Control of the harmonic-generation efficiency in photonic crystals formed by optically anisotropic layers

Abstract

Photonic crystals remain one of the most actively discussed topics of the modern optics. In particular, they are very promising for the control of such nonlinear-optical processes as harmonic generation and light self-action as well as for sensor applications. Porous silicon (PS) produced by electrochemical etching of the crystalline silicon (c-Si) due to possibility of the pore filling with liquids and embedding nanoparticles is a very promising medium for the formation of the nanocomposites for various optical applications. Variation of the etching-current density results in variation of the PS layer porosity and its refractive index; alternating the high and low porosity samples we can form a photonic crystal. PS-based photonic crystal easily allows the phase matching to be reached, which was demonstrated in experiments on the second-harmonic (SH) enhancement [1]. The ordered pore propagation, which is typical for mesoporous silicon, causes strong birefringence of the PS layers; the photonic crystals consisting of the birefringent layers demonstrate photonic band gap (PBG) depending on the light polarization [2]. As a result, the harmonic generation in photonic crystals can be also controlled by the light polarization [3], which enriches phase-matching opportunities. New experimental geometries opened by photonic crystals with birefringent layers are very promising both for the enhancement of the nonlinear-optical signal in nanopomposite and for the development of novel sensors based on phase-matched interactions. Thus, features of the phase matching effect on the nonlinear-optical process efficiency in the photonic crystals formed by birefringent layers should be studied in more detail.