Arrayed waveguide grating structure for improving optical indexes of CWDM AWG

Abstract

The application relates to the field of optical communication technology and provides an array waveguide grating structure for improving the optical indexes of a CWDM AWG; the current CWDM used in a data module needs to have a large bandwidth, a small size and channel loss; however, according to the design theory of a flat spectrum AWG, the bandwidth, adjacent channel crosstalk and channel insertion loss of the CWDM AWG under the single-mode input / output condition are contradictory in the selection of the AWG design parameters; how to consider these parameter indexes is a challenge for designers; especially, the CWDM AWG device applied to the data communication module needs to strictly meet the size and shape requirements of the module packaging; thus, the selection of the design parameters is additionally increased with the constraint conditions; therefore, a simple and feasible design method is found to widen the output waveguide width of the CWDM device, improve the bandwidth, adjacent channel crosstalk and channel insertion loss and other indexes of the AWG without obviously changing the size and shape of the CWDM device.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, and in particular to an arrayed waveguide grating structure for improving the optical performance of CWDM AWG. Background Technology

[0002] With the advent of the era of big data and cloud computing, the use of various social networks and high-definition video has become increasingly widespread, leading to an explosive growth in the demand for data center bandwidth. This will increasingly strain fiber optic resources, the medium for data transmission. Re-laying fiber optic cables involves a series of issues, including digging trenches, overhead installations, and burying pipes, causing problems for urban construction. Furthermore, fiber optic cable laying is time-consuming, often taking several months and requiring significant manpower, resulting in high costs. How to select a low-cost, highly reliable network system is a problem the telecommunications industry must address. CWDM technology, with its low cost and flexible service support, solves the current problem of scarce fiber optic resources. It eliminates the need for new fiber optic cables and discarding existing equipment, utilizing existing resources to complete large-scale data transmission services.

[0003] CWDM (Cable Wavelength Division Multiplexing) uses an optical multiplexer at the transmitting end to combine light of different wavelengths into a single optical fiber for transmission. At the receiving end, a demultiplexer separates the combined light and sends it to different receivers via different optical fibers. Therefore, only two optical fibers are needed to transmit multiple signals, greatly increasing the transmission capacity of the optical fiber and improving the utilization rate of optical fiber resources. Wavelength division multiplexing devices are an important component of wavelength division multiplexing systems. To ensure the performance of wavelength division multiplexing systems, basic requirements are set for wavelength division multiplexing devices, mainly low insertion loss, high isolation, flat in-band signal, steep out-of-band insertion loss variation, good temperature stability, and small size. Wavelength division multiplexing devices are classified into demultiplexers and multiplexers according to their applications. A multiplexer combines signals of different wavelengths from different light sources and outputs them through a single optical fiber; conversely, a demultiplexer decomposes multi-wavelength signals from the same optical fiber into several wavelengths for separate output.

[0004] Currently, CWDMs used in data communication modules require large bandwidth, small form factor, and low channel loss. However, based on the design theory of flat-spectrum AWGs, the bandwidth, adjacent channel crosstalk, and channel insertion loss of CWDM AWGs under single-mode input / output conditions are contradictory in the selection of AWG design parameters. Balancing these parameters is a challenge for designers. Especially for CWDM AWG devices used in data communication modules, which need to strictly meet the form factor and size requirements of the module package, this adds additional constraints to the selection of design parameters. Therefore, finding a simple and easy-to-implement design method that improves AWG bandwidth, adjacent channel crosstalk, and channel insertion loss without significantly altering the form factor of the CWDM device is a key problem to be solved.

[0005] Therefore, overcoming the shortcomings of the existing technology is an urgent problem to be solved in this technical field. Summary of the Invention

[0006] To address the aforementioned shortcomings or improvement needs, current CWDMs used in data communication modules require large bandwidth, small form factor, and low channel loss. However, based on the design theory of flat-spectrum AWGs, the bandwidth, adjacent channel crosstalk, and channel insertion loss of CWDMAWGs under single-mode input / output conditions are contradictory in the selection of AWG design parameters.

[0007] The present invention adopts the following technical solution:

[0008] Firstly, an arrayed waveguide grating structure for improving the optical performance of CWDM AWG includes an input waveguide, an input planar waveguide, an arrayed waveguide, an output planar waveguide, and an output waveguide, wherein the input waveguide, the input planar waveguide, the arrayed waveguide, the output planar waveguide, and the output waveguide are sequentially coupled together. Specifically:

[0009] The width of the output waveguide is widened to a preset parameter value.

[0010] Preferably, the center wavelength of the optical signal to be adapted by the AWG is set one by one, and the width of the output waveguide, the refractive index of the waveguide layer, and the refractive index of the cladding are preset under each center wavelength. Then, the equivalent refractive index of the 0th to 4th order modes is calculated under each output waveguide width condition.

[0011] When the equivalent refractive index of the 0th to 4th order modes is greater than or equal to the preset cladding refractive index, the output waveguide width corresponding to the equivalent refractive index supports the 0th to 4th order modes.

[0012] Preferably, when the selected center wavelength is 1.303 μm and the preset output waveguide width, waveguide layer refractive index, and cladding refractive index are 4.4 μm, 1.47004, and 1.44784, respectively, the width of the first waveguide is 11.4 μm.

[0013] Preferably, when the output waveguide width is greater than the first waveguide width, the output waveguide width supports 0th-order modes to 4th-order modes.

[0014] Preferably, for the selected center wavelength, the initial output waveguide width is set to the first waveguide width, and the output waveguide width is gradually increased based on the first waveguide width until the crosstalk between adjacent channels is minimized. The output waveguide width at this point is the second waveguide width; the second waveguide width is the optimal operating waveform under the set value.

[0015] Preferably, the optimal working waveform includes:

[0016] One or more of the parameters Insertion Loss, 0.5dB Bandwidth, 1dB Bandwidth, 3dB Bandwidth, and Ripple are the optimal values ​​under the given settings.

[0017] Preferably, when the selected center wavelength is 1.33 μm, the width of the second waveguide is 13 + 0.1 μm.

[0018] Preferably, when the output waveguide includes multiple channels, each channel corresponds to a center wavelength, then the center wavelength of the optical signal to be adapted by the AWG is set one-to-one with the center wavelength corresponding to each channel.

[0019] Preferably, the optical signal diverges at the input planar waveguide and then enters the array waveguide.

[0020] Preferably, the optical signal is converged in the output planar waveguide and then output from the arrayed waveguide.

[0021] This invention provides an arrayed waveguide grating structure to improve the optical performance of CWDM AWGs, while simultaneously improving the bandwidth, crosstalk between adjacent channels, and channel insertion loss of the AWG without significantly altering the external dimensions of the CWDM device. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of an arrayed waveguide grating structure for improving the optical performance of CWDM AWG provided in an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the refractive index variation of the 0th mode of an arrayed waveguide grating structure for improving the optical performance of CWDM AWG, provided by an embodiment of the present invention.

[0025] Figure 3 This is a schematic diagram of the first-order mode refractive index variation of an arrayed waveguide grating structure for improving the optical performance of CWDM AWG, provided by an embodiment of the present invention.

[0026] Figure 4 This is a schematic diagram of the second-order mode refractive index variation of an arrayed waveguide grating structure for improving the optical performance of CWDM AWG, provided by an embodiment of the present invention.

[0027] Figure 5 This is a schematic diagram of the refractive index variation of the third mode of an arrayed waveguide grating structure for improving the optical performance of CWDM AWG, provided by an embodiment of the present invention.

[0028] Figure 6 This is a schematic diagram of the refractive index variation of the fourth mode of an arrayed waveguide grating structure for improving the optical performance of CWDM AWG, provided by an embodiment of the present invention.

[0029] Figure 7 This is a schematic diagram of the 0th-order mode output spectrum of an arrayed waveguide grating structure with an output waveguide width of 4.4 μm, provided by an embodiment of the present invention.

[0030] Figure 8 This is a schematic diagram of the first-order mode output spectrum of an arrayed waveguide grating structure with an output waveguide width of 4.4 μm, provided by an embodiment of the present invention to improve the optical performance of CWDM AWG.

[0031] Figure 9 This is a schematic diagram of the actual output spectrum of the 0th and 1st order modes after superposition when the output waveguide width is 4.4 μm, provided by an embodiment of the present invention, which is an arrayed waveguide grating structure for improving the optical performance of CWDM AWG.

[0032] Figure 10 This is a partially enlarged view of the actual output spectrum of the arrayed waveguide grating structure for improving the optical performance of CWDM AWG provided in this embodiment of the invention, with an output waveguide width of 4.4µm, after the superposition of the 0th and 1st modes.

[0033] Figure 11This is a schematic diagram of the 0th-order mode output spectrum of an arrayed waveguide grating structure with an output waveguide width of 13µm, provided by an embodiment of the present invention to improve the optical performance of CWDM AWG.

[0034] Figure 12 This is a schematic diagram of the first-order mode output spectrum of an arrayed waveguide grating structure with an output waveguide width of 13µm, provided by an embodiment of the present invention to improve the optical performance of CWDM AWG.

[0035] Figure 13 This is a schematic diagram of the second-order mode output spectrum of an arrayed waveguide grating structure with an output waveguide width of 13µm, provided by an embodiment of the present invention to improve the optical performance of CWDM AWG.

[0036] Figure 14 This is a schematic diagram of the third-order mode output spectrum of an arrayed waveguide grating structure with an output waveguide width of 13µm, provided by an embodiment of the present invention to improve the optical performance of CWDM AWG.

[0037] Figure 15 This is a schematic diagram of the fourth-order mode output spectrum of an arrayed waveguide grating structure with an output waveguide width of 13µm, provided by an embodiment of the present invention to improve the optical performance of CWDM AWG.

[0038] Figure 16 This is a schematic diagram of the actual output spectrum of the arrayed waveguide grating structure for improving the optical performance of CWDM AWG provided by an embodiment of the present invention, after superimposing the 0th, 1st, 2nd, 3rd and 4th order modes with an output waveguide width of 13µm.

[0039] Figure 17 This is a partially enlarged view of the actual output spectrum of the arrayed waveguide grating structure for improving the optical performance of CWDM AWG provided in this embodiment of the invention, with an output waveguide width of 13µm, after superimposing the 0th, 1st, 2nd, 3rd and 4th order modes.

[0040] Figure 18 This is a schematic diagram of the actual output spectrum of the 0th, 1st, 2nd, 3rd and 4th order modes after superposition, when the output waveguide width is 12.5 μm, according to an embodiment of the present invention.

[0041] Figure 19 This is a schematic diagram of the actual output spectrum of the 0th, 1st, 2nd, 3rd and 4th order modes after superposition, when the output waveguide width is 13.5 μm, according to an embodiment of the present invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0043] In the description of this invention, the terms "inner", "outer", "longitudinal", "lateral", "upper", "lower", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and do not require that this invention must be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0044] In the data communication module, the transmitting end uses a CWDM with MUX functionality, while the receiving end uses a CWDM with DEMUX functionality. Since MUX and DEMUX are typically used in pairs in optical paths, reducing the loss at either the MUX or DEMUX end reduces the overall optical path loss. Observing the usage of MUX and DEMUX reveals that the MUX is connected to the semiconductor laser via coupling to a single-mode fiber; while the DEMUX is directly coupled to receiving optoelectronic devices such as PDs, APDs, or PINs. We found that the CWDM at the DEMUX end does not need to be coupled to the single-mode fiber, therefore maintaining single-mode output is unnecessary.

[0045] Therefore, this invention employs waveguide integration technology to design the AWG at the CWDM DEMUX end as a multimode output. While meeting the crosstalk requirements under actual use conditions (e.g., greater than 26dB), it reduces losses and improves optical parameters such as bandwidth and ripple.

[0046] Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0047] Example 1:

[0048] Embodiment 1 of the present invention provides an arrayed waveguide grating structure for improving the optical performance of CWDM AWG, such as Figure 1 As shown, it specifically includes:

[0049] The waveguide consists of an input planar waveguide, an arrayed waveguide, an output planar waveguide, and an output waveguide, wherein the input waveguide, input planar waveguide, arrayed waveguide, output planar waveguide, and output waveguide are sequentially coupled together. Specifically:

[0050] The width of the output waveguide is widened to a preset parameter value.

[0051] The preset parameter value is specifically 13 + 0.1 μm. Examples 2, 3 and 4 will further demonstrate the preferred selection value of the preset parameter value.

[0052] When the structure is used as a demultiplexer (DEMUX), the input waveguide includes one channel, and the output waveguide includes a preset number of channels. The optical signal is input from a single channel of the input waveguide, diverges after passing through the input planar waveguide, and then enters the array waveguide. The array waveguide introduces different phase differences for input signals of different wavelengths. The optical signals output different wavelengths of output signals from waveguides of different lengths and then converge on the output planar waveguide. There is an image plane between the output planar waveguide and the output waveguide. The signals of different wavelengths converge at different positions on the image plane after being output from the output planar waveguide, corresponding to output from different channels within the output waveguide.

[0053] When the structure is used as a multiplexer (MUX), the input waveguide includes a preset number of channels, and the output waveguide includes one channel. Optical signals are input from the preset number of channels of the input waveguide, diverge after passing through the input planar waveguide, and then enter the array waveguide. The array waveguide introduces different phase differences for input signals of different wavelengths. After outputting output signals of different wavelengths from waveguides of different lengths, the optical signals converge on the output planar waveguide and are output from a single channel of the output waveguide.

[0054] This invention provides an arrayed waveguide grating structure to improve the optical performance of CWDM AWGs, while simultaneously improving the bandwidth, crosstalk between adjacent channels, and channel insertion loss of the AWG without significantly altering the external dimensions of the CWDM device.

[0055] The preset quantities mentioned herein can be set by those skilled in the art based on actual circumstances and should not limit the scope of protection of this solution.

[0056] The center wavelength of the optical signal to be adapted by the AWG is set one by one, and the width of the output waveguide, the refractive index of the waveguide layer, and the refractive index of the cladding are preset at each center wavelength. Then, the equivalent refractive index of the 0th to 4th order modes is calculated under each output waveguide width condition.

[0057] When the equivalent refractive index of the 0th to 4th order modes is greater than or equal to the preset cladding refractive index, the output waveguide width corresponding to the equivalent refractive index supports the 0th to 4th order modes.

[0058] Specifically, the equivalent refractive index of the 0th to 4th order modes is calculated under different output waveguide widths. When the equivalent refractive index of the order mode is greater than the cladding refractive index, the output waveguide width corresponding to the refractive index supports the order mode.

[0059] like Figures 2 to 6As shown, when the selected center wavelength is 1.303 μm, and the preset output waveguide width, waveguide layer refractive index, and cladding refractive index are 4.4 μm, 1.47004, and 1.44784, respectively.

[0060] like Figure 4 As shown, when the output waveguide width is less than 5.8 μm, only the equivalent refractive index corresponding to the 0th and 1st order modes is greater than the cladding refractive index. Therefore, when the output waveguide width is less than 5.8 μm, the corresponding output waveguide width supports the 0th and 1st order modes, but does not support the 2nd, 3rd, and 4th order modes.

[0061] like Figure 5 As shown, when the output waveguide width is less than 8.6 μm, the equivalent refractive indices corresponding to the 0th, 1st, and 2nd order modes are all greater than the cladding refractive index. Therefore, when the output waveguide width is less than 8.6 μm, the corresponding output waveguide width supports the 0th, 1st, and 2nd order modes, but does not support the 3rd and 4th order modes.

[0062] like Figure 6 As shown, when the output waveguide width is less than 11.4 μm, the equivalent refractive indices corresponding to the 0th, 1st, 2nd and 3rd modes are all greater than the cladding refractive index. Therefore, when the output waveguide width is less than 11.4 μm, the corresponding output waveguide width supports the 0th, 1st, 2nd and 3rd modes, but does not support the 4th mode.

[0063] When the output waveguide width is greater than 11.4 μm, the equivalent refractive index of the 0th to 4th order modes corresponding to the output waveguide width is greater than the cladding refractive index. At this time, the output waveguide width supports the 0th to 4th order modes.

[0064] Since the more modes the output waveguide width supports, the better the final working waveform, the working waveform corresponding to an output waveguide width greater than 11.4µm is better than the working waveform corresponding to an output waveguide width less than 11.4µm. Therefore, the first waveguide width is defined as 11.4µm, and when the output waveguide width is greater than the first waveguide width, it supports modes from 0th to 4th order.

[0065] For the selected center wavelength, the initial output waveguide width is set to the first waveguide width. The output waveguide width is gradually increased based on the first waveguide width until the crosstalk between adjacent channels is minimized. The output waveguide width at this point is the second waveguide width. The second waveguide width is the optimal working waveform under the set value.

[0066] The adjacent channel crosstalk setting is 26dB. The adjacent channel crosstalk needs to be greater than 26dB. When the output waveguide width increases, the corresponding adjacent channel crosstalk decreases monotonically. Therefore, the initial output waveguide width is set to the first waveguide width, and the output waveguide width is gradually increased until the adjacent channel crosstalk value is closest to 26dB. At this time, the output waveguide width can obtain the optimal working waveform under the setting value.

[0067] The optimal working waveform includes:

[0068] One or more of the parameters Insertion Loss, 0.5dB Bandwidth, 1dB Bandwidth, 3dB Bandwidth, and Ripple are the optimal values ​​under the given settings.

[0069] The Insertion Loss is the insertion loss; 0.5dB Bandwidth is the 0.5dB bandwidth; 1dB Bandwidth is the 1dB bandwidth; 3dB Bandwidth is the 3dB bandwidth; and Ripple is the ripple. The conditions for each parameter to be biased towards the optimal value under the given settings are as follows: the smaller the Insertion Loss value compared to the value obtained before widening the output waveguide, the closer it is to the optimal value; the larger the 0.5dB Bandwidth value compared to the value obtained before widening the output waveguide, the closer it is to the optimal value; the larger the 1dB Bandwidth value compared to the value obtained before widening the output waveguide, the closer it is to the optimal value; the larger the 3dB Bandwidth value compared to the value obtained before widening the output waveguide, the closer it is to the optimal value; and the smaller the Ripple value compared to the value obtained before widening the output waveguide, the closer it is to the optimal value.

[0070] When the selected center wavelength is 1.33 μm, the width of the second waveguide is 13 + 0.1 μm.

[0071] Among them, with a center wavelength of 1.33µm as a condition, when the output waveguide width is the second waveguide width 13+0.1µm, the working waveform can reach the optimal state while ensuring that the crosstalk between adjacent channels is greater than 26dB.

[0072] When the output waveguide includes multiple channels, each channel corresponds to a center wavelength. Therefore, the center wavelength of the optical signal to be adapted by the AWG is set one by one with the center wavelength of each channel.

[0073] The optical signal diverges at the input star coupler and then enters the array waveguide.

[0074] The optical signal is diverged into a corresponding number of optical signals at the input planar waveguide according to the number of waveguides in the array waveguide, and then enters each corresponding waveguide in the array waveguide.

[0075] The optical signal converges at the output planar waveguide and is then output from the arrayed waveguide.

[0076] The optical signals are output from waveguides of different lengths in the array waveguide and converge at the output planar waveguide. There is an image plane between the output planar waveguide and the output waveguide. The signals of different wavelengths are output from the output planar waveguide and converge at different positions on the image plane, corresponding to output from different channels in the output waveguide.

[0077] Example 2:

[0078] Embodiment 2 of the present invention provides an arrayed waveguide grating structure for improving the optical performance of CWDM AWG.

[0079] Compared to Example 1, Example 2 presents more specific data to demonstrate the various optical properties of the CWDM4 DEMUX AWG when the output waveguide width is not widened. These properties will be compared with the various optical properties of the CWDM4 DEMUX AWG after the output waveguide width is widened in Example 3 to highlight the superiority of this structure.

[0080] Under the incident condition of a center wavelength of 1.303 μm, when the output waveguide width is 4.4 μm, the refractive index of the waveguide layer is 1.47004 and the refractive index of the cladding is 1.44784. Using the effective refractive index method, the actual refractive index of the 3D waveguide is converted into the equivalent refractive index of the 2D waveguide. The equivalent refractive indices of the 0th to 4th order modes are calculated under different output waveguide widths. When the equivalent refractive index of these modes is greater than the refractive index of the cladding (1.44784), it can be considered that the output waveguide width corresponding to this refractive index can support the mode.

[0081] like Figures 2 to 5 As shown, the horizontal axis represents the output waveguide width, and the vertical axis represents the refractive index. Figures 2 to 5 The upper line shows the change of the equivalent refractive index corresponding to the output waveguide width in this mode as the output waveguide width increases; the lower line shows the change of the cladding refractive index, which shows that the cladding refractive index remains at 1.44784 as the output waveguide width increases.

[0082] Therefore, according to Figures 2 to 5 As shown, when the output waveguide width increases to a certain value, the number of modes that the corresponding output waveguide width can support also increases; for example... Figure 2 , Figure 3 and Figure 4As shown, when the output waveguide width is 4.4µm, the corresponding output waveguide width can support mode 0 and mode 1. At this time, the output spectrum shape of the output waveguide is the shape of the superposition of the output spectra of all the corresponding supported modes of the output waveguide.

[0083] like Figures 7 to 10 As shown in the figure, the horizontal axis represents wavelength and the vertical axis represents channel loss.

[0084] like Figure 7 As shown, Figure 7 This represents the output spectral shape corresponding to the 0th order mode when the output waveguide width is 4.4µm.

[0085] like Figure 8 As shown, Figure 8 This represents the output spectral shape corresponding to the first-order mode when the output waveguide width is 4.4µm.

[0086] like Figure 9 As shown, Figure 9 This represents the shape of the output spectrum obtained by superimposing the output spectra corresponding to the 0th and 1st modes when the output waveguide width is 4.4µm.

[0087] like Figure 10 As shown, Figure 10 for Figure 9 A magnified view showing the channel loss variation trend when the wavelength is from 1.326µm to 1.34µm.

[0088] Therefore, according to Figures 7 to 10 From this, we can derive the following optical specifications for the CWDM4 DEMUX AWG when the output waveguide is 4.4µm:

[0089] Center wavelength: 1.33301815018150um;

[0090] Insertion Loss: 1.44608736614190 dB;

[0091] 0.5dB Bandwidth: 9.20115201152005um;

[0092] 1dB Bandwidth: 10.25056250562506um;

[0093] 3dB Bandwidth: 12.75000750007505um;

[0094] Ripple: 0.97287785720273dB;

[0095] Adj-crosstalk (left) (adjacent channel crosstalk (left side of the spectrum)): 35.44465514154404dB;

[0096] Adj-crosstalk (right): 35.64894256708234dB.

[0097] Example 3:

[0098] Embodiment 3 of the present invention provides an arrayed waveguide grating structure for improving the optical performance of CWDM AWG.

[0099] Compared to Example 1, Example 3 uses more specific data to demonstrate the various optical properties of the CWDM4 DEMUX AWG after the output waveguide width is widened. These properties will be compared with the various optical properties of the CWDM4 DEMUX AWG before the output waveguide width is widened in Example 2 to demonstrate the superiority of this structure.

[0100] Under the incident condition of a center wavelength of 1.303 μm, when the waveguide layer width is 13 μm, the refractive index of the waveguide layer is 1.47004 and the refractive index of the cladding is 1.44784. Using the effective refractive index method, the actual refractive index of the 3D waveguide is converted into the equivalent refractive index of the 2D waveguide. The equivalent refractive indices of the 0th to 4th order modes are calculated under different output waveguide widths. When the equivalent refractive index of these modes is greater than the refractive index of the cladding (1.44784), it can be considered that the output waveguide width corresponding to this refractive index can support the mode.

[0101] like Figures 2 to 5 As shown, when the output waveguide width increases to a certain value, the number of modes that the corresponding output waveguide width can support also increases; for example... Figures 2 to 5 As shown, when the output waveguide width is 13µm, the corresponding output waveguide width can support mode reduction from 0 to 4. At this time, the output spectrum shape of the output waveguide is the shape of the superposition of the output spectra of the modes supported by the output waveguide.

[0102] like Figure 11 As shown, Figure 11 This is the output spectral shape corresponding to the 0th order mode when the output waveguide width is 13µm;

[0103] like Figure 12 As shown, Figure 12 This is the output spectral shape corresponding to the first-order mode when the output waveguide width is 13µm;

[0104] like Figure 13 As shown, Figure 13This is the output spectral shape corresponding to the second-order mode when the output waveguide width is 13µm;

[0105] like Figure 14 As shown, Figure 14 This is the output spectral shape corresponding to the 3rd mode when the output waveguide width is 13µm;

[0106] like Figure 15 As shown, Figure 15 This is the output spectral shape corresponding to the 4th mode when the output waveguide width is 13µm;

[0107] like Figure 16 As shown, Figure 16 The shape of the output spectrum after superimposing the output spectra corresponding to the 0th, 1st, 2nd, 3rd and 4th modes when the output waveguide width is 13µm;

[0108] like Figure 17 As shown, Figure 10 for Figure 9 A magnified view showing the channel loss variation trend when the wavelength is from 1.325µm to 1.341µm.

[0109] Therefore, according to Figures 11 to 17 The following optical specifications of the CWDM4 DEMUX AWG can be obtained when the output waveguide is 13µm:

[0110] Center wavelength: 1.33302508025080um;

[0111] Insertion Loss: 0.03608162173110 dB;

[0112] 0.5dB Bandwidth: 14.06342063420629um;

[0113] 1dB Bandwidth: 15.08577085770857um;

[0114] 3dB Bandwidth: 17.34299342993451um;

[0115] Ripple: 0.02627016471329dB;

[0116] Adj-crosstalk (left) (adjacent channel crosstalk (left side of the spectrum)): 26.84920726358276dB;

[0117] Adj-crosstalk (right) (adjacent channel crosstalk (right side of the spectrum)): 26.13715252878535dB.

[0118] The optical specifications of the CWDM4 DEMUX AWG with an output waveguide of 13µm are compared with those with an output waveguide of 4.4µm, as shown in Table 1:

[0119] Center wavelength 1.33301815018150 1.33302508025080 um No comparison Insertion Loss 1.44608736614190 0.03608162173110 dB The smaller the better 0.5dB Bandwidth 9.20115201152005 14.06342063420629 um The bigger the better 1dB Bandwidth 10.25056250562506 15.08577085770857 um The bigger the better 3dB Bandwidth 12.75000750007505 17.34299342993451 um The bigger the better Ripple 0.97287785720273 0.02627016471329 dB The smaller the better Adj-crosstalk(left) 35.44465514154404 26.84920726358276 dB As long as it is satisfied Adj-crosstalk (right) 35.64894256708234 26.13715252878535 dB As long as it is satisfied

[0120] Table 1

[0121] Where Parameters is the output waveguide width, Unit is the unit, and Remark is the comparison condition;

[0122] As shown in Table 1, the optical properties of CWDM4 DEMUX AWG with an output waveguide width of 13µm are compared with those with an output waveguide width of 4.4µm. It can be seen that, under the condition that the crosstalk between adjacent channels is greater than 26dB, all the optical properties of CWDM4 DEMUX AWG are optimized after the output waveguide width is extended to 13µm.

[0123] Example 4:

[0124] Embodiment 3 of the present invention provides an arrayed waveguide grating structure for improving the optical performance of CWDM AWG.

[0125] Compared to Example 3, Example 4 will further select values ​​around 13um for the output waveguide width of 13um, and conduct tests for output waveguide widths of 12.5um and 13.5um. The CWDM4 DEMUX AWG optical specifications corresponding to output waveguide widths of 12.5um and 13.5um will be obtained and compared with the CWDM4 DEMUX AWG optical specifications for an output waveguide width of 13um. This further demonstrates that an output waveguide width of around 13um is a globally optimal value that meets the application scenario requirements.

[0126] Since the output waveguide widths of 12.5µm and 13.5µm are both greater than the first waveguide width in Example 1, both the output waveguide widths of 12.5µm and 13.5µm support modes 0 to 4.

[0127] like Figure 18 As shown, Figure 18 The shape of the output spectrum is the superposition of the output spectra corresponding to the 0th, 1st, 2nd, 3rd and 4th modes when the output waveguide width is 12.5µm.

[0128] Therefore, the following optical specifications of the CWDM4 DEMUX AWG can be derived when the output waveguide is 12.5µm:

[0129] Center wavelength: 1.33351430014300um;

[0130] Insertion Loss: 0.23646364296813 dB;

[0131] 0.5dB Bandwidth: 13.04173041730405um;

[0132] 1dB Bandwidth: 13.88608886088871um;

[0133] 3dB Bandwidth: 15.88030880308811um;

[0134] Ripple: 0.19973839949804dB;

[0135] Adj-crosstalk (left) (adjacent channel crosstalk (left side of the spectrum)): 32.21772604038134dB;

[0136] Adj-crosstalk (right) (adjacent channel crosstalk (right side of the spectrum)): 31.54494253501418dB.

[0137] The optical specifications of the CWDM4 DEMUX AWG with an output waveguide of 12.5µm are compared with those with an output waveguide of 13µm, as shown in Table 2:

[0138] Center wavelength 1.33351430014300 1.33302508025080 um No comparison Insertion Loss 0.23646364296813 0.03608162173110 dB The smaller the better 0.5dB Bandwidth 13.04173041730405 14.06342063420629 um The bigger the better 1dB Bandwidth 13.88608886088871 15.08577085770857 um The bigger the better 3dB Bandwidth 15.88030880308811 17.34299342993451 um The bigger the better Ripple 0.19973839949804 0.02627016471329 dB The smaller the better Adj-crosstalk(left) 32.21772604038134 26.84920726358276 dB As long as it is satisfied Adj-crosstalk (right) 31.54494253501418 26.13715252878535 dB As long as it is satisfied

[0139] As shown in Table 2, the optical properties of CWDM4 DEMUX AWG with an output waveguide width of 12.5µm are compared with those with an output waveguide width of 13µm. It can be seen that, under the condition that the crosstalk between adjacent channels is greater than 26dB, the optical properties of CWDM4 DEMUX AWG are better after the output waveguide width is extended to 13µm.

[0140] like Figure 19 As shown, Figure 19The shape of the output spectrum is the superposition of the output spectra corresponding to the 0th, 1st, 2nd, 3rd and 4th modes when the output waveguide width is 13.5µm.

[0141] Therefore, the following optical specifications of the CWDM4 DEMUX AWG can be derived when the output waveguide is 13.5µm:

[0142] Center wavelength: 1.33301256012560um;

[0143] Insertion Loss: 0.08847241302493 dB;

[0144] 0.5dB Bandwidth: 14.93853938539391um;

[0145] 1dB Bandwidth: 15.79659796597965um;

[0146] 3dB Bandwidth: 17.79567795677972um;

[0147] Ripple: 0.06537901932147dB;

[0148] Adj-crosstalk (left) (adjacent channel crosstalk (left side of the spectrum)): 24.01592816083928dB;

[0149] Adj-crosstalk (right): 23.44036030880466dB.

[0150] The optical specifications of the CWDM4 DEMUX AWG with an output waveguide of 13.5µm are compared with those with an output waveguide of 13µm, as shown in Table 3:

[0151] Center wavelength 1.33301256012560 1.33302508025080 um No comparison Insertion Loss 0.08847241302493 0.03608162173110 dB The smaller the better 0.5dB Bandwidth 14.93853938539391 14.06342063420629 um The bigger the better 1dB Bandwidth 15.79659796597965 15.08577085770857 um The bigger the better 3dB Bandwidth 17.79567795677972 17.34299342993451 um The bigger the better Ripple 0.06537901932147 0.02627016471329 dB The smaller the better Adj-crosstalk(left) 24.01592816083928 26.84920726358276 dB As long as it is satisfied Adj-crosstalk (right) 23.44036030880466 26.13715252878535 dB As long as it is satisfied

[0152] As shown in Table 2, the optical specifications of CWDM4 DEMUX AWG with an output waveguide width of 13.5µm are compared with those with an output waveguide width of 13µm. It can be seen that although the optical specifications of CWDM4 DEMUX AWG with an output waveguide width of 13.5µm are better, including center wavelength, insertion loss, 0.5dB bandwidth, 1dB bandwidth, 3dB bandwidth and ripple, it does not meet the condition that the crosstalk between adjacent channels is greater than 26dB. Therefore, the optical specifications of CWDM4 DEMUX AWG are still better when the output waveguide width is extended to 13µm.

[0153] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An arrayed waveguide grating structure for improving the optical performance of CWDM AWG, characterized in that, It includes an input waveguide, an input planar waveguide, an arrayed waveguide, an output planar waveguide, and an output waveguide, wherein the input waveguide, input planar waveguide, arrayed waveguide, output planar waveguide, and output waveguide are sequentially coupled together. Specifically: The width of the output waveguide is widened to a preset parameter value; The center wavelength of the optical signal to be adapted by the AWG is set one by one, and the width of the output waveguide, the refractive index of the waveguide layer, and the refractive index of the cladding are preset at each center wavelength. Then, the equivalent refractive index of the 0th to 4th order modes is calculated under each output waveguide width condition. When the equivalent refractive index of the 0th to 4th order modes is greater than or equal to the preset cladding refractive index, the output waveguide width corresponding to the equivalent refractive index supports the 0th to 4th order modes, that is, the preset parameter value is obtained. For the selected center wavelength, the initial output waveguide width is set as the first waveguide width, which is 11.4 μm. The output waveguide width is gradually increased based on the first waveguide width until the crosstalk between adjacent channels is minimized. The output waveguide width at this point is the second waveguide width. The second waveguide width is the optimal operating waveform under the set value. When the selected center wavelength is 1.33µm, the width of the second waveguide is 13 + 0.1µm; under the condition that the crosstalk between adjacent channels is greater than 26dB, the width of the output waveguide is extended to the width of the second waveguide.

2. The arrayed waveguide grating structure for improving the optical performance of CWDM AWG according to claim 1, characterized in that, When the selected center wavelength is 1.303µm, and the preset output waveguide width, waveguide layer refractive index, and cladding refractive index are 4.4µm, 1.47004, and 1.44784, respectively.

3. The arrayed waveguide grating structure for improving the optical performance of CWDM AWG according to claim 2, characterized in that, When the output waveguide width is greater than the first waveguide width, the output waveguide width supports 0th to 4th order modes.

4. The arrayed waveguide grating structure for improving the optical performance of CWDM AWG according to claim 1, characterized in that, The optimal working waveform includes: One or more of the parameters Insertion Loss, 0.5dB Bandwidth, 1dB Bandwidth, 3dB Bandwidth, and Ripple are the optimal values ​​under the given settings.

5. The arrayed waveguide grating structure for improving the optical performance of CWDM AWG according to claim 1, characterized in that, When the output waveguide includes multiple channels, each channel corresponds to a center wavelength. Therefore, the center wavelength of the optical signal to be adapted by the AWG is set one by one with the center wavelength of each channel.

6. The arrayed waveguide grating structure for improving the optical performance of CWDM AWG according to claim 1, characterized in that, The optical signal diverges at the input planar waveguide and then enters the array waveguide.

7. The arrayed waveguide grating structure for improving the optical performance of CWDM AWG according to claim 1, characterized in that, The optical signal is converged in the output planar waveguide and then output from the arrayed waveguide.

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