Super Fast Spectrum Real-time Correction Of Pump - Detection Technology Research

In the ultrafast pump-probe technology, SNR is one of the biggest limit of its development and application. This paper introduces the basic principle and experimental methods of ultrafast pump-probe technology in ultrafast spectrum technology, and introduces the theoretical alalysis of the problems of detecting noise in the pump-probe system, from three points of the light source, optical system and detector. On the basis of analysis of the cause, some kinds of spectral real-time correction schemes is proposed.It can be mainly divided into two kinds of methods:The first method is Adding a chopper in the light path and combining with the lock-in amplifier technique. This method can be used only under the conditions that the frequency of pulse repetition is higher, and it can only detect the relative intensity of the signal. The second approach is the introduction of the reference beam, which have three ways:the BOXCAR acquisition method, time related single photon technology (TCSPC) and CCD parallel detection method. BOXCAR acquisition method takes the adjacent pulse of tested pulse as the reference beam; TCSPC method split the same pulse to two parts, one as probe beam and the other as reference beam. These above two methods are not effective. Based on this, the spectral real-time correction scheme is proposed which uses the space grating splitting the beam and CCD surface detectors to in-parallel detect the two beams of spatially separated. This mathod is effective, for51.8%fluctuation of the light intensity, the correction results error within.98%is obtained. We made simple test of the transmission rate characteristic of graphene for pulse laser, and verified the effectiveness of the proposed scheme.