High repetition frequency laser spectrum measurement device based on optical fiber time domain stretching dispersion Fourier transform

Abstract

The invention discloses a high repetition frequency laser spectrum measurement device based on optical fiber time domain stretching dispersion Fourier transform. The high repetition frequency laser spectrum measurement device comprises a light attenuation unit, a dispersion Fourier transform unit, a multi-channel wavelength selection unit and a signal detection processing unit. A pulse to be detected firstly enters the light attenuation unit to perform power attenuation, then enters the dispersion Fourier transform unit to stretch a time domain pulse, spectral information of the pulse is mapped to a time waveform, the multichannel wavelength selection unit divides a spectrum into a plurality of wave bands, and finally, the signal detection processing unit receives a processing signal. According to the invention, through the dispersion Fourier transform unit, conversion from a frequency domain to a time domain of the pulse to be detected is realized; and through wavelength selection of the multi-channel wavelength selection unit, the repetition frequency upper limit and the spectral resolution of the pulse to be detected are improved. The device has the characteristics of simple structure, high spectral resolution, real-time measurement and the like, and can be used for carrying out real-time measurement on the spectrum of a GHz-level high-repetition-frequency laser.

Description

technical field [0001] The invention belongs to the field of optical technology, and relates to a time domain stretching dispersion Fourier transform device, in particular to a high repetition frequency laser spectrum measuring device based on optical fiber time domain stretching dispersion Fourier transform. Background technique [0002] Picosecond and femtosecond laser pulses are widely used in the analysis of ultrafast phenomena, such as chemical reactions, biomedicine, nonlinear optics and other disciplines. Spectrometers are usually used to measure spectral changes in such processes, but the scan time of spectrometers is often much longer than the duration of such ultrafast phenomena, making it impossible to perform real-time single-shot measurements, while single-shot measurement methods such as frequency-domain resolution optical switching methods ( FROG) and Spectral Phase Coherent Electric Field Reconstruction (SPIDER) can achieve a single measurement, but when the ...

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Problems solved by technology

Spectrometers are usually used to measure spectral changes in such processes, but the scan time of spectrometers is often much longer than the duration of such ultrafast phenomena, making it impossible to perform real-time single-shot measurements, while single-shot measurement methods such as frequency-domain resolution optical switching methods ( FROG) and Spectral Phase Coherent Electric Field Reconstruction (SPIDER) can achieve a single measurement, but when the pulse repetition frequency to be measured is greater than the refresh rate of the detector, the pulse spectrum overlaps, so real-time spectral information cannot be obtained.

[0003]The emergence of time-domain stretched dispersion Fourier transform (TS-DFT) technology solves this problem. Its core is to use the dispersion characteristics of the dispersion element to satisfy the In far-field conditions, the spectral information of the incident pulse can be mapped to the time domain, and then the spectral information can be received by a high-speed photodetector and a large-bandwidth oscilloscope. Compared with traditional spectral measurement techniques, it has high resolution and high sampling. With the advantages of high speed and large bandwidth, it is widely used in the real-time spectrum measurement of ultrashort pulses. It mainly uses optical components with dispersion effects, such as optical fibers, gratings, waveguides, etc., but if the repetition frequency of the optical pulse reaches GHz, the pulse in There may be partial overlap between the pulses after being dispersed by a dispersive element such as an optical fiber, so the signal received by the oscilloscope will be a continuous signal, and the spectral information of a single pulse cannot be obtained at this time

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