Time Domain Integration System

Abstract

The invention discloses a time domain integration system, comprising a laser source (1), an optical coupler A (2), an optical frequency modulator (3), a delay module (4) and an optical coupler B (5), characterized in that: the laser source (1) is connected to the input end of the optical coupler A (2), the output end 1 (2a) of the optical coupler A (2) is connected to the input end of the optical frequency modulator (3), the optical frequency modulator (3) is provided with a radio frequency end, the output port 2 (2b) of the optical coupler A (2) is connected to the input end of the delay module (4), the output end of the optical frequency modulator (3) is connected to the input port 1 (5a) of the optical coupler B (5), the output end of the optical delay module (4) is connected to the input port 2 (5b) of the optical coupler B (5), and the output end of the optical coupler B (5) is the final output end. The invention avoids spectral filtering, has a simple structure and is easy to adjust.

Description

Technical Field

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

[0002] An integrator is a type of device that can integrate the input signal in the time domain. It has important applications in analog-to-digital conversion and waveform transformation. Compared with electronic technology, photonic technology has a larger bandwidth. Integrators based on photonic technology can well overcome the electronic bottleneck problem, so optical time-domain integrators are favored by people. Existing optical time-domain integrators (Malacarne. A, Ashrafi. R, Li. M, LaRochelle. S, Yao. J, Azana. J, “Single-shot photonic time-intensity integration based on a time-spectrum convolutionsystem,” Opt. Lett., vol. 37, no. 8, pp. 1355-1357, 2012.) have strict requirements on dispersion, are difficult to control, and have high costs. Therefore, it is of great scientific significance and application value to realize optical time-domain integration in a simple and controllable way. Summary of the invention

[0003] The purpose of the present invention is to overcome the above disadvantages and provide a time domain integration system which avoids spectral filtering, has a simple structure and is easy to adjust.

[0004] The technical solution of the present invention is: a time domain integration system, comprising a laser source, an optical coupler A, an optical frequency modulator, a delay module and an optical coupler B, wherein: the laser source is connected to the input end of the optical coupler A, the output end 1 of the optical coupler A is connected to the input end of the optical frequency modulator, the optical frequency modulator is provided with a radio frequency end, the output port 2 of the optical coupler A is connected to the input end of the delay module, the output end of the optical frequency modulator is connected to the input port 1 of the optical coupler B, the output end of the delay module is connected to the input port 2 of the optical coupler B, and the output end of the optical coupler B5 is the final output end.

[0005] In the above-mentioned time-domain integration system, the optical frequency modulator is an electro-optical frequency modulation modulator, which is used to complete the frequency modulation of the signal to be integrated.

[0006] In the above-mentioned time domain integration system, the delay module is an optical delay line, which mainly introduces a fixed phase difference in the downstream so that the phase difference between the two optical fields falls within the linear region of the rising edge of the phase detection curve, and finally linearly maps the phase difference into an intensity signal in the time domain.

[0007] In the above-mentioned time-domain integration system, the optical coupler A and the optical coupler B are optical couplers (50:50).

[0008] Compared with the prior art, the present invention has obvious beneficial effects. From the above technical scheme, it can be seen that the laser source of the present invention can output a continuous light as a carrier. The optical coupler A (50:50) can divide the continuous light output by the laser source into two paths with equal power. The optical frequency modulator can complete the frequency modulation of the signal to be integrated, so that the frequency of the upper optical field changes with the signal to be integrated. At this time, the phase of the optical field is the integral of the frequency, that is, the phase changes with the integrated signal. The optical delay line can introduce a fixed phase difference to control the phase difference change of the upper and lower optical fields to fall within the rising edge linear region of the cosine curve generated by the interference process. The optical coupler B (50:50) can complete the convergence of the upper and lower optical fields, complete the required optical interference, and finally linearly map the phase difference change of the upper and lower optical fields into an intensity signal in the time domain. The signal to be integrated is used to complete the frequency modulation of a continuous light. At this time, the phase of the optical field is the result of the integration of frequency over time. Since the interference process has a cosine phase detection function, the phase difference of the upper and lower optical fields can be converted into an intensity signal. By controlling the frequency offset and adjusting the delay appropriately, the phase difference can be linearly mapped to an intensity signal in the time domain, and the whole process completes the integration operation of the input signal. By using the relationship that the phase in optical physics is the integral result of frequency over time, the light is first frequency modulated with the signal to be integrated. At this time, the phase change is the integral result of the frequency change over time. Finally, through an interference process with a phase detection function, the phase change is linearly mapped to an intensity signal in the time domain. By comparing the input signal and the output signal, the whole process completes the integration operation of the signal to be integrated. The whole process avoids spectral filtering, has a simple structure, and is easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a structural schematic diagram of the present invention.

[0010] Figure 2 It is a working principle diagram of the present invention.

[0011] Reference numerals:

[0012] 1. Laser source, 2. Optical coupler A, 2a. Optical coupler output port 1, 2b. Optical coupler output port 2, 3. Optical frequency modulator, 4. Delay module, 5. Optical coupler B, 5a. Optical coupler input port 1, 5b. Optical coupler input port 2. DETAILED DESCRIPTION

[0013] The specific implementation manner, structure, features and functions of a time domain integration system proposed according to the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0014] See also Figure 1 A time domain integration system of the present invention comprises a laser source 1, an optical coupler A2 (50:50), an optical frequency modulator 3, a delay module 4 and an optical coupler B5 (50:50), wherein: the laser source 1 is connected to the input end of the optical coupler A2 (50:50), the output end 2a of the optical coupler A2 (50:50) is connected to the input end of the optical frequency modulator 3, the optical frequency modulator 3 is provided with a radio frequency end, the output port 2b of the optical coupler A2 (50:50) is connected to the input end of the delay module 4, the output end of the optical frequency modulator 3 is connected to the input port 5a of the optical coupler B5 (50:50), the output end of the delay module 4 is connected to the input port 2 5b of the optical coupler B5 (50:50), and the output end of the optical coupler B5 (50:50) is the final output end.

[0015] In the above-mentioned time-domain integration system, the optical frequency modulator 3 is an electro-optical frequency modulation modulator, which is used to perform frequency modulation on the signal to be integrated.

[0016] In the above-mentioned time domain integration system, the delay module 4 is an optical delay line, which mainly introduces a fixed phase difference in the downstream so that the phase difference between the two optical fields falls within the linear region of the rising edge of the phase detection curve, and finally linearly maps the phase difference into an intensity signal in the time domain.

[0017] Working process: see Figure 1-2 , because in optical physics, frequency and phase naturally have a derivative and integral relationship, that is, the derivative of phase change is frequency change, and the integral of frequency change is phase change. Based on this relationship, to realize the integral operation, the light can be frequency modulated with the modulation signal (signal to be integrated) first, so that the frequency of the light field changes according to the law of the modulation signal. At this time, the phase change of the light field is the integral result of the frequency change of the light field. Finally, it is only necessary to find an optical process that can complete the phase detection function to complete the conversion from phase to intensity, and then the integral operation of the modulated signal can be realized. It happens that an optical interference process has a phase detection function, which can convert the phase difference between two light fields into an intensity signal in the time domain. By adjusting the frequency offset and delay, the rising edge of the cosine phase detection curve generated by the interference process will linearly map the phase change to an intensity signal in the time domain, and finally complete the integral operation of the signal to be integrated.

[0018] The continuous light emitted by the laser source 1 is output from the optical coupler output port 1 2a and the optical coupler output port 2 2b with equal power through the optical coupler A2 (50:50). The light output from the optical coupler output port 1 2a is modulated by the signal to be integrated through the optical frequency modulator 3. Assume that the modulated signal (or the signal to be integrated) is expressed as: ; The light field output by laser source 1 is: ,in, is the light field amplitude, is an imaginary unit, is the carrier angular frequency, is the initial phase of the light field, then the light field after frequency modulation is: ,in , is the proportionality coefficient. At this point we notice that the angular frequency in the light field is no longer a constant, but changes with the modulation signal, that is: Since the frequency at this time is a function of time, the corresponding phase is the integral of frequency over time, and the total phase of the resulting FM wave is: .

[0019] The light output from the optical coupler output port 2b passes through the delay module 4, where the delay module 4 is an optical delay line, and the delay amount is adjusted to This introduces a phase shift: , the corresponding light field is: , at this time the total phase of the downstream light field is: .

[0020] Obviously, the phase difference between the upper and lower light fields is: .

[0021] In order to convert the phase difference into intensity, the uplink light field enters the input port 1 5a of the optical coupler B5 (50:50), and the downlink light field enters the input port 2 5b of the optical coupler B5 (50:50). At this time, the total light field can be expressed as:

[0022] .

[0023] The intensity of the two lights after interference is expressed as: ,in( )This formula shows that the interference process is equivalent to a cosine phase detector. Since the rising edge of the cosine curve has a certain linear region, the frequency offset and the optical delay of the downstream path can be adjusted to Falling in the linear region of the rising edge, the phase difference can be linearly mapped into a temporal intensity signal, namely: . From the input signal The final output signal From the perspective of the whole process, the signal to be integrated is realized. For example, when the integrated signal is a sawtooth wave, optical frequency modulation is first performed. At this time, the frequency change of the light field is consistent with the sawtooth wave change. After integrating the frequency change over time, the phase change obtained is a dark parabola. By controlling the offset and the lower delay, the phase change of the dark parabola can be linearly mapped into an intensity signal in the time domain through the linear region of the rising edge of the phase-locked curve generated by interference, which is a proportionally scaled dark parabola intensity signal. From the perspective of the input sawtooth wave signal and the final output dark parabola intensity signal, the whole process is an integral operation.

[0024] The present invention is not limited to the embodiments described in the specific embodiments. Those skilled in the art may derive other embodiments 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 time domain integration system, comprising a laser source (1), an optical coupler A (2), an optical frequency modulator (3), a delay module (4) and an optical coupler B (5), characterized in that: The laser source (1) is connected to the input end of the optical coupler A (2), the output end 1 (2a) of the optical coupler A (2) is connected to the input end of the optical frequency modulator (3), the optical frequency modulator (3) is provided with a radio frequency end, the output port 2 (2b) of the optical coupler A (2) is connected to the input end of the delay module (4), the output end of the optical frequency modulator (3) is connected to the input port 1 (5a) of the optical coupler B (5), the output end of the delay module (4) is connected to the input port 2 (5b) of the optical coupler B (5), and the optical coupler B (5 ) is the final output end; the continuous light emitted by the laser source (1) passes through the optical coupler A (2) and is output from the optical coupler output port 1 (2a) and the optical coupler output port 2 (2b) with equal power; the light output from the optical coupler output port 1 (2a) is modulated by the signal to be integrated through the optical frequency modulator (3); the light output from the optical coupler output port 2 (2b) is adjusted by the delay module (4); the upstream light field enters the input port 1 (5a) of the optical coupler B (5), and the downstream light field enters the input port 2 (5b) of the optical coupler B (5); the optical coupler B (5) completes the convergence of the upstream light field and the downstream light field to complete the required optical interference; the size of the frequency offset and the downstream optical delay are adjusted so that the phase difference between the upstream light field and the downstream light field falls within the rising edge linear region of the phase-locked curve of the optical interference, and the phase difference is linearly mapped into an intensity signal in time, and the whole process realizes the integration operation of the signal to be integrated.

2. The time domain integration system according to claim 1, characterized in that: The optical frequency modulator (3) is an electro-optical frequency modulation modulator.

3. The time domain integration system according to claim 1, characterized in that: The delay module (4) is an optical delay line.

4. The time domain integration system according to any one of claims 1 to 3, characterized in that: The coupling ratio of the optical coupler A (2) and the optical coupler B (5) is 50:50.

Images