All-optical time-domain integration system

Abstract

The invention discloses an all-optical integration system, comprising: an optical envelope to be integrated is connected to the input end of a first-stage two-tap positive coefficient microwave photon filter (1); the output end of the first-stage two-tap positive coefficient microwave photon filter (1) is connected to the first input end (9a) of a three-port optical circulator; the output end of a laser source (6) is connected to the input end of an optical isolator (7); the output end of the optical isolator (7) is connected to the input end of an optical envelope detection module (8); the output end of the optical envelope detection module (8) is connected to the second input end (9b) of the three-port optical circulator; the output end (9c) of the three-port optical circulator is connected to the input end of a second-stage two-tap positive coefficient microwave photon filter (10); and the output end of the second-stage two-tap positive coefficient microwave photon filter (10) is the final output end. The invention avoids complex spectral filtering, has simple devices, and is easy to adjust.

Description

Technical Field

[0001] The invention relates to the field of signal processing, in particular to an all-optical time-domain integration system. Background Art

[0002] An integrator is a device that can perform an integration operation on an input signal. As a basic signal processing device, it has a wide range of applications, such as analog-to-digital conversion, waveform transformation, etc. Since photonic technology has the advantage of large bandwidth, the all-optical time-domain integrator based on photonic technology can effectively overcome the electronic bottleneck problem existing in electronic systems. Therefore, the all-optical integrator has received widespread attention. The existing all-optical time-domain integrator (Malacarne.A, Ashrafi.R, Li.M, LaRochelle.S, Yao.J, Azana.J, "Single-shot photonic time-intensity integration based on a time-spectrum convolution system," Opt. Lett., vol.37, no.8, pp.1355-1357, 2012.) is costly, difficult to operate, and has strict requirements on dispersion. Therefore, it is of great scientific significance and application value to realize all-optical time-domain integration in a simple, controllable and easy-to-adjust way. Summary of the invention

[0003] The purpose of the present invention is to overcome the above disadvantages and provide an all-optical time-domain integration system which avoids complex spectral filtering, has simple components and is easy to adjust.

[0004] The technical solution of the present invention is: an all-optical integration system, comprising a first-stage two-tap positive coefficient microwave photon filter, a laser source, an optical isolator, an optical envelope detection module, a three-port optical circulator and a second-stage two-tap positive coefficient microwave photon filter, wherein: the optical envelope to be integrated is connected to the input end of the first-stage two-tap positive coefficient microwave photon filter, the three-port optical circulator is provided with an input end one, an input end two and an output end three, the output end of the first-stage two-tap positive coefficient microwave photon filter is connected to the input end one of the three-port optical circulator, the output end of the laser source is connected to the input end of the optical isolator, the output end of the optical isolator is connected to the input end of the optical envelope detection module, the output end of the optical envelope detection module is connected to the input end two of the three-port optical circulator, the output end three of the three-port optical circulator is connected to the input end of the second-stage two-tap positive coefficient microwave photon filter, and the output end of the second-stage two-tap positive coefficient microwave photon filter is the final output end. In the above-mentioned all-optical time-domain integration system, the optical envelope detection module is a semiconductor optical amplifier (SOA), which uses its cross-gain modulation effect to complete the detection of the output optical envelope of the first-stage two-tap positive coefficient microwave photonic filter.

[0005] The above-mentioned all-optical time-domain integration system, wherein: the first-stage two-tap positive coefficient microwave photon filter is composed of an optical coupler, a polarization controller A1, a polarization controller A2, an optical delay line, and a polarization combiner. The two output ends of the optical coupler are respectively connected to the input end of the polarization controller A1 and the input end of the polarization controller A2, the output end of the polarization controller A1 is connected to the input end of the optical delay line, and the output end of the optical delay line and the output end of the polarization controller A2 are respectively connected to the two input ends of the polarization combiner.

[0006] The above-mentioned all-optical time-domain integration system, wherein: the second-stage two-tap positive coefficient microwave photon filter is composed of an optical coupler, a polarization controller B1, a polarization controller B2, an optical delay line, and a polarization combiner. The two output ends of the optical coupler are respectively connected to the input end of the polarization controller B1 and the input end of the polarization controller B2, the output end of the polarization controller B1 is connected to the input end of the optical delay line, and the output end of the optical delay line and the output end of the polarization controller B2 are respectively connected to the two input ends of the polarization combiner.

[0007] Compared with the prior art, the present invention has obvious beneficial effects. It can be seen from the above technical solutions that the optical coupler of the present invention provides the two-way tap number required by the microwave photon filter, and the polarization controller A1 and the polarization controller A2 can obtain the desired tap weights in the first-stage two-tap positive coefficient microwave photon filter. The polarization beam combiner can avoid light interference and ensure that the two-way light fields from the coupler complete envelope superposition in orthogonal directions. The laser source can provide a continuous detection light. The optical isolator can not only ensure the unidirectional transmission of the laser source, but also avoid the light of the optical envelope detection module from being reflected back to the laser source. The optical envelope detection module can provide optical-to-optical modulation due to the dynamic characteristics of the carriers, and complete the detection of the output optical envelope of the first-stage two-tap positive coefficient microwave photon filter by the detection light. The three-port optical circulator can realize the reverse injection of both the detection light and the optical envelope to be detected into the optical envelope detection module to complete the optical-to-optical modulation, and allow the detection light after envelope detection to smoothly enter the second-stage two-tap positive coefficient microwave photon filter. The optical coupler provides the two-way tap number required by the microwave photon filter, and the polarization controller B1 and the polarization controller B2 can obtain the desired tap weights in the second-stage two-tap positive coefficient microwave photon filter. The polarization beam combiner can avoid light interference and ensure that the two light fields from the coupler complete envelope superposition in orthogonal directions. In the present invention, when the repetition frequency of the light envelope to be integrated changes, since the weight of the tap is independent of the repetition frequency of the light envelope to be integrated, it is only necessary to adjust the delay of the two two-tap positive coefficient microwave photon filters to obtain the integrated light envelope output at different repetition frequencies. Mainly starting from the frequency domain characteristics of the integral operation, by adjusting its weight and delay, the system transfer function generated by the cascade of two two-tap positive coefficient microwave photon filters can approach the transfer function of the ideal integral. When the light envelope to be integrated passes through the system, the integration operation will be completed from the perspective of the frequency domain, and the corresponding integrated light envelope will be obtained in the time domain. The whole process avoids spectral filtering, and the control is simple and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 A schematic diagram of the structure of the present invention

[0009] Figure 2 It is a working principle diagram of the present invention.

[0010] Reference numerals:

[0011] 1. First-stage two-tap positive coefficient microwave photon filter, 2. Optical coupler A, 3-1. Polarization controller A1, 3-2. Polarization controller A2, 4. Optical delay line A, 5. Polarization beam combiner A, 6. Laser source, 7. Optical isolator, 8. Optical envelope detection module, 9. Three-port optical circulator, 9a. Three-port optical circulator port one, 9b. Three-port optical circulator port two, 9c. Three-port optical circulator port three, 10. Second-stage two-tap positive coefficient microwave photon filter, 11. Optical coupler B, 12-1. Polarization controller B1, 12-2. Polarization controller B2, 13. Optical delay line B, 14. Polarization beam combiner B. DETAILED DESCRIPTION

[0012] In conjunction with the accompanying drawings and preferred embodiments, the specific implementation, structure, features and functions of a full light integration system proposed according to the present invention are described in detail below. Figure 1 An all-optical integration system comprises a first-stage two-tap positive coefficient microwave photon filter 1, a laser source 6, an optical isolator 7, an optical envelope detection module 8, a three-port optical circulator 9 and a second-stage two-tap positive coefficient microwave photon filter 10, wherein: the optical envelope to be integrated is connected to the input end of the first-stage two-tap positive coefficient microwave photon filter 1, the three-port optical circulator 9 is provided with an input end 1 9a, an input end 2 9b and an output end 3 9c, the output end of the first-stage two-tap positive coefficient microwave photon filter 1 is connected to the input end 1 9a of the three-port optical circulator, the output end of the laser source 6 is connected to the input end of the optical isolator 7, the output end of the optical isolator 7 is connected to the input end of the optical envelope detection module 8, the output end of the optical envelope detection module 8 is connected to the input end 2 9b of the three-port optical circulator, the output end 3 9c of the three-port optical circulator is connected to the input end of the second-stage two-tap positive coefficient microwave photon filter 10, and the output end of the second-stage two-tap positive coefficient microwave photon filter 10 is the final output end.

[0013] The first-stage two-tap positive coefficient microwave photon filter 1 is composed of an optical coupler 2, a polarization controller A1 3-1, a polarization controller A2 3-2, an optical delay line 4, and a polarization combiner 5. The two output ends of the optical coupler 2 are respectively connected to the input end of the polarization controller A1 3-1 and the input end of the polarization controller A2 3-2, the output end of the polarization controller A1 3-1 is connected to the input end of the optical delay line 4, and the output end of the optical delay line 4 and the output end of the polarization controller A2 3-2 are respectively connected to the two input ends of the polarization combiner 5.

[0014] The second-stage two-tap positive coefficient microwave photon filter 10 is composed of an optical coupler 11, a polarization controller B112-1, a polarization controller B212-2, an optical delay line 13, and a polarization beam combiner 14. The two output ends of the optical coupler 11 are respectively connected to the input end of the polarization controller B112-1 and the input end of the polarization controller B212-2, the output end of the polarization controller B112-1 is connected to the input end of the optical delay line 13, and the output end of the optical delay line 13 and the output end of the polarization controller B212-2 are respectively connected to the two input ends of the polarization beam combiner 14.

[0015] The optical envelope detection module 8 is a semiconductor optical amplifier (SOA), which uses its cross-gain modulation effect to detect the output optical envelope of the first-stage two-tap positive coefficient microwave photonic filter 1.

[0016] Working principle: See Figure 1 and Figure 2 , the light envelope to be integrated enters the first-stage two-tap positive coefficient microwave photon filter 1, which is composed of an optical coupler 2, a polarization controller A1 3-1, a polarization controller A2 3-2, an optical delay line 4, and a polarization combiner 5. Among them, the polarization controller A1 3-1 and the polarization controller A2 3-2 are mainly used to control the relative weights of the upper and lower paths, the optical delay line 4 is used to control the relative delay of the two paths, and the polarization combiner 5 can avoid the interference of light and ensure that the two paths of light complete the superposition of the light envelope from the orthogonal polarization directions. At this time, the transfer function of the first-stage two-tap positive coefficient microwave photon filter can be expressed as: H 1 (jf) = 1 + a 1 exp(-j2πfτ 1 ), where f is the microwave frequency, a 1 ∈[0,1] is the weight of the second tap, FSR=1 / τ 1 Characterizes the spectral periodicity of the transfer function. By properly adjusting the weight and delay, the expected first-order transfer function H 1 (jf). After the integrated light envelope passes through the two-tap positive coefficient microwave photon filter, an optical envelope will be output.

[0017] Since the second-stage two-tap positive coefficient microwave photon filter 10 also includes a polarization beam combiner 14, in order to avoid light interference, the output result of the first-stage microwave photon filter 1 must be envelope-detected before entering the second-stage microwave photon filter 10. The optical envelope detection module 8 here is a semiconductor optical amplifier (SOA), and the specific envelope detection process is: the optical envelope output by the first-stage microwave photon filter 1 passes through the three-port optical circulator input terminal 1 9a, and enters the semiconductor optical amplifier (SOA) from the three-port optical circulator input terminal 2 9b. At this time, the continuous light output by the laser source 6 also enters the semiconductor optical amplifier (SOA). The optical isolator 7 has two functions: to ensure that the continuous light enters the SOA smoothly, and to prevent the light entering the SOA from the three-port optical circulator input terminal 2 9b from being reflected back to the laser source 6. By properly adjusting the power of the input light envelope and continuous light and the bias current of the SOA, due to the dynamic characteristics of the SOA carriers, the input light envelope and the continuous light will undergo a cross-gain modulation effect in the SOA, so that the input light envelope information is copied to the continuous light, which is finally output from the output terminal 9c of the three-port optical circulator.

[0018] The optical envelope outputted from the output terminal 9c of the three-port optical circulator enters the second-stage two-tap positive coefficient microwave photon filter 10, which is composed of an optical coupler 11, a polarization controller B1 12-1, a polarization controller B2 12-2, an optical delay line 13, and a polarization beam combiner 14. The functions of the devices are the same as those of the first-stage microwave photon filter. The second-stage two-tap positive coefficient microwave photon filter 10 provides another transfer function: H 2 (jf) = 1 + a 2 exp(-j2πfτ 2 ). From the perspective of the entire system, the first-stage two-tap positive coefficient microwave photon filter 1 and the second-stage two-tap positive coefficient microwave photon filter 10 form a cascade relationship, so the transfer function of the entire system can be expressed as: H 12 (jf) = H 1 (jf)H 2 (jf) = [1 + a 1 exp(-j2πfτ 1 )][1+a 2 exp(-j2πfτ 2 )]. In theory, the ideal integral transfer function H(jf) = 1 / (jf) = (1 / f)exp[j(-π / 2)], which shows that the essence of an integral operation is to let the envelope to be integrated pass through a signal with an amplitude-frequency characteristic of (1 / f) (or a power spectrum characteristic of (1 / f) 2 ) and a system with a phase-frequency characteristic of -π / 2 (each spectral component has a phase shift of -π / 2). In order to approximate the transfer function of the ideal integral, we take: a 1 =0.4, τ 1=0.288τ 0 , a 2 =0.65, τ 2 =0.164τ 0 (τ 0 =1 / f 0 is the period of the light envelope to be integrated). Under this parameter, H 12 (jf) can well approximate H(jf), so that the integral operation can be completed on the light envelope to be integrated.

[0019] From the perspective of the system parameter arrangement, when the repetition frequency of the optical envelope to be integrated changes, the weight is fixed because it is independent of the repetition frequency. It is only necessary to adjust the delay of two two-tap positive coefficient microwave photon filters to obtain the integrated optical envelope output at different repetition frequencies. For example, to integrate a sawtooth optical envelope with a repetition frequency of 1GHz, the parameter selection is: a 1 =0.4, τ 1 =0.288ns, a 2 =0.65, τ 2 =0.164ns. Here we are mainly concerned with the changes in the spectral components of the sawtooth envelope. When the optical envelope passes through a system of two two-tap positive coefficient microwave photon filters cascaded, the transfer function of the system approaches the transfer function of the ideal integral, so that the amplitude and phase of the spectral components of the final optical envelope meet the integration requirements. Finally, a dark parabola waveform will be obtained in the time domain, which is exactly the expected optical envelope after the sawtooth wave is integrated. When changing the repetition frequency, just change τ accordingly according to the formula 1 and τ 2 The value of can output dark parabolas with different repetition frequencies.

[0020] The present invention starts from the perspective of frequency domain. The integral operation has a system transfer function, which acts on the amplitude and phase of the spectral components of the optical envelope to be integrated according to a certain rule, and finally outputs an integrated optical envelope. Since the object of the microwave photon filter (MPF) is exactly the spectral components of the optical envelope, two two-tap positive coefficient microwave photon filters are cascaded, and by properly controlling their weights and relative delays, the cascaded transfer function can be made close to the ideal integral transfer function. When an optical envelope to be integrated passes through a system composed of two two-tap positive coefficient microwave photon filters cascaded, since the requirements of integration are met in the frequency domain, an integrated optical envelope will be output in the time domain, and the integral operation of the optical envelope to be integrated will be finally completed.

[0021] The present invention is not limited to the embodiments described in the specific implementation manner. Those skilled in the art may derive other implementation manners based on the technical solution of the present invention, which also fall within the technical innovation scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the invention without departing from the spirit and scope of the present invention. Thus, if these changes and modifications of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and modifications.

Claims

1. A full light integration system, characterized in that: The invention comprises a first-stage two-tap positive coefficient microwave photon filter (1), a laser source (6), an optical isolator (7), an optical envelope detection module (8), a three-port optical circulator (9) and a second-stage two-tap positive coefficient microwave photon filter (10), wherein the optical envelope to be integrated is connected to the input end of the first-stage two-tap positive coefficient microwave photon filter (1), the three-port optical circulator (9) is provided with an input end 1 (9a), an input end 2 (9b) and an output end 3 (9c), and the output end of the first-stage two-tap positive coefficient microwave photon filter (1) is connected to the input end 1 (9a) of the three-port optical circulator. The output end of the laser source (6) is connected to the input end of the optical isolator (7), the output end of the optical isolator (7) is connected to the input end of the optical envelope detection module (8), the output end of the optical envelope detection module (8) is connected to the second input end (9b) of the three-port optical circulator, the output end (9c) of the three-port optical circulator is connected to the input end of the second-stage two-tap positive coefficient microwave photon filter (10), and the output end of the second-stage two-tap positive coefficient microwave photon filter (10) is the final output end; the first-stage two-tap positive coefficient microwave photon filter (1) is composed of an optical coupler (2), a polarization The optical coupler (2) is composed of a controller A1 (3-1), a polarization controller A2 (3-2), an optical delay line (4), and a polarization beam combiner (5); the two output ends of the optical coupler (2) are respectively connected to the input end of the polarization controller A1 (3-1) and the input end of the polarization controller A2 (3-2); the output end of the polarization controller A1 (3-1) is connected to the input end of the optical delay line (4); the output end of the optical delay line (4) and the output end of the polarization controller A2 (3-2) are respectively connected to the two input ends of the polarization beam combiner (5); the second-stage two-tap positive coefficient microwave photon filter (10) The invention is composed of an optical coupler (11), a polarization controller B1 (12-1), a polarization controller B2 (12-2), an optical delay line (13), and a polarization beam combiner (14). The two output ends of the optical coupler (11) are respectively connected to the input end of the polarization controller B1 (12-1) and the input end of the polarization controller B2 (12-2). The output end of the polarization controller B1 (12-1) is connected to the input end of the optical delay line (13). The output end of the optical delay line (13) and the output end of the polarization controller B2 (12-2) are respectively connected to the two input ends of the polarization beam combiner (14).

2. The all-optical time-domain integration system according to claim 1, characterized in that: The optical envelope detection module (8) is a semiconductor optical amplifier (SOA), which uses its cross-gain modulation effect to complete the detection of the output optical envelope of the first-stage two-tap positive coefficient microwave photon filter (1).

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