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 χ (2 ) and χ (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.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics