High-speed switching n-bit path selective silicon-based integrated microwave photonic delay line structure

Abstract

A high-speed switching N-bit path selective silicon-based integrated microwave photonic delay line structure comprises a wavelength tunable external cavity laser, an electro-optical modulator, an N-bit wavelength selective delay line, and a photodetector, the wavelength selective delay line being composed of N+1 2×2 wavelength interleavers and N sets of delay and reference waveguide pairs. Output light of the external cavity laser is modulated by a microwave signal, then input to the N-bit wavelength selective delay line, and finally converted by the photodetector into a microwave signal to be output. By means of switching the wavelength of the laser, high-speed switching of the delay optical path can be implemented, and high-speed phase shifting of the microwave signal can also be implemented. In the solution, the wavelength selective delay line is designed by using a passive device, so that low loss can be implemented more easily compared with a conventional optical switch delay line, and voltage regulation is not required, thereby having a low overall system power consumption.

Description

A high-speed switching N-bit path-selective silicon-based integrated microwave photonic delay line structure Technical Field

[0001] This invention belongs to the field of integrated optoelectronic device technology, specifically relating to an N-bit path-selective silicon-based integrated microwave photonic delay line structure that utilizes a tunable external cavity laser to achieve high-speed switching. Background Technology

[0002] In recent years, optical delay lines have been widely used in microwave photonic signal processing, such as beamforming and microwave photonic filtering, due to their characteristics of large bandwidth, low loss, and no electromagnetic interference. Silicon-based optoelectronic integration has advantages such as high integration density, CMOS process compatibility, and low cost, making it suitable for fabricating highly integrated optical delay line array chips.

[0003] However, existing silicon photonics tunable delay line structures, including cascaded Mach-Zehnder switches (MZS) and microring resonators (MRRs), have certain limitations. MZS-type tunable delay lines consist of multiple 2×2 MZSs cascaded with delay waveguides. Adjustment of the delay is achieved by switching different delay paths through the MZS switching states. This approach offers a large delay adjustment range, but the delay accuracy depends on the unit delay. MRR-type tunable delay lines achieve tunable delay by adjusting the resonance of the microring. This approach is compact and offers continuously adjustable delay, but its adjustment range is relatively small and requires complex feedback control to stabilize the resonant wavelength.

[0004] Currently, most silicon-based optical delay chips reported in the literature achieve delay control based on the thermo-optical effect, with switching times typically on the order of 10 microseconds. This is insufficient to meet the requirements of high-speed beamforming / deflection and microwave signal processing. To achieve high-speed tunable delay lines, electro-optic phase shifters based on the free carrier dispersion effect are generally used on silicon photonics platforms to control the switching state of the MZS. Although this approach can achieve nanosecond-level response, it introduces significant carrier absorption losses, which increase significantly with the scale of the delay line. Nanosecond switching speed optical delay lines can also be achieved based on thin-film lithium niobate platforms; however, the large size of the unit devices hinders the large-scale integration of optical delay lines.

[0005] High-performance on-chip laser sources are an indispensable part of microwave photonic signal processing. Single-crystal silicon is an indirect bandgap material; electron-hole recombination cannot generate photons, thus it cannot be directly used to fabricate lasers. Typically, III-V group lasers and silicon materials need to be hybridized and integrated to fabricate lasers on a silicon photonics platform. There are two main hybrid integration methods: one is direct coupling and integration of a III-V group laser and a silicon photonic chip, where the III-V group laser is an independent chip with its output directly connected to a silicon photonic waveguide; the other is the formation of a hybrid cavity by a III-V group gain chip and a silicon photonic chip, with the laser cavity composed of both III-V group waveguides and silicon photonic waveguides. Silicon waveguides have low transmission loss and can be used to form high-performance tunable filters (including gratings, microring resonators, multi-arm interference structures, etc.), which are beneficial for reducing laser linewidth and achieving wide-range tuning in external cavity lasers.

[0006] The change in laser output wavelength is mainly achieved by altering the phase within the laser cavity. Thermo-optical switching is limited by the thermal diffusion rate, allowing for switching speeds on the order of microseconds. To achieve higher switching speeds, one approach is to introduce an electro-optical phase shifter based on PN or PIN diodes within the cavity to achieve wavelength switching on the order of nanoseconds.

[0007] Near-infrared photodetectors on silicon substrates are primarily achieved through the epitaxial growth of germanium material on the silicon substrate. Germanium-silicon photodetectors can employ waveguide-coupled lateral or longitudinal PIN structures. Compared to metal-semiconductor-metal (MSM) structures, PIN detectors exhibit higher quantum efficiency and lower dark current. Summary of the Invention

[0008] To achieve an adjustable delay scheme supporting high-speed switching, this invention proposes an N-bit path-selective integrated microwave photonic delay line chip supporting high-speed optical path switching. This chip consists of a wavelength-tunable laser, a modulator, an N-bit wavelength-selective optical delay line, and a photodetector. High-speed wavelength tuning of the external cavity laser is achieved using the electro-optic effect or piezoelectric effect. The optical signal generated by the laser is modulated by the modulator and then input to the N-bit wavelength-selective optical delay line. The delay path selection of the wavelength-selective delay line is achieved using a passive wavelength interleaver, eliminating the drawbacks of high power consumption and high thermal crosstalk associated with active modulation in traditional path-selective integrated optical delay lines. Furthermore, it avoids the complex state calibration process required for series-connected optical switch arrays in traditional path-selective integrated optical delay lines. Furthermore, traditional nanosecond-level high-speed delay switching requires carrier injection into the waveguide within the optical switch during switching to achieve high-speed phase shift. This phase shift introduces additional and progressively accumulating carrier absorption losses. However, by using a passive wavelength interleaver, the input wavelength of the external cavity laser can be adjusted through the carrier injection effect to achieve delay path switching, thus maintaining nanosecond-level switching speed while avoiding performance degradation of the delay chip caused by carrier absorption losses.

[0009] The technical solution of the present invention is as follows:

[0010] A high-speed wavelength-switching N-bit path-selective integrated microwave photonic delay line is characterized by comprising a wavelength-tunable external cavity laser, an electro-optic modulator, an N-bit wavelength-selective delay line, and a photodetector.

[0011] Let the center wavelength of the first channel of the k-th (k = 1, 2, ..., N+1) 2×2 wavelength interleaver be λ. k Free spectral range is FSR k The passband bandwidth is B k The design satisfies the following: (1) The center wavelength of the first channel of the (k+1)th 2×2 wavelength interleaver is equal to the center wavelength λ of the kth 2×2 wavelength interleaver. k In addition to its bandwidth B k Half of, that is (2) Free spectral range (FSR) of the (k+1)th 2×2 wavelength interleaver k+1 ) equals the free spectral range (FSR) of the k-th 2×2 wavelength interleaver. k Twice that of FSR k+1 =2FSR k (3) The bandwidth of the (k+1)th 2×2 wavelength interleaver is equal to twice the bandwidth of the kth 1×2 wavelength interleaver, i.e., B k+1 =2B k .

[0012] The N-bit wavelength-selective delay line includes N+1 2×2 wavelength interleavers, N sets of delay and reference waveguide pairs.

[0013] A delay waveguide (of length L) connects the k-th (k = 1, 2, ..., N) and k+1-th 2×2 wavelength interleavers. k The delay waveguide and the reference waveguide (of length L0) have a length difference of ΔL. k =L k -L0=2 k-1 ΔL, where ΔL is the unit delay length, and the unit delay introduced by the unit delay length is Δτ. Therefore, N+1 wavelength interleavers constitute a 2 N One wavelength channel, center wavelength λ k Belongs to set Each wavelength channel undergoes a unique delay path, for which a delay amount belonging to the set {Δτ} can be generated. k |Δτ k =kΔτ,k∈0,1,2,...,2 N -1}.

[0014] The longitudinal mode spacing Δv of a wavelength-tunable laser and the adjacent wavelength channel spacing of the corresponding N-bit wavelength-selective delay line Alignment is achieved by tuning the wavelength of the external cavity laser to switch the optical path, thereby obtaining different optical delays.

[0015] The high-speed switching N-bit path-selective silicon-based integrated microwave photonic delay line is characterized in that the N-bit wavelength interleaver includes structures such as a micro-ring assisted Mach-Zehnder filter, an unbalanced Mach-Zehnder filter, a cascaded unbalanced Mach-Zehnder filter, a micro-ring resonant filter, a cascaded micro-ring resonant filter, and an arrayed waveguide grating; the input / output waveguides, delay waveguides, reference waveguides, and wavelength interleaver can all be implemented on integrated platforms such as SOI, silicon oxide, silicon oxynitride, silicon nitride, lithium niobate, barium titanate, and lithium tantalate.

[0016] The high-speed switching N-bit path-selective silicon-based integrated microwave photonic delay line is characterized in that the N-bit wavelength interleaver can integrate phase change material as a non-volatile phase shifter to achieve one-time correction of phase errors caused by manufacturing process deviations.

[0017] The high-speed switching N-bit path-selective integrated optical delay line structure is characterized in that N+1 wavelength interleavers are connected in series in pairs, that is, the two output terminals O of the previous stage wavelength interleaver are connected in series in pairs. k ,P k They are respectively connected to the two output terminals I of the subsequent wavelength interleaver. k+1 J k+1 The O k End and I k+1 Between the ends, a delay waveguide (of length L) is used. k ) connection; the P k End and J k+1 The ends are connected by a reference waveguide (of length L0). The length difference L between the delay waveguide and the reference waveguide is... k -L0 is 2 of the unit delay length ΔL k-1 times.

[0018] The center wavelength and free spectral range of the first channel of the first-stage wavelength interleaver are λ1 and FSR1, respectively. The center wavelength and free spectral range of the first channel of the k-th-stage wavelength interleaver are respectively... and 2 k-1 FSR1.

[0019] The tunable laser outputs wavelength λ k After modulating the microwave signal, it is input into the N-bit wavelength-selective delay line structure, and after passing through N+1 wavelength interleavers, the k-th delay channel is selected, resulting in a delay amount. Where Δτ0 is the unit delay, Γ k ∈{0,1} is a control factor. When the optical signal passes through the k-th order delay waveguide, Γ k Take 1; when the optical signal passes through the k-th order reference waveguide, Γ k Take 0. By configuring different sequences Γ={Γ k |k=1,2,...,N}, in the output waveguide of the N-bit wavelength selective delay line, the input signal is delayed, and the set of delay amounts is T={kΔτ0|k=0,1,2,...,2}. N -1}.

[0020] The modulator is integrated into the wavelength-tunable laser to achieve internal modulation, or located between the wavelength-tunable laser and the N-bit wavelength-selective delay line to achieve external modulation.

[0021] The technical approaches for the modulators include, but are not limited to, Mach-Zehnder modulators, micro-ring modulators, and micro-ring coupled Mach-Zehnder modulators.

[0022] The photodetector can be made of single-crystal germanium grown on silicon, using a lateral or vertical PIN junction structure.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] To achieve a low-loss, nanosecond-level high-speed adjustable delay line, this invention proposes an N-bit path-selective integrated microwave photonic delay line chip that supports high-speed optical path switching. Its technical advantages are as follows:

[0025] (1) The output signal wavelength of the tunable laser is switched at a nanosecond-level speed and then modulated and input into an N-bit path-selective integrated optical delay line structure. On the one hand, this enables high-speed delay optical path switching and eliminates the carrier absorption loss introduced by traditional high-speed electro-optic switch arrays during high-speed switching. On the other hand, the optical path switching is achieved by changing the output optical signal wavelength through the tunable laser, rather than by adjusting the state of the optical switch. This also eliminates the complex switch state calibration process of traditional path-selective integrated optical delay lines and the complex switch array drive circuit.

[0026] (2) By using a passive design to achieve the target filtering characteristics of the wavelength interleaver, or by using a phase change material to achieve the adjustable filtering characteristics of the wavelength interleaver, near-zero power consumption and non-volatile state maintenance of each wavelength channel (i.e., delay path) can be achieved, while avoiding the chip performance degradation caused by thermal crosstalk. Attached Figure Description

[0027] Figure 1 is a schematic diagram of the high-speed switching N-bit path selection silicon-based integrated microwave photonic delay line structure of the present invention.

[0028] Figure 2 is a schematic diagram of the N-bit wavelength-selective optical delay line of the present invention;

[0029] Figure 3 is a schematic diagram of a Mach-Zehnder wavelength interleaver based on a tunably coupled micro-ring assisted Mach-Zehnder wavelength interleaver.

[0030] Figure 4 is a schematic diagram of a cascaded unbalanced Mach-Zehnder wavelength interleaver.

[0031] Figure 5 is a schematic diagram of the working principle of the 5-bit wavelength-selective optical delay line in the embodiment;

[0032] Figure 6 is a delay state lookup table for the 5-bit wavelength-selective optical delay line in the embodiment;

[0033] Figure 7 is a schematic diagram of an external cavity laser based on the dual micro-ring vernier effect;

[0034] Figure 8 is a schematic diagram of a Mach-Zehnder modulator;

[0035] Figure 9 is a schematic diagram of a photodetector. Detailed Implementation

[0036] The present invention will be further defined below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the scope of protection of the present invention.

[0037] Figure 1 is a schematic diagram of the high-speed switching N-bit path-selective silicon-based integrated microwave photonic delay line structure of the present invention. As shown in the figure, it includes: a tunable laser 1.1, a modulator 1.2, an N-bit wavelength-selective optical delay line 1.3, and a photodetector 1.4.

[0038] The N-bit wavelength-selective optical delay line, as shown in Figure 2, includes one input waveguide (2.1), N+1 wavelength interleavers (2.2), N delay waveguides (2.3), N reference waveguides (2.4), and one output waveguide (2.5). Wavelength interleaver k (k = 1, 2, ..., N) and wavelength interleaver k+1 are each connected by a waveguide of length L. k A delayed waveguide (2.3) and a reference waveguide (2.4) of length L0 are provided, with a length difference of ΔL between the delayed waveguide and the reference waveguide. k =L k -L0=2 k-1 ΔL, where ΔL is the unit delay length, corresponding to the unit delay amount Δτ0.

[0039] The 2 consists of N+1 wavelength interleavers. N One wavelength routing channel, center wavelength λ k Belongs to set Each routing channel corresponds to a delay state. If the modulation bandwidth of the modulator for the laser is B... LThe allowable bandwidth of the wavelength interleaver is B. I Then the maximum allowable operating bandwidth of the device is B = min{B L B I Theoretically, the maximum allowable number of bits N for path-selective integrated optical delay lines is N. max = [log2(B / FSR1)], where [·] represents the largest integer not exceeding ·.

[0040] Figure 3 illustrates an embodiment of a tunable-coupled microring-assisted Mach-Zehnder wavelength interleaver, comprising a set of input waveguides (3.1) I and J, a set of output waveguides (3.4) O and P, two 3-dB couplers (3.2) and their connecting modulation arms, one of which is a straight waveguide and the other is a coupled tunable microring. This forms a microring-coupled Mach-Zehnder filter. By adjusting the coupling factor of the microring and the phase of the two arms using a phase shifter (3.3), a flat-top filter can be obtained, and the center wavelength and passband shape of the filter can be adjusted. Near-zero power consumption and non-volatile phase shifters (3.3) can be implemented using phase change materials, thereby enabling non-volatile configuration and correction of the filtering characteristics of each wavelength interleaver. The on-chip heater that excites the phase change material phase change includes, but is not limited to, TiN based on thermo-optic effects, waveguide-doped thermal resistor schemes, and pin junction schemes based on carrier dispersion effects.

[0041] Figure 4 illustrates another embodiment based on a cascaded unbalanced Mach-Zehnder wavelength interleaver, comprising a set of input waveguides (4.1)I and J, a set of output waveguides (4.7)O and P, three broadband couplers (4.2, 4.3, 4.4) with defined splitting ratios, and two phase-shifting waveguides (4.5, 4.6). A flat-top filter can also be obtained by precisely setting the coupling coefficients of the three broadband couplers and the phase shifts of the two phase-shifting waveguides. The phase shifts of the phase-shifting waveguides can be non-volatilely corrected using phase change material phase shifters (4.8, 4.9) to modify the filter shape of the interleaver.

[0042] The two wavelength interleaver examples given above are only for illustrating the principle of wavelength interleavers and available technical solutions. Other technologies not described above, such as microring filters, cascaded multi-microring filters, multi-microring assisted Mach-Zehnder filters, waveguide array gratings, etc.

[0043] Figure 5 illustrates the working principle of a 5-bit wavelength-selective delay line, which includes six wavelength interleavers that divide the working bandwidth into 32 wavelength channels, each wavelength experiencing a unique delay path. Assume that the center wavelength and bandwidth of wavelength interleaver 1 are λ1 and B1, respectively, and the FSR is twice the bandwidth B1. Then the center wavelength λ of the first channel of interleaver k (k = 1, 2, 3, ..., 6) is... kand bandwidth B k They are respectively and 2 k-1 B1. Taking wavelength channel λ1 as an example, all five wavelength interleavers it passes through are in a straight-through state (bar state), therefore it passes through T={Δτ0,2Δτ0,2 2 Δτ0,...,2 4 The waveguide with delay Δτ0} has a relative delay experienced by the wavelength channel of (1+2+2) / 2. 2 +...+2 4 )Δτ0, i.e., 31Δτ0. The lookup table for the working state of the 5-bit wavelength-selective delay line in this embodiment is shown in Figure 6. When the output wavelength of the tunable laser is switched at high speed, the delay of the optical path can be adjusted at high speed.

[0044] Wavelength-tunable lasers can be integrated onto the same chip as wavelength-selective routing arrays or implemented discretely. Materials used, in addition to III-V group gain materials, include, but are not limited to, commonly used materials such as silicon, silicon nitride, silicon oxide, lithium niobate, barium titanate, and silicon carbide, or combinations thereof. Laser generation can be achieved through electrical pumping or optical pumping (primarily utilizing nonlinear effects, including but not limited to stimulated Raman and stimulated Brillouin effects). The laser can be a standalone monolithic laser, with its output directly supplied to a silicon-based waveguide, including but not limited to Fabry-Perot (FP) lasers, distributed feedback lasers (DFB), distributed Bragg reflector lasers (DBR), and vertical-cavity surface-emitting lasers (VCSELs); it can also be a hybrid cavity composed of a III-V group active component and a silicon-based chip. The longitudinal mode selection structure of the laser includes, but is not limited to, commonly used structures such as gratings, microring resonators, and multi-arm interference structures. Hybrid cavity lasers include, but are not limited to, external cavity lasers (ECLs) and self-injection locked lasers (SILs). Integration methods include, but are not limited to, commonly used integration methods such as epitaxial growth, heterogeneous integration, and hybrid integration. External cavity lasers can be designed to align their longitudinal mode spacing Δv with the adjacent wavelength spacing Δλ of the wavelength-selective routing, and by utilizing electro-optic and piezoelectric effects, the laser can operate at wavelength λ. i The single-mode output and high-speed switching are realized between i = 1, 2, ..., N.

[0045] The modulator can be integrated into the laser to achieve internal modulation, or it can be located between the laser and the N×N wavelength selective routing array to achieve external modulation; the modulator can be fabricated based on common integrated platforms including but not limited to silicon-based, lithium niobate, lithium tantalate, and barium titanate.

[0046] Figure 7 illustrates an embodiment of a tunable laser. The laser connects a gain unit 7.1 and a lithium niobate external cavity chip 7.2 via end-face coupling. The external cavity chip mainly consists of a mode converter 7.3, a phase shifter 7.4, and two microrings 7.5 and 7.6 with phase shifters. The mode converter 7.3 improves the coupling efficiency between the gain and the external cavity. Additionally, it has a tilt angle to reduce reflections at the contact end face. The vernier filter formed by the two microrings 7.5 and 7.6 is primarily used for mode selection. By design, the two microrings have slightly different circumferences, resulting in different transmission spectra. When one resonant peak of the transmission spectra of the two microrings aligns, the other resonant peaks will not align, thus ensuring single-mode output. By changing the phase of one microring through the phase shifter, the transmission spectrum of that microring can be shifted, causing the two transmission spectra to align at the other resonant peak, thereby achieving wavelength switching of the laser. The phase shifter 7.4 is mainly used to compensate for the phase difference between the center wavelength of the filter and the longitudinal mode of the laser.

[0047] Figure 8 illustrates an embodiment of a modulator consisting of two 1×2 multimode interferometers 8.1 and 8.2 and two phase shifters 8.3 and 8.4. When a signal is applied to the two phase shifters and there is a phase difference between the two arms, the input light intensity changes, thereby achieving light intensity modulation.

[0048] Figure 9 illustrates an embodiment of a photodetector. It mainly consists of an input waveguide 9.1, a tapered structure 9.2 with a gradually varying width, a germanium absorption region 9.3, and electrodes 9.4. Laser light is input through the single-mode waveguide 9.1, passes through the tapered structure 9.2, and is directed from the input to the silicon multimode waveguide beneath the germanium layer. Under interlayer evanescent wave coupling, the light is continuously coupled into the 9.3 Ge absorption region to generate photogenerated carriers. A bias voltage can be applied and the photogenerated current can be read out through the electrodes 9.4.

Claims

1. A high-speed switching N-bit path-selective silicon-based integrated microwave photonic delay line, characterized in that, include: A wavelength-tunable external cavity laser is used to generate tunable optical signals; An electro-optic modulator is used to modulate the optical signal generated by the external cavity laser; An N-bit wavelength-selective delay line consists of N+1 2×2 wavelength interleavers and N sets of delay waveguides and reference waveguides, where the k-th and (k+1)-th 2×2 wavelength interleavers are connected by a line of length L. k A delayed waveguide and a reference waveguide of length L0 are given, wherein the length difference between the delayed waveguide and the reference waveguide is ΔL. k =L k -L0=2 k-1 ΔL, where ΔL is the unit delay length, and the delay introduced by the unit delay length is Δτ; the N+1 2×2 wavelength interleavers constitute 2 N Each wavelength channel, with its center wavelength, free spectral range (FSR), and passband bandwidth (B) satisfying the following conditions: (a) The center wavelength of the first channel of the (k+1)th 2×2 wavelength interleaver is equal to the center wavelength λ of the kth 2×2 wavelength interleaver. k In addition to its bandwidth B k Half of, that is (b) The FSR of the (k+1)th 2×2 wavelength interleaver k+1 Equal to the kth 2×2 wavelength interleaver FSR k Twice that, i.e., FSR k+1 =2FSR k ; (c) The bandwidth B of the (k+1)th 2×2 wavelength interleaver k+1 Equal to the bandwidth B of the k-th 1×2 wavelength interleaver k twice that, i.e., B k+1 =2B k ;as well as, A photodetector is used to receive and detect the optical signal after processing by the N-bit wavelength-selective delay line; By adjusting the wavelength of the external cavity laser, the passive characteristics of the wavelength interleaver are utilized to achieve rapid switching of the optical path, thereby obtaining different optical delays and avoiding carrier absorption loss. The longitudinal mode spacing Δv of a wavelength-tunable laser and the adjacent wavelength channel spacing of the corresponding N-bit wavelength-selective delay line Alignment is achieved by tuning the wavelength of the external cavity laser to switch the optical path, thereby obtaining different optical delays.

2. The high-speed switching N-bit path-selective silicon-based integrated microwave photonic delay line according to claim 1, characterized in that, The wavelength interleaver includes an unbalanced Mach-Zehnder filter, a cascaded unbalanced Mach-Zehnder filter, and a micro-ring assisted Mach-Zehnder filter.

3. The high-speed switching N-bit path-selective silicon-based integrated microwave photonic delay line according to claim 1 or 2, characterized in that, The wavelength interleaver can integrate phase change materials to achieve non-volatile phase shift, and can be used to correct phase errors caused by deviations in the manufacturing process.

4. The high-speed switching N-bit path-selective silicon-based integrated microwave photonic delay line according to claim 1 or 2, characterized in that, The N+1 wavelength interleavers are connected in series in pairs, and the two outputs of the k-th 2×2 wavelength interleaver are connected to the two inputs of the (k+1)-th 2×2 wavelength interleaver through a delay waveguide and a reference waveguide, respectively. The length difference between the delay waveguide and the reference waveguide is 2 times the unit delay length ΔL. k-1 times.

5. The high-speed switching N-bit path-selective silicon-based integrated microwave photonic delay line according to claims 1-3, characterized in that, The center wavelength and free spectral range of the first channel of the first-stage wavelength interleaver are λ1 and FSR1, respectively. The center wavelength and free spectral range of the first channel of the k-th-stage wavelength interleaver are respectively... and 2 k-1 FSR1.

6. The high-speed switching N-bit path-selective silicon-based integrated microwave photonic delay line according to claim 1, characterized in that, The external cavity laser outputs wavelength λ k After modulating the microwave signal, it is input into the N-bit wavelength-selective delay line, and after passing through N+1 wavelength interleavers, the k-th delay channel is selected, resulting in a delay amount. Where Δτ0 is the unit delay, Γ k ∈{0,1} is a control factor. When the optical signal passes through the k-th order delay waveguide, Γ k Take 1; when the optical signal passes through the k-th order reference waveguide, Γ k Take 0. By configuring different sequences Γ={Γ k |k=1,2,...,N}, in the output waveguide of the N-bit wavelength selective delay line, the input signal is delayed, and the set of delay amounts is T={kΔτ0|k=0,1,2,...,2}. N -1}.

7. The high-speed switching N-bit path-selective silicon-based integrated microwave photonic delay line according to claim 6, characterized in that, By configuring different sequences of delay waveguides and reference waveguide combinations, the input signal is delayed on the output waveguide of the N-bit wavelength selective delay line. The set of delay amounts is determined by the unit delay amount and the control factor. When the optical signal passes through the delay waveguide, the control factor is 1; when the optical signal passes through the reference waveguide, the control factor is 0.

8. The high-speed switching N-bit path-selective silicon-based integrated microwave photonic delay line according to claim 1, characterized in that, The modulator can be integrated into the external cavity laser to achieve internal modulation, or located between the external cavity laser and the N-bit wavelength selective delay line to achieve external modulation.

9. The high-speed switching N-bit path-selective silicon-based integrated microwave photonic delay line according to claim 6, characterized in that, The photodetector can be made of single-crystal germanium grown on silicon, using a lateral or vertical PIN junction structure.

10. The high-speed switching N-bit path-selective integrated microwave photonic delay line according to any one of claims 1 to 9, characterized in that, The external cavity laser utilizes the electro-optic effect or piezoelectric effect to achieve high-speed wavelength tuning.

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