High-efficiency generation of ultrashort second-harmonic pulses based on the Čerenkov geometry

Abstract

Simultaneous phase- and group-velocity-matched generation of ultrashort optical second-harmonic pulses based on a quasi-phase-matched Cerenkov second-harmonic generation scheme is proposed. We compare our scheme with other schemes with respect to its ability to achieve high conversion efficiency, its enhancement with respect to cw second-harmonic generation, and its sensitivity to waveguide-period fluctuation; ion-exchanged KTP and LiNbO(3) waveguides are considered in the evaluation. We believe our proposed scheme is easy to implement, and there is no constraint on crystal length in achieving high efficiency as well as in preserving an ultrashort pulse width. 100% efficiency is potentially obtainable from sufficiently long crystals.

Broadband Second-Harmonic Generation in the Near-Infrared Region in a Tapered Zinc Selenide Slab Using Total Internal Reflection Quasi-Phase Matching

“…More recently, research on QPM has centered on nonlinear optical materials, wherein various techniques have been devised to fabricate QPM waveguides, which generally involve periodic poling of a nonlinear material such as LiNbO 3 , LiTaO 3 , KTiOPO 4 , or GaN. [3][4][5][6][7][8][9][10][11] There has been considerable effort to enhance the BW of SHG through QPM a) by adopting special geometries such as domain-engineered nonlinear gratings, and Cerenkov phase matching, 12,13) which are strictly wavelength dependent, and b) by choosing specific material systems that exhibit zero group velocity mismatch around the phasematching wavelength for SHG. 14,15) However, it is often not possible to exploit the maximum nonlinear coefficient of the crystal, leading to smaller conversion efficiencies.…”

Control of the effects of crystal dispersion at different orders in the mixing of three phase-matched waves on a 5- to 100-fs time scale

“…A number of groups proposed a more fundamental approach to the problem of GVM and developed interaction schemes that allow GVM compensation [6][7][8][9][10][11][12]. These schemes are obviously specific for each nonlinear material and type of PM: while those developed for high-quality SH generation must only couple the GV's of fundamental and SH pulses [3][4][5][6][7]13], those for optimizing the parametric interactions of pulses at three different wavelengths can ensure the fulfillment of various GV matching conditions that are all of interest. As to sum-frequency generation, schemes linking the GV's of the pulses at ω 1 and ω 2 either to each other or to GV ω 1 +ω 2…”