ULTRASHORT-PULSE 2ND-HARMONIC GENERATION IN OPTIMIZED NONLINEAR POLYMER THIN-FILM STRUCTURES

Methods to optimize the generation of ultrashort second harmonic pulse s are investigated. The goal is to maximize the conversion efficiency while maintaining a short pulse. The first method exploits the effects of anomalous-dispersion phase-matching. In a nonlinear polymer we sho w that an optimum concentration of chromophore exists that maximizes t he conversion efficiency without causing unacceptable pulse-spreading. In the second method we use unipolar and bipolar quasi-phase-matched (QPM) structures to increase the nonlinear interaction length. Unipola r and bipolar (QPM) structures not only provide significant enhancemen t in ultrashort pulse second harmonic generation but also reduce the p ulse distortion.