Designing photonic quasi-crystal fibers of various folds: onto optimization of efficiency and bandwidth of second harmonic generation

TLDR: The detailed numerical results reveal that, while the relative efficiency increases appreciably, the phase-matching bandwidth increases marginally, as and when the number of folds increases.

Abstract: We design photonic quasi-crystal fibers (PQFs) of six-, eight-, ten-, and twelve-folds for determining the optimized efficiency as well as the bandwidth of second harmonic generation (SHG). We report a maximum SHG relative efficiency of 941.36% W⁻¹ cm⁻² for a twelve-fold PQF of 2 μm pitch. The detailed numerical results reveal that, while the relative efficiency increases appreciably, the phase-matching bandwidth increases marginally, as and when the number of folds increases. As the primary interest of this work is to enhance the relative efficiency, we focus our analysis with a twelve-fold PQF for which the efficiency turns a maximum. In line with the practical feasibility of poling, we keep the pitch at 7 μm and report an optimized relative efficiency and phase-matching bandwidth as 95.28% W⁻¹ cm⁻² and 50.51 nm.cm, respectively.