Generation In One-dimensional Photonic Crystals Research Articles

Third-harmonic generation in one-dimensional photonic crystal with graphene-based defect

Third-harmonic generation in one-dimensional photonic crystal with graphene-based defect

Terahertz pulse generation using one-dimensional photonic crystals via optical rectification effect

Generation in one-dimensional photonic crystals of a single-cycle terahertz (THz) pulse via the optical rectification effect was studied by using the Green's function method. The bandwidth and the carrier frequency of the generated THz pulse are, respectively, in the range 2–8 THz and 2–18 THz. By decreasing the duration of the input pulses these ranges can be enlarged, but pulse shape is also deformed. The results show that by setting the carrier frequency of the input pulse on the edges of the gap, the amplitude of the generated THz pulse is maximized and its bandwidth is narrowed, but for carrier frequencies located inside the gap the situation is reversed. Moreover, by adjusting the carrier frequency of the input pulse on upper gaps few-cycles THz pulses are generated.

Computational design of one-dimensional nonlinear photonic crystals with material dispersion for efficient second-harmonic generation

A computational study of the second-harmonic generation in one-dimensional photonic crystals made of GaAs and AlAs with quadratic optical nonlinearity and material dispersion is presented. The computational approach uses a shooting method to solve nonlinear wave equations for coupled fundamental and second-harmonic fields and the invariant imbedding method to obtain the linear transmittance and group index spectra. The photonic crystal is built with an elementary cell consisting of four sublayers whose thicknesses are systematically varied. Doubly-resonant second harmonic generation with high conversion efficiency is achieved by choosing the geometrical parameters of the elementary cell optimally and controlling the band structure.

Modeling of amplification and light generation in one-dimensional photonic crystal using a multiwavelength transfer matrix approach

We present an analysis of amplification and lasing in one-dimensional isotropic nonlinear photonic crystal (1D PC), which is based on a generalized (multiwavelength) transfer matrix method. This approach was used for modeling a Raman signal amplification in 1D PC and in an homogenous structure, showing advantages of a stratified medium. Moreover, the threshold operation of a 1D PC Raman laser is studied, assuming both strong as well as depleted pump. The normalized threshold gain characteristics for various end reflections and photonic crystal laser length were calculated.

High efficiency second harmonic generation in one-dimensional photonic crystal coupled cavity structures

Second harmonic generation of coupled cavity structures (CCSs) fabricated in one-dimensional photonic crystals, which are composed of dispersive materials, is investigated. The fundamental wave is a localized mode, and the second harmonic wave is a traveling mode of the CCS. Using transfer matrix and effective refractive index methods, we analyze the localization and phase matching of the two modes. Using a nonlinear finite-difference time-domain method, we simulate the nonlinear process with a Gaussian pumping pulse, and both transmitted and reflected second harmonic signals are obtained. We investigate the effect of cavity number on the conversion efficiency and find the material dispersion can be compensated by the structural dispersion. For this reason, the conversion efficiency in a CCS is three orders larger than that in a bulk material of the coherence length.

Noncollinear type-II second-harmonic generation in a Al(0.3)Ga(0.7)As/Al2O3 one-dimensional photonic crystal

We demonstrate noncollinear type-II second-harmonic generation in one-dimensional photonic crystals. A 15-period Al(0.3)Ga(0.7)As/Al2O3 structure, 3.5 μm long, was designed, fabricated, and experimentally characterized. We measured an effective nonlinearity of (52±12) pm/V in perfect phase-matching conditions.

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.

Simultaneous second- and third-harmonic generation in one-dimensional photonic crystals

By use of the envelope-function approach, the equation governing propagation of the TE plane wave in a one-dimensional periodic structure is reduced to a set of coupled-mode dynamical equations for slowly varying amplitudes. We applied this method to layered media possessing both χ(2) and χ(3) nonlinearities, to study the possibility of simultaneous second- and third-harmonic generation. The phenomenon is based on the geometry of the structure and is observed in a wide class of photonic crystals of different natures, provided that the thickness and refractive indices of alternating dielectric layers are appropriately chosen. By imposing various initial distributions of the energy among the individual modes, we studied the evolution of the intensities. We found that the presence of two channels for the energy transfer from the fundamental mode prevents concentration of the total energy in either of the higher modes. In all the cases considered the energy exchange among the modes is observed. We present a particular solution for the energy transfer from the fundamental and the third harmonic to the second harmonic, obtained when the cubic nonlinearity is negligible.