Cladding based GaN waveguide engineering for efficient octave-spanning spectra generation and fceo detection

Abstract

Extending the spectral content of femtosecond lasers to span at least one octave is key for their stabilization through self-referencing. An effective way to achieve this goal is to leverage soliton dynamics and dispersive wave (DW) generation in third-order nonlinear waveguides or fibers. Tuning of the DW position at the second harmonic of the pump is still a challenge, and it results in an excessive power requirement on the input pulse. Here, we show a new tuning mechanism of DW position in GaN waveguides by controlling the thickness of the cladding deposition. We demonstrate efficient octave-spanning supercontinuum generation by controlling the position of the DW and detecting the carrier-envelope offset frequency with only 22 pJ of pulse energy with, respectively, 100 kHz resolution and 100 Hz video bandwidth.