Balancing the trade-off between absorption and nonlinearity in NLO polymers for practical applications

Abstract

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 susceptibilities imply the fundamental trade-off between optical absorption and nonlinearity. Our theoretical analysis elucidates the effect of absorption losses on second-harmonic generation, difference-frequency generation, and cascaded wavelength conversion. We compare analytically maximum conversion efficiencies for those NLO processes with several NLO polymers and suggest that the cascaded wavelength conversion is a plausible application of NLO polymers. Furthermore, we 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 wavelength converters.