Dual-signal-resonant optical parametric oscillator intracavity driven by a coaxially end-pumped laser with compound gain media.

A flexible method of generating stable dual-wavelength laser pulses with tunable power ratio and pulse interval is proposed, through integrating a coaxially end-pumped laser with compound gain media and an intracavity pumped optical parametric oscillator (IOPO). A theoretical model was built by a set of time-domain coupling wave equations containing both the generation of two fundamental waves from a shared pump source and the conversion to signal waves through the parametric process. Simulations showed that by simply varying the pump focal position or pump wavelength, the gains in two laser crystals could be changed, leading to simultaneous change in average power ratio and time interval between two wavelengths. Experimental verifications were performed with combined laser crystals (Nd:YAG and a-cut Nd:YLF) and a nonlinear crystal (KTA), which enabled dual-wavelength signal output in the 1.5-1.6 μm eye-safe region and demonstrated coincident conclusions with theoretical results. As there was no gain competition between two fundamental waves, stable signal output was obtained. Moreover, various wavelength pairs in any wavelength ranges are possible by using different laser crystals and nonlinear crystals. It is believed that this is a promising method for generating simultaneous dual-wavelength laser pulses for applications in lidar, remote sensing, nonlinear frequency conversion, etc.