Reconfigurable band-rejection optical chip based on double-sideband amplitude-phase equalization

Abstract

The application provides a reconfigurable band-stop filtering optical chip based on double-sideband amplitude-phase equalization, and relates to the field of optoelectronic technology.The reconfigurable band-stop filtering optical chip divides the input multi-band optical signal into multiple channels according to the optical carrier frequency through a pair of optical wave frequency channel division units, each channel independently performs narrow-band band-stop filtering through an optical filter unit, the band-stop filtering optical chip can be reconfigured, and has the reconfigurable band-stop filtering capability;and through controlling the amplitude-phase modulation in each optical filter unit and the tuning of the band-stop optical filter, the input light double-sideband amplitude-phase equalization is realized, the stop-band rejection of the band-stop filtering is improved, and the spectral resolution is improved;the application is flexible to use, has wide application range, has simple structure, and is suitable for integrated optical chips.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic technology, and more specifically to a reconfigurable bandstop filter optical chip based on double-side band amplitude-phase equalization. Background Technology

[0002] Microwave photonic bandstop filters offer advantages such as high stopband rejection, high resolution, and immunity to electromagnetic interference, making them crucial functional units in microwave signal processing and widely used in filtering, spectral analysis, and other fields. However, most existing microwave photonic bandstop filter solutions are composed of discrete components, resulting in narrow passbands that are difficult to reconstruct. Furthermore, the overall filter structure is complex, bulky, and difficult to integrate, limiting their applicability.

[0003] Existing research, in order to improve filter resolution and achieve passband reconfigurability, generally requires multiple devices such as optical amplifiers, optical isolators, and optical circulators, resulting in integration difficulties. In other words, existing microwave photonic bandstop filters face the technical challenge of simultaneously achieving reconfigurability, resolution, and integration efficiency. Summary of the Invention

[0004] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a reconfigurable bandstop filter optical chip based on double-side band amplitude-phase equalization, which solves the technical problem that existing microwave photonic bandstop filters cannot simultaneously achieve reconfigurability, resolution, and integration.

[0005] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: This invention provides a reconfigurable bandstop filter optical chip based on double-side band amplitude and phase equalization, comprising a first optical frequency channel partitioning unit, n optical filtering units, and a second optical frequency channel partitioning unit, wherein n≥1; Each of the optical filtering units includes a complementary optical filter, a band-blocking filter, an intensity and phase modulation module, and an optical beam combiner. The first optical frequency channel division unit divides the multi-wavelength input light into optical carrier frequencies of... , , ..., The n output beams are respectively input into n optical filtering units; The complementary optical filter in each optical filtering unit filters the input light and splits it into two paths. One path is input to a band-stop filter for band-stop filtering; the other path is modulated by an intensity and phase modulation module. The two outputs of the intensity and phase modulation module and the band-stop filter are combined by an optical combiner. n beams are combined into one path through the second optical frequency channel dividing unit, which serves as the output light of the reconfigurable band-stop filter optical chip.

[0006] Preferably, the complementary optical filter filters the input light and outputs two optical signals, wherein one output of the complementary optical filter in the nth optical filtering unit includes the upper sideband of the input light. With optical carrier frequency The optical signal is input into a light-blocking filter in one path; the other path contains the lower sideband of the input light. In the optical signal input intensity and phase modulation module, among which, The frequency of the broadband radio frequency signal modulated in multi-wavelength input light. , This is the minimum frequency of the radio frequency signal. This represents the maximum frequency of the radio frequency signal.

[0007] Preferably, the band-stop filter is a tunable band-stop filter, wherein the stopband center frequency of the band-stop filter in the nth optical filtering unit is... The stopband center frequency can be adjusted, and the upper sideband of the input light filtered by the complementary optical filter is... After filtering with a light-blocking filter, the frequency point is The amplitude of the optical signal is Phase is ;in, , This is the minimum frequency of the radio frequency signal. This represents the maximum frequency of the radio frequency signal.

[0008] Preferably, both the first optical frequency channel partitioning unit and the second optical frequency channel partitioning unit are wavelength division multiplexers.

[0009] Preferably, both the first optical frequency channel division unit and the second optical frequency channel division unit are arrayed waveguide gratings.

[0010] Preferably, the intensity and phase modulation module includes an intensity modulator and a phase modulator.

[0011] Preferably, in the nth optical filtering unit, the intensity modulator and the phase modulator respectively filter the lower sideband of the input light filtered by the complementary optical filter. Amplitude and phase modulation are performed, where the frequency is... The amplitude of the optical signal is Phase is And through amplitude and phase adjustment, , .

[0012] (III) Beneficial Effects This invention provides a reconfigurable bandstop filter optical chip based on double-side band amplitude-phase equalization. Compared with existing technologies, it has the following advantages: The reconfigurable band-stop filter optical chip of this invention divides the input multi-band optical signal into multiple channels according to the optical carrier frequency through a pair of optical frequency channel division units. Each channel is independently subjected to narrowband band-stop filtering by an optical filtering unit, which can reconstruct the stopband of the band-stop filter optical chip and has the capability of band-stop filtering reconfigurability. Furthermore, by controlling the amplitude and phase modulation and band-stop optical filter tuning within each optical filtering unit, the amplitude and phase equalization of the input light on both sides is achieved, improving the stopband suppression degree and spectral resolution of the band-stop filter. It is flexible in use, has a wide range of applications, and has a simple structure, making it suitable for integrated optical chips. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of a reconfigurable bandstop filter optical chip based on double-side band amplitude-phase equalization. Figure 2 This is a schematic diagram of the structure of a reconfigurable bandstop filter optical chip based on double-side band amplitude-phase equalization, as shown in Example 1. Figure 3 This is a schematic diagram of the structure of a reconfigurable bandstop filter optical chip based on double-side band amplitude-phase equalization, as shown in Example 2. Figure 4 The output optical spectrum of the first optical filtering unit in Example 2; Figure 5 This is the radio frequency spectrum diagram of the band-stop filtering of the first optical filtering unit in Example 2; Figure 6 This is a reconfigurable band-stop filter RF spectrum diagram. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] This application provides a reconfigurable bandstop filter optical chip based on double-side band amplitude-phase equalization, solving the technical problem that existing microwave photonic bandstop filters struggle to balance reconfigurability, resolution, and integration. By using a pair of optical frequency channel division units, the input multi-band optical signal is divided into multiple channels according to the optical carrier frequency. Each channel undergoes independent narrowband bandstop filtering through an optical filtering unit, enabling reconfiguration of the bandstop filter's stopband and providing bandstop filter reconfigurability. Furthermore, by controlling the amplitude-phase modulation and bandstop filter tuning within each optical filtering unit, double-side band amplitude-phase equalization of the input light is achieved, improving the stopband suppression and spectral resolution of the bandstop filter. It is flexible in use, widely applicable, and has a simple structure, making it suitable for integrated optical chips.

[0017] The technical solution in this application is to solve the above-mentioned technical problems, and the general idea is as follows: CN103278888B, a wide-passband reconfigurable microwave photonic filter device and method, published on 2015-06-03; CN109450540B, a tunable dual-passband microwave photonic filter implementation device and method, published on 2020-05-08. Both of these prior art technologies improve filter resolution and achieve passband reconfigurability through the stimulated Brillouin effect. This is achieved by inputting multiple high-power pump lights of various frequency bands into an optical fiber to excite the stimulated Brillouin effect, thereby realizing the passband bandwidth reconfigurability function. However, the above schemes are based on the back-stimulated Brillouin scattering effect of optical fibers and generally require multiple devices such as optical amplifiers, optical isolators, and optical circulators, making them difficult to integrate into optical chips. Furthermore, due to the threshold power limitation of the optical chip input port, when multiple frequency band pump lights are simultaneously input through the same optical chip port, the optical power allocated to each frequency band is limited, resulting in a low stimulated Brillouin gain generated by the pump light in each frequency band, thus limiting the passband suppression and spectral resolution. Therefore, chip integration based on the above schemes presents certain difficulties. Existing technology CN106249354B, a microwave photonic bandstop filter based on a microring and Mach-Zehnder interference structure, published on 2019-07-23, utilizes the amplitude and phase response characteristics of the microring combined with the MRI structure of the MR-MZI integrated optical filter unit to generate destructive phases, achieving an ultra-high suppression ratio on a narrow bandwidth. However, this scheme is suitable for tunable narrowband bandstop filtering and lacks the reconfigurable function of the bandstop filter stopband. As can be seen from the above description, the existing technology cannot simultaneously achieve reconfigurability, resolution, and integration. Therefore, this invention proposes a bandstop filter optical chip suitable for integrated optical chips, which can improve the stopband suppression ratio and spectral resolution while possessing reconfigurability.

[0018] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0019] This invention provides a reconfigurable bandstop filter optical chip based on double-side band amplitude-phase equalization, such as... Figure 1 As shown, the chip includes a first optical frequency channel partitioning unit, n optical filtering units, and a second optical frequency channel partitioning unit, where n≥1; Each of the optical filtering units includes a complementary optical filter, a band-blocking filter, an intensity and phase modulation module, and an optical beam combiner. The first optical frequency channel division unit divides the multi-wavelength input light into optical carrier frequencies of... , , ..., The n output beams are respectively input into n optical filtering units; The complementary optical filter in each optical filtering unit filters the input light and splits it into two paths. One path is input to a band-stop filter for band-stop filtering; the other path is modulated by an intensity and phase modulation module. The two outputs of the intensity and phase modulation module and the band-stop filter are combined by an optical combiner. n beams are combined into one path through the second optical frequency channel dividing unit, which serves as the output light of the reconfigurable band-stop filter optical chip.

[0020] The reconfigurable band-stop filter optical chip of this invention divides the input multi-band optical signal into multiple channels according to the optical carrier frequency through a pair of optical frequency channel division units. Each channel is independently subjected to narrowband band-stop filtering by an optical filtering unit, which can reconstruct the stopband of the band-stop filter optical chip and has the capability of band-stop filtering reconfigurability. Furthermore, by controlling the amplitude and phase modulation and band-stop optical filter tuning within each optical filtering unit, the amplitude and phase equalization of the input light on both sides is achieved, improving the stopband suppression degree and spectral resolution of the band-stop filter. It is flexible in use, has a wide range of applications, and has a simple structure, making it suitable for integrated optical chips.

[0021] The reconfigurable bandstop filter optical chip will be described in detail below through specific embodiments.

[0022] Example 1: In specific implementation, the first optical frequency channel partitioning unit and the second optical frequency channel partitioning unit can be integrated units with optical frequency channel partitioning functions, such as arrayed waveguide gratings and wavelength division multiplexers. Example 1 uses a wavelength division multiplexer as an example. The intensity and phase modulation module includes an intensity modulator and a phase modulator. In specific implementation, the positions of the intensity modulator and the phase modulator can be interchanged; that is, the second path of light output from the complementary optical filter can be intensity modulated first and then phase modulated, or vice versa.

[0023] like Figure 2As shown, this embodiment of the invention provides a reconfigurable bandstop filter optical chip based on double-sideband amplitude and phase equalization. The chip comprises a first wavelength division multiplexer, a second wavelength division multiplexer, and a first optical filter unit, a second optical filter unit, ..., an nth optical filter unit, where n ≥ 1. The first optical filter unit includes a first complementary optical filter, a first bandstop optical filter, a first intensity modulator, a first phase modulator, and a first optical combiner. The nth optical filter unit includes an nth complementary optical filter, an nth bandstop optical filter, an nth intensity modulator, an nth phase modulator, and an nth optical combiner. The first wavelength division multiplexer divides the multi-wavelength input light into n input channels according to the optical carrier frequency, namely input channel 1, ..., input channel n. Input channel 1 outputs... The input light enters the first complementary optical filter of the first optical filtering unit. The first complementary optical filter filters the input light and splits it into two paths. One path is input to the first band-stop filter for band-stop filtering, and the other path is input to the first intensity modulator for intensity modulation, and then input to the first phase modulator for phase modulation. The output light of the first phase modulator and the output light of the first band-stop filter are combined by the first optical combiner. The combined light is output through output channel 1. Similarly, the output light of input channel n enters the nth optical filtering unit for band-stop filtering and is output through output channel n. The output light of the n output channels, namely the output light of output channel 1, ..., the output light of output channel n, are combined into one path by the second wavelength division multiplexer as the output light of the chip.

[0024] The first wavelength division multiplexer divides the multi-wavelength input light into n input channels based on the optical carrier frequency, namely input channel 1, ..., input channel n; the input optical carrier frequency of input channel 1 is... The input light, ..., the input channel n, the input light carrier frequency is The input light, of which, , ..., This refers to the input optical carrier frequency for multiple wavelengths.

[0025] The first complementary optical filter filters the input light and outputs two optical signals, one of which contains the upper sideband of the input light. With optical carrier The optical signal is input into the first band-blocking filter; the other path contains the lower sideband of the input light. The optical signal is input into the first intensity modulator, wherein, The frequency of the broadband radio frequency signal modulated in multi-wavelength input light is [value missing]. The maximum value is ,therefore, Similarly, the nth complementary optical filter filters the input light and outputs two optical signals, one of which contains the upper sideband of the input light. With optical carrier The optical signal from one path is input into the nth band light-blocking filter; the other path contains the lower sideband of the input light. The optical signal is input into the nth intensity modulator.

[0026] The first band stop filter is a tunable band stop filter, with a stopband center frequency of [frequency missing]. The stopband center frequency can be adjusted, and the upper sideband of the input light filtered out by the first complementary optical filter... After filtering by the first bandgap filter, the frequency point is The amplitude of the optical signal is Phase is Similarly, the nth band light-blocking filter is a tunable band light-blocking filter with a stopband center frequency of . The stopband center frequency can be adjusted, and the upper sideband of the input light filtered by the nth complementary optical filter... After filtering by the nth band light-blocking filter, the frequency point is The amplitude of the optical signal is Phase is .in, , ..., .

[0027] The first intensity modulator and the first phase modulator respectively modulate the lower sideband of the input light filtered out by the first complementary optical filter. Amplitude and phase modulation are performed, where the frequency is... The amplitude of the optical signal is Phase is And through amplitude and phase adjustment, , Similarly, the nth intensity modulator and the nth phase modulator respectively filter the lower sideband of the input light filtered by the nth complementary optical filter. Amplitude and phase modulation are performed, where the frequency is... The amplitude of the optical signal is Phase is And through amplitude and phase adjustment, , This achieves phase-amplitude equalization of the input light on both sides.

[0028] The first optical beam combiner combines the output light from the first phase modulator with the output light from the first band-blocking filter to achieve upper sideband of the input light. Input optical carrier and input light lower sideband The beam combiner outputs a band-stop filtered light with phase and amplitude equalization on both sides, which then enters output channel 1. Similarly, the nth beam combiner combines the output light from the nth phase modulator with the output light from the nth band-stop filter to achieve upper sideband equalization of the input light. Input optical carrier and input light lower sideband The beams are combined, and the output light with double-sided amplitude and phase equalization and band-stop filtering enters the output channel n. The second wavelength division multiplexer combines the output light from the n output channels into one as the chip output light, and the n output channels are output channel 1, ..., output channel n.

[0029] Example 2: The principle of the present invention will be further analyzed below with reference to Embodiment 2. The structural schematic diagram of Embodiment 2 is shown below. Figure 3 As shown. Example 2 is analyzed as follows: A multi-wavelength laser outputs n frequency band optical carriers, namely... , ..., The frequency band is The broadband radio frequency signal is input into the electro-optic modulator for electro-optic conversion. The input frequency range is The first wavelength division multiplexer divides the multi-wavelength input light into n input channels based on the optical carrier frequency, namely input channel 1, ..., input channel n. Taking input channel 1 as an example: the input light in input channel 1 includes... Top band and the bottom band The input light is filtered by a first complementary optical filter, which outputs two optical signals, one of which contains the upper sideband of the input light. With optical carrier The optical signal is input into the first band-stop filter for band-stop filtering. After band-stop filtering, the center frequency of the stopband is... The amplitude of the optical signal at that location is Phase is The other path includes the lower sideband of the input light. The optical signal is sequentially input into the first intensity modulator and the first phase modulator for amplitude and phase adjustment. After amplitude and phase adjustment, the frequency point... The amplitude of the optical signal at that location is Phase is And through amplitude and phase adjustment, , This achieves bilateral band amplitude and phase equalization. The output light from the first phase modulator and the output light from the first band-blocking filter are combined by the first optical combiner to form the output light spectrum as shown in the figure. Figure 4 As shown, the upper sideband, carrier, and lower sideband optical field forms of the output light can be represented as follows: Above is a light field: ; Optical carrier light field: ; The lower band light field: ; in, The amplitude of the optical carrier wave. This refers to the phase of the optical carrier.

[0030] The output light passes through the second optical frequency channel division unit and is then output to the photodetector to complete the photoelectric conversion. The output frequency is... The radio frequency signal strength can be expressed as: when ,and hour, That is, when the bilateral band amplitude-phase equalization condition is satisfied, the frequency is The RF signal output from the band-stop filter optical chip has a signal strength of 0, at which point the band-stop filter optical chip has the maximum stopband suppression. The band-stop filtered RF spectrum formed by the output light of the first optical filtering unit passing through the photodetector is as follows: Figure 5 As shown, by comparing the spectrum with that of the first band-stop filter, it can be found that by using double-side band amplitude-phase equalization, the stopband suppression and spectral resolution of the band-stop filter can be further improved.

[0031] Similarly, for input channel n, a center frequency of n can be formed by the nth optical filter unit, the second optical frequency channel division unit, and the photodetector. The band-stop filtered RF spectrum. Since the n optical filter units are independently adjustable, the RF spectrum of the photodetector output can be reconstructed using the n optical filter units. The reconstructable band-stop filtered RF spectrum is shown in the figure below. Figure 6 As shown, the present invention has a reconfigurable stopband function.

[0032] In summary, compared with existing technologies, it has the following beneficial effects: 1. In this embodiment of the invention, the upper and lower sidebands of the input light are separated by complementary optical filters on the optical chip, and the upper and lower sidebands are modulated separately. Since the optical chip is small in size, the phase of the upper and lower sidebands is the same due to environmental factors such as temperature and vibration. Therefore, after the optical combiner combines the upper and lower sidebands, the phase effects caused by environmental changes cancel each other out and do not affect the phase of the output light of the band-stop filter.

[0033] 2. In this embodiment of the invention, the amplitude of the lower sideband signal of the input light is adjusted by an amplitude modulator. After amplitude adjustment, the amplitude of the lower sideband signal is equal to the amplitude of the upper sideband signal of the input light after being filtered by a band-stop filter. The phase of the lower sideband of the input light is shifted by adjusting the phase modulator, so that the phase of the lower sideband signal is 180 degrees different from the phase of the signal of the upper sideband after being filtered by a band-stop filter. This achieves amplitude and phase balance of the input light on both sidesbands, and improves the stopband suppression degree and spectral resolution of the band-stop filter.

[0034] 3. In this embodiment of the invention, by designing a pair of optical frequency channel division units on the optical chip, the input multi-band optical signal is divided into multiple channels according to the optical carrier frequency. Each channel is independently narrowband bandstop filtered by an optical filtering unit. By controlling the amplitude and phase modulation and bandstop optical filter tuning in each optical filtering unit, the stopband of the bandstop filtering optical chip can be reconstructed, thus possessing bandstop filtering reconfigurable capability.

[0035] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0036] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A reconfigurable bandstop filter optical chip based on double-side band amplitude-phase equalization, characterized in that, The first optical frequency channel partitioning unit, n optical filtering units, and the second optical frequency channel partitioning unit, wherein n≥1; Each of the optical filtering units includes a complementary optical filter, a band-blocking filter, an intensity and phase modulation module, and an optical beam combiner. The first optical frequency channel division unit divides the multi-wavelength input light into optical carrier frequencies of... , , ..., The n output beams are respectively input into n optical filtering units; The complementary optical filter in each optical filtering unit filters the input light and splits it into two paths. One path is input to a band-stop filter for band-stop filtering; the other path is modulated by an intensity and phase modulation module. The two outputs of the intensity and phase modulation module and the band-stop filter are combined by an optical combiner. n beams are combined into one path through the second optical frequency channel dividing unit, which serves as the output light of the reconfigurable band-stop filter optical chip. The complementary optical filter filters the input light and outputs two optical signals. One of the output signals of the complementary optical filter in the nth optical filtering unit contains the upper sideband of the input light. With optical carrier frequency The optical signal is input into a light-blocking filter in one path; the other path contains the lower sideband of the input light. In the optical signal input intensity and phase modulation module, among which, The frequency of the broadband radio frequency signal modulated in multi-wavelength input light. , This is the minimum frequency of the radio frequency signal. This represents the maximum frequency of the radio frequency signal. The band-stop filter is a tunable band-stop filter, wherein the stopband center frequency of the band-stop filter in the nth optical filtering unit is... The stopband center frequency can be adjusted, and the upper sideband of the input light filtered by the complementary optical filter is... After filtering with a light-blocking filter, the frequency point is The amplitude of the optical signal is Phase is ;in, , This is the minimum frequency of the radio frequency signal. This represents the maximum frequency of the radio frequency signal.

2. The reconfigurable band-stop filter optical chip as described in claim 1, characterized in that, Both the first optical frequency channel partitioning unit and the second optical frequency channel partitioning unit are wavelength division multiplexers.

3. The reconfigurable band-stop filter optical chip as described in claim 1, characterized in that, Both the first optical frequency channel division unit and the second optical frequency channel division unit are arrayed waveguide gratings.

4. The reconfigurable band-stop filter optical chip as described in claim 1, characterized in that, The intensity and phase modulation module includes an intensity modulator and a phase modulator.

5. The reconfigurable band-stop filter optical chip as described in claim 4, characterized in that, In the nth optical filtering unit, the intensity modulator and the phase modulator respectively filter the lower sideband of the input light filtered out by the complementary optical filter. Amplitude and phase modulation are performed, where the frequency is... The amplitude of the optical signal is Phase is And through amplitude and phase adjustment, , .

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