Arbitrary waveform generating device and method based on integer-order time domain Talbot effect
阅读说明：本技术 基于整数阶时域Talbot效应的任意波形产生装置及其方法 (Arbitrary waveform generating device and method based on integer-order time domain Talbot effect ) 是由 胡淑云 唐向宏 池灏 杨波 欧军 杨淑娜 翟彦蓉 于 2020-06-05 设计创作，主要内容包括：本发明涉及信号处理和信号产生领域,具体为一种基于整数阶时域Talbot效应的任意波形产生装置,射频信号发生器与推挽式马赫-曾德尔调制器连接；窄线宽连续光激光器产生的高斯光脉冲序列与射频信号发生器产生的周期模拟射频信号同时加入推挽式马赫-曾德尔调制器；高斯光脉冲序列对周期模拟射频信号采样获得周期模拟射频信号瞬时频率的周期光脉冲序；周期光脉冲序列进入一阶色散系数满足整数阶时域Talbot效应的色散光纤；经色散光纤输出光脉冲序列。本发明根据输出的光脉冲序列与输入的周期模拟射频信号之间的关系,产生预期理想的输出时间波形。(The invention relates to the field of signal processing and signal generation, in particular to an arbitrary waveform generating device based on an integral-order time domain Talbot effect, wherein a radio frequency signal generator is connected with a push-pull type Mach-Zehnder modulator; a Gaussian optical pulse sequence generated by a narrow-linewidth continuous optical laser and a periodic analog radio frequency signal generated by a radio frequency signal generator are simultaneously added into a push-pull type Mach-Zehnder modulator; sampling the periodic analog radio frequency signal by the Gaussian optical pulse sequence to obtain a periodic optical pulse sequence of the instantaneous frequency of the periodic analog radio frequency signal; the periodic optical pulse sequence enters a dispersion optical fiber with a first-order dispersion coefficient meeting an integral-order time domain Talbot effect; and outputting the optical pulse sequence through the dispersive optical fiber. The invention generates the expected ideal output time waveform according to the relation between the output optical pulse sequence and the input periodic analog radio frequency signal.)
1. An arbitrary waveform generating device based on an integer order time domain Talbot effect is characterized in that:
the device comprises a narrow-linewidth continuous optical laser (1), a radio frequency signal generator (2), a push-pull type Mach-Zehnder modulator (3), a dispersion optical fiber (4) and a photoelectric detector (5);
the narrow-linewidth continuous optical laser (1), the push-pull Mach-Zehnder modulator (3), the dispersion optical fiber (4) and the photoelectric detector (5) are sequentially connected; the radio frequency signal generator (2) is connected with the push-pull Mach-Zehnder modulator (3); a Gaussian optical pulse sequence generated by the narrow-linewidth continuous optical laser (1) and a periodic analog radio frequency signal generated by the radio frequency signal generator (2) are simultaneously added into the push-pull Mach-Zehnder modulator (3); in the push-pull Mach-Zehnder modulator (3), a periodic optical pulse sequence of the instantaneous frequency of the periodic analog radio frequency signal is obtained by sampling the periodic analog radio frequency signal by a Gaussian optical pulse sequence; the periodic optical pulse sequence enters a dispersion optical fiber (4) with a first-order dispersion coefficient meeting the integral-order time domain Talbot effect; the optical pulse sequence is output through the dispersion optical fiber (4), and the optical power of the output optical pulse sequence is displayed by the photoelectric detector (5).
2. The apparatus according to claim 1, wherein: the frequency of the periodic analog radio frequency signal is less than or equal to 1/2 times of the Gaussian pulse train repetition frequency generated by the narrow linewidth continuous optical laser (1).
3. The apparatus according to claim 1, wherein:
frequency of periodic analog radio frequency signalWherein, Δ t2For the output optical pulse train, the distance of each pair of optical pulses from the center position;
periodic analog radio frequency signal amplitude mr＝2hr(ii) a Wherein h isrFor the output optical pulse train, the pulse amplitude value in each period.
4. The apparatus according to claim 1, wherein: the modulation of the push-pull Mach-Zehnder modulator (3) on the periodic analog radio-frequency signal is partial carrier suppression modulation; the push-pull type Mach-Zehnder modulator (3) is used for obtaining a symmetrical time waveform for double-sideband modulation of partial carrier suppression of the periodic analog radio frequency signal; the push-pull Mach-Zehnder modulator (3) is used for obtaining an asymmetric time waveform for single-sideband modulation of periodic analog radio frequency signal partial carrier suppression.
5. The apparatus according to claim 1, wherein:
first order dispersion coefficient of dispersive optical fiber (4)Wherein, T0Is the repetition period of the Gaussian light pulse sequence.
6. The method for generating the arbitrary waveform based on the integral-order time domain Talbot effect is characterized by comprising the following steps of,
s1: a Gaussian optical pulse sequence generated by a narrow-linewidth continuous optical laser and a periodic analog radio frequency signal generated by a radio frequency signal generator are simultaneously added into a push-pull type Mach-Zehnder modulator;
s2: in the push-pull Mach-Zehnder modulator, a periodic optical pulse sequence of the instantaneous frequency of the periodic analog radio frequency signal is obtained by sampling the periodic analog radio frequency signal by a Gaussian optical pulse sequence; the push-pull type Mach-Zehnder modulator is used for carrying out suppression modulation on a part of the periodic analog radio-frequency signal;
s3: the periodic optical pulse sequence enters a dispersion optical fiber with a first-order dispersion coefficient meeting an integral-order time domain Talbot effect;
s4: and outputting an optical pulse sequence through the dispersive optical fiber, wherein the optical power of the optical pulse sequence is displayed on a photoelectric detector.
7. The method of generating an arbitrary waveform based on the integer-order time-domain Talbot effect of claim 6, wherein:
in step S1, the frequency of the periodic analog rf signal is less than or equal to 1/2 times the repetition frequency of the gaussian pulse train generated by the narrow linewidth continuous optical laser.
8. The method of generating an arbitrary waveform based on the integer-order time-domain Talbot effect of claim 6, wherein:
in step S1, the frequency of the periodic analog rf signalWherein, Δ t2For the output optical pulse train, the distance of each pair of optical pulses from the center position;
9. The method of generating an arbitrary waveform based on the integer-order time-domain Talbot effect of claim 6, wherein:
in step S2, performing double-sideband modulation on the periodic analog radio frequency signal to obtain a symmetrical time waveform; and carrying out single-sideband modulation on the periodic analog radio frequency signal part carrier suppression to obtain an asymmetric time waveform.
10. The method of generating an arbitrary waveform based on the integer-order time-domain Talbot effect of claim 6, wherein:
in step S3, the first-order dispersion coefficient of the dispersion fiber isWherein, T0Is the repetition period of the Gaussian light pulse sequence.
Technical Field
The invention relates to the field of signal processing and signal generation, in particular to an arbitrary waveform generation device and method based on an integer order time domain Talbot effect.
Background
With the continuous and rapid development of scientific information technology, it is urgent to obtain efficient signal generation and processing. The programmable envelope high-speed optical pulse sequence also has a great application scene in the processing of all-optical signals and the generation of arbitrary waveforms. Conventional progressive pulse spectral shaping is often limited by the spectral resolution of the optical device. Since the highest spectral resolution of modern optics is 10GHZ, the process of handling light pulses below 10GHZ is very difficult; the system structure combining the high-speed electro-optical modulator and the broadband arbitrary waveform generator to generate the arbitrary time waveform has the defect of low energy utilization rate, and the structure also influences the processing and the generation of signals because the bandwidth of the electro-optical modulator is limited.
The 18 th century Talbot discovered that self-imaging occurs in spatial diffraction, i.e., a beam of coherent light is transmitted through a periodic grating, the same pattern as the grating is generated at a certain distance from the grating, and the special positions are periodically distributed. According to space-time duality, the Talbot effect also exists in a time domain, a Gaussian optical pulse sequence with a repetition period passes through a dispersion optical fiber with a specific size, the Gaussian optical pulse sequence can output a periodic signal which is the same as an input signal or increases the pulse repetition rate, and the characteristics of a single pulse sequence are kept unchanged, namely the Talbot effect in the time domain. The time domain Talbot effect is divided into an integer order effect and a fractional order effect. The integer order is a replica of the input signal, while the fractional order effect has the effect of increasing the repetition frequency of the input optical pulse train. The system has the advantages of simple structural configuration and easy operation, and more importantly, the structure has high energy utilization rate and low loss. In a structure of fractional order time domain Talbot effect, proposed by the chatter Shu in hong kong in 2019, an optical pulse sequence with a repetition period is modulated by a discrete signal, then passes through a dispersive optical fiber satisfying the fractional order Talbot effect, and finally the amplitude of the output optical pulse is determined by the amplitude of the modulation signal, namely, the discrete fourier transform of the modulation signal is proportional to the amplitude of the output signal, and the repetition frequency of the output optical pulse sequence is increased by integral multiple, which has important significance for the generation of any waveform.
The invention provides an arbitrary waveform generating device based on an integer order time domain Talbot effect, which is characterized in that under the structure of the integer order time domain Talbot effect, a Gaussian optical pulse sequence is utilized to sample an input analog signal generated by a periodic analog radio frequency signal, the optical pulse sequence output after passing through a dispersion optical fiber with a first-order dispersion coefficient meeting the integer order time domain Talbot effect is periodic, the Gaussian pulse in each period is symmetrical along the central position in the period, the distance between each pair of optical pulses and the central position is related to the frequency of the input analog signal, and the pulse amplitude in each period is determined by the amplitude of the input analog signal. According to the relation between the input analog signal and the waveform of the system output pulse, the input analog signal generated by the periodic analog radio frequency signal is sampled by the Gaussian pulse train, and then the time interval of the system output pulse can be changed into the original fractional times through the dispersion optical fiber with the first-order dispersion coefficient related to the sampling period, so that the problem that the modulation is difficult due to the overhigh rate of the optical pulse sequence is solved, and the expected high-speed optical pulse time waveform is output at a lower rate. The system structure is of great significance to arbitrary time waveform generation.
Disclosure of Invention
The invention aims to solve the problems that the optical pulse rate is too high and the modulation of an expected signal is difficult in the prior art, and provides an arbitrary waveform generating device and method based on an integer order time domain Talbot effect. The invention provides a method for generating any pre-coded time waveform by adopting photonics, which is applied to signal processing and signal generation, can improve the energy utilization rate of signals and reduce loss. The invention samples the periodic analog radio frequency signal and then passes through the dispersion optical fiber which meets the integral order time domain Talbot effect. And pre-coding any time waveform according to the relationship between the frequency and the amplitude of the periodic analog radio frequency signal and the position and the amplitude of the optical pulse sequence output by the system, wherein the repetition frequency of the system output pulse is changed into integral multiple of the original frequency, and a high-speed output signal is obtained.
In order to achieve the technical purpose, the invention adopts the following technical scheme:
an arbitrary waveform generating device based on an integer order time domain Talbot effect comprises a narrow linewidth continuous optical laser, a radio frequency signal generator, a push-pull type Mach-Zehnder modulator, a dispersion optical fiber and a photoelectric detector; the narrow-linewidth continuous optical laser, the push-pull Mach-Zehnder modulator, the dispersion optical fiber and the photoelectric detector are connected in sequence; the radio frequency signal generator is connected with the push-pull Mach-Zehnder modulator; a Gaussian optical pulse sequence generated by a narrow-linewidth continuous optical laser and a periodic analog radio frequency signal generated by a radio frequency signal generator are simultaneously added into a push-pull type Mach-Zehnder modulator; in the push-pull Mach-Zehnder modulator, a periodic optical pulse sequence of the instantaneous frequency of the periodic analog radio frequency signal is obtained by sampling the periodic analog radio frequency signal by a Gaussian optical pulse sequence; the periodic optical pulse sequence enters a dispersion optical fiber with a first-order dispersion coefficient meeting an integral-order time domain Talbot effect; and outputting the optical pulse sequence through the dispersion optical fiber, and displaying the optical power of the output optical pulse sequence by the photoelectric detector.
Further, the frequency of the periodic analog radio frequency signal is less than or equal to 1/2 times the repetition frequency of the Gaussian pulse train generated by the narrow-linewidth continuous optical laser.
Further, the frequency of the periodic analog radio frequency signal
Furthermore, the modulation of the push-pull Mach-Zehnder modulator on the periodic analog radio-frequency signal is partial carrier suppression modulation; the push-pull type Mach-Zehnder modulator is used for obtaining a symmetrical time waveform for double-sideband modulation of partial carrier suppression of the periodic analog radio frequency signal; the push-pull type Mach-Zehnder modulator is used for obtaining an asymmetric time waveform through single-sideband modulation of the periodic analog radio frequency signal partial carrier suppression.
Further, the first order dispersion coefficient of the dispersion fiber
The invention also provides an arbitrary waveform generation method based on the integral order time domain Talbot effect, which comprises the following steps,
s1: a Gaussian optical pulse sequence generated by a narrow-linewidth continuous optical laser and a periodic analog radio frequency signal generated by a radio frequency signal generator are simultaneously added into a push-pull type Mach-Zehnder modulator;
s2: in the push-pull Mach-Zehnder modulator, a periodic optical pulse sequence of the instantaneous frequency of the periodic analog radio frequency signal is obtained by sampling the periodic analog radio frequency signal by a Gaussian optical pulse sequence; the push-pull type Mach-Zehnder modulator is used for carrying out suppression modulation on a part of the periodic analog radio-frequency signal;
s3: the periodic optical pulse sequence enters a dispersion optical fiber with a first-order dispersion coefficient meeting an integral-order time domain Talbot effect;
s4: and outputting an optical pulse sequence through the dispersive optical fiber, wherein the optical power of the optical pulse sequence is displayed on a photoelectric detector.
Further, in step S1, the frequency of the periodic analog rf signal is less than or equal to 1/2 times the repetition frequency of the gaussian pulse train generated by the narrow-linewidth continuous optical laser.
Further, in step S1, the frequency of the periodic analog rf signal
Further, in step S2, performing double-sideband modulation on the periodic analog radio frequency signal to obtain a symmetric time waveform; and carrying out single-sideband modulation on the periodic analog radio frequency signal part carrier suppression to obtain an asymmetric time waveform.
Further, in step S3, the first-order dispersion coefficient of the dispersion fiber isWherein, T0Is the repetition period of the Gaussian light pulse sequence.
Compared with the prior art, the invention has the beneficial technical effects that:
compared with the existing scheme for generating arbitrary waveforms, on one hand, the invention solves the bottleneck that the traditional electro-optical modulator is difficult to generate high-speed signals due to the limited bandwidth, and simultaneously improves the energy utilization rate; on the other hand, according to the relation between the output optical pulse sequence and the input periodic analog radio frequency signal, an expected ideal output time waveform is generated, the frequency and the amplitude of the periodic analog radio frequency signal are obtained through calculation, the calculation is simple, the operation is convenient, and the complexity of generating any signal is reduced.
Drawings
FIG. 1 is a schematic structural diagram of an arbitrary waveform generating device based on an integer-order time domain Talbot effect according to the present invention;
FIG. 2 is a simulation diagram of an arbitrary waveform generating device based on an integer-order time domain Talbot effect, which is provided by the invention, after sampling a periodic analog radio frequency signal by a Gaussian pulse sequence by using matlab;
fig. 3 is a simulation diagram of the arbitrary waveform generating device for the integer-order time domain Talbot effect according to the present invention, which generates a triangular wave with a pulse sequence envelope as a period by using matlab.
In the figure, 1 narrow linewidth continuous optical laser, 2 radio frequency signal generator, 3 push-pull type Mach-Zehnder modulator, 4 dispersive optical fiber and 5 photoelectric detector.
Detailed Description
The invention will be further described with reference to specific examples, but the scope of the invention is not limited thereto.