Design Of Nonlinear Optical Devices Research Articles

Artificial Domain Patterning in Ultrathin Ferroelectric Films via Modifying the Surface Electrostatic Boundary Conditions.

Nanoscale spatially controlled modulation of the properties of ferroelectrics via artificial domain pattering is crucial to their emerging optoelectronics applications. New patterning strategies to achieve high precision and efficiency and to link the resultant domain structures with device functionalities are being sought. Here, we present an epitaxial heterostructure of SrRuO3/PbTiO3/SrRuO3, wherein the domain configuration is delicately determined by the charge screening conditions in the SrRuO3 layer and the substrate strains. Chemical etching of the top SrRuO3 layer leads to a transition from in-plane a domains to out-of-plane c domains, accompanied by a giant (>105) modification in the second harmonic generation response. The modulation effect, coupled with the plasmonic resonance effect from SrRuO3, enables a highly flexible design of nonlinear optical devices, as demonstrated by a simulated split-ring resonator metasurface. This domain patterning strategy may be extended to more thin-film ferroelectric systems with domain stabilities amenable to electrostatic boundary conditions.

Synthesis, growth, and optical applications of N, N′-bis (2-aminophenyl) ethane-1,2-diammonium picrate: An organic crystal

Futuristic organic nonlinear optical single AEDP crystal bearing the IUPAC nomenclature of N, N′-Bis(2-Aminoethyl) Ethane-1,2-Diammonium Picrate was grown via slow evaporation approach in aqueous solvent. The single crystal X-ray diffraction studies were employed for resolving lattice parameters of AEDP single crystal. The data regarding triclinic crystalline structure, bonds vibrations and symmetries of molecular vibrations of the prepared single crystal were realized adopting XRD, FT-IR and vibrational measurements techniques respectively. Evidences regarding excellent crystal optical transparency and maximum crystal non-linear optical properties for the prepared AEDP crystal in the range 200–2000 nm were revealed by Optical absorbance spectrum documented in the UV–vis–NIR wavelength range enhances the scope of unearthing and evolving potential nonlinear systems. Thermal stability and nonlinear optical (NLO) nature of AEDP crystal were inspected by applying differential thermal-thermo gravimetric analysis (DTA–TGA) and second harmonic generation test respectively. The promising features of the crystal leads towards application in the design of nonlinear optical devices and light-controlled electrical switches.

Experimental characterization of the thermo-optic coefficient vs. temperature for 4H-SiC and GaN semiconductors at the wavelength of 632 nm

The design of semiconductor-based photonic devices requires precise knowledge of the refractive index of the optical materials, a not constant parameter over the operating temperature range. However, the variation of the refractive index with the temperature, the thermo-optic coefficient, is itself temperature-dependent. A precise characterization of the thermo-optic coefficient in a wide temperature range is therefore essential for the design of nonlinear optical devices, active and passive integrated photonic devices and, more in general, for the semiconductor technology explored at different wavelengths, from the visible domain to the infrared or ultraviolet spectrum. In this paper, after an accurate ellipsometric and micro-Raman spectroscopy characterization, the temperature dependence of the thermo-optic coefficient (frac{partial n}{partial T}) for 4H-SiC and GaN in a wide range of temperature between room temperature to T = 500 K in the visible range spectrum, at a wavelength of λ = 632.8 nm, is experimentally evaluated. For this purpose, using the samples as a Fabry–Perot cavity, an interferometric technique is employed. The experimental results, for both semiconductors, show a linear dependence with a high determination coefficient, R2 of 0.9648 and 0.958, for 4H-SiC and GaN, respectively, in the considered temperature range.

Optical Properties of LiGdF4 Single Crystal in the Terahertz and Infrared Ranges

The basic mechanisms of absorption of THz range radiation in optically perfect LiGdF4 single crystals were studied using the broadband experimental data and the dielectric response function analysis within the harmonic oscillator model. The polarized IR reflection spectra have allowed one to determine the phonon contribution in the absorption coefficient in the THz range, while transmission spectra in the THz range were used to obtain the birefringence value and the effects of various mulitparticle processes. Additionally, we established the optical and electrodynamic parameters of the LiGdF4 single crystal, which are necessary for the design of nonlinear optical devices.

Nonlinear tunneling and robust energy transfer in sum frequency generation

Based on the counter-diabatic protocol in quantum physics and the quasi-phase-matching method in nonlinear optics, we present a method of achieving robust energy transfer between the sum frequency and signal fields in an optical crystal system by adding a counter-diabatic field (CDF). Adding the CDF does not loosen the adiabatic condition, but rather separates the single original diabatic step into two so that the system remains adiabatic. The two resulting diabatic steps exhibit nonlinear tunneling, where the second step is the inverse of the first one. Moreover, we predict the fabrication of a nonlinear optical crystal with quasi-periodicity in terms of the CDF. Not only does this work provide a solid theoretical foundation for the design of nonlinear optical devices, but it also elucidates physical processes that can be applied in many areas of modern science, ranging from quantum information processing and coherent manipulation of quantum systems to high-precision measurements.

Nonlinear optical propagation in a tandem structure comprising nonlinear absorption and scattering materials

Laser propagation in a tandem structure comprising carbon nanotubes and phthalocyanines is studied by Z-scan method. Due to the different mechanisms of the two materials, the laser beam can be attenuated with different absorptivities, by changing the sequence of light passing through each material. Numerical simulations considering the effect of path length and the change of nonlinear coefficient within each material are conducted for understanding the distribution of laser intensity in the tandem system and hence, fitting of the asymmetric Z-scan curves. The results are helpful for the design of nonlinear optical devices comprising multiple nonlinear materials and mechanisms.

Design of robust and efficient photonic switches using topology optimization

The aim of this article is to introduce a systematic approach for design of non-linear optical devices. The designs are obtained using gradient-based topology optimization coupled with a time-domain Maxwell's equations solver. Direct application of the optimization procedure results in devices with a performance which is very sensitive to geometric manufacturing errors (under- or over-etching). Such behavior is undesirable and robustness is achieved by optimizing for several design realizations. The possible geometric uncertainties are modeled by random variables. It is shown that the designs are insensitive with respect to variations of signal parameters, such as signal amplitudes and phase shifts. The obtained robust designs of a 1D photonic switch can substantially outperform simple bandgap designs, known from the literature, where switching takes place due to the bandgap shift produced by a strong control pulse.

Analysis of Colinear Quasi-Phase-Matching in Nonlinear Photonic Crystals

Standard quasi-phase-matching (QPM) schemes assume exact momentum relations between the interacting beams, thus necessitating the direct use of a reciprocal lattice vector to satisfy momentum balance. Usage of finite width beams for colinear interactions permits to use a projection of the reciprocal lattice vector along the propagation direction of the beams. We analytically derive this result and exam the new options given by this projection-based QPM for the analysis and design of nonlinear optical devices.

DSP Approach to the Design of Nonlinear Optical Devices

Discrete-time signal processing (DSP) tools have been used to analyze numerous optical filter configurations in order to optimize their linear response. In this paper, we propose a DSP approach to design nonlinear optical devices by treating the desired nonlinear response in the weak perturbation limit as a discrete-time filter. Optimized discrete-time filters can be designed and then mapped onto a specific optical architecture to obtain the desired nonlinear response. This approach is systematic and intuitive for the design of nonlinear optical devices. We demonstrate this approach by designing autoregressive (AR) and autoregressive moving average (ARMA) lattice filters to obtain a nonlinear phase shift response.

Analytical Expression for the Fourier Spectrum of a Quasiperiodic Fibonacci Superlattice with k Components (k ? 3)

The two-component quasiperiodic optical superlattice has been proved useful to some coupled parametric processes such as the direct third-harmonic generation. In this paper a three-component quasiperiodic superlattice has been studied theoretically. Using the projection method, the analytical expression of its Fourier spectrum has been deduced. The results might be conducive to the design of nonlinear optical devices related to the coupled parametric processes, such as the fifth-harmonic generation.

Three-component quasiperiodic superlattice and its Fourier spectrum

The domain-inverted ferroelectric materials, or simply the dielectric superlattice, can be patterned into different configurations. For example, there are the periodic, quasiperiodic, Thue-Morse and several other types. The periodic superlattice is widely used for the second-harmonic generation, sum-frequency generation and optical parametric oscillation, for which only one optical parametric process is involved. The two-components quasiperiodic superlattice has been proved useful to some coupled parametric processes such as the direct third-harmonic generation. In this paper a three-component quasiperiodic superlattice has been discussed theoretically. Using the projection method, the analytical expression of its Fourier spectrum has been derived. Relations with the periodic and two-components quasiperiodic superlattices has been given. The results might be useful to the design of nonlinear optical devices related to the coupled parametric processes.

New materials and their characterization for photonic device applications

Recent advances in materials technology has led to the development of new and improved optically nonlinear materials that can be used for a wide variety of applications ranging from deep UV conversion for laser fusion experiments to fast optical switching devices in future telecommunication systems. The processibility that many of these new materials have to offer will allow devices to be designed for specific applications. Some recent developments in the search for new materials are described and the future role that some of these may play in the design of nonlinear optical devices is discussed.