Demultiplexing system and method for preparing a demultiplexing system

Abstract

This invention provides a demultiplexing system and a method for fabricating the demultiplexing system, comprising: an optical beamsplitter including a first input terminal and first and second output terminals; an input optical signal including multiple optical waves ordered based on their wavelengths, the input optical signal including an odd-numbered optical wave and an even-numbered optical wave; a first frequency interval between adjacent optical waves in the input optical signal; a first interference arm connected to the first output terminal; a second interference arm connected to the second output terminal; a difference in arm length between the first and second interference arms; a second input terminal of an optical beam combiner connected to the first interference arm, a third input terminal of the optical beam combiner connected to the second interference arm, and third and fourth output terminals of the optical beam combiner respectively used to output one of the odd-numbered or even-numbered optical waves; a cascaded dual-ring micro-ring filter connected to the third and fourth output terminals respectively; the arm length difference and the first frequency interval satisfy a relationship.

Description

Technical Field

[0001] This invention relates to the field of semiconductors, and in particular to a demultiplexing system and a method for preparing the demultiplexing system. Background Technology

[0002] As data center communication network transmission rates rapidly evolve towards 1.6Tbps and higher, increasing the number of parallel channels or adopting higher-order modulation formats has become an important technical approach to improve system transmission capacity, given that single-channel baud rates are limited by factors such as device bandwidth and power consumption. Compared to spatial parallel transmission schemes, wavelength division multiplexing (WDM) technology can simultaneously transmit multiple optical signals of different wavelengths in a single optical fiber, increasing link transmission capacity while reducing the number of optical fibers deployed and system costs. Therefore, it is widely used in high-speed communication systems.

[0003] On the other hand, traditional optical modules mostly adopt discrete device packaging solutions. Although the technology is mature, it suffers from problems such as large package size, complex assembly process, and low optoelectronic integration. With the development of near-package optics and optoelectronic co-packaging technologies, optical transceiver systems are gradually evolving towards high-density integration, which places higher demands on the monolithic or heterogeneous integration of large-scale optoelectronic devices.

[0004] To meet the demands of ultra-high-capacity data transmission, the number of on-chip integrated wavelength division multiplexing (WDM) channels is constantly increasing, while the spacing between adjacent wavelength channels is continuously decreasing. For example, in CW-DWDM systems, the spacing between adjacent channels in the O-band can reach 200 GHz. In such high-density WDM systems, realizing WDM devices with smaller channel spacing, higher channel count, and smaller footprint has become one of the key technical challenges.

[0005] It should be noted that the above introduction to the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of this application and facilitating understanding by those skilled in the art. It should not be assumed that these technical solutions are known to those skilled in the art simply because they have been described in the background section of this application. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a demultiplexing system and a method for preparing the demultiplexing system, which provides a demultiplexing system suitable for dense channel spacing and suitable for integrated packaging.

[0007] To achieve the above and other related objectives, the present invention provides a demultiplexing system, comprising:

[0008] An optical beamsplitter includes a first input terminal, a first output terminal, and a second output terminal. The first input terminal is used to receive an input optical signal. The input optical signal includes light waves of multiple wavelengths, ordered according to the wavelengths of the light waves in the input optical signal. The input optical signal includes odd-numbered light waves and even-numbered light waves. Adjacent light waves in the input optical signal have a first frequency interval. The power splitting ratio of the optical beamsplitter for the same wavelength is 50%:50%.

[0009] The first interference arm is connected to the first output terminal;

[0010] The second interference arm is connected to the second output terminal; wherein there is a difference in arm length between the first interference arm and the second interference arm;

[0011] An optical beam combiner includes a second input terminal, a third input terminal, a third output terminal, and a fourth output terminal; wherein the second input terminal is connected to the first interferometer arm, the third input terminal is connected to the second interferometer arm, the third output terminal and the fourth output terminal are respectively used to output one of the odd-numbered light waves or the even-numbered light waves, and the types of light waves output by the third output terminal and the fourth output terminal are different; the power splitting ratio of the optical beam combiner for the same wavelength is 50%:50%; there is a second frequency interval between adjacent light waves in the light waves output by the third output terminal and between adjacent light waves in the light waves output by the fourth output terminal; the second frequency interval is equal to twice the first frequency interval;

[0012] A cascaded dual-ring micro-ring filter is connected to the third output terminal and the fourth output terminal; wherein the third output terminal and the fourth output terminal are respectively connected to a cascaded dual-ring micro-ring filter.

[0013] Wherein, the arm length difference Spacing from the first frequency The following relationship must be satisfied so that the third output terminal and the fourth output terminal respectively output one of the odd-numbered light wave or the even-numbered light wave;

[0014]

[0015] Where c is the speed of light in a vacuum; Let be the group refractive index of the first and second interferometer arms.

[0016] In one embodiment, the demultiplexing system further includes:

[0017] A heated phase shifter includes heating electrodes located on one side of the first interference arm and the second interference arm, respectively, for modulating the group refractive index of the first interference arm and the second interference arm.

[0018] In one embodiment, the heating electrode is made of titanium nitride, nickel silicide, or titanium silicide.

[0019] In one embodiment, the cascaded dual-ring micro-ring filter includes:

[0020] The first direct waveguide is connected to either the third or the fourth output terminal;

[0021] Multiple double-ring micro-ring waveguides are located on one side of the first straight waveguide; each double-ring micro-ring waveguide includes a first micro-ring waveguide and a second micro-ring waveguide, the first micro-ring waveguide being coupled to the first straight waveguide and the second micro-ring waveguide respectively; the resonant wavelengths of the multiple double-ring micro-ring waveguides correspond to the wavelengths of the odd-numbered optical wave and the even-numbered optical wave.

[0022] Multiple second straight waveguides are provided, one of which is coupled to a second micro-ring waveguide, and the second straight waveguide is used to output an optical wave.

[0023] In one embodiment, the demultiplexing system further includes:

[0024] A variable optical attenuator, connected to the output of the cascaded dual-ring micro-ring filter, is used to modulate the power of the light wave passing through the variable optical attenuator.

[0025] In one embodiment, the variable optical attenuator includes:

[0026] A ridge waveguide includes an intrinsically doped region and P-type and N-type doped regions located on either side of the intrinsically doped region, respectively; wherein the light wave is transmitted via the intrinsically doped region; and the P-type and N-type doped regions are each connected to a voltage.

[0027] In one embodiment, the waveguide shapes of the first interference arm and the second interference arm are folded runway shapes.

[0028] In one embodiment, the wavelength range of the input optical signal is 1260 nanometers to 1360 nanometers.

[0029] In one embodiment, the first frequency interval is 200 GHz and the second frequency interval is 400 GHz.

[0030] Secondly, this application also provides a method for preparing a demultiplexing system, the method comprising:

[0031] A substrate is provided, the substrate comprising a substrate and an insulating layer and a silicon layer sequentially stacked on the substrate;

[0032] The silicon layer is etched to form an optical beamsplitter, a first interferometer arm, a second interferometer arm, an optical beam combiner, and a cascaded dual-ring micro-ring filter. The optical beamsplitter includes a first input terminal, a first output terminal, and a second output terminal. The first input terminal receives an input optical signal. The input optical signal includes light waves of multiple wavelengths, ordered based on the wavelengths of the light waves in the input optical signal. The input optical signal includes odd-numbered light waves and even-numbered light waves. Adjacent light waves in the input optical signal have a first frequency interval. The power splitting ratio of the optical beamsplitter for the same wavelength is 50%:50%. The first interferometer arm is connected to the first output terminal. The second interferometer arm is connected to the second output terminal. There is a length difference between the first and second interferometer arms. The optical beam combiner includes a second input terminal, a third input terminal, and a third output terminal. The optical combiner is configured with a second input terminal and a fourth output terminal. The second input terminal is connected to the first interference arm, and the third input terminal is connected to the second interference arm. The third and fourth output terminals are respectively used to output one of the odd-numbered or even-numbered light waves, and the types of light waves output by the third and fourth output terminals are different. The power splitting ratio of the optical combiner for the same wavelength is 50%:50%. Adjacent light waves in the light waves output by the third output terminal and adjacent light waves in the light waves output by the fourth output terminal have a second frequency interval. The second frequency interval is equal to twice the first frequency interval. The cascaded dual-ring micro-ring filter is connected to the third and fourth output terminals. The third and fourth output terminals are respectively connected to a cascaded dual-ring micro-ring filter. The arm length difference... Spacing from the first frequency The following relationship must be satisfied so that the third output terminal and the fourth output terminal respectively output one of the odd-numbered light wave or the even-numbered light wave;

[0033]

[0034] Where c is the speed of light in a vacuum; Let be the group refractive index of the first and second interferometer arms.

[0035] As described above, the demultiplexing system and its preparation method of the present invention have the following beneficial effects:

[0036] The demultiplexing system and its fabrication method described in this application split each light wave in the input optical signal into two beams using an optical beam splitter. These two beams are input into the first and second interferometer arms, respectively. Since there is a length difference between the first and second interferometer arms, and this length difference satisfies the relationship between the first and second interferometer arms and the first frequency interval... Therefore, the light propagating through the first interference arm and the light propagating through the second interference arm interfere within the optical combiner. This causes the odd-numbered light wave to undergo constructive interference at one of the third or fourth output terminals and destructive interference at the other output terminal, resulting in the odd-numbered light wave being output from one of the third or fourth output terminals of the optical combiner. Conversely, the even-numbered light wave undergoes constructive interference at the output terminal of the third or fourth output terminal where the odd-numbered light wave is not output, and destructive interference at the other output terminal, thus causing the odd-numbered light wave and the even-numbered light wave to interfere with each other. The light wave is split, increasing the frequency spacing of the light waves output from the third or fourth output terminal. A cascaded dual-ring micro-ring filter is then connected to the third and fourth output terminals to demultiplex the odd-numbered and even-numbered light waves with increased frequency spacing. Since there is an inherent performance trade-off between the channel spacing of the micro-ring filter and crosstalk between adjacent channels, compared to directly using a micro-ring filter for demultiplexing, this application is applicable to demultiplexing with denser channel spacing under low adjacent channel crosstalk. Furthermore, the fabrication process is simple, the footprint is small, and it is suitable for integrated packaging. In addition, the dual-ring micro-ring filter has a flatter filtering spectrum than the single-ring micro-ring filter, avoiding the problem of a sharp increase in insertion loss due to slight frequency drift during light wave transmission. Attached Figure Description

[0037] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the embodiments of this application and to illustrate the implementation of this application, together with the textual description, to explain the principles of this application. Obviously, the drawings described below are merely some embodiments of this application.

[0038] Figure 1 This is a schematic diagram of the demultiplexing system provided in one embodiment of this application;

[0039] Figure 2 This is a schematic diagram of the structure of a variable optical attenuator provided in one embodiment of this application. Detailed Implementation

[0040] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0041] It should be emphasized that the term "including / comprises" as used herein refers to the presence of a feature, whole, step, or component, but does not exclude the presence or addition of one or more other features, wholes, steps, or components.

[0042] Features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

[0043] In the detailed description of embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged and not to scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0044] For ease of description, spatial relation terms such as “below,” “under,” “lower than,” “below,” “above,” and “upper” may be used herein to describe the relationship between one element or feature shown in the accompanying drawings and other elements or features. It will be understood that these spatial relation terms are intended to include directions other than those depicted in the drawings for devices in use or operation. Furthermore, when a layer is referred to as being “between” two layers, it may be the only layer between the two layers, or there may be one or more layers in between.

[0045] In the context of this application, the structure described above the first feature may include embodiments in which the first and second features are formed in direct contact, or embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0046] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0047] As mentioned in the background section, achieving wavelength demultiplexing devices with small channel spacing, high channel count, and small footprint is a key technical challenge in high-density wavelength division multiplexing (WDM) systems. Furthermore, in practical WDM systems, the output power of different semiconductor lasers typically varies, and different wavelength optical signals are affected by varying degrees of absorption loss and insertion loss during transmission. Moreover, the spectral response of WDM devices is often difficult to maintain perfectly flat, resulting in differences in the output optical power of each demultiplexed channel. With the increase in the number of channels, the imbalance in optical power between channels is further exacerbated, affecting the performance consistency of subsequent detection and signal processing circuits and increasing the difficulty of system power budget design. Therefore, there is an urgent need for an on-chip integrated WDM solution suitable for high-density WDM systems. This solution should achieve small-channel-spaced wavelength demultiplexing while significantly reducing the chip area occupied by the device to meet the requirements of large-scale monolithic integration applications; and it should be able to tunably and evenly control the center wavelength and optical power of each output channel to meet the comprehensive requirements of high integration, miniaturization, high consistency, and low power consumption in high-speed optical communication systems.

[0048] Based on the above issues, please refer to Figure 1 This application provides a demultiplexing system, including: an optical beam splitter 10, a first interferometer 210, a second interferometer 220, an optical beam combiner 40, and a cascaded dual-ring micro-ring filter 50.

[0049] The optical beam splitter 10 includes a first input terminal, a first output terminal, and a second output terminal; the first input terminal is used to receive an input optical signal; wherein, the input optical signal includes light waves of multiple wavelengths, which are ordered based on the wavelengths of the light waves in the input optical signal, and the input optical signal includes odd-numbered light waves and even-numbered light waves; there is a first frequency interval between adjacent light waves in the input optical signal; the power splitting ratio of the optical beam splitter 10 for the same wavelength is 50%:50%.

[0050] As an example, the optical beam splitter 10 may include a 1×2 multimode interferometer.

[0051] As an example, the light waves in the input light signal are sorted based on their wavelengths. For example, they can be sorted in descending order of wavelength. The odd-numbered light waves can be included in the Nth light wave in the sort, where N can be an odd number such as 1, 3, 5, 7, or 9. The even-numbered light waves can be included in the (N+1)th light wave in the sort.

[0052] The first interference arm 210 is connected to the first output terminal.

[0053] The second interference arm 220 is connected to the second output terminal; wherein, there is a difference in arm length between the first interference arm 210 and the second interference arm 220.

[0054] As an example, the first interferometer arm 210 and the second interferometer arm 220 may include strip waveguides, and the difference in arm length is the absolute value of the difference between the waveguide length of the first interferometer arm 210 and the waveguide length of the second interferometer arm 220.

[0055] The optical beam combiner 40 includes a second input terminal, a third input terminal, a third output terminal, and a fourth output terminal. The second input terminal is connected to the first interference arm 210, and the third input terminal is connected to the second interference arm 220. The third and fourth output terminals are used to output either an odd-numbered or an even-numbered light wave, and the types of light waves output by the third and fourth output terminals are different. The power splitting ratio of the optical beam combiner 40 for the same wavelength is 50%:50%. There is a second frequency interval between adjacent light waves in the light waves output by the third output terminal and between adjacent light waves in the light waves output by the fourth output terminal. The second frequency interval is equal to twice the first frequency interval.

[0056] As an example, the optical combiner 40 may include a 2×2 multimode interferometer. The light wave type may include an odd-numbered light wave and an even-numbered light wave. The third output terminal and the fourth output terminal are respectively used to output one of the odd-numbered light waves or the even-numbered light waves, and the light wave types output by the third output terminal and the fourth output terminal are different, which may include: the third output terminal outputs the odd-numbered light wave and the fourth output terminal outputs the even-numbered light wave, or the third output terminal outputs the even-numbered light wave and the fourth output terminal outputs the odd-numbered light wave.

[0057] A cascaded dual-ring micro-ring filter is connected to the third and fourth output terminals respectively; wherein the third and fourth output terminals are respectively connected to a first-stage cascaded dual-ring micro-ring filter.

[0058] Among them, arm length difference Spacing from the first frequency The following relationship must be satisfied so that the third output terminal and the fourth output terminal respectively output one of the odd-numbered light wave or the even-numbered light wave;

[0059]

[0060] Where c is the speed of light in a vacuum; Let be the group refractive index of the first and second interferometer arms.

[0061] As an example, based on the input optical signal being in the O band and the first frequency interval being 200 GHz, with a group refractive index of 4.37, the arm length difference can be set to 160-180 micrometers, or precisely controlled to 171 micrometers.

[0062] In the above embodiment, each light wave in the input optical signal is split into two beams by an optical beam splitter. The two beams correspond to the first interferometer arm and the second interferometer arm, respectively. Since there is a difference in arm length between the first and second interferometer arms, and the difference in arm length satisfies the relationship between the first frequency interval and the optical beam splitter, the optical beam splitter is used to split each light wave into two beams. Therefore, the light propagating through the first interference arm and the light propagating through the second interference arm interfere within the optical combiner. This causes the odd-numbered light wave to undergo constructive interference at one of the third or fourth output terminals and destructive interference at the other output terminal, resulting in the odd-numbered light wave being output from one of the third or fourth output terminals of the optical combiner. Conversely, the even-numbered light wave undergoes constructive interference at the output terminal of the third or fourth output terminal where the odd-numbered light wave is not output, and destructive interference at the other output terminal, thus causing the odd-numbered light wave and the even-numbered light wave to interfere with each other. The light wave is split, increasing the frequency spacing of the light waves output from the third or fourth output terminal. A cascaded dual-ring micro-ring filter is then connected to the third and fourth output terminals to demultiplex the odd-numbered and even-numbered light waves with increased frequency spacing. Since there is an inherent performance trade-off between the channel spacing of the micro-ring filter and crosstalk between adjacent channels, compared to directly using a micro-ring filter for demultiplexing, this application is applicable to demultiplexing with denser channel spacing under low adjacent channel crosstalk. Furthermore, the fabrication process is simple, the footprint is small, and it is suitable for integrated packaging. In addition, the dual-ring micro-ring filter has a flatter filtering spectrum than the single-ring micro-ring filter, avoiding the problem of a sharp increase in insertion loss due to slight frequency drift during light wave transmission. In some embodiments, the wavelength range of the input optical signal is 1260 nm to 1360 nm.

[0063] As an example, the wavelength of the input optical signal may include 1295.56 nm, 1296.34 nm, 1297.12 nm, 1297.91 nm, etc.

[0064] In some embodiments, the first frequency interval is 200 GHz and the second frequency interval is 400 GHz.

[0065] In some embodiments, the materials of the optical beam splitter, the first interferometer arm, the second interferometer arm, the optical beam combiner, and the cascaded dual-ring micro-ring filter include silicon; the demultiplexing system further includes a substrate and an insulating layer; wherein the insulating layer is located on the substrate, and the optical beam splitter, the first interferometer arm, the second interferometer arm, the optical beam combiner, and the cascaded dual-ring micro-ring filter are located on the insulating layer.

[0066] In the above embodiments, by making the demultiplexing system based on the silicon-on-insulator (SOI) platform, the cost is low and the fabrication process is simple.

[0067] In some embodiments, the waveguide shapes of the first interference arm and the second interference arm are folded runway shapes.

[0068] In the above embodiments, by making the waveguide shape of the first interferometer arm and the second interferometer arm into a folded runway shape, the volume occupied by the first interferometer arm and the second interferometer arm can be reduced, thereby reducing the volume of the demultiplexing system and facilitating improved integration.

[0069] In some embodiments, the bending radius of the curved area in the folded runway shape is greater than or equal to 5 micrometers.

[0070] The curved region refers to the waveguide in a curved area. A folded runway-shaped waveguide may include both a straight waveguide region and a curved region. As an example, the curvature of the curved region in a folded runway-shaped waveguide is 5 micrometers, 6 micrometers, 7 micrometers, 8 micrometers, 9 micrometers, 10 micrometers, etc.

[0071] In the above embodiments, by making the bending radius of the curved area in the folded runway greater than or equal to 5 micrometers, the influence of bending loss on interference contrast can be avoided. In addition, the bending radius of the curved area in the folded runway cannot be too large, otherwise the volume occupied will increase.

[0072] In some embodiments, please refer to Figure 1 The demultiplexing system also includes a heating phase shifter 30, which includes heating electrodes located on one side of the first interference arm 210 and the second interference arm 220, respectively, for modulating the group refractive index of the first interference arm 210 and the second interference arm 220.

[0073] As an example, by applying a voltage to the heating phase shifter 30, the heating phase shifter 30 is heated, thereby utilizing the thermo-optical effect of silicon material to modulate the group refractive index of the first interferometer arm 210 and the second interferometer arm 220. During the fabrication of the demultiplexing system, slight deviations in the effective refractive index and group refractive index of the actually fabricated waveguide are inevitable due to process tolerances and other factors. Since the arm length difference is designed and fabricated based on theoretical calculations, even slight deviations in the group refractive index of the first interferometer arm 210 and the second interferometer arm 220 can cause wavelength drift at the third and fourth output terminals, affecting the demultiplexing effect. By setting the heating phase shifter 30 to modulate the group refractive index of the first interferometer arm 210 and the second interferometer arm 220, the accuracy of demultiplexing can be improved.

[0074] In some embodiments, the heating electrode is made of titanium nitride, nickel silicide, or titanium silicide.

[0075] In the above embodiments, by making the heating electrode material include titanium nitride, nickel silicide, and titanium silicide, the adhesion performance between the heating electrode and the insulating layer can be guaranteed, and the heating electrode can be prevented from falling off.

[0076] In some embodiments, please refer to Figure 1The cascaded dual-ring micro-ring filter 50 includes: a first straight waveguide 510, multiple dual-ring micro-ring waveguides 520, and multiple second straight waveguides 530; the first straight waveguide 510 is connected to a third output terminal and a fourth output terminal; the multiple dual-ring micro-ring waveguides 520 are located on one side of the first straight waveguide 510; each dual-ring micro-ring waveguide 520 includes a first micro-ring waveguide and a second micro-ring waveguide, the first micro-ring waveguide being coupled to the first straight waveguide 510 and the second micro-ring waveguide respectively; the resonant wavelengths of the multiple dual-ring micro-ring waveguides 520 correspond to the wavelengths of the odd-numbered and even-numbered optical waves; a second straight waveguide 530 is coupled to a second micro-ring waveguide for outputting an optical wave.

[0077] In some embodiments, please refer to Figure 1 The demultiplexing system also includes a variable optical attenuator 60, which is connected to the output of the cascaded dual-ring micro-ring filter 50 and is used to modulate the power of the light wave passing through the variable optical attenuator 60.

[0078] In the above embodiments, by modulating the power of the light waves through the variable optical attenuator, the power of the multiple light waves after demultiplexing can be made to be consistent, which alleviates the power inconsistency caused by different wavelength optical signals being affected by different degrees of absorption loss and device insertion loss during transmission, improves the optical power balance between channels, and realizes dual tuning of power and wavelength.

[0079] In some embodiments, please refer to Figure 2 The variable optical attenuator includes a ridge waveguide, which includes an intrinsic doped region 620 and P-type doped regions 630 and N-type doped regions 610 located on both sides of the intrinsic doped region, respectively. The light wave is transmitted through the intrinsic doped region 620. The P-type doped region 630 and the N-type doped region 610 are respectively connected to a voltage, so as to modulate the carrier concentration of the intrinsic doped region 620 by adjusting the voltage of the P-type doped region 630 and the N-type doped region 610, thereby modulating the power of the light wave passing through the intrinsic doped region 620.

[0080] In some embodiments, this application also provides a method for fabricating a demultiplexing system, the method comprising: providing a substrate, the substrate including a substrate and an insulating layer located on the substrate; forming a silicon layer on the insulating layer; etching the silicon layer to form an optical beamsplitter, a first interferometer arm, a second interferometer arm, an optical beam combiner, and a cascaded dual-ring micro-ring filter; wherein, the optical beamsplitter includes a first input terminal, a first output terminal, and a second output terminal; the first input terminal is used to receive an input optical signal; the input optical signal includes light waves of multiple wavelengths, ordered based on the wavelengths of the light waves in the input optical signal, the input optical signal including odd-numbered light waves and even-numbered light waves; adjacent light waves in the input optical signal have a first frequency interval; the power splitting ratio of the optical beamsplitter for the same wavelength is 50%:50%; the first interferometer arm is connected to the first output terminal; the second interferometer arm is connected to the second output terminal; wherein, There is a length difference between the first and second interferometer arms; the optical beam combiner includes a second input end, a third input end, a third output end, and a fourth output end, wherein the second input end is connected to the first interferometer arm, the third input end is connected to the second interferometer arm, and the third and fourth output ends are respectively used to output one of the odd-numbered or even-numbered light waves, and the types of light waves output by the third and fourth output ends are different; the power splitting ratio of the optical beam combiner for the same wavelength is 50%:50%; there is a second frequency interval between adjacent light waves in the light waves output by the third output end and between adjacent light waves in the light waves output by the fourth output end; the second frequency interval is equal to twice the first frequency interval; a cascaded dual-ring micro-ring filter is connected to the third and fourth output ends; wherein the third and fourth output ends are respectively connected to a cascaded dual-ring micro-ring filter; arm length difference Spacing from the first frequency The following relationship must be satisfied so that the third output terminal and the fourth output terminal respectively output one of the odd-numbered light wave or the even-numbered light wave;

[0081]

[0082] Where c is the speed of light in a vacuum; Let be the group refractive index of the first and second interferometer arms.

[0083] In some embodiments, before etching the silicon layer to form the optical beamsplitter, the first interferometer arm, the second interferometer arm, the optical combiner, and the cascaded dual-ring micro-ring filter, the method further includes: determining the arm length difference. Spacing from the first frequency Correspondence The steps.

[0084] As an example, determine the arm length difference. Spacing from the first frequency The correspondence includes: making the free spectral region (FSR) of the optical beam splitter, the first interferometer arm, the second interferometer arm, and the optical beam combiner correspond to the first frequency interval. Satisfying the relation To separate the odd-numbered and even-numbered light waves in the input optical signal; based on the interference conditions of the optical beam splitter, the first interferometer arm, the second interferometer arm, and the optical beam combiner, the arm length difference is determined. Correspondence with FSR in the free spectral region Based on the difference in arm length Correspondence with FSR in the free spectral region And the free spectral region (FSR) of the optical beam splitter, the first interferometer arm, the second interferometer arm, and the optical combiner, and the first frequency interval. relational formula The difference in arm length was obtained. Spacing from the first frequency Correspondence The steps include determining the arm length difference based on the interference conditions of the optical beam splitter, the first interferometer arm, the second interferometer arm, and the optical beam combiner. The correspondence with the free spectral region FSR includes: the interference conditions of the optical beam splitter, the first interferometer arm, the second interferometer arm, and the optical beam combiner are given by formula (1):

[0085] Formula (1): ;

[0086] in, Let be the phase difference of a certain light wave after passing through the first and second interferometer arms. The wavelength of a certain light wave in the input optical signal;

[0087] Because the free spectral range (FSR) is much smaller than the wavelength of a certain light wave in the input optical signal. ,right Performing a first-order Taylor expansion, we obtain formula (2):

[0088] Formula (2): ;

[0089] Substituting formula (2) into formula (1) yields formula (3):

[0090] Formula (3): ;

[0091] Based on the phase difference of a certain light wave after passing through the first and second interferometer arms Difference from arm length relational formula Formula (4) can be obtained:

[0092] Formula (4): ;

[0093] in, The effective refractive index of a certain light wave in the first and second interferometer arms;

[0094] Based on the group refractive index of a certain light wave in the first and second interferometer arms The effective refractive index of a certain light wave in the first and second interferometer arms relational formula From formula (4), we can obtain formula (5):

[0095] Formula (5): ;

[0096] Based on formulas (5) and (3), we can obtain formula (6):

[0097] Formula (6): ;

[0098] Transforming formula (6) to the frequency domain yields the arm length difference. Correspondence with FSR in the free spectral region:

[0099] .

[0100] In summary, the demultiplexing system and its fabrication method of the present invention split each light wave in the input optical signal into two beams using an optical beam splitter. These two beams are input into the first and second interferometer arms, respectively. Since there is a length difference between the first and second interferometer arms, and this length difference satisfies the relationship between the first and second interferometer arms and the first frequency interval, the demultiplexing method achieves the desired result. Therefore, the light propagating through the first interference arm and the light propagating through the second interference arm interfere within the optical combiner. This causes the odd-numbered light wave to undergo constructive interference at one of the third or fourth output terminals and destructive interference at the other output terminal, resulting in the odd-numbered light wave being output from one of the third or fourth output terminals of the optical combiner. Conversely, the even-numbered light wave undergoes constructive interference at the output terminal of the third or fourth output terminal where the odd-numbered light wave is not output, and destructive interference at the other output terminal, thus causing the odd-numbered light wave... The even-numbered light waves are split, increasing the frequency interval of the light waves output from the third or fourth output terminal. Then, a cascaded dual-ring micro-ring filter is connected to the third and fourth output terminals to demultiplex the odd-numbered and even-numbered light waves with increased frequency intervals. Since the cascaded micro-ring filter has a lower limit on the applicable channel interval, compared to the channel crosstalk caused by using a single cascaded micro-ring filter for demultiplexing, this application can be applied to demultiplexing with denser channel intervals. Furthermore, the fabrication process is simple, the volume is small, and it is suitable for integrated packaging. Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial applicability.

[0101] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A demultiplexing system, characterized in that, include: An optical beamsplitter includes a first input terminal, a first output terminal, and a second output terminal. The first input terminal is used to receive an input optical signal. The input optical signal includes light waves of multiple wavelengths, ordered according to the wavelengths of the light waves in the input optical signal. The input optical signal includes odd-numbered light waves and even-numbered light waves. Adjacent light waves in the input optical signal have a first frequency interval. The power splitting ratio of the optical beamsplitter for the same wavelength is 50%:50%. The first interference arm is connected to the first output terminal; The second interference arm is connected to the second output terminal; wherein there is a difference in arm length between the first interference arm and the second interference arm; An optical beam combiner includes a second input terminal, a third input terminal, a third output terminal, and a fourth output terminal; wherein the second input terminal is connected to the first interferometer arm, the third input terminal is connected to the second interferometer arm, the third output terminal and the fourth output terminal are respectively used to output one of the odd-numbered light waves or the even-numbered light waves, and the types of light waves output by the third output terminal and the fourth output terminal are different; the power splitting ratio of the optical beam combiner for the same wavelength is 50%:50%; there is a second frequency interval between adjacent light waves in the light waves output by the third output terminal and between adjacent light waves in the light waves output by the fourth output terminal; the second frequency interval is equal to twice the first frequency interval; A cascaded dual-ring micro-ring filter is connected to the third output terminal and the fourth output terminal; wherein the third output terminal and the fourth output terminal are respectively connected to a cascaded dual-ring micro-ring filter. The arm length difference The first frequency interval The third output end and the fourth output end respectively output one of the first odd-numbered light wave or the first even-numbered light wave. where c is the speed of light in vacuum; n1, n2are the group refractive indices of the first and second interference arms, respectively.

2. The demultiplexing system of claim 1, wherein, The demultiplexing system also includes: A thermo-optical phase shifter includes heating electrodes located on one side of the first interferometer arm and the second interferometer arm, respectively, for modulating the group refractive index of the first interferometer arm and the second interferometer arm.

3. The demultiplexing system of claim 2, wherein, The materials of the heating electrode include titanium nitride, nickel silicide, and titanium silicide.

4. The demultiplexing system of claim 1, wherein, The cascaded dual-ring micro-ring filter includes: The first direct waveguide is connected to either the third or the fourth output terminal; Multiple double-ring micro-ring waveguides are located on one side of the first straight waveguide; each double-ring micro-ring waveguide includes a first micro-ring waveguide and a second micro-ring waveguide, the first micro-ring waveguide being coupled to the first straight waveguide and the second micro-ring waveguide respectively; the resonant wavelengths of the multiple double-ring micro-ring waveguides correspond to the wavelengths of the odd-numbered optical wave and the even-numbered optical wave. Multiple second straight waveguides are provided, one of which is coupled to a second micro-ring waveguide, and the second straight waveguide is used to output an optical wave.

5. The demultiplexing system of claim 1, wherein, The demultiplexing system also includes: A variable optical attenuator, connected to the output of the cascaded dual-ring micro-ring filter, is used to modulate the power of the light wave passing through the variable optical attenuator.

6. The demultiplexing system according to claim 5, characterized in that, The variable optical attenuator includes: A ridge waveguide includes an intrinsically doped region and P-type and N-type doped regions located on either side of the intrinsically doped region, respectively; wherein the light wave is transmitted via the intrinsically doped region; and the P-type and N-type doped regions are each connected to a voltage.

7. The demultiplexing system according to claim 1, characterized in that, The waveguide shapes of the first interferometer arm and the second interferometer arm are folded runway shapes.

8. The demultiplexing system of claim 1, wherein, The wavelength range of the input optical signal is 1260 nanometers to 1360 nanometers.

9. The demultiplexing system of claim 7, wherein, The first frequency interval is 200 GHz, and the second frequency interval is 400 GHz.

10. A method of producing a de-multiplexing system, characterized by, The method includes: A substrate is provided, the substrate comprising a substrate and an insulating layer and a silicon layer sequentially stacked on the substrate; The silicon layer is etched to form an optical beamsplitter, a first interferometer arm, a second interferometer arm, an optical beam combiner, and a cascaded dual-ring micro-ring filter. The optical beamsplitter includes a first input terminal, a first output terminal, and a second output terminal. The first input terminal receives an input optical signal. The input optical signal includes light waves of multiple wavelengths, ordered based on the wavelengths of the light waves in the input optical signal. The input optical signal includes odd-numbered light waves and even-numbered light waves. Adjacent light waves in the input optical signal have a first frequency interval. The power splitting ratio of the optical beamsplitter for the same wavelength is 50%:50%. The first interferometer arm is connected to the first output terminal. The second interferometer arm is connected to the second output terminal. There is a length difference between the first and second interferometer arms. The optical beam combiner includes a second input terminal, a third input terminal, and a third output terminal. The optical combiner is configured with a second input terminal and a fourth output terminal. The second input terminal is connected to the first interference arm, and the third input terminal is connected to the second interference arm. The third and fourth output terminals are respectively used to output one of the odd-numbered or even-numbered light waves, and the types of light waves output by the third and fourth output terminals are different. The power splitting ratio of the optical combiner for the same wavelength is 50%:50%. Adjacent light waves in the light waves output by the third output terminal and adjacent light waves in the light waves output by the fourth output terminal have a second frequency interval. The second frequency interval is equal to twice the first frequency interval. The cascaded dual-ring micro-ring filter is connected to the third and fourth output terminals. The third and fourth output terminals are respectively connected to a cascaded dual-ring micro-ring filter. The arm length difference... Spacing from the first frequency The following relationship must be satisfied so that the third output terminal and the fourth output terminal respectively output one of the odd-numbered light wave or the even-numbered light wave; Where c is the speed of light in a vacuum; Let be the group refractive index of the first and second interferometer arms.

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