Lithium niobate (LN), widely used in optoelectronics, is an excellent photonic material with a large electro-optic (EO) coefficient. In this talk, I will talk about the development of the emerging integrated low-loss LN platform, and show the developments of novel EO devices for 1) temporal and spectral shaping of light based on the EO time lens, 2) frequency-domain shifters and beamsplitters, 3) efficient EO frequency combs based on coupled resonators. I will discuss the potential of LN-based platform for accelerating quantum technologies in terms of information processing and communication networks.

Ridge waveguides carved in bulk nonlinear crystals such as KTiOPO4 are used to reach a strong confinement of electromagnetic waves with large second- or third-order non-linearity. We report on the possibility to shape the birefringence phase-matching conditions (BPM) for direct Third-Harmonic Generation (THG) in micrometric KTP ridge waveguides by acting on their transverse dimensions. The real goal of this preliminary experimental study is to design quantum optical experiments based on Triple Photons Generation that is the reverse process of THG, thus exhibiting the same BPM conditions.

We report on the fabrication of ridge waveguides formed in congruent periodically poled lithium niobate (PPLN). The waveguides were fabricated by periodic poling, proton exchange, subsequent annealing and reverse proton exchange followed by diamond blade dicing. Up to 1 W of single-pass second-harmonic generation at 775 nm has been realized in 50 mm long ridge waveguides with internal conversion efficiency of 70%. Furthermore, difference frequency generation at 3.3 µm of two pump waves at 1.05 µm and 1.55 µm has been obtained in similarly fabricated PPLN ridge waveguides with an appropriate poling period.

Plasmonic metamaterials show potential for realizing flat nonlinear photonic devices. Especially, periodic structures supporting collective responses known as surface lattice resonances (SLRs) are promising for realizing this goal. Here, we demonstrate multiply-resonant enhancement of second-harmonic generation (SHG) from aluminum metasurfaces by utilizing SLRs at both pump and signal wavelengths. The measured SH signals correspond to nonlinear susceptibility values of 0.4 pm/V, demonstrating the potential of aluminum nanostructures for nonlinear optics. Our results motivate further investigations with other nonlinear processes.

The quest for efficient nanoscale light sources has increased over the years due to their applications in the photonic circuitry, quantum optics, and bio-sensing. Resonant excitation of plasmonic structures can be utilized to enhance nonlinear light matter interactions at the nanoscale in general, however, key factors that contribute towards efficient nonlinear wave-mixing at the small scale are often difficult to satisfy simultaneously. Here, we report an optimal second-harmonic generation using hybrid-plasmonic film-coupled nanopatch antennas.