Fig. 5: Comparison of quantum efficiency and pump threshold of the demonstrated χ⁽²⁾ micro-waveguide based on birefringence PM with the state-of-art single-pass parametric conversions.

a Summary of quantum efficiencies and saturated pump pulse energy of single-pass parametric sources including representative OPA^{18,24,25,26,27,28}, OPG^29,30,31, DFG^{32,33,34,35,36,37,38} and IPDFG^{3,39,40,41,42,43,44,45} in the LWIR region (>5 μm) based on bulk nonlinear crystals, and the demonstrated OPG based on ZGP χ⁽²⁾ micro-waveguide platform. A quantum efficiency of 74% at a pump pulse energy of 6.5 nJ is demonstrated, which is enhanced by more than 2 folds compared to the state-of-art LWIR single-pass parametric conversions in bulk crystals. b Comparison of the threshold pulse energy and peak power of the demonstrated OPG in the χ⁽²⁾ waveguide based on birefringence PM and other MIR OPGs with quasi-PM, based on PPLN^46,47,48,49 and OP-GaAs crystals²⁹. The measured threshold pump energy of ZGP χ⁽²⁾ waveguide is 616 pJ, corresponding to a peak power of 1.9 kW, which is reduced by more than 1-order of magnitude compared to the reported MIR OPGs in the literature.