10 km dynamic laser oscillation with a coupled cavity assisted by four wave mixing

Abstract

In this report, we present results of dynamic laser oscillation over a 10 km distance using a coupled-cavity structure assisted by four wave mixing (FWM). The system consists of a master cavity and a slave cavity that are coupled together through FWM in a nonlinear medium. The master and slave laser beams each form two arms of the four wave mixing structure. The master laser consists of a cavity formed by two highly reflective mirrors, in which there is a gain medium and the FWM nonlinear medium. For the slave laser cavity, one of the end mirrors is the grating formed inside the FWM medium, and the other mirror is the remote moving target. In this case, this target is a retro-reflector located on a moving airplane. The laser tracking was completed with a rotating gimbal mirror system that locked on the target. Successful lasing field tests at distances over 10 km have been achieved, and further results can potentially be obtained at longer distances. The laser oscillations are free running with a pump pulse width of 2-5 milliseconds. Based on the time separations between the pulses from the master and slave cavities, the target distance can be precisely calculated.

Observation of laser formation inside a laser cavity containing a phase conjugate mirror

“…Similar to coupled cavity scheme to be published in reference [8], the coupled cavity based DFWM is shown in Figure 4. Here, TIL oscillator is the slave cavity while the master laser medium functions as DFWM medium and the gain medium for the master cavity.…”