Ilya R. Prudnikov

Four-wave mixing in one-dimensional photonic crystals: inhomogeneous-wave excitation

We present what is to our knowledge the first study of nonlinear four-wave mixing in one-dimensional photonic crystals. The possibility of inhomogeneous-wave excitation at the four-wave mixing frequency ω3=2ω1-ω2 for two noncollinear beams of femtosecond laser pulses is demonstrated. As a result of this effect the wave at the frequency of four-wave mixing may be guided along the surface of the photonic crystal. Experiments of this type open the possibility of development of a new tool based on photonic crystal devices for coherent Raman spectroscopy of surfaces and of nanometer and submicrometer scale layers.

Nonlinear process in photonic crystals under the noncollinear interaction

We analyzed theoretically and studied experimentally the sum-frequency generation and four-wave-mixing processes under the noncollinear geometry of interaction in finite-length periodic photonic crystals. The efficiency of the surface and the bulk mechanisms of sum-frequency generation are compared. It is shown that surface and bulk mechanisms cannot be separated on the polarization of the sum-frequency signal only but that the angular dependencies of the sum-frequency signal intensity enable us to separate them. The excitation of inhomogeneous waves at the four-wave-mixing frequency of ω3=2ω1-ω2 is discussed and demonstrated.

Band gaps in the spectra of terahertz surface plasmons on metallic diffraction gratings

The effect of the appearance of band gaps in the energy spectra of terahertz surface plasmons has been experimentally observed and investigated. The band gaps are formed due to the interference interaction of the surface plasmons excited by pulsed terahertz radiation on metallic diffraction gratings. It has been shown that the experimental dispersion curves of terahertz plasmons are in good agreement with the dispersion curves obtained in the numerical simulation.

Peculiarities of surface plasmon enhanced third-harmonic generation on a metal grating for different surface plasmon excitation geometries

Third-harmonic generation (THG) enhancement caused by the surface-plasmon excitation on a metal diffraction grating is investigated theoretically. Basic features of THG are considered for different ways of the surface plasmon excitation. Nonlinear interactions between the plasmons are analyzed and explained.

SiC-Si Grooved Surface Bonding

SiC Lely platelets and SiC epilayers on large area SiC substrates were directly bonded to non-oxidized grooved surface silicon wafers in order to obtain structures prospective for the design of power bipolar devices with wide band-gap emitter junctions. The reported capabilities of grooved interfaces to reduce elastic strain and intrinsic sources of an interfacial potential barrier were utilized. The influence of surface morphology on the structural perfection of the bonded samples was studied in detail by X-ray and AFM techniques. As compared to traditional bonding technology, experimental data showed an easier smooth-to-grooved surface bonding accomplished in the formation of the boundary with better continuity and strength. For 2 in. diameter SiC wafers with root mean square height of roughness σ=16 A and lateral coherence length L =1.8 μm bonding continuity not smaller than 90% was reached, while the crystals with σ=30 A, L =5 μm failed to bond to Si even under an external force.