Demonstration of Optical Nonlinearity in InGaAsP/InP Passive Waveguides

TL;DR

This study demonstrates significant third-order nonlinear optical effects in InGaAsP/InP waveguides, highlighting their potential for integrated nonlinear photonic devices at specific wavelengths.

Contribution

The paper presents the first detailed measurements of nonlinear interactions in InGaAsP/InP waveguides, including self-phase modulation and four-wave mixing, with optimized structures for enhanced nonlinearity.

Findings

Observed nonlinear phase shift of up to 2.5π in self-phase modulation

Measured two-photon absorption coefficient of 15 cm/GW

Achieved a four-wave mixing wavelength conversion range of 45 nm

Abstract

We report on the study of the third-order nonlinear optical interactions in In$_{x}$Ga$_{1-x}$As$_{y}$P$_{1-y}$/InP strip-loaded waveguides. The material composition and waveguide structures were optimized for enhanced nonlinear optical interactions. We performed self-phase modulation, four-wave mixing and nonlinear absorption measurements at the pump wavelength 1568 nm in our waveguides. The nonlinear phase shift of up to $2.5\pi$ has been observed in self-phase modulation experiments. The measured value of the two-photon absorption coefficient $\alpha_2$ was 15 cm/GW. The four-wave mixing conversion range, representing the wavelength difference between maximally separated signal and idler spectral components, was observed to be 45 nm. Our results indicate that InGaAsP has a high potential as a material platform for nonlinear photonic devices, provided that the operation wavelength range outside the two-photon absorption window is selected.