A high-peak-power orthogonally-polarized multi-wavelength laser at 16-17 µm based on the cascaded nonlinear optical frequency conversion

We demonstrated a high-peak-power orthogonally polarized multi-wavelength laser at 1.6-1.7 µm based on the intracavity cascaded nonlinear optical frequency conversion (CNOFC). This CNOFC can be characterized by a configuration of "series-parallel optical circuit", where the OPO pumped Raman conversion operates in the "series-mode" and orthogonally-polarized waves are simultaneously converted in the "parallel-mode". The fundamental wave at 1064 nm was first simultaneously converted to orthogonally-polarized 1534 and 1572 nm by the x-cut KTA and KTP optical parametric oscillation (OPO), respectively. Then the x-cut KTA and KTP acted as the Raman crystal to each other with the X(ZZ)X Raman configuration, converting the OPO signals to multi-order Raman emissions with the wavelengths at 1601, 1632, 1673, 1697, 1752 and 1767nm. A maximum total average output power of 1.2 W and a minimum pulse width of 10.5 ns were achieved from this CNOFC-based laser, corresponding to a pulse peak power of 28.5 kW and a pulse energy of 0.3 mJ.