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AlN is a promising candidate for photonic integrated circuits. In this study, horizontally stacked transverse quasi‐phase‐matched (QPM) waveguides with an AlN center core and Si3N4, Ta2O5, and TiO2 side cores were designed to generate squeezed light at 920 nm. The squeezing level was calculated by considering the propagation loss at the wavelengths of the squeezed light and pump light. Using TiO2 for the side cores enhanced the electric field amplitude of the pump light in the AlN center core, and a high nonlinear coupling coefficient was obtained. Owing to the small propagation loss of the AlN waveguide on sapphire and high nonlinear coupling coefficient of the transverse QPM with TiO2 side cores, a squeezing level of over 8.1 dB was expected with a 1 cm long waveguide and pump power of 70 mW. [ABSTRACT FROM AUTHOR]

GaN is an attractive material for integrating optical quantum devices. Adding a large optical nonlinearity of MgO doped congruent LiNbO3 (MgO:CLN) to GaN will improve the efficiency of quantum light sources. In this work, we proposed transverse quasi-phase-matched wavelength conversion devices with waveguide core materials of MgO:CLN and GaN. The waveguide core is formed by an adhesion-free surface activated bonding (SAB). A high thin film transfer yield was achieved with a high bonding strength of 4 MPa by optimizing the bonding conditions and reducing the surface roughness of the GaN film to be 0.5 nm in a 100 × 100 μ m2 area using chemical mechanical polishing. The MgO:CLN/GaN waveguide structure was successfully fabricated by MgO:CLN thin film transfer, lift-off and dry etching processes. This MgO:CLN/GaN adhesion-free SAB technique is expected to be applied to various devices, such as optical devices and electronic devices, to enhance their functionality. [ABSTRACT FROM AUTHOR]

Watt-class wavelength conversion is expected by enlarging the mode size of the channel waveguides to dozens of micrometers to avoid optical damage with high-power pump lasers. In this work, uniform periodically-poled (PP) structures in MgO doped stoichiometric LiTaO3 were fabricated by applying voltage with a SiO2 insulation layer. Annealed proton-exchanged waveguides with a full width at 1/ e 2 maximum in a width of 43 ÎĽ m with an in-depth of 28 ÎĽ m were obtained by proton exchanging for 4 h and thermal diffusion for 75 h. This waveguide can be excited by pump waves with a power of 8.6 W considering the optical damage threshold. Second harmonic generation with a wavelength of 515 nm was conducted in the low power region of about 35 mW to investigate the basic characteristics. Normalized wavelength conversion efficiency in the 15 mm long PP structures was estimated to be 4.3% Wâˆ'1. [ABSTRACT FROM AUTHOR]