Evaluation of nonlinear optical polymers for second-harmonic generation: toward the balance of absorption and nonlinearity against intrinsic trade-off

Despite many advantages toward nonlinear optical (NLO) waveguide devices, NLO polymers have not been adopted successfully into practical wavelength converters due to their high absorption losses. Empirical and theoretical understandings about NLO susceptibility imply the fundamental trade-off between optical absorption and nonlinearity. Our theoretical analysis elucidates the effect of absorption losses on second-harmonic generation (SHG). We compare analytically maximum conversion efficiencies for several NLO polymers and found a convincing approach for the development of NLO polymers with the optimum combination of high optical nonlinearity and low material absorption, which leads us to realize efficient polymeric SHG devices.