Absorption effects on second-harmonic generation and cascaded wavelength conversion in nonlinear optical polymers

Although nonlinear optical (NLO) polymers often exhibit very high optical nonlinearities, they have barely been applied to tentative NLO devices. The main reason lies in their high absorption losses, and this fundamental trade-off between optical nonlinearity and absorption, stems further advancement. Our theoretical analyses inform us that absorption effect is much less critical in cascaded wavelength conversion (CWC) than in second-harmonic generation (SHG), especially when absorption loss is very high at a given second-harmonic wavelength. Based on this result, we propose CWC as a more practical application of NLO polymers than SHG.