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Third-harmonic generation (THG) in silicon nitride waveguides is an ideal source of coherent visible light, suited for ultrafast pulse characterization, telecom signal monitoring and self-referenced comb generation due to its relatively large nonlinear susceptibility and CMOS compatibility. We demonstrate third-harmonic generation in silicon nitride waveguides where a fundamental transverse mode at 1,596 nm is phase-matched to a TM02 mode at 532 nm, confirmed by the far-field image. We experimentally measure the waveguide width-dependent phase-matched wavelength with a peak-power-normalized conversion efficiency of 5.78 × 10−7 %/W2 over a 660-μm-long interaction length.

Indium Phosphide (InP) is one of the most widely commercialized III–V semiconductor materials for making efficient lasers operating in the O-band and C-band. It is also gaining significant attention as a material platform for passive integrated optical devices operating in the telecommunication wavelength range for optical communication networks and sensing. Fabrication of such devices requires a process of lithography for pattern writing followed by plasma etching for transferring the pattern into the semiconductor material. InP is one of the most difficult materials to etch due to the fact that the etching by-products ( InCl x) are not volatile at temperatures less than 150 ° C. There have been some studies showing InP etching at lower temperatures and room temperatures. However, after carefully studying these processes using multiple plasma etching tools, we found that the claimed processes are not repeatable because of the low volatility of the by-products at room temperature. In this work, we demonstrate a systematic study of etching InP using methane-hydrogen-based chemistry at low temperatures (60 ° C) and chlorine-based chemistry at high temperatures (190 ° C). [ABSTRACT FROM AUTHOR]

Practical applications implementing integrated photonic circuits can benefit from nonlinear optical functionalities such as wavelength conversion, all-optical signal processing, and frequency-comb generation, among others. Numerous nonlinear waveguide platforms have been explored for these roles; the group of materials capable of combining both passive and active functionalities monolithically on the same chip is III–V semiconductors. AlGaAs is the most studied III–V nonlinear waveguide platform to date; it exhibits both second- and third-order optical nonlinearity and can be used for a wide range of integrated nonlinear photonic devices. In this review, we conduct an extensive overview of various AlGaAs nonlinear waveguide platforms and geometries, their nonlinear optical performances, as well as the measured values and wavelength dependencies of their effective nonlinear coefficients. Furthermore, we highlight the state-of-the-art achievements in the field, among which are efficient tunable wavelength converters, on-chip frequency-comb generation, and ultra-broadband on-chip supercontinuum generation. Moreover, we overview the applications in development where AlGaAs nonlinear functional devices aspire to be the game-changers. Among such applications, there is all-optical signal processing in optical communication networks and integrated quantum photonic circuits. [ABSTRACT FROM AUTHOR]