An integrated optical filter

Abstract

The present invention provides an integrated optical filter, comprising: an input optical waveguide connected to a first port of an input curved grating-assisted reverse coupler of a micro-ring optical filter with an integrated grating-assisted reverse coupler in a filtering unit, for inputting an optical signal to be processed; a filtering unit comprising a micro-ring optical filter with an integrated grating-assisted reverse coupler and a reverse coupler, for filtering the optical signal, wherein a second port of the input curved grating-assisted reverse coupler of the micro-ring optical filter is connected to a first intermediate optical waveguide; a fourth port of an output curved grating-assisted reverse coupler of the micro-ring optical filter is connected to the first intermediate optical waveguide through a waveguide crossing; a third port of an output curved grating-assisted reverse coupler of the micro-ring optical filter is connected to a straight input periodic corrugated waveguide of the reverse coupler through a second intermediate optical waveguide; and an output optical waveguide, for outputting the filtered optical signal.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to the field of optical fiber communication technology, and more specifically, to an integrated optical filter. Background Art

[0002] Optical filters are instruments used for wavelength selection. They can select the desired wavelength from a large number of wavelengths, and light other than this wavelength will be rejected. Therefore, optical filters play an important role in dense wavelength division multiplexing optical fiber communication, frequency division multiplexing optical fiber communication, spectrum testing, optical fiber sensors and optical fiber amplifier applications.

[0003] Research has found that optical filters with a higher roll-off rate and a narrower passband bandwidth in related technologies still have defects, such as the problem of low integration. Summary of the invention

[0004] In view of this, an embodiment of the present disclosure provides an integrated optical filter.

[0005] One aspect of an embodiment of the present disclosure provides an integrated optical filter, comprising:

[0006] An input optical waveguide is connected to a first port on an input bent grating-assisted reverse coupler of a micro-ring optical filter with an integrated grating-assisted reverse coupler in a filter unit, and is used for inputting an optical signal to be processed;

[0007] A filtering unit, comprising: a micro-ring optical filter with an integrated grating-assisted reverse coupler and a reverse coupler, for filtering the optical signal, wherein the micro-ring optical filter comprises an input curved grating-assisted reverse coupler, an output curved grating-assisted reverse coupler and a connecting curved waveguide;

[0008] An intermediate optical waveguide unit, comprising a first intermediate optical waveguide, a second intermediate optical waveguide and a waveguide crossover, for transmitting the optical signal in the above-mentioned integrated optical filter;

[0009] The second port on the input curved grating assisted reverse coupler is connected to the first intermediate optical waveguide; the fourth port on the output curved grating assisted reverse coupler is connected to the first intermediate optical waveguide through the waveguide crossover; the third port on the output curved grating assisted reverse coupler is connected to the straight input periodic corrugated waveguide of the reverse coupler through the second intermediate optical waveguide;

[0010] The output optical waveguide is used to output the filtered optical signal.

[0011] According to an embodiment of the present disclosure, the central wavelengths of the input curved grating assisted reverse coupler and the output curved grating assisted reverse coupler are aligned with the same longitudinal mode wavelength of the micro-ring optical filter of the integrated grating assisted reverse coupler.

[0012] According to an embodiment of the present disclosure, the above-mentioned filtering unit is used to filter the above-mentioned optical signal to be processed twice, wherein the above-mentioned optical signal to be processed is input into different input ports of the micro-ring optical filter of the above-mentioned integrated grating-assisted reverse coupler according to different transmission directions of the above-mentioned optical signal to be processed.

[0013] According to an embodiment of the present disclosure, the manufacturing platform of the above-mentioned filter unit includes: lithium niobate, silicon, silicon dioxide, indium phosphide and gallium arsenide platform.

[0014] According to an embodiment of the present disclosure, the filtering unit is also used to: when tuning the center wavelength of the integrated optical filter, determine to independently tune the center wavelengths of the filtering curves of the micro-ring optical filter of the integrated grating-assisted reverse coupler and the reverse coupler.

[0015] According to an embodiment of the present disclosure, the above-mentioned input curved grating assisted reverse coupler and the above-mentioned output curved grating assisted reverse coupler both include: a curved bus periodic corrugated waveguide and a curved micro-ring periodic corrugated waveguide.

[0016] According to an embodiment of the present disclosure, the average waveguide width and corrugation depth of the curved bus periodic corrugation waveguide of the input curved grating assisted reverse coupler and the output curved grating assisted reverse coupler are the same; the corrugation depth of the curved microring periodic corrugation waveguide of the input curved grating assisted reverse coupler and the output curved grating assisted reverse coupler is the same.

[0017] According to the embodiments of the present disclosure, because a micro-ring optical filter with an integrated grating-assisted reverse coupler and a reverse coupler combination are used for filtering, the problem of excessive area and volume of the device is at least partially overcome, thereby achieving a higher device integration while having a narrower bandwidth and a higher roll-off rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0019] Figure 1 The structure diagram of the integrated optical filter according to the embodiment of the present disclosure is schematically shown;

[0020] Figure 2AA schematic diagram of a two-pass filtering path of an integrated optical filter according to an embodiment of the present disclosure is shown;

[0021] Figure 2B A schematic diagram of two download-end filtering paths of an integrated optical filter according to an embodiment of the present disclosure is shown;

[0022] Figure 3 Schematically showing a schematic diagram of a curved micro-ring periodic corrugated waveguide and a curved bus periodic corrugated waveguide of an integrated optical filter according to an embodiment of the present disclosure;

[0023] Figure 4A Schematically showing a filtering curve of a micro-ring filter with an integrated grating-assisted reverse coupler according to an embodiment of the present disclosure;

[0024] Figure 4B Schematically shows a filtering curve of a reverse coupler according to an embodiment of the present disclosure;

[0025] Figure 4C The filtering curve of the integrated optical filter according to the embodiment of the present disclosure is schematically shown.

[0026] Description of Reference Numerals

[0027] 100 Input optical waveguide

[0028] 200 filter units

[0029] 201 Micro-ring Optical Filter with Integrated Grating-Assisted Back Coupler

[0030] 2011 Input Bend Grating Assisted Back Coupler

[0031] 2012 Output Bent Grating Assisted Back Coupler

[0032] 2013 Connecting curved waveguides

[0033] 202 Reverse Coupler

[0034] 2021 Direct Input Periodic Corrugated Waveguide

[0035] 2022 Direct Output Periodic Corrugated Waveguide

[0036] 20111 Curved Bus Periodic Corrugated Waveguide

[0037] 20112Bent Microring Periodic Corrugated Waveguide

[0038] 300 Intermediate optical waveguide unit

[0039] 301 First intermediate optical waveguide

[0040] 302 second intermediate optical waveguide

[0041] 303 Third intermediate optical waveguide

[0042] 1 First port

[0043] 2 Second Port

[0044] 3 Third port

[0045] 4 Fourth port DETAILED DESCRIPTION

[0046] The present disclosure is further described in detail below in conjunction with the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are only used to explain the present disclosure, rather than to limit the present disclosure, and the various features recorded in the embodiments can be combined to form multiple optional solutions. It should also be noted that, for ease of description, only parts related to the present disclosure are shown in the accompanying drawings, rather than all structures.

[0047] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0048] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0049] In the case of using expressions such as "at least one of A, B, and C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.). In the case of using expressions such as "at least one of A, B, or C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, or C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0050] During the research process, it was found that common narrow bandwidth, high roll-off rate optical filters have the defects of low integration and are limited by limited FSR.

[0051] In view of this, an embodiment of the present disclosure provides an input optical waveguide of an integrated optical filter, which is connected to a first port on an input curved grating-assisted reverse coupler of a micro-ring optical filter of an integrated grating-assisted reverse coupler in a filtering unit, and is used to input an optical signal to be processed; the filtering unit comprises: a micro-ring optical filter of an integrated grating-assisted reverse coupler and a reverse coupler, which are used to filter the optical signal, wherein the micro-ring optical filter comprises an input curved grating-assisted reverse coupler, an output curved grating-assisted reverse coupler and a connecting curved waveguide; an intermediate optical waveguide unit comprises a first intermediate optical waveguide, a second intermediate optical waveguide and a waveguide crossing, which are used to transmit the optical signal in the integrated optical filter; wherein the second port on the input curved grating-assisted reverse coupler is connected to the first intermediate optical waveguide; the fourth port on the output curved grating-assisted reverse coupler is connected to the first intermediate optical waveguide through a waveguide crossing; the third port on the output curved grating-assisted reverse coupler is connected to the straight input periodic corrugated waveguide of the reverse coupler through the second intermediate optical waveguide; and the output optical waveguide is used to output the filtered optical signal.

[0052] Figure 1 The structural diagram of the integrated optical filter according to the embodiment of the present disclosure is schematically shown.

[0053] like Figure 1 As shown, the integrated optical filter includes an input optical waveguide 100 , a filtering unit 200 , an intermediate optical waveguide unit 300 and an output optical waveguide 400 .

[0054] The input optical waveguide 100 is connected to the first port 1 on the input bent grating-assisted reverse coupler 201 of the micro-ring optical filter with integrated grating-assisted reverse coupler in the filtering unit, and is used for inputting the optical signal to be processed.

[0055] The filtering unit 200 includes: a micro-ring optical filter 201 with an integrated grating-assisted reverse coupler and a reverse coupler 202, which is used to filter the optical signal, wherein the micro-ring optical filter includes an input curved grating-assisted reverse coupler 2011, an output curved grating-assisted reverse coupler 2012 and a connecting curved waveguide 2013.

[0056] The intermediate optical waveguide unit 300 includes a first intermediate optical waveguide 301, a second intermediate optical waveguide 302 and a waveguide cross 303, and is used to transmit optical signals in an integrated optical filter.

[0057] Among them, the second port 2 on the input curved grating assisted reverse coupler 2011 is connected to the first intermediate optical waveguide 301; the fourth port 4 on the output curved grating assisted reverse coupler 2012 is connected to the first intermediate optical waveguide 301 through a waveguide cross 303; the third port 3 on the output curved grating assisted reverse coupler 2012 is connected to the straight input periodic corrugated waveguide 2021 of the reverse coupler 202 through the second intermediate optical waveguide 302.

[0058] The output optical waveguide 400 is used to output the filtered optical signal.

[0059] According to an embodiment of the present disclosure, the waveguide thickness, waveguide spacing, corrugation period, duty cycle, number of periods, and bending radius of the input curved grating assisted reverse coupler and the output curved grating assisted reverse coupler are all the same.

[0060] According to an embodiment of the present disclosure, the output optical waveguide 400 is connected to the straight output periodic corrugated waveguide of the reverse coupler and can be used to output the filtered optical signal.

[0061] According to the embodiments of the present disclosure, because a micro-ring optical filter with an integrated grating-assisted reverse coupler and a reverse coupler combination are used for filtering, the problem of excessive area and volume of the device is at least partially overcome, thereby achieving a higher device integration while having a narrower bandwidth and a higher roll-off rate.

[0062] According to an embodiment of the present disclosure, the micro-ring optical filter 201 with integrated grating-assisted reverse coupler includes four ports located on the input curved grating-assisted reverse coupler and the output curved grating-assisted reverse coupler. According to different ports for optical signal input, the four ports can be divided into an input port, a through port, a download port and an upload port. For example, when the optical signal is input from the first port, the first port is the input port, the second port is the through port, the third port is the upload port and the fourth port is the download port; when the optical signal is input from the second port, the second port is the input port, the first port is the through port, the third port is the download port and the fourth port is the upload port; when the optical signal is input from the fourth port, the fourth port is the input port, the third port is the through port, the first port is the download port and the second port is the upload port.

[0063] According to an embodiment of the present disclosure, the waveguide crossing 302 includes but is not limited to waveguide crossings using multimode interference couplers, Maxwell fisheyes, subwavelength gratings, asymmetric qualitative couplers, asymmetric Y branches, transformation optics, inverse design, shallowly etched waveguides, and double-layer waveguide designs.

[0064] According to an embodiment of the present disclosure, the central wavelengths of the input curved grating assisted reverse coupler and the output curved grating assisted reverse coupler are aligned with one longitudinal mode wavelength of the micro-ring optical filter of the integrated grating assisted reverse coupler.

[0065] According to an embodiment of the present disclosure, a manufacturing platform of the filter unit includes: lithium niobate, silicon, silicon dioxide, indium phosphide and gallium arsenide platform.

[0066] According to an embodiment of the present disclosure, the filtering unit is further used to: when tuning the central wavelength of the integrated optical filter, determine to independently tune the central wavelengths of the filtering curves of the micro-ring optical filter and the reverse coupler of the integrated grating-assisted reverse coupler.

[0067] According to the embodiments of the present disclosure, when tuning the central wavelength of the filtering spectrum of the integrated optical filter, it is necessary to separately tune the micro-ring optical filter and the reverse coupler of the integrated grating-assisted reverse coupler.

[0068] Figure 2A The schematic diagram of the two-pass filtering path of the integrated optical filter according to the embodiment of the present disclosure is schematically shown.

[0069] Figure 2B The schematic diagram of the two-download-end filtering path of the integrated optical filter according to the embodiment of the present disclosure is schematically shown.

[0070] According to an embodiment of the present disclosure, the filtering unit is used to filter the optical signal to be processed twice, wherein the optical signal to be processed is input to different input ports of the micro-ring optical filter of the integrated grating-assisted reverse coupler according to different transmission directions of the optical signal to be processed.

[0071] According to an embodiment of the present disclosure, due to the properties of the micro-ring optical filter with an integrated grating-assisted reverse coupler, the filtering unit performs two filtering operations on the optical signal to be processed, including: two straight-through-end filtering and two download-end filtering, wherein the two straight-through-end filtering is a complete filtering, and the two download-end filtering is a complete filtering.

[0072] According to the embodiments of the present disclosure, Figure 2AAs shown, when the optical signal to be processed enters the filtering unit from the first port of the micro-ring optical filter 201 of the integrated grating-assisted reverse coupler through the input optical waveguide 100, the optical signal to be processed is divided into a first optical signal to be processed and a second optical signal to be processed, wherein the first optical signal to be processed is output to the first intermediate optical waveguide after being straight-through filtered at the second port through the micro-ring optical filter 201 of the integrated grating-assisted reverse coupler, completing the first straight-through filtering to obtain the first optical signal, at which point the first port is the input port and the second port is the straight-through port; then the first optical signal is input to the fourth port through the first intermediate optical waveguide and the waveguide crossover, and is output to the second intermediate optical waveguide after being straight-through filtered at the third port to obtain the second optical signal, at which point the fourth port is the input port and the third port is the straight-through port. Thus, the second optical signal that has completed two consecutive straight-through filterings at the third port is obtained.

[0073] According to the embodiments of the present disclosure, Figure 2B As shown, the second optical signal to be processed is output to the waveguide intersection and the first intermediate optical waveguide after download filtering at the fourth port of the micro-ring optical filter 201 of the integrated grating-assisted reverse coupler, completing the first download filtering to obtain the third optical signal. At this time, the first port is the input end and the fourth port is the download end; then the third optical signal enters from the second port, and is output to the second intermediate optical waveguide after download filtering at the fourth port to obtain the fourth optical signal. At this time, the second port is the input end and the third port is the download end. So far, the fourth optical signal that has completed two consecutive download filterings at the third port is obtained.

[0074] According to an embodiment of the present disclosure, the second optical signal and the fourth optical signal are combined in the second intermediate optical waveguide. Since the input curved grating-assisted reverse coupler and the output curved grating-assisted reverse coupler of the micro-ring optical filter with integrated grating-assisted reverse coupler have the same parameters, it is ensured that the filtering curves of the two filterings at the through end and the download end have consistent waveforms and central wavelengths, and the result of the superposition of the two filterings will produce an electromagnetically induced transparency (EIT) spectrum out of the second intermediate optical waveguide, that is, there is a narrow peak located in the groove in the filtering spectrum.

[0075] Figure 3 Schematic diagrams of a curved micro-ring periodic corrugated waveguide and a curved bus periodic corrugated waveguide of an integrated optical filter according to an embodiment of the present disclosure are schematically shown.

[0076] According to the embodiments of the present disclosure, Figure 3 As shown, the input curved grating assisted reverse coupler and the output curved grating assisted reverse coupler both include: a curved bus periodic corrugated waveguide 20111 and a curved micro-ring periodic corrugated waveguide 20112.

[0077] According to an embodiment of the present disclosure, the average waveguide width and corrugation depth of the curved bus periodic corrugation waveguide of the input curved grating assisted reverse coupler and the output curved grating assisted reverse coupler are the same; the corrugation depth of the curved microring periodic corrugation waveguide of the input curved grating assisted reverse coupler and the output curved grating assisted reverse coupler is the same.

[0078] According to the embodiments of the present disclosure, the settings of the curved bus periodic corrugated waveguide and the curved microring periodic corrugated waveguide of the input curved grating assisted reverse coupler and the output curved grating assisted reverse coupler are made the same, thereby avoiding the situation in which the center wavelengths of the filtering curves of the two optical signals obtained after two download end filtering and two through end filtering are different when the filtering unit filters the optical signal to be processed, thereby ensuring that the electromagnetically induced transparency (EIT) spectrum can be generated from the second intermediate optical waveguide.

[0079] Figure 4A The filtering curve of the micro-ring filter integrated with the grating-assisted reverse coupler according to the embodiment of the present disclosure is schematically shown.

[0080] Figure 4B The filtering curve of the reverse coupler according to the embodiment of the present disclosure is schematically shown.

[0081] Figure 4C The filtering curve of the integrated optical filter according to the embodiment of the present disclosure is schematically shown.

[0082] According to an embodiment of the present disclosure, the filtering curve of the micro-ring optical filter with integrated grating assisted reverse coupler in the working state is as follows: Figure 4A As shown in the figure, it can be seen that the filtering curve of the micro-ring optical filter with integrated optical assisted reverse coupler that can perform double filtering has initially possessed the advantages of narrow bandwidth and high roll-off rate. Figure 4B The filtering spectrum diagram of the reverse coupler in the working state can be used to obtain the filtering spectrum diagram of the entire integrated optical filter as shown in Figure 4(c). At this time, the filtering spectrum has the advantages of no free spectral range, narrower bandwidth and higher roll-off rate. The optical signal passing through the filter also has the advantages of no free spectral range, that is, strong band selection ability, narrower bandwidth and higher roll-off rate.

[0083] The above are only preferred embodiments of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. An integrated optical filter, comprising: An input optical waveguide is connected to a first port on an input bent grating-assisted reverse coupler of a micro-ring optical filter with an integrated grating-assisted reverse coupler in a filter unit, and is used for inputting an optical signal to be processed; A filtering unit, comprising: a micro-ring optical filter with an integrated grating-assisted reverse coupler and a reverse coupler, for filtering the optical signal, wherein the micro-ring optical filter comprises an input curved grating-assisted reverse coupler, an output curved grating-assisted reverse coupler and a connecting curved waveguide; An intermediate optical waveguide unit, comprising a first intermediate optical waveguide, a second intermediate optical waveguide and a waveguide crossover, for transmitting an optical signal in the integrated optical filter; The second port on the input curved grating assisted reverse coupler is connected to the first intermediate optical waveguide; the fourth port on the output curved grating assisted reverse coupler is connected to the first intermediate optical waveguide through the waveguide crossover; the third port on the output curved grating assisted reverse coupler is connected to the straight input periodic corrugated waveguide of the reverse coupler through the second intermediate optical waveguide; The output optical waveguide is used to output the filtered optical signal.

2. The integrated optical filter according to claim 1, wherein the central wavelengths of the input curved grating assisted reverse coupler and the output curved grating assisted reverse coupler are aligned with the same longitudinal mode wavelength of the micro-ring optical filter of the integrated grating assisted reverse coupler.

3. The integrated optical filter according to claim 1, wherein: The filtering unit is used to filter the optical signal to be processed twice, wherein the optical signal to be processed is input to different input ports of the micro-ring optical filter of the integrated grating-assisted reverse coupler according to different transmission directions of the optical signal to be processed.

4. The integrated optical filter according to claim 1, wherein: The manufacturing platform of the filter unit includes: lithium niobate, silicon, silicon dioxide, indium phosphide and gallium arsenide platform.

5. The integrated optical filter according to claim 1, wherein: The filtering unit is further used for: when tuning the central wavelength of the integrated optical filter, determining to independently tune the central wavelengths of the filtering curves of the micro-ring optical filter of the integrated grating-assisted reverse coupler and the reverse coupler.

6. The integrated optical filter according to claim 1, wherein: The input curved grating assisted reverse coupler and the output curved grating assisted reverse coupler both include: a curved bus periodic corrugated waveguide and a curved micro-ring periodic corrugated waveguide.

7. The integrated optical filter according to claim 6, wherein: The average waveguide width and corrugation depth of the curved bus periodic corrugated waveguides of the input curved grating assisted reverse coupler and the output curved grating assisted reverse coupler are the same; The corrugation depths of the curved micro-ring periodic corrugation waveguides of the input curved grating assisted reverse coupler and the output curved grating assisted reverse coupler are the same.

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