Band-gap nonlinear optical generation: The structure of internal optical field and the structural light focusing

Abstract

A novel approach for the enhancement of nonlinear optical effects inside globular photonic crystals (PCs) is proposed and systematically studied via numerical simulations. The enhanced optical harmonic generation is associated with two- and three-dimensional PC pumping with the wavelength corresponding to different PC band-gaps. The interactions between light and the PC are numerically simulated using the finite-difference time-domain technique for solving the Maxwell's equations. Both empty and infiltrated two-dimensional PC structures are considered. A significant enhancement of harmonic generation is predicted owing to the highly efficient PC pumping based on the structural light focusing effect inside the PC structure. It is shown that a highly efficient harmonic generation could be attained for both the empty and infiltrated two- and three-dimensional PCs. We are demonstrating the ability for two times enhancement of the parametric decay efficiency, one order enhancement of the second harmonic generation, and two order enhancement of the third harmonic generation in PC structures in comparison to the nonlinear generations in appropriate homogenous media. Obviously, the nonlinear processes should be allowed by the molecular symmetry. The criteria of the nonlinear process efficiency are specified and calculated as a function of pumping wavelength position towards the PC globule diameter. Obtained criterion curves exhibit oscillating characteristics, which indicates that the highly efficient generation corresponds to the various PC band-gap pumping. The highest efficiency of nonlinear conversions could be reached for PC pumping with femtosecond optical pulses; thus, the local peak intensity would be maximized. Possible applications of the observed phenomenon are also discussed.

Optical properties of mesoporous photonic crystals, filled with dielectrics, ferroelectrics and piezoelectrics

“…Furthermore, the first Stokes component for benzene and the anti-Stokes component for carbon disulfide are located directly in the region of the corresponding stop bands. According to the theory, 18 an anomalous increase in the spectral density of the effective electromagnetic field at the frequency of pump radiation and at the frequencies of SRS should be expected in these cases. This in turn should increase the gain of generation of stimulated Raman scattering and, correspondingly, reduce the threshold of SRS observation.…”

Reduction of the threshold of stimulated Raman scattering in Raman-active media introduced into pores of a globular photonic crystal

“…Furthermore, the first Stokes com ponent for benzene and the anti Stokes component for carbon disulfide are located directly in the region of the corresponding stopbands. According to the the ory [24], an anomalous increase in the spectral density of the effective electromagnetic field at the frequency of pump radiation and at the frequencies of stimulated Raman scattering should be expected in these cases. This in turn should increase the gain of generation of stimulated Raman scattering and, correspondingly, reduce the threshold of the observation of stimulated Raman scattering.…”

“…Similar one dimen sional structures can be used to increase the efficiency of generation of the anti Stokes component of stimu lated Raman scattering, whose intensity under normal conditions is much lower than the intensity of the cor responding Stokes component. It was shown in [24] that the effect of a sharp increase in the spectral energy density of the electromagnetic field near the surface of two and three dimensional photonic crystals occurs when the frequency of the electromagnetic wave is directly in the region of the stopband.…”

Enhancement of second harmonic generation in NaNO2-infiltrated opal photonic crystal using structural light focusing

“…It was found that if the pumping wavelength corresponds to the PC BG, k x ¼ k BGi (where i ¼ 1, 2,…, N are indexes of the BG order), the light could penetrate only to a depth of several PC layers. Strong optical field localization in particular near-surface PC regions appears in this case as a result of the structural light focusing phenomenon, 48,49 i.e., as a result of the coherent waveform distortion on the curvature of PC components.…”

“…48. It was found that if the pumping wavelength corresponds to the PC BG, k x ¼ k BGi (where i ¼ 1, 2,…, N are indexes of the BG order), the light could penetrate only to a depth of several PC layers.…”