Improving signal-to-noise ratio of chirped laser pulse using Mach-Zehnder interferometer

Based on Mach-Zehnder interferometer placed in electro-optic crystal, and using the principles of double beam interference of the Mach-Zehnder interferometer and the linear electro-optic effect of the crystal, a new method of scanning filtering for improving the signal to noise ratio (SNR) of chirped pulse was proposed. The spectral characteristics of the scanning filter were analyzed quantitatively. The effects of the delay time of the prepulse on the output SNR were analyzed. Moreover, the effects of the control parameters of the electro-optic crystal voltage on the SNR were discussed in detail. The results show that the variation of controlling voltage and the delay time of the prepulse have significant impact on the filtering effect and that the SNR of the chirp pulse can be improved nearly two magnitudes by using the scanning filtering method and the transmittance of signal can be as high as 95% or more.