Trigger signal generator for ultrafast time-domain spectroscopy system

Abstract

The invention discloses a trigger signal generator for an ultrafast time-domain spectroscopy system. According to the invention, by utilizing the principles of laser spectral coherence, an optical trigger signal is generated when the laser pulses of a pump laser and a probe laser of the ultrafast time-domain spectroscopy system coincide, and then the optical trigger signal is converted into an electrical trigger signal by a high-speed photodiode; and then the electrical trigger signal is processed by an operational amplifier, a high-pass filter, a Schmitt trigger and then sent to the ultrafasttime-domain spectroscopy system as a trigger signal for a signal acquisition system, so an extremely stable THz time-domain spectrum can be obtained. The high-speed photodiode, the operational amplifier, the high-pass filter and the Schmitt trigger are all packaged on a same PCB, so two columns of optical pulses that coincide with each other periodically are converted into square signals with thesame period and sharp rising edges. The trigger signal generator of the invention has the advantages of high integration level, simple structure, high bandwidth, sharp rising edge, easy adjustment and stable performance.

Description

technical field [0001] The invention belongs to the technical field of terahertz, and in particular relates to a trigger signal generator for an ultrafast time-domain spectroscopy system. Background technique [0002] The current ultra-fast time-domain spectroscopy system uses the principle of asynchronous sampling to achieve high-speed acquisition of time-domain spectroscopy. The terahertz ultrafast time-domain spectroscopy system based on asynchronous sampling uses two femtosecond lasers with slightly different repetition rates. The repetition frequency of one path is f as the detection pulse, and the repetition frequency of the other femtosecond laser pulse is f+Δf. as pump pulses with their repetition rate controlled by high-bandwidth feedback electronics. There is a difference of Δf between the two femtosecond pulse repetition frequencies, thereby increasing the time delay between the pump pulse and the probe pulse, and its scanning period T can be given by Δf, ie T=1 / ...

AI Technical Summary

Problems solved by technology

[0005] There are two methods based on optical generation: 1. Two-photon detector method, the two-photon absorption effect will only be generated under two strong lasers, so two strong lasers will cause great damage to the photodiode, and the detector is easily damaged

2. The method of frequency doubling crystal, this method is to use the frequency doubling principle of frequency doubling crystal, but the conversion efficiency is low, the anti-interference is poor, the packaging is difficult, and it is inconvenient to use

Disadvantages: poor stability in high frequency circuits, has been abandoned

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