Supercontinuum generation in high-index doped silica photonic integrated circuits under diverse pumping settings

Abstract

Recent advances in supercontinuum light generation have been remarkable, particularly in the context of highly nonlinear photonic integrated waveguides. In this study, we thoroughly investigate supercontinuum (SC) generation in high-index doped silica glass integrated waveguides, exploring various femtosecond pumping wavelengths and input polarization states. We demonstrate broadband SC generation spanning from 700 nm to 2400 nm when pumping within the anomalous dispersion regime at 1200 nm, 1300 nm, and 1550 nm. In contrast, pumping within the normal dispersion regime at 1000 nm results in narrower SC spectra, primarily due to coherent nonlinear effects such as self-phase modulation and optical wave breaking, and also dispersive wave generation in the anomalous dispersion regime. We further examine the impact of both TE and TM polarization modes on SC generation, shedding light on the polarization-dependent characteristics of the broadening process. Additionally, we report the observation of two new Raman peaks at 48.8 THz and 75.1 THz in high-index glass using a confocal Raman micro-spectrometer. Incorporating these two peaks in the Raman gain modeling, we achieved good agreement between numerical simulations based on the modified nonlinear Schrödinger equation and experimental results. Finally, we present relative intensity noise measurements of the supercontinuum generated at 1550 nm using the real-time dispersive Fourier transform technique.