A.A. Fedyanin

Optical second-harmonic generation induced by a dc electric field at the Si–SiO 2 interface

For what is to our knowledge the first time, electric-field-induced optical second-harmonic generation (SHG) is studied at the Si-SiO(2) interface by the use of a metal-oxide-semiconductor (MOS) structure. The crystallographic anisotropy of this phenomenon is studied for MOS structures. Experimental results indicate that the MOS technique of dc electric-field application to the Si-SiO(2) interface can be effectively used for studying electroinduced effects on SHG.

Frontiers in Magneto-optics of Magnetophotonic Crystals

The recently published and new results on design and fabrication of magnetophotonic crystals of different dimensionality are surveyed. Coupling of polarized light to 3D photonic crystals based on synthetic opals was studied in the case of low dielectric contrast. Transmissivity of opals was demonstrated to strongly depend on the propagation direction of light and its polarization. It was shown that in a vicinity of the frequency of a single Bragg resonance in a 3D photonic crystal the incident linearly polarized light excites inside the crystal the TE- and TM-eigen modes which passing through the crystal is influenced by Bragg diffraction of electromagnetic field from different (hkl) sets of crystallographic planes. We also measured the Faraday effect of opals immersed in a magneto-optically active liquid. It was shown that the behavior of the Faraday rotation spectrum of the system of the opal sample and magneto-optically active liquid directly interrelates with transmittance anisotropy of the opal sample. The photonic band structure, transmittance and Faraday rotation of the light in three-dimensional magnetophotonic crystals of simple cubic and face centered cubic lattices formed from magneto-optically active spheres where studied by the layer Korringa-Kohn-Rostoker method. We found that a photonic band structure is most significantly altered by the magneto-optical activity of spheres for the high-symmetry directions where the degeneracies between TE and TM polarized modes for the corresponding non-magnetic photonic crystals exist. The significant enhancement of the Faraday rotation appears for these directions in the proximity of the band edges, because of the slowing down of the light. New approaches for one-dimensional magnetophotonic crystals fabrication optimized for the magneto-optical Faraday effect enhancement are proposed and realized. One-dimensional magnetophotonic crystals utilizing the second and the third photonic band gaps optimized for the Faraday effect enhancement have been successfully fabricated. Additionally, magnetophotonic crystals consist of a stack of ferrimagnetic Bi-substituted yttrium-iron garnet layers alternated with dielectric silicon oxide layers of the same optical thickness. High refractive index difference provides the strong spatial localization of the electromagnetic field with the wavelength corresponding to the long-wavelength edge of the photonic band gap.

Surface wave-induced enhancement of the Goos-Hänchen effect in one-dimensional photonic crystals

The excitation conditions of surface electromagnetic waves in one-dimensional photonic crystals (Bragg reflectors) are studied. Surface electromagnetic waves are visualized by the far-field optical microscopy of the surface of the photonic crystal. The enhancement of the Goos-Hänchen effect by surface electromagnetic waves excited in one-dimensional photonic crystals has been experimentally observed. The Goos-Hänchen shift reaches 30λ for a wavelength of λ = 532 nm.

Anisotropic Photonic Crystals and Microcavities Based on Mesoporous Silicon

A technique to prepare one-dimensional anisotropic photonic crystals and microcavities based on anisotropic porous silicon exhibiting optical birefringence has been developed. Reflectance spectra demonstrate the existence of a photonic band gap and of an allowed microcavity mode at the photonic band gap center. The spectral position of these bands changes under rotation of the sample about its normal and/or under rotation of the plane of polarization of the incident radiation. The dependence of the shift of the spectral position of the photonic band gap edges and of the microcavity mode on the orientation of the polarization vector of incident electromagnetic wave with respect to the optical axis of the photonic crystals and microcavities was studied.

DC-induced generation of the reflected second harmonic in silicon

DC-induced generation of the reflected second harmonic is experimentally observed on the surface of a centrosymmetric silicon single crystal. A direct current with a surface density of jmax ∼ 103 A/cm2 violates the symmetry of the electron distribution function and induces the optical second harmonic with an intensity corresponding to the dipole quadratic susceptibility χ(2)d(jmax) ∼ 3 × 10−15 m/V.

Magneto-Optical Effect of One-Dimentional Magnetophotonic Crystal Utilizing the Second Photonic Band Gap

We fabricated new one-dimensional magnetophotonic crystal (1D-MPC) utilizing the second and third photonic band gaps where localized modes existed. Structure of the 1D-MPC was (Ta₂O?/SiO₂)?/Bi:YIG/(SiO₂/Ta₂O?)? with optical thicknesses of 3 λ/4 for Ta₂O? and SiO₂ dielectric layers and λ/2 for Bi:YIG defect layer, where λ is a wavelength of a localized mode in the second photonic band gap. Faraday rotation at the localized mode in the second photonic band gap was enhanced, which was confirmed by calculation using 4×4 matrix method.

Optical third-harmonic generation in one-dimensional photonic crystals and microcavities

The formalism of nonlinear transfer matrices is used to develop a phenomenological model of a cubic nonlinear-optical response of one-dimensional photonic crystals and microcavities. It is shown that third-harmonic generation can be resonantly enhanced by frequency-angular tuning of the fundamental wave to the photonic band-gap edges and the microcavity mode. The positions and amplitudes of third-harmonic resonances at the edges of a photonic band gap strongly depend on the value and sign of the dispersion of refractive indexes of the layers that constitute the photonic crystal. Model calculations elucidate the role played by phase matching and spatial localization of the fundamental and third-harmonic fields inside a photonic crystal as the main mechanisms of enhancement of third-harmonic generation. The experimental spectrum of third-harmonic intensity of a porous silicon microcavity agrees with the calculated results.

Optical second-harmonic phase spectroscopy of the Si(111)–SiO2 interface

Abstract The two-photon interband electron transitions in a silicon layer directly underneath the Si(111)–SiO 2 interface in the vicinity of the E 2 critical point (CP) are probed by optical second-harmonic (SH) spectroscopy. The combination of the SH phase and intensity spectroscopy allows the complete deconvolution of the spectral behavior of the amplitude and phase of the quadratic susceptibility χ (2) near the E 2 critical point of silicon.

Optical Third-Harmonic Generation in Coupled Microcavities Based on Porous Silicon

The resonance features of the third-harmonic generation have been observed in 1D coupled microcavities consisting of three Bragg reflectors and two identical half-wave layers of mesoporous silicon. The third-harmonic intensity increases by a factor of about 103 in the resonance of fundamental radiation with each of the modes of coupled microcavities. It has been shown that the resonance positions in the angular spectra of the third-harmonic intensity depend on the coupling between microcavities that is determined by the transmission of the intermediate Bragg reflector. In the framework of the transfer-matrix method with nonlinear sources, it has been shown that the basic mechanism of the enhancement of the third-harmonic generation in coupled microcavities based on porous silicon is the constructive interference of the partial third-harmonic waves that are generated by near-surface layers.

Probe of the vicinal surface by second harmonic phase spectroscopy

The intrinsic surface sensitive technique of optical second harmonic (SH) phase and intensity measurements is used to probe a slightly miscut natively oxidized Sið 111 Þ surface. The experiments have been performed in a spectral interval covering the E2 resonance of silicon band structure. The phase and intensity of the SH wave measured at several azimuthal angular positions allow to separate the vicinal contributions. # 2001 Elsevier Science Ltd. All rights reserved.