On-chip polarization resolution online optical power monitoring method

Abstract

The invention discloses an on-chip polarization resolution online optical power monitoring method and a corresponding system structure, and belongs to the field of integrated photonics. According to the method, the problems of large size, non-real-time and destructive detection and the like of a traditional polarization detection technology are solved through an innovative function modular design and a structural integration scheme. The core of the method is to realize the functional steps of polarization beam splitting, power extraction, photoelectric detection and polarization beam combination by using an on-chip optical waveguide: firstly, an input optical signal is decomposed into a transverse electric (TE) polarization component and a transverse magnetic (TM) polarization component through a polarization beam splitting structure, and then a small part of power is separated from each polarized light by a power extraction structure for monitoring; meanwhile, low-loss transmission of a main optical path is ensured; monitoring optical signals are converted into electric signals through the germanium-silicon detection structure, and beam combination output of main optical signals is achieved through the polarization beam combination structure. The method supports the flexible implementation mode of each step, and has the advantages of high-precision monitoring, compact structure and good process compatibility through the structural design of a function-integrated device. The polarization state monitoring device is suitable for the fields of polarization multiplexing optical communication, quantum, biosensing and the like, and an efficient solution is provided for polarization state monitoring in a photon integrated circuit.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of integrated photonics, and particularly relates to a kind of on-chip polarization-resolved online optical power monitoring method, suitable for polarization state real-time monitoring in integrated optical path, especially suitable for polarization multiplexing optical communication, quantum and biological sensing fields. BACKGROUND

[0002] With the rapid development of integrated photonics technology, silicon optical integration is increasingly widely used in optical communication, quantum computing and biological sensing fields.Polarization state, as one of the core attributes of optical signal, its efficient management and accurate monitoring has become the key to improve system performance.In polarization multiplexing system, independent control of transverse electric (TE) polarization component or transverse magnetic (TM) polarization component can significantly improve channel capacity, if real-time monitoring of TE polarization and TM polarization power can be realized simultaneously, it is possible to dynamically compensate channel polarization-dependent loss;In quantum information processing, polarization beam splitting and online feedback of optical power directly affect the stability of quantum bits;In the field of biological sensing, the coordinated monitoring of polarization state analysis and optical intensity fluctuation can improve the signal recognition accuracy of molecular interaction.However, traditional polarization detection technology often relies on bulky discrete components, and is usually non-real-time detection, which is difficult to realize online monitoring.Therefore, there is an urgent need for a low-loss, high-integration on-chip polarization-resolved online optical power monitoring method. SUMMARY

[0003] Therefore, the embodiments of the present application provide an on-chip polarization-resolved online optical power monitoring method and system to solve at least one problem in the background art.Through innovative functional modular design and structural integration scheme, the problems of large volume, non-real-time in the prior art are solved.

[0004] The embodiments of the present application provide an on-chip polarization-resolved online optical power monitoring method, comprising the following steps:

[0005] S1. Polarization beam splitting: the input optical signal is separated into transverse electric (TE) polarization component and transverse magnetic (TM) polarization component by polarization beam splitting structure;

[0006] S2. Power extraction: a small amount of power is extracted from each polarization state optical signal by power extraction structure, preferably in the range of 1%-10%, while maintaining low-loss transmission of the main optical path signal;

[0007] S3. Photoelectric detection: the extracted optical signals are converted into electrical signals by germanium-silicon detection structure, and the optical power of TE polarization component and TM polarization component is obtained in real time;

[0008] S4. Polarization beam combining: the TE polarization and TM polarization optical signals in the main optical path are combined and output by silicon-based polarization beam combining structure;

[0009] The silicon-based structures in steps S1-S4 are integrated on a chip by a silicon optical process, and the structures in each step are interconnected by a silicon-based optical waveguide to achieve low-loss transmission of optical signals.

[0010] According to a specific implementation of an embodiment of the present disclosure, the silicon-based optical power monitor is characterized in that:

[0011] After the two polarization states are separated in S1, steps S2 and S3 can be physically implemented by the same silicon-based device or structure for TE and / or TM polarization components.

[0012] According to a specific implementation of an embodiment of the present disclosure, the silicon-based optical power monitor is characterized in that:

[0013] Steps S1 and S2 can be physically implemented by the same silicon-based device or structure for TE and / or TM polarization components.

[0014] According to a specific implementation of an embodiment of the present disclosure, the silicon-based optical power monitor is characterized in that:

[0015] In the case where steps S1 and S2 are implemented by the same device or structure, a simplified method without step S4 is supported.

[0016] According to the on-chip polarization-resolved online optical power monitoring method, an embodiment of the present disclosure further provides an on-chip polarization-resolved online optical power monitoring system, which is characterized by comprising:

[0017] A polarization beam splitter configured to separate an input optical signal into TE and TM modes;

[0018] A TE power extractor connected to a TE port of the polarization beam splitter to extract a small amount of power, preferably in a range of 1%-10%, from a TE main light path;

[0019] A TM power extractor connected to a TM port of the polarization beam splitter to extract a small amount of power, preferably in a range of 1%-10%, from a TM main light path;

[0020] A TE photodetector connected to the TE power extractor to convert the optical power extracted from the TE main light path into a photocurrent signal;

[0021] A TM photodetector connected to the TM power extractor to convert the optical power extracted from the TM main light path into a photocurrent signal;

[0022] A polarization combiner connected to the main light paths of the TE power extractor and the TM power extractor to combine TE and TM light for output;

[0023] All the units above are integrated by silicon optical process, and are interconnected by silicon optical waveguide.

[0024] According to a specific implementation manner of the embodiment of the present disclosure, the system comprises:

[0025] The TE power extractor and the TE photodetector in the system are integrated as a TE power extraction detector through structural design, and simultaneously realize the functions of power extraction and photodetection for the TE polarization state.

[0026] The TM power extractor and the TM photodetector in the system are integrated as a TM power extraction detector through structural design, and simultaneously realize the functions of power extraction and photodetection for the TM polarization state.

[0027] According to a specific implementation manner of the embodiment of the present disclosure, the system comprises:

[0028] The polarization beam splitter and the TE power extractor and the TM power extractor in the system are integrated as a power extractor for the TE polarization and a power extractor for the TM polarization through device structural design, and simultaneously realize the function of small amount of power extraction for a single polarization state without affecting the other polarization state.

[0029] According to a specific implementation manner of the embodiment of the present disclosure, the system comprises:

[0030] Based on the architecture of the TE polarization power extractor and the TM polarization power extractor in the system, most of the TE and TM polarization components in the input light have been contained in the main light path, and a polarization beam combiner is not needed.

[0031] According to a specific implementation manner of the embodiment of the present disclosure, the system comprises:

[0032] The TE photodetector and the TM photodetector in the system both adopt a germanium-silicon detection structure, and can be further integrated through electrode common ground.

[0033] According to a specific implementation manner of the embodiment of the present disclosure, the system comprises:

[0034] The devices in the system are all silicon optical devices.

[0035] According to a specific implementation manner of the embodiment of the present disclosure, the system comprises:

[0036] The TE and / or TM power extraction detector in the system is a germanium-silicon hybrid structure, and can simultaneously realize low-loss transmission and online power monitoring of the corresponding polarization input optical signal.

[0037] According to a specific implementation manner of the embodiment of the present disclosure, the system comprises:

[0038] The silicon optical devices in the system can be designed and obtained by using an optimization algorithm or a reverse design method.

[0039] The method of the application is based on the functional steps of S1 polarization beam splitting, S2 power extraction, S3 photoelectric detection, and S4 polarization beam combining, and uses on-chip optical waveguides to achieve efficient and compact polarization component power monitoring. At the physical structure level, the application supports flexible implementation of the functional steps, which can use separate on-chip devices (such as directional couplers, multimode interference devices, and germanium-silicon detectors) or integrate multiple functions into a single device to achieve system functions.

[0040] The application provides an on-chip polarization-resolved online optical power monitoring method and system, which can obtain the optical power information of the TE and TM orthogonal polarization components in the optical signal in real time and online, and accurately realize polarization resolution. By extracting only a small amount of power (preferably 1%-10%) for detection, while reducing the system insertion loss through optimized design, the low-loss transmission of the main optical path signal is ensured. All core functional units are integrated on a single chip through standard silicon optical technology, which has the advantages of compact structure, small size, excellent process compatibility, and easy integration with existing silicon optical platforms. At the same time, it supports multiple structure implementation methods (such as separate devices or highly integrated multifunctional devices), has strong design flexibility, and can optimize system performance and size according to specific application requirements. Therefore, the application is particularly suitable for integrated optical system sensitive to polarization state or requiring polarization multiplexing, such as high-speed optical communication (compensating polarization-dependent loss), quantum information processing (polarization state feedback), and biological sensing (polarization state analysis and cooperative monitoring), etc. in various fields, which significantly improves the performance and reliability of related systems. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0042] Figure 1 A typical system structure diagram of an on-chip polarization-resolved online optical power monitoring method provided for the first embodiment of the application is shown in FIG. 1, in which 1001 is a polarization beam splitter, 1002 is a TE power extractor, 1003 is a TM power extractor, 1004 is a TE photoelectric detector, 1005 is a TM photoelectric detector, and 1006 is a polarization beam combiner.

[0043] Figure 2A structure schematic diagram of a specific example of a polarization-resolved on-line optical power monitoring method on chip provided by the embodiment one of the present application, wherein 101 is a first waveguide region, 102 is a coupling arm of a first coupling region, 103 is a straight-through arm of the first coupling region, 104 is a second waveguide region, 105 is a third waveguide region, 106 is a coupling arm of a second coupling region, 107 is a straight-through arm of the second coupling region, 108 is a straight-through arm of a third coupling region, 109 is a coupling arm of the third coupling region, 110 is a silicon waveguide of a first photoelectric detection region, 111 is a germanium absorption material of the first photoelectric detection region, 112 is an electrode of the first photoelectric detection region, 113 is a silicon waveguide of a second photoelectric detection region, 114 is a germanium absorption material of the second photoelectric detection region, 115 is an electrode of the second photoelectric detection region, 116 is a fourth waveguide region, 117 is a fifth waveguide region, 118 is a coupling arm of a fourth coupling region, 119 is a straight-through arm of the fourth coupling region, and 120 is a sixth waveguide region.

[0044] Figure 3 A light field distribution diagram of a first coupling region of a specific example of a polarization-resolved on-line optical power monitoring method on chip provided by the embodiment one of the present application, Figure 3 a is a light field distribution diagram when a TM polarization state optical signal is input, Figure 3 b is a light field distribution diagram when a TE polarization state optical signal is input, wherein 201 is a coupling arm of a first coupling region, and 202 is a straight-through arm of the first coupling region.

[0045] Figure 4 A light field distribution diagram of an alternative structure of a first coupling region of a specific example of a polarization-resolved on-line optical power monitoring method on chip provided by the embodiment one of the present application, Figure 4 a is a light field distribution diagram when a TM polarization state optical signal is input, Figure 4 b is a light field distribution diagram when a TE polarization state optical signal is input, wherein 301 is a straight-through arm of a first coupling region, 302 is a first-level coupling arm of the first coupling region, 303 is a second-level coupling arm of the first coupling region, and 304 is a third-level coupling arm of the first coupling region.

[0046] Figure 5 A system structure diagram of a polarization-resolved on-line optical power monitoring method provided by the embodiment two of the present application, wherein 5001 is a polarization beam splitter, 5002 is a TE power extraction detector, 5003 is a TM power extraction detector, and 5004 is a polarization beam combiner.

[0047] Figure 6A structure schematic diagram of a specific example of a polarization-resolved on-line optical power monitoring method on chip provided by the second embodiment of the present application, wherein 401 is a first waveguide region, 402 is a straight-through arm of a first coupling region, 403 is a coupling arm of the first coupling region, 404 is a second waveguide region, 405 is a third waveguide region, 406 is a first waveguide region of a first absorption region, 407 is a second waveguide region of the first absorption region, 408 is a third waveguide region of the first absorption region, 409 is a fourth waveguide region of the first absorption region, 410 is a fifth waveguide region of the first absorption region, 421 is germanium absorption material of the first absorption region, 411 is a first waveguide region of a second absorption region, 412 is a second waveguide region of the second absorption region, 413 is a third waveguide region of the second absorption region, 414 is a fourth waveguide region of the second absorption region, 415 is a fifth waveguide region of the second absorption region, 422 is germanium absorption material of the second absorption region, 423 is a metal electrode, 416 is a fourth waveguide region, 417 is a fifth waveguide region, 418 is a straight-through arm of a second coupling region, 419 is a coupling arm of the second coupling region, and 420 is a sixth waveguide region.

[0048] Figure 7 A side sectional view of a specific example of a polarization-resolved on-line optical power monitoring method on chip provided by the second embodiment of the present application, wherein 501 is an N(P) ion heavily doped region, 502 is an N(P) ion lightly doped region, 503 is an undoped region, 504 is a P(N) ion lightly doped region, 505 is a P(N) ion heavily doped region, 421 is germanium absorption material, and 423 is a metal electrode.

[0049] Figure 8 A system structure diagram of a polarization-resolved on-line optical power monitoring method on chip provided by the third embodiment of the present application, wherein 8001 is a TE polarization power extractor, 8002 is a TM polarization power extractor, 8003 is a TM photodetector, and 8004 is a TE photodetector.

[0050] Figure 9 A structure schematic diagram of a specific example of a polarization-resolved on-line optical power monitoring method on chip provided by the third embodiment of the present application, wherein 601 is a first waveguide region, 602 is a straight-through arm of a coupling region, 603 is a first coupling arm of the coupling region, 604 is a second coupling arm of the coupling region, 605 is a silicon waveguide of a first photodetection region, 606 is germanium absorption material of the first photodetection region, 607 is an electrode of the first photodetection region, 608 is a silicon waveguide of a second photodetection region, 609 is germanium absorption material of the second photodetection region, 610 is an electrode of the second photodetection region, and 611 is a second waveguide region.

[0051] Figure 10A structure schematic diagram of a specific example of a polarization-resolved on-line optical power monitoring method on chip provided by the fourth embodiment of the present application is shown in the figure, wherein 701 is a first waveguide region, 702 is a straight-through arm of a first coupling region, 703 is a coupling arm of the first coupling region, 704 is a second waveguide region, 705 is a third waveguide region, 706 is a straight-through arm of a second coupling region, 707 is a deep-etched waveguide structure, 708 is a coupling arm of the second coupling region, 709 is a silicon waveguide of a first absorption region, 715 is a third waveguide region, 716 is a fourth waveguide region, 712 is an electrode structure, 713 is an electrode structure, 714 is an electrode structure, 710 is germanium absorption material of the first absorption region, and 711 is germanium absorption material of the second coupling region.

[0052] Figure 11 A side sectional view of a specific example of a polarization-resolved on-line optical power monitoring method on chip provided by the fourth embodiment of the present application is shown in the figure, Figure 11 a is a waveguide structure schematic diagram, Figure 11 b is an ion doping schematic diagram, wherein 707 is a deep-etched waveguide structure, 710 is germanium absorption material, 711 is germanium absorption material, 801 is a metal electrode, 802 is a full-etched silicon waveguide, 803 is a metal electrode, 804 is a full-etched silicon waveguide, 805 is a metal electrode, 806 is a full-etched silicon waveguide, 706 is a straight-through arm of a second coupling region, 708 is a coupling arm of the second coupling region, 709 is a silicon waveguide of a first absorption region, 901 is a P-type ion heavily doped region, 902 is a P-type ion lightly doped region, 903 is a non-ion doped region, 904 is an N-type ion lightly doped region, and 905 is an N-type ion heavily doped region. DETAILED DESCRIPTION

[0053] A typical system diagram of a polarization-resolved on-line optical power monitoring method on chip proposed by the present application is shown in the figure. Figure 1 The light in the on-chip optical waveguide is split into two light beams with specific polarization states, TE polarization component and TM polarization component, by a polarization beam splitter. The two light beams pass through a TE / TM power extractor respectively, a small amount of power is separated and transmitted to a TE / TM photodetector respectively, and is converted into a photocurrent, which represents the optical signal power of different polarization states in the input signal. The remaining optical signals are combined by a polarization combiner and output. In this process, low-loss stable transmission of optical signals is realized, and photocurrent information reflecting the optical power of different polarization states of the transmitted optical signals in real time is obtained, realizing polarization-resolved on-line optical power monitoring. The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0054] Example 1

[0055] Referring to Figure 1 , Figure 2 , Figure 3 , Figure 4The embodiment of the present application provides a system structure diagram of an on-chip polarization-resolved online monitoring method and a specific example, and the on-chip polarization-resolved online monitoring method comprises the following steps:

[0056] S1. Polarization beam splitting: separating input light signals into transverse electric (TE) polarization components and transverse magnetic (TM) polarization components through a polarization beam splitting structure;

[0057] S2. Power extraction: extracting a small amount of power from each polarization state light signal through a power extraction structure, preferably in the range of 1%-10%, while maintaining low-loss transmission of the main light path signal;

[0058] S3. Photoelectric detection: converting the extracted light signals into electrical signals through a germanium-silicon detection structure, and obtaining the optical power of the TE polarization component and the TM polarization component in real time;

[0059] S4. Polarization beam combining: combining and outputting the TE polarization and TM polarization light signals in the main light path through a silicon-based polarization beam combining structure;

[0060] The silicon-based structure in steps S1-S4 is integrated on a chip through a silicon optical process, and the structures of each step are interconnected by a silicon-based optical waveguide to achieve low-loss transmission of the optical signal.

[0061] The specific example of the on-chip polarization-resolved online monitoring method comprises a first waveguide region 101 for inputting light signals, a coupling arm 102 and a straight-through arm 103 in a first coupling region for signal transmission, a second waveguide region 104, a third waveguide region 105, a coupling arm 106 and a straight-through arm 107 in a second coupling region, a straight-through arm 108 and a coupling arm 109 in a third coupling region, a silicon waveguide 110, a germanium absorption material 111 and an electrode 112 in a first photoelectric detection region, a silicon waveguide 113, a germanium absorption material 114 and an electrode 115 in a second photoelectric detection region, a fourth waveguide region 116, a fifth waveguide region 117, a coupling arm 118 and a straight-through arm 119 in a fourth coupling region, and a sixth waveguide region 120 for outputting signals;

[0062] The first waveguide region 101 is a bar-shaped adiabatic tapered structure, and the waveguide width narrows along the transmission direction to ensure single-mode low-loss transmission of the optical signal in the waveguide;

[0063] The first coupling region comprises the coupling arm 102 and the straight-through arm 103, which are two bar-shaped waveguides with uniform width. The straight-through arm 103 has the same width as the end of the first waveguide region 101. The width of the coupling arm 103 can satisfy the phase matching condition of the TM polarization state in the straight-through arm 103, and the specific length of the coupling arm 103 completely couples the TM polarization state light signal in the straight-through arm 103 into the coupling arm 103, realizing the polarization beam splitting function of step S1;

[0064] The initial width of the second waveguide region 104 is the same as the width of the coupling arm 103 of the first coupling region, the terminal width is the same as the width of the through arm 107 of the second coupling region, and the intermediate waveguide structure is designed to ensure low-loss stable transmission of optical signals through optimization;

[0065] The initial width of the third waveguide region 105 is the same as the width of the through arm 103 of the first coupling region, and the terminal is the same as the width of the through arm 108 of the third coupling region. The waveguide structure is optimized to ensure low-loss stable transmission of optical signals;

[0066] The second coupling region includes a coupling arm 106 and a through arm 107, which are two strip waveguides with the same width. Through a specific coupling length, the coupling arm 106 couples out a small amount of optical signal power from the through arm 107, realizing the power extraction function of the TM polarization state in S2 step;

[0067] The third coupling region includes a through arm 108 and a coupling arm 109, which are two strip waveguides with the same width. Through a specific coupling length, the coupling arm 109 couples out a small amount of optical signal power from the through arm 108, realizing the power extraction function of the TE polarization state in S2 step;

[0068] The first photodetector region is a typical germanium-silicon photodetector structure, including a silicon waveguide 110 with P-type and N-type ion doping, a germanium absorption material 111, and an electrode 112. The germanium absorption material 111 absorbs the optical power in the underlying silicon waveguide 110 to convert it into carriers, which form a photocurrent under the action of an external electric field and are conducted by the electrode 112, realizing the photodetection function in S3 step and real-time characterization of the power of the TM polarization state in the optical signal;

[0069] The second photodetector region is a typical silicon-based germanium-silicon photodetector structure, including a silicon waveguide 113 with P-type and N-type ion doping, a germanium absorption material 114, and an electrode 115. The germanium absorption material 114 absorbs the optical power in the underlying silicon waveguide 113 to convert it into carriers, which form a photocurrent under the action of an external electric field and are conducted by the electrode 115, realizing the photodetection function in S3 step and real-time characterization of the power of the TE polarization state in the optical signal;

[0070] The fourth waveguide region 116 is a strip waveguide, which has the same structure as the second waveguide region 104, and connects the through arm 107 of the second coupling region and the coupling arm 118 of the fourth coupling region;

[0071] The fifth waveguide region 117 is a strip waveguide, which has the same structure as the third waveguide region 105, and connects the through arm 108 of the third coupling region and the through arm 119 of the fourth coupling region;

[0072] The fourth coupling region comprises a coupling arm 118 and a straight-through arm 119, which are two uniform-width strip waveguides with the same structure as the first coupling region, and the TM polarization state in the coupling arm 118 is completely coupled to the straight-through arm 119 during transmission, thereby realizing the polarization beam combining function of the S4 step;

[0073] The sixth waveguide region 120 is a strip adiabatic taper structure, which has the same starting width as the straight-through arm 119 of the fourth coupling region and the same terminal width as a standard common single-mode strip waveguide, thereby realizing low-loss and stable transmission of optical signals;

[0074] The specific example of the embodiment works as follows: the optical signal is input from the first waveguide region 101, and when passing through the first coupling region, the TM polarization state optical signal power is completely extracted to enter the second coupling region through the third waveguide region 105. A small amount of TM polarization state optical power is coupled out to enter the first photodetection region and is absorbed by the germanium absorption material 111 to generate photo-generated carriers, which are converted into photocurrent by the doping ions and the electrode 112, thereby real-time representing the power of the TM polarization state optical signal in the input optical signal. The TE polarization state optical signal enters the third coupling region through the first coupling region and the third waveguide region 105, and a small amount of TE polarization state optical power is coupled out to enter the second photodetection region and is absorbed by the germanium absorption material 114 to be converted into carriers, which are converted into photocurrent by the doping ions and the electrode 115, thereby real-time representing the power of the TE polarization state optical signal in the input optical signal. The remaining TM and TE polarization state optical signals enter the fourth coupling region through the fourth waveguide region 116 and the fifth waveguide region 117, the TM polarization state optical signal is completely coupled into the straight-through arm 119, and the combined optical signal is output through the sixth waveguide region 120.

[0075] In the specific example, the first coupling region is a polarization beam splitter, which can realize the polarization beam splitting function by using a double-waveguide directional coupler structure, as shown in Figure 3 The equivalent structure capable of realizing the same or similar function, such as a multi-waveguide coupler (as shown in Figure 4 ), a multimode interferometer, etc., all belong to the protection scope of the patent. Without departing from the core concept of the present application, equivalent replacement or simple modification of the specific structure of each part in the embodiment, as long as the same function steps can be realized, should be considered to fall within the protection scope of the claims of the patent.

[0076] Example Two

[0077] Referring to Figure 5 , Figure 6 , Figure 7The embodiment of the present application provides a system structure diagram of an on-chip polarization-resolved online monitoring method and a specific example, and the on-chip polarization-resolved online monitoring method comprises the following steps:

[0078] S1. Polarization beam splitting: input light signals are separated into transverse electric (TE) polarization components and transverse magnetic (TM) polarization components through a polarization beam splitting structure;

[0079] S2. Power extraction: a small amount of power is extracted from each polarization state light signal through a power extraction structure, preferably in the range of 1%-10%, while maintaining low-loss transmission of the main light path signal;

[0080] S3. Photoelectric detection: the extracted light signals are converted into electrical signals through a germanium-silicon detection structure, and the optical power of the TE polarization component and the TM polarization component is obtained in real time;

[0081] S4. Polarization beam combining: the TE polarization and TM polarization light signals in the main light path are combined and output through a silicon-based polarization beam combining structure;

[0082] The silicon-based structure in steps S1-S4 is integrated on a chip through a silicon optical process, and the structures of each step are interconnected by a silicon-based optical waveguide to realize low-loss transmission of the optical signal.

[0083] The specific example of the on-chip polarization-resolved online monitoring method comprises a first waveguide region 401 for inputting light signals, a straight-through arm 402 and a coupling arm 403 of a first coupling region, a second waveguide region 404, a third waveguide region 405, first absorption regions 406-410, second absorption regions 411-415, a fourth waveguide region 416, a fifth waveguide region 417, a straight-through arm 418 and a coupling arm 419 of a second coupling region, and a sixth waveguide region 420.

[0084] The first waveguide region 401 is a strip-shaped adiabatic tapered structure, the waveguide width narrows along the transmission direction, ensuring low-loss stable transmission of the optical signal in the waveguide and increasing the optical mode field along the transmission direction;

[0085] The first coupling region comprises the straight-through arm 402 and the coupling arm 403, which are two uniform strip-shaped waveguides. The straight-through arm 402 has the same width as the end of the first waveguide region 401. The width of the coupling arm 403 can satisfy the phase matching condition of the TM polarization state in the straight-through arm 402, and through a specific waveguide length, the TM polarization state light signal can be completely coupled from the straight-through arm 402 to the coupling arm 403, realizing the polarization beam splitting function of step S1;

[0086] The second waveguide region 404 is a strip-shaped waveguide, connecting the coupling arm 403 of the first coupling region and the first absorption region;

[0087] The third waveguide region 405 is a strip waveguide, connecting the through arm 402 of the first coupling region and the second absorption region;

[0088] The first absorption region is a Ge-Si hybrid structure detector, which has both optical signal transmission and optical power detection functions, and includes a first waveguide region 406, a second waveguide region 407, a third waveguide region 408, a fourth waveguide region 409, a fifth waveguide region 410 and a Ge material 421. The first waveguide region 406 is a strip adiabatic taper structure. The second waveguide region 407 is a strip waveguide with a width greater than that of the first waveguide region 406, which can excite multiple waveguide modes at the start end and enable a stable spatial light field intensity distribution in the third waveguide region 408 due to multi-mode interference. The third waveguide region 408 is a ridge waveguide. The fourth waveguide region 409 is a strip waveguide structure with a width consistent with that of the second waveguide region 407, and is cut off at the self-image position of the light field in the waveguide. The Ge material 421 is located above the center position of the light field weak area of the third waveguide region 408, with a waveguide width smaller than the transmission waveguide width of the third waveguide region 408 and a length smaller than or equal to the length of the third waveguide region 408. The third waveguide region 408 is sequentially doped with N(P) ions for heavy doping 501, N(P) ions for light doping 502, no doping 503, P(N) ions for light doping 504 and P(N) ions for heavy doping 505 along the vertical light field transmission direction, wherein the heavy doping ion concentration is greater than the light doping ion concentration. The first absorption region converts the optical transmission signal into a light signal weak area in the third waveguide region 408 and absorbs it by the Ge material 421 above the weak area to convert it into carriers, and outputs the photocurrent through the electrode 423 under the action of an external electric field, realizing both real-time detection of a small amount of power of the TM polarized light signal and low-loss transmission of the TM light signal, and realizing the power extraction of S2 and the photoelectric detection function of S3;

[0089] The second absorption region is a Ge-Si hybrid structure detector, which has the same structure as the first absorption region and realizes real-time detection of a small amount of power of the TE polarized light signal;

[0090] The fourth waveguide region 416 is a strip waveguide, which has the same structure as the second waveguide region 404, connecting the coupling arm 419 of the second coupling region and the fifth waveguide region 410 of the first absorption region;

[0091] The fifth waveguide region 417 is a strip waveguide, which has the same structure as the third waveguide region 405, connecting the through arm 418 of the second coupling region and the fifth waveguide region 415 of the second absorption region;

[0092] The second coupling region comprises a straight-through arm 418 and a coupling arm 419, which are two uniform strip waveguides with the same structure as the first coupling region, and the TM polarization state in the coupling arm 419 is completely coupled to the straight-through arm 418 during transmission, so as to realize the polarization beam combining function of the S4 step.

[0093] The sixth waveguide region 420 is a strip adiabatic tapered structure, the starting width of which is the same as the width of the straight-through arm 418 of the second coupling region, and the terminal width is the same as that of a standard common single-mode strip waveguide, so as to realize low-loss stable transmission of the optical signal.

[0094] The working principle of the embodiment is as follows: the optical input signal enters the first coupling region through the first waveguide region 401 to realize polarization beam splitting, the two optical signals after beam splitting enter the first absorption region and the second absorption region respectively to realize real-time detection of a small amount of optical power and low-loss transmission, power extraction and photoelectric detection are completed, then the optical signal enters the second coupling region to realize polarization beam combining, and finally the sixth waveguide region 420 is used to realize low-loss stable output of the optical signal.

[0095] Different from the embodiment 1, the specific example integrates the functions of S2 power extraction and S3 photoelectric detection into a TE / TM power extraction detector in the structure layer, although the method steps are the same as those of the embodiment 1, the structure is more compact.

[0096] Example three

[0097] Referring to Figure 8 、 Figure 9 , the embodiment of the present application provides a system structure diagram of an on-chip polarization-resolved online monitoring method and a specific example, the on-chip polarization-resolved online monitoring method comprises the following steps:

[0098] S1. Polarization beam splitting: separating the input optical signal into a transverse electric (TE) polarization component and a transverse magnetic (TM) polarization component through a polarization beam splitting structure;

[0099] S2. Power extraction: extracting a small amount of power, preferably in the range of 1%-10%, from each polarization state optical signal through a power extraction structure, while maintaining low-loss transmission of the main optical signal;

[0100] S3. Photoelectric detection: converting the extracted optical signals into electrical signals through a germanium-silicon detection structure to obtain the optical power of the TE polarization component and the TM polarization component in real time;

[0101] Among them, the silicon-based structure in steps S1-S3 is integrated on a single chip through a silicon optical process, and the structures of each step are interconnected by a silicon-based optical waveguide to realize low-loss transmission of the optical signal.

[0102] The specific example of the on-chip polarization-resolved online monitoring method includes a first waveguide region 601 for inputting an optical signal, a straight-through arm 602 in a coupling region for signal transmission, a first coupling arm 603 and a second coupling arm 604, a silicon waveguide 605 in a first photodetection region, a germanium absorption material 606 and an electrode 607, a silicon waveguide 608 in a second photodetection region, a germanium absorption material 609 and an electrode 610, and a second waveguide region 611 for outputting a signal;

[0103] The first waveguide region 601 is a strip-shaped adiabatic tapered structure, and the waveguide width is narrowed along the transmission direction, thereby ensuring single-mode low-loss transmission of the optical signal in the waveguide.

[0104] The coupling region includes the straight-through arm 602, the first coupling arm 603 and the second coupling arm 604, which are three strip-shaped waveguides with uniform widths. The straight-through arm 602 has the same width as the end of the first waveguide region 601. The width of the first coupling arm 603 can satisfy the phase matching condition of the TE polarization state in the straight-through arm 602, and the specific length of the coupling arm 603 can couple a small amount of the optical signal of the TE polarization state in the straight-through arm 602 into the coupling arm 603, thereby realizing the S1 step polarization beam splitting and the S2 step power extraction of the TE polarization state. The width of the second coupling arm 604 can satisfy the phase matching condition of the TM polarization state in the straight-through arm 602, and the specific length of the coupling arm 604 can couple a small amount of the optical signal of the TM polarization state in the straight-through arm 602 into the coupling arm 604, thereby realizing the S1 step polarization beam splitting and the S2 step power extraction of the TM polarization state.

[0105] The first photodetection region is a typical germanium-silicon photodetector structure, which includes a silicon waveguide 605 with P-type and N-type ion doping, a germanium absorption material 606 and an electrode 607. The germanium absorption material 606 absorbs the optical power in the underlying silicon waveguide 605 to convert it into carriers, and forms a photocurrent under the action of an external electric field, which is led out by the electrode 607, thereby realizing the S3 step photodetection function and real-time characterization of the power of the TE polarization state in the optical signal.

[0106] The second photodetection region is a typical silicon-based germanium-silicon photodetector structure, which includes a silicon waveguide 608 with P-type and N-type ion doping, a germanium absorption material 609 and an electrode 610. The germanium absorption material 609 absorbs the optical power in the underlying silicon waveguide 608 to convert it into carriers, and forms a photocurrent under the action of an external electric field, which is led out by the electrode 610, thereby realizing the S3 step photodetection function and real-time characterization of the power of the TM polarization state in the optical signal.

[0107] The second waveguide region 611 is a strip-shaped adiabatic tapered structure, and the starting width thereof is the same as the width of the straight-through arm 602 of the coupling region, and the end width thereof is the same as that of a standard ordinary single-mode strip waveguide, thereby realizing low-loss stable transmission of the optical signal.

[0108] The working principle of the embodiment is as follows: the optical signal is input from the first waveguide region 601 to the coupling region, the TE polarization state optical signal power is extracted a small amount to enter the first photodetector region through the first coupling arm 603, the germanium absorption material 606 absorbs the optical power in the silicon waveguide 605 to generate photo-generated carriers, and the photo-generated carriers are converted into a photocurrent by the doping ions and the electrode 607, so as to real-time represent the power of the TE polarization state optical signal in the input optical signal. The TM polarization state optical signal power is extracted a small amount to enter the second photodetector region through the second coupling arm 604, the germanium absorption material 609 absorbs the optical power in the silicon waveguide 608 to generate photo-generated carriers, and the photo-generated carriers are converted into a photocurrent by the doping ions and the electrode 610, so as to real-time represent the power of the TM polarization state optical signal in the input optical signal. The remaining optical signal in the through arm 602 is output through the second waveguide region 611.

[0109] Different from the embodiments 1 and 2, the method described in this embodiment does not have the S4 polarization beam combining step, because the polarization beam splitter and the TE power extractor and the TM power extractor described in the embodiment 1 are integrated into the power extractor for TE polarization and the power extractor for TM polarization through the device structure design, and the functions of the power extraction for a single polarization state are realized, and there is no influence on the other polarization state. Based on the architecture of the TE polarization power extractor and the TM polarization power extractor, most of the TE and TM polarization components in the input light are contained in the main light path, and the polarization beam combiner is not needed.

[0110] Example four

[0111] Referring to Figure 10 , Figure 11 , the embodiment of the present application provides a system structure diagram of an on-chip polarization-resolved online monitoring method and specific examples, and the on-chip polarization-resolved online monitoring method comprises the following steps:

[0112] S1. Polarization beam splitting: separating the input optical signal into a transverse electric (TE) polarization component and a transverse magnetic (TM) polarization component through a polarization beam splitting structure;

[0113] S2. Power extraction: extracting a small amount of power, preferably in the range of 1%-10%, from each polarization state optical signal through a power extraction structure, while maintaining low-loss transmission of the main light path signal;

[0114] S3. Photodetection: converting the extracted optical signals into electrical signals through a germanium-silicon detection structure to obtain the optical power of the TE polarization component and the TM polarization component in real time;

[0115] Among them, the silicon-based structure in steps S1-S3 is integrated on a single chip through a silicon optical process, and the structures of each step are interconnected by a silicon-based optical waveguide to realize low-loss transmission of the optical signal.

[0116] The specific example of the on-chip polarization-resolved online monitoring method includes a first waveguide region 701 for inputting an optical signal, a through arm 702 and a coupling arm 703 of a first coupling region for signal transmission, a second waveguide region 704, a third waveguide region 705, a through arm 706 and a coupling arm 708 of a second coupling region, a silicon waveguide 709 and a germanium absorption material 710 in a first absorption region, a fourth waveguide region 715, and a fifth waveguide region 716 for outputting an optical signal;

[0117] The first waveguide region 701 is a bar-shaped adiabatic tapered structure, and the waveguide width narrows along the transmission direction to ensure single-mode transmission of the optical signal in the waveguide and gradual change of the optical mode field;

[0118] The first coupling region includes the through arm 702 and the coupling arm 703, which are two bar-shaped waveguids with uniform widths. The through arm 702 has the same width as the end of the first waveguide region 701. The width of the coupling arm 703 can satisfy the phase matching condition of the TE polarization state in the through arm 702, and a small amount of optical signal power of the TE polarization state is coupled out from the through arm 702 in combination with the specific length of the coupling arm 703, thereby realizing the S1 step polarization splitting of the TE polarization state and the S2 step power extraction;

[0119] The second waveguide region 704 has the same starting width as the width of the through arm 702 of the first coupling region, the same end width as the through arm 706 of the second coupling region, and an intermediate waveguide structure that is optimized to ensure low-loss stable transmission of the optical signal;

[0120] The third waveguide region 705 has the same starting width as the width of the coupling arm 703 of the first coupling region, and the waveguide structure is changed to make the optical signal transmission in the coupling arm 703 away from the through arm 702 of the first coupling region, thereby avoiding power coupling with the through arm 702. The end has the same width as the silicon waveguide 709 in the first absorption region, and the waveguide structure is optimized to ensure low-loss stable transmission of the optical signal;

[0121] The second coupling region includes a through arm 706, a coupling arm 708, and a germanium absorbing material 711. The waveguide structure of the through arm 706 is a ridge waveguide, and its width satisfies the requirement for low-loss stable transmission of the TM polarization state. The width of the coupling arm 708 satisfies the phase-matching condition of the TM polarization state in the through arm 706. A small amount of TM polarization state optical signal power is coupled out from the through arm 708 by combining the specific length of the coupling arm 708. By depositing the germanium absorbing material 711 on the coupling arm 708, the small amount of TM polarization state optical signal power in the coupling arm 708 is absorbed by the germanium absorbing material 711 and converted into a photocurrent signal, characterizing the power of the TM polarization state in the optical input signal. The second coupling region realizes the S1 step polarization beam splitting, the S2 step power extraction, and the S3 step photoelectric detection of the TM polarization state.

[0122] The first absorption region includes a straight waveguide 709 and a germanium absorbing material 710. The straight waveguide 709 is a ridge waveguide with a width that meets the requirements for germanium material 710 deposition and the minimum waveguide width for low-loss and stable transmission of the TE polarization state. By depositing germanium material 710 on the straight waveguide 709 in the first absorption region, the optical signal power is absorbed and converted into a photocurrent signal, which characterizes the power of the TE polarization state in the optical input signal, thus realizing photoelectric detection in step S3.

[0123] The first absorption region and the second coupling region are perpendicular to the transmission direction of the cross-sectional waveguide structure, as shown in the figure. Figure 11 As shown in figure a, the doping method in the waveguide is as follows: Figure 11 As shown in b, the doping order is P-ion heavy doping 901, P-ion light doping 902, no doping 903, N-ion light doping 904, N-ion heavy doping 905, N-ion light doping 904, no doping 903, P-ion light doping 902 and P-ion heavy doping 901, where the concentration of heavy doped ions is greater than the concentration of light doped ions.

[0124] The fourth waveguide region 715 is a ridge-shaped, thermally adiabatic, and gradually changing structure. It connects the straight arm 706 in the second coupling region with the fifth waveguide region 716. The initial structure is the same as the end of the straight arm 706 in the second coupling region. Through optimized design, the optical signal can be transmitted stably from the ridge waveguide structure to the strip waveguide structure with low loss.

[0125] The fifth waveguide region 716 is a strip-shaped thermally insulated conical structure with a width that varies thermally along the transmission direction to achieve stable low-loss transmission of optical signals. The width at the end is the same as that of a standard ordinary strip single-mode waveguide.

[0126] The positive electrode 801 and the negative electrode 803 are electrically connected with the P ion heavily doped region silicon waveguide 901, and the positive electrode 805 and the negative electrode 801 are electrically connected with the N ion heavily doped region silicon waveguide 905, so as to convert the carriers generated by the germanium absorption material 710 and the germanium absorption material 711 into photocurrent;

[0127] The working principle of the embodiment is as follows: the optical signal is input from the first waveguide region 701, a small amount of TE polarized light signal power is extracted when passing through the first coupling region, enters the first absorption region through the third waveguide region 705, is absorbed by the germanium material 710 to generate photo-generated carriers, and the photo-generated carriers are converted into photocurrent by the doped ions, the electrode 803 and the electrode 805, so as to represent the power of the TE polarized light signal in the input optical signal. The remaining optical signal enters the second coupling region through the second waveguide region 704, a small amount of TM polarized light signal power is extracted and absorbed by the germanium material 711 to convert into photo-generated carriers, and the photo-generated carriers are converted into photocurrent by the doped ions, the electrode 801 and the electrode 803, so as to represent the power of the TM polarized light signal in the input optical signal. The remaining optical signal power is stably transmitted and output through the fourth waveguide region 715 and the fifth waveguide region 716.

[0128] Different from the embodiment 3, the specific example integrates the functions of the TM polarized S1 step polarization beam splitting, the S2 step power extraction and the S3 step photoelectric detection, and further integrates the TE photoelectric detector and the TM photoelectric detector through the common electrode.

[0129] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for on-chip polarization-resolved online optical power monitoring, characterized in that, The method comprises the following steps: S1. Polarization beam splitting: separating the input optical signal into transverse electric (TE) and transverse magnetic (TM) polarization components by a polarization beam splitting structure; S2. Power extraction: extracting a small amount of power, preferably in the range of 1%-10%, from each polarization state optical signal by a power beam splitting structure, while maintaining low-loss transmission of the main optical path signal; S3. Photoelectric detection: converting the extracted optical signals into electrical signals by a germanium-silicon detection structure, and obtaining the optical power of the TE and TM polarization components in real time; S4. Polarization beam combining: combining the TE and TM polarization optical signals in the main optical path and outputting by a silicon-based polarization beam combining structure; Wherein, the silicon-based structures in steps S1-S4 are integrated on the chip by silicon optical technology, and the structures of each step are interconnected by silicon optical waveguide to realize low-loss transmission of optical signals.

2. The method of claim 1, wherein: After separating the two polarization states in S1, for TE and / or TM polarization components, steps S2 and S3 can be physically implemented by the same silicon-based device or structure.

3. The method of claim 1, wherein: For TE and / or TM polarization components, steps S1 and S2 are physically implemented by the same silicon-based device or structure.

4. The method of claim 3, wherein: In the case that steps S1 and S2 are implemented by the same device or structure, a simplified method without step S4 is supported.

5. An on-chip polarization-resolved in-line optical power monitoring system, characterized by It comprises: A polarization beam splitter configured to separate the input optical signal into TE and TM modes; A TE power extractor connected to the TE port output of the polarization beam splitter to extract a small amount of power, preferably in the range of 1%-10%, from the TE main optical path; A TM power extractor connected to the TM port output of the polarization beam splitter to extract a small amount of power, preferably in the range of 1%-10%, from the TM main optical path; A TE photodetector connected to the TE power extractor to convert the optical power extracted from the TE main optical path into a photocurrent signal; A TM photodetector connected to the TM power extractor to convert the optical power extracted from the TM main optical path into a photocurrent signal; A polarization beam combiner connected to the main optical paths of the TE and TM power extractors for combining the TE and TM light output; Wherein, all the above units are integrated by silicon optical technology, and are interconnected by silicon optical waveguide.

6. The system of claim 5, wherein: The TE power extractor and TE photodetector are integrated as a TE power extraction detector by structural design, simultaneously implementing the power extraction and photoelectric detection functions for the TE polarization state; The TM power extractor and TM photodetector are integrated as a TM power extraction detector by structural design, simultaneously implementing the power extraction and photoelectric detection functions for the TM polarization state.

7. The system of claim 5, wherein: The polarization beam splitter and the TE power extractor and the TM power extractor are integrated into a power extractor for TE polarization and a power extractor for TM polarization respectively by device structure design, and the power extraction function for a single polarization state is realized without affecting the other polarization state.

8. The system of claim 7, wherein: Based on the TE polarization power extractor and the TM polarization power extractor architecture, most of the TE and TM polarization components in the input light have been included in the main light path, and a polarization beam combiner is not needed.

9. The system of claim 5 or 6, wherein: The TE photodetector and the TM photodetector both adopt a germanium-silicon detection structure, and the two can be further integrated by electrode commoning.

10. The system of claim 5, wherein: The silicon optical devices in the system can be obtained by optimization algorithm or inverse design method.

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