A Trigger Signal Generator in Ultrafast Time-Domain Spectroscopy System

Abstract

The invention discloses an ultrafast time domain spectral system trigger signal generator which can generate a trigger signal of high bandwidth, sharp rising edge, easy adjustment and stable performance. The photodiodes, the trans-impedance amplifier and the operational amplifier use the mode of positive feedback regulation, i.e. when two beams of light pulses irradiate to the two photodiodes, thegenerated electric signals can pass two different paths of circuits and then the two electric signals of the same period can be obtained, i.e. one path passes the high-frequency trans-impedance amplifier TIA and the amplifier Amp3, and one path passes two resistors and then inputs to the amplifiers Amp1 and Amp2 and then inputs to the amplifier Amp4. The electric signals outputted by the amplifier Amp3 are identical in period and property, the signals are simultaneously inputted to the operational amplifier Amp5 to perform amplification or operation of the signals of the amplifier Amp4 and the amplifier Amp3 and then perform positive feedback regulation on the trans-impedance amplifier TIA so that the signal-to-noise ratio of the signals can be enhanced, the signals are enabled to be moreaccurate and false triggering cause by the noise can be avoided.

Description

technical field [0001] The invention belongs to the technical field of ultrafast time domain spectroscopy, in particular to a trigger signal generator in an ultrafast time domain spectroscopy system. Background technique [0002] The current ultrafast 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, one of which has a repetition rate of femtosecond laser pulses of 1 GHz as the detection pulse, and the other has a repetition rate of around 1 GHz regulated, as pump pulses, with their repetition rate controlled by high-bandwidth feedback electronics. The repetition frequency difference of the two femtosecond pulses is Δf, and Δf can be adjusted in 1Hz-20KHz, thereby providing the time delay of the pump pulse and the probe pulse, and i...

AI Technical Summary

Problems solved by technology

The disadvantages of this method are: (1) It is difficult to adjust and the anti-interference is poor. This method requires the focus of the two beams of light to be precisely focused on the photodiode photosensitive probe of the hundred micron level. The adjustment is very difficult. change requires readjustment

(2) The two-photon absorption effect will only occur under two strong lasers, so the two strong lasers will cause great damage to the photodiode, and the detector is easily damaged

The disadvantages of this method are: (1) difficult adjustment, poor anti-interference, and difficult packaging. This method requires the focus of the two beams of light to be precisely focused on the same point on the frequency doubling crystal, and then adjust the polarization state of the two incident beams to make It matches the optical axis of the frequency doubling crystal, and the adjustment is very difficult. If there is a slight change in the optical path after the adjustment is completed, it must be readjusted

(2) Since they are all optical devices, there are too many parameters to be adjusted, so packaging is difficult and inconvenient to use

Disadvantages: poor stability in high frequency circuits, such as figure 2 As shown, the offset of the Trigger signal has a great influence on the spectrum

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