Wafer-scale inverted gallium phosphide-on-insulator rib waveguides for nonlinear photonics

Abstract

We report a gallium phosphide-on-insulator (GaP-OI) photonic platform fabricated by an intermediate-layer bonding process aiming to increase the manufacture scalability in a low-cost manner. This is enabled by the “etch-n-transfer” sequence, which results in inverted rib waveguide structures. The shallow-etched 1.8 µm-wide waveguide has a propagation loss of 23.5 dB/cm at 1550 nm wavelength. Supercontinuum generation based on the self-phase modulation effect is observed when the waveguides are pumped by femtosecond pulses. The nonlinear refractive index of GaP, n2, is extracted to be 1.9 × 10−17 m2/W, demonstrating the great promise of the GaP-OI platform in third-order nonlinear applications.

Investigation of χ (2)-Translated Optical Frequency Combs Tunability in Gallium Phosphide-on- Insulator Resonators

“…On the contrary, the |𝛽| of TM30 drops due to a reduction of mode intensity as the waveguide cross-section enlarges. Finally, the waveguide geometry is set to be a Wwg × Hwg = 555 nm × 600 nm as a comprise of the optimization results and the availability of our GaP epitaxial wafer film stack [14].…”

“…Among them, gallium phosphide (GaP) stands out due to its intriguing nonlinear and linear optical properties [13]. GaP has a conspicuous third-order nonlinearity with n2 = 1.9×10 -17 m 2 W -1 [14] and an intrinsic second-order nonlinearity with d36 = 41 pm/V at 1550 nm [15]. Besides, two-photon absorption can be neglected above 1.1 μm, which renders high power pump in the entire telecommunication bands possible.…”

“…This study is a vital complement to previous experimental work [13], in which modeling and controlling of the χ (2) -based frequency translation were missing. Distinguished from other works of GaP-OI integrated nonlinear devices which solely focused on either second- [17], [18], [20] or third-order [14], [21] nonlinearity, this work emphasizes the frequency translation that links the χ (3) process and the χ (2) process, paving the way towards realizing highly efficient two-color frequency combs [15]. What's more, we improved the CLLE model so that it can not only work with the modal phase-matching condition [22] but also the cyclic phase-matching condition which is commonly encountered in ring resonators, extending the application scope of the framework for the nonlinear coupling between the χ (2) and χ (3) processes.…”