Pulse compression of a single-frequency Q-switched fiber laser based on the cascaded four-wave mixing effect

Abstract

A pulse compressing technology of single-frequency Q-switched laser based on the cascaded four-wave mixing (CFWM) effect is demonstrated theoretically and experimentally, for the first time to the best of our knowledge. A theoretical model of the pulse compression is established through deconstructing the pulse duration evolution in the high-order Stokes and anti-Stokes lights of CFWM. A pulse compression ratio of (2|m|+1)1/2 is quantificationally obtained with m corresponding to the order number of the CFWM light. Utilizing dual-wavelength (DW) single-frequency Q-switched laser injected into a highly nonlinear fiber (HNLF), the pulse compression and the spectral broadening phenomenon are observed simultaneously. As the order number of the CFWM light increases from 0-order to 3-order, the pulse duration has reduced from 115 ns to 47 ns with a compression ratio of 2.45, which is essentially consistent with the theoretical analysis. The pulse compressing technique by CFWM is conducive to promoting the performance development of the single-frequency Q-switched laser, which can improve the system precision in the Lidar, trace gas detection, and high-precision ranging. Furthermore, this technology based on time-frequency transformation dynamics may be generally applicable to other single-frequency pulsed fiber lasers.

Rate Equations Model to Simulate the Performance of Passive Q-Switched Laser with Raman Medium Optical System

“…In order to as certain the physical concepts and the mathematical relations https://www.indjst.org/ (8,9) of this model, the model was tested theoretically by numerical simulation of a laser system consist of Nd:YVO 4 used as AM and Cr +4 : YAG as a SA, and PbWO 4 crystal used as the RM. showed good agreement with studies which dealt the Stokes anti-Stokes pulses generation by Raman scattering theory as shown in reference exhibit a steeper gaussian pulse shape and smoother pulse edges.as shown in ref (12) . Also the results of simulation showed good agreement with physical concepts in second and third terms of Eq.1.…”