Robust, efficient, and broadband SHG of ultrashort pulses in composite crystals

We experimentally demonstrate efficient second-harmonic generation (SHG) of tunable ultrashort pulses of 100 femtoseconds, using a novel method based on composite segmented periodically poled (CSPP) design. The scheme was borrowed from the nuclear magnetic resonance (NMR) composite pulses (CP) of Shaka and Pines. Using CSPP, a broadband and efficient conversion over a bandwidth of 35 nm in very short interaction length was achieved. In addition, CSPP showed robustness to temperature changes up to 90 degrees C. Two CSPP schemes with 15 and 31 segments and periodically poled design were implemented on Mg-doped LiNbO3 crystal. The CSPP performance was shown to be superior in all aspects. The experimental results are compared to numerical simulation with excellent agreement. (c) 2019 Optical Society of America