Photonic bandgap structures in planar nonlinear waveguides: application to squeezed-light generation

Abstract

Quadrature-amplitude and phase squeezing are theoretically investigated in a planar waveguide geometry where the use of a linear grating fabricated on top of the waveguide reproduces a photonic bandgap structure. The introduction of a nonlinear grating, obtained with a modulation of the nonlinear susceptibility χ(2), provides an additional degree of freedom that allows, together with the linear grating, tuning of the fundamental field in a selected resonance of the transmission spectrum and, at the same time, control of the phase-matching condition between the fundamental and second-harmonic fields. The results show that quadrature-amplitude squeezing is achieved for the fundamental field, increasing the second-harmonic input intensity. The second-harmonic field is tuned in the passband of the photonic bandgap. The low nonlinear conversion efficiency, given by a suitable selection of the mismatch, gives rise to the possibility of having a fundamental field of quite the same intensity, but less noisy than at the entry.