We studied a flexible design for directional quasi-phase-matching (DQPM) in AlGaAs waveguide resonators, which can be exploited for implementing optical frequency combs (OFCs) in cavity-enhanced second-harmonic generation.

We investigated the design and fabrication of monolithic resonators from lithium tantalate, with a radial photonic structure of periodically inverted ferroelectric domains. A first characterization of the nonlinear performance has been done.

We theoretically modeled and experimentally demonstrated, for the first time, the generation of quadratic frequency combs in a cw-pumped, nearly degenerate, doubly resonant optical parametric oscillator (OPO)

A novel and general method, named FACE, capable of characterizing the frequency comb generation within quantum cascade lasers (QCLs) by directly measuring the Fourier phases of laser comb modes has been developed and demonstrated.

We investigated second-harmonic generation in a strained silicon waveguide engineered to achieve multimodal phase-matching. We determined a second order nonlinear coefficient of about 0.3 pm/V.

We study silicon microring resonators on silica layer, cladded by a Si₃N₄ layer, surrounded by air, in order to determine the conditions allowing an efficient second harmonic generation

We theoretically predict quadratic frequency combs in a dispersive second-harmonic generation cavity system. We identify different dynamical regimes and demonstrate that the same system can exhibit both bright and dark localized cavity solitons in the absence of a temporal walk-off.

We considered optical frequency comb generation in the presence of nonlinear polarization effects. Our in-depth study of the polarization modulational instability permits to demonstrate the appearance of novel types of instabilities and frequency comb states.

We show that a strong mode-interaction in microcavities can trigger single soliton Kerr combs deterministically. The soliton number tends to be reduced to 1 to decrease the nonlinear loss into mode-interaction induced Cherenkov radiation.

This review summarises recent exciting achievements in the field of micro-combs, namely optical frequency combs based on high-Q microresonators, with a perspective on both the potential of this technology, as well as the open questions and challenges that remain.

Four Wave Mixing control in a photonic molecule made by silicon microring resonators

This work is the theoretical and experimental demonstration of the four wave mixing (FWM) intensity tuning in a photonic molecule. Manipulating the eigenfrequencies and the inter-phase of two microresonators side coupled by two straight waveguides, we show that the FWM can be enhanced or even suppressed. Interestingly, a superior level of coherent control of the FWM output with respect to single resonators is achieved.

Frequency comb generation in a doubly resonant SHG system

We demonstrated frequency comb generation in a doubly resonant SHG system and implemented an offset locking scheme which allows for slow laser-to-cavity frequency scans over several cavity resonance linewidths.