provide the same current. This avoids problems such as high impedance and high power consumption when multiple metal electrodes 3011 are connected in series. For example, the multiple metal electrodes 3011 corresponding to a phase shifter subarray can be treated as a group. Accordingly, the multiple metal electrodes 3011 corresponding to each phase shifter subarray can be connected in series, and the same current is provided to the multiple metal electrodes 3011 corresponding to multiple phase shifter subarrays. This also simplifies metal wiring and avoids metal wiring crossover.

[0095] See also Figure 9 As shown, Figure 9 yes Figure 4 A schematic diagram illustrating the connection of multiple metal electrodes 3011 in a corresponding embodiment. When the phase shifter array 300 includes a first phase shifter sub-array 210 and a second phase shifter sub-array 220, the first phase shifter sub-array 210 includes multiple metal electrodes 3011 corresponding to the first transmission waveguides in odd-numbered rows, and the multiple metal electrodes 3011 corresponding to the first transmission waveguides in odd-numbered rows are connected in series. The current corresponding to the multiple metal electrodes 3011 corresponding to the first transmission waveguides in odd-numbered rows can be represented as I1. The second phase shifter sub-array 220 includes multiple metal electrodes 3011 corresponding to the first transmission waveguides in even-numbered rows, and the multiple metal electrodes 3011 corresponding to the first transmission waveguides in even-numbered rows are sequentially connected in series. The same current is provided to the multiple metal electrodes 3011 corresponding to the first transmission waveguides in odd-numbered rows and the multiple metal electrodes 3011 corresponding to the first transmission waveguides in even-numbered rows, respectively.

[0096] In other embodiments, see Figure 10 As shown, Figure 10 Another embodiment of the present application provides Figure 4 The connection diagram of the plurality of metal electrodes 3011 in FIG. 1 can also provide the same voltage V0 for the plurality of metal electrodes 3011 corresponding to the first transmission waveguides in the odd-numbered rows and the plurality of metal electrodes 3011 corresponding to the first transmission waveguides in the even-numbered rows. Accordingly, the arrayed waveguide grating can also include a resistor R c , a plurality of metal electrodes 3011 and resistors R arranged corresponding to the first transmission waveguides in even rows c They are connected in series to ensure that the current flowing through the metal electrodes 3011 corresponding to the first transmission waveguides in odd-numbered rows is the same.

[0097] Thus far, the technical solutions of the present application have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is readily understood by those skilled in the art that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present application.

Claims

1. An arrayed waveguide grating, characterized in that: The invention comprises a first arrayed waveguide, a second arrayed waveguide and a phase shifter array, wherein: The first arrayed waveguide includes a group of first transmission waveguides arranged at intervals, each of the first transmission waveguides includes a first sub-waveguide and a second sub-waveguide arranged at intervals in the signal transmission direction; The second arrayed waveguide includes a group of second transmission waveguides arranged at intervals, the first transmission waveguides and the second transmission waveguides are arranged in a one-to-one correspondence, and the thermo-optic coefficient of the second transmission waveguide is greater than the thermo-optic coefficient of the first transmission waveguide; The phase shifter array includes a plurality of phase shifters, and the phase shifters are arranged in a one-to-one correspondence with the second transmission waveguides; The optical signal is coupled and transmitted from the first sub-waveguide to the corresponding second transmission waveguide, and is phase-modulated by the phase shifter. The phase-modulated optical signal is then coupled and transmitted to the corresponding second sub-waveguide.

2. The arrayed waveguide grating according to claim 1, wherein Along the thickness direction of the second transmission waveguide, the second transmission waveguide is located between the first transmission waveguide and the phase shifter, wherein a lower cladding layer is provided between the second transmission waveguide and the first transmission waveguide, and an upper cladding layer is provided between the second transmission waveguide and the phase shifter.

3. The arrayed waveguide grating according to claim 1 or 2, characterized in that: The orthographic projection of the second transmission waveguide on the plane where the first arrayed waveguide is located coincides with the interval area between the corresponding first sub-waveguide and the second sub-waveguide, part of the first sub-waveguide, and part of the second sub-waveguide.

4. The arrayed waveguide grating according to claim 3, wherein: The first sub-waveguide includes a first strip waveguide region and a first tapered waveguide region, the second sub-waveguide includes a second tapered waveguide region and a second strip waveguide region, and the first tapered waveguide region is spaced apart from the second tapered waveguide region by the spacing region; The second transmission waveguide includes a third tapered waveguide region, a third strip waveguide region and a fourth tapered waveguide region. The orthographic projection of the third tapered waveguide region on the plane where the first arrayed waveguide is located partially overlaps with the corresponding first tapered waveguide region, the orthographic projection of the third strip waveguide region on the plane where the first arrayed waveguide is located overlaps with the spacing region, and the orthographic projection of the fourth tapered waveguide region on the plane where the first arrayed waveguide is located partially overlaps with the corresponding second tapered waveguide region.

5. The arrayed waveguide grating according to any one of claims 1 to 4, wherein: The orthographic projections of the phase shifter and the corresponding second transmission waveguide on the plane where the first arrayed waveguide is located at least partially overlap.

6. The arrayed waveguide grating according to claim 5, wherein: The plurality of phase shifters are aligned and spaced apart in a direction perpendicular to the signal transmission direction; Alternatively, the phase shifter array includes a plurality of phase shifter sub-arrays, and each phase shifter sub-array includes a plurality of phase shifters; A plurality of phase shifter sub-arrays are arranged at intervals in the signal transmission direction; In each phase shifter sub-array, a plurality of phase shifters are aligned in a direction perpendicular to the signal transmission direction, and a preset number of first transmission waveguides are spaced between any two adjacent phase shifters.

7. The arrayed waveguide grating according to any one of claims 1 to 4, characterized in that: In the set of first transmission waveguides, the lengths of the respective first transmission waveguides are in an arithmetic progression; In the signal transmission direction, the lengths of the second transmission waveguides corresponding to each first transmission waveguide are the same or in an arithmetic progression; The phases modulated by the phase shifters corresponding to the group of second transmission waveguides are in an arithmetic progression.

8. The arrayed waveguide grating according to claim 7, wherein: The phase shifter includes metal electrodes. When the lengths of the second transmission waveguides corresponding to each first transmission waveguide are the same, the resistances of all the metal electrodes in the phase shifter array are in an arithmetic progression and operate under the same current.

9. The arrayed waveguide grating according to claim 8, wherein: All metal electrodes in the phase shifter array are connected in series; Alternatively, the phase shifter array includes a first phase shifter sub-array and a second phase shifter sub-array, wherein the first phase shifter sub-array includes a plurality of metal electrodes arranged corresponding to the first transmission waveguides located in odd-numbered rows, and the plurality of metal electrodes arranged corresponding to the first transmission waveguides located in odd-numbered rows are connected in series; and the second phase shifter sub-array includes a plurality of metal electrodes arranged corresponding to the first transmission waveguides located in even-numbered rows, and the plurality of metal electrodes arranged corresponding to the first transmission waveguides located in even-numbered rows and resistors are connected in series.

10. The arrayed waveguide grating according to any one of claims 1 to 9, characterized in that: The arrayed waveguide grating further comprises: an input waveguide, a first slab waveguide, a second slab waveguide and an output waveguide; The first slab waveguide is used to transmit and distribute the optical signal provided by the input waveguide and provide it to the first arrayed waveguide; the second slab waveguide is used to focus the optical signals of different wavelengths after phase modulation by the second arrayed waveguide and the phase shifter array, and output them to the corresponding output waveguides respectively.

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