Supercontinuum generation in orientation-patterned gallium phosphide

Abstract

Supercontinuum generation from nanojoule femtosecond lasers is well known in photonic-crystal fibers, channel waveguides, and micro-resonators, in which strong confinement shapes their dispersion and provides sufficient intensity for self-phase modulation, four-wave mixing, and Raman scattering to cause substantial spectral broadening. Until now, supercontinuum generation in bulk media has not been observed at equivalent energies, but here we introduce a new mechanism combining second- and third-order nonlinearities to produce broadband visible light in orientation-patterned gallium phosphide. A supercontinuum from the blue/green to the red is produced from 32 nJ 1040 nm femtosecond pulses, and a nonlinear-envelope-equation model including chi((2) )and chi((3) ) nonlinearities implies that high-order parametric gain pumped by the second-harmonic light of the laser and seeded by self-phase-modulated sidebands is responsible. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License.