Quadratic Electro-optic Effect Research Articles

Experimental study of DC Kerr effect of chalcogenide glass film by free space coupling method

Chalcogenide glass is an important nonlinear optical material that has attracted much attention in the areas of integrated photonics, supercontinuum sources, and all-optical switches in recent years. However, the current research mainly focuses on the nonlinear effect excited by light, and the research on its properties under the action of a DC field is still deficient. Here, a metal-cladding optical waveguide, which is composed of a chalcogenide glass film coated on a glass substrate, is presented to analyze the quadratic electro-optic (QEO) effect of the chalcogenide glass film. The DC Kerr coefficient and the whole components of the QEO tensor of the sample were experimentally determined by the free space coupling method.

One-Dimensional Modulational Instability of Broad Optical Beams In Photorefractive Crystals with Both Linear and Quadratic Electro-Optic Effects

One-Dimensional Modulational Instability of Broad Optical Beams In Photorefractive Crystals with Both Linear and Quadratic Electro-Optic Effects

Why phenomenological theory cannot be used to analyze the dynamics of dark photorefractive solitons

The currently used theory of both bright and dark spatial photorefractive (PR) solitons is a phenomenological theory. In the work we consider the dynamics of dark beams using a microscopic model based on the PR transport equations. It is generally believed that such a theory is more accurate. It has been found that these two approaches can give completely different predictions regarding the formation time of dark beams. The discrepancies can reach up to two orders of magnitude. An approximate analytical solution was presented and a new time constant was introduced taking into account crystals from three classes of PR materials: ferroelectrics, sillenites and semiconductors. Full Text: PDF References A. Katti, R.A. Yadav, Optical Spatial Solitons in Photorefractive Materials (Singapore, Springer, 2021) CrossRef E. DelRe, M. Segev, Ch. 23 in Self-focusing: Past and Present, ed. by R.W. Boyd, S.G. Lukishova, Y.R. Shen (New York, Springer, 2009). CrossRef M. Wichtowski, "On conformity of solutions for one-dimensional photorefractive screening solitons with the Kukhtarev–Vinetskii model", Appl. Phys. B 120, 527 (2015). CrossRef M. Segev, B. Crosignani, P. Di Porto et al., in Photorefractive Spatial Solitons, (Kluwer Academic Publisher, New York, 2002). DirectLink K. Zhan, Ch. Hou, S. Pu, "Temporal behavior of spatial solitons in centrosymmetric photorefractive crystals", Opt. Laser Technol. 43, 1274 (2011). CrossRef J. Maufoy, N. Fressengeas, D.Wolfersberger, G. Kugel, "Simulation of the temporal behavior of soliton propagation in photorefractive media", Phys. Rev. E 59, 6116 (1999). CrossRef A. Katti, M.S. Pande, "Formation characteristics of dark solitons in photorefractive crystals having both linear and quadratic electro-optic effect simultaneously", Opt. Quantum Electron. 55, 1132 (2023). CrossRef

Formation characteristics of dark solitons in photorefractive crystals having both linear and quadratic electro-optic effect simultaneously

Formation characteristics of dark solitons in photorefractive crystals having both linear and quadratic electro-optic effect simultaneously

PVDF-based (V2O5)x. (Mn0.4Fe2.6O4)(2−x), x = [0.2, 0.4, 0.6, 0.8, and 1] nanocomposites for tailoring the optical and nonlinear optical properties of PVDF

Nanocomposites comprising (V2O5)x. (Mn0.4Fe2.6O4)(2−x), where x = [0.2, 0.4, 0.6, 0.8, and 1], were successfully synthesized by milling each single phase of V2O5 and Mn0.4Fe2.6O4 nanostructured samples. We studied the structure and morphology of the prepared samples through X-ray diffraction and scanning electron microscopy. UV–Vis. spectrum analysis was used to study the optical characteristics. As an attempt to improve the optical and nonlinear optical properties of the PVDF blend, the prepared nanocomposites were used as nanofillers for the poly (vinylidene fluoride) (PVDF) polymer. Optical and nonlinear optical properties of the PVDF polymer were tuned using (V2O5)x. (Mn0.4Fe2.6O4)(2−x), where x = [0.2, 0.4, 0.6, 0.8, and 1] nanocomposite. The obtained results showed a tunable spectrum, absorption, refractive index, and dielectric constant at wavelengths ranging from 200 to 800 nm. However, the results showed that the (V2O5)0.6. (Mn0.4Fe2.6O4)1.4, sample was the best for obtaining the lowest transmittance percentage and bandgap energy. The nonlinear optical properties and Kerr effect (quadratic electro-optic effect) showed a significant response, which can be tuned in the range from 200 to 1200 nm of wavelength using the investigated samples. Finally, incorporating (V2O5)x. (Mn0.4Fe2.6O4)(2−x), where x = [0.2, 0.4, 0.6, 0.8, and 1], nanoparticles in the PVDF polymer improved the hydrophilic behavior of the PVDF films. This study suggests a promising nanocomposite material for tunable optoelectronics and useful polymer membranes.

Temporal behavior of bright and dark spatial solitons in photorefractive crystals having both the linear and quadratic electro-optic effects based on low amplitude approximations

We investigate the formation or time evolution characteristics of bright and dark optical spatial solitons in novel photorefractive media with linear and quadratic electro-optic effects. This study was carried out at low amplitude. By the application of low amplitude approximation to the time-dependent wave (soliton) propagation equation, bright soliton solution (BSS) and dark soliton solution (DSS) were each obtained analytically, and both are exact solutions. The change in soliton width or the intensity full width at half maximum (FWHM) of two soliton types can also be calculated directly from the BSS and the DSS, providing a suitable description of the bright and dark solitons time evolution in novel photorefractive media. Only steady state solitons are formed in low amplitude, and the quasi-steady state soliton does not exist as reported at high saturation values. We compare analytical BSS with numerical calculation results of previous studies and find good agreement between analytics and numerics on the amplitude limit. In contrast to bright solitons, which can arise in the dominant linear or quadratic electro-optic effect, dark solitons in novel photorefractive media always exist under the dominant quadratic electro-optic effects only. We found that the time evolution of dark solitons from the DSS corresponds with time-independent optical spatial solitons studies in a similar media. Lastly, BSS and DSS found at low amplitude limits are fundamental soliton solutions or initial state soliton (at low peak intensity ratio regime) that can play an important role in further investigations of optical spatial solitons formation in novel photorefractive media.

Suppression of Pre-Pulse of Chirped Laser Pulse by Scanning Amplitude Limiting Approach Based on Quadratic Electro-Optic Effect

The too intense pre-pulse breaks the conditions of interaction of main pulse with target in experiments where laser pulses interact with matter. An approach of pre-pulse suppression by scanning amplitude limiting is proposed based on quadratic electro-optic effect, according to the characteristics of frequency varies with time of the chirped laser pulse. The scanning amplitude limiting scheme with a Mach-Zehnder interferometer system is depicted and the properties of pre-pulse suppression are analysed both theoretically and numerically. For 800nm central wavelength and magnitude ns duration chirped laser pulse, the simulation result shows that the pre-pulse is suppressed on a scale of 10% to 1‰ or more on the premise of appropriate controlling voltage. Furthermore, the suppressing performance of pre-pulse is sensitive to the deviation and time-delay of voltage which affects the transmittance of system, and it is necessary to reduce the voltage deviation and time-delay so as to suppress the pre-pulse more severe.

Temperature effects on soliton pairs in novel photorefractive crystals having both the linear and quadratic electro-optic effects

We investigate and formulate a detailed theory studying the temperature effects on bright-dark optical spatial soliton pair in the novel photorefractive crystals having both the nonlinearities i.e., the quadratic and linear electro-optic effects. The coupled modified Nonlinear Schrodinger (NLS) equations is solved exactly to obtain analytical solutions for both the components. There are few physical factors which are dependent on the temperature: the dielectric constant, dark irradiance and the diffusion current. We consider the variation of dielectric constant and dark irradiance to study the effect on the nonlinearity. Various FWHM curves are plotted which give us an idea of the self trapping nonlinearity’s dependence on the temperature

Quadratic electro-optic effect in the nonconjugated conductive polymer iodine-doped polyethylene terephthalate

Quadratic electro-optic effect has been measured in the nonconjugated conductive polymer iodine-doped polyethylene terephthalate (PET). Films of PET were doped with iodine in the vapor phase using standard procedure. The optical absorption and FTIR spectroscopic results show that iodine doping causes a charge-transfer from the terephthalic ring to iodine, thus forming a metallic quantum dot of subnanometer dimension. Nonlinear optical measurements were performed on the iodine-doped PET samples using field-induced birefringence method at 633 nm with lock-in detection. The magnitude of the Kerr coefficient for varying doping levels was determined. The magnitudes were shown to increase with doping level. For an iodine molar concentration of 0.28, a Kerr coefficient of ∼1.5 × 10−11 m/V2 was measured. For a molar concentration of iodine of 0.83, the measured Kerr coefficient was ∼5 × 10−11 m/V2. These magnitudes are comparable to (slightly smaller than) the Kerr coefficients measured in other iodine-doped nonconjugated conductive polymers representing metallic quantum dots of subnanometer dimensions.

Temperature effects on Manakov solitons in biased photorefractive crystals exhibiting the linear and quadratic electro-optic effect simultaneously

We investigate the effect of temperature on Manakov solitons in biased photorefractive crystals having both linear and quadratic electro-optic effects simultaneously. Two different physical quantities, namely, the dielectric constant and the dark irradiance, have a temperature dependence which in turn affects the Manakov solitons. We consider three realizations of the Manakov solitons for our present analysis, namely, the bright–bright, dark–dark and bright–dark Manakov soliton pair. The existence curve and its modification due to temperature has been studied in detail for each of the Manakov soliton pair. A comprehensive investigation of the functional dependence of the soliton width with temperature is undertaken for different parameters like beam intensity and external electric field for each of the Manakov soliton pair. The tuning of photorefractive soliton characteristics by changing of temperature has potential practical applications in optical networks and optical waveguiding.

Nonlinear terahertz Kerr effect in quasi-2D MnPS3

The quadratic electro-optic effect (Kerr effect) is shown to be efficiently induced by a terahertz (THz) electric field in the quasi-two-dimensional (2D) material MnPS3. The waveform of the THz-induced response practically follows the intensity of the employed nearly single-cycle THz pulse. While neither THz-induced absorption nor the linear electro-optical effect are observed, we demonstrate that the THz electric field induces the refraction coefficient anisotropy experienced by light at the wavelength of 800 nm. In our experiment, the anisotropy results in polarization rotation of the light and corresponds to a nonlinear refractive index of the sample of approximately 13.1 × 10−14 W−1 cm2. This promotes the quasi-2D MnPS3 as a promising candidate for practical application in future ultrafast electro-optical devices.

Enormous electro-optic effect in paraelectric nanodisordered KTa1-xNbxO3 crystal.

Recent experiments have revealed that the order of the electro-optic (EO) effect depends on the frequency of electric field in paraelectric nanodisordered KTa1-xNbxO3 (KTN) crystal. Through the dielectric frequency spectrum under the bias electric field, enormous linear and quadratic EO effects were discovered at the resonance frequencies, which changed the perception that only the quadratic EO effect exists. Applying just a small AC electric field of 6 V/mm, the effective linear EO coefficient reached 478 pm/V at 609 kHz, and the effective quadratic EO coefficient reached 4.39*10-13m2V-2at 302 kHz. The reason why an extremely low electric field results in an enormous EO coefficient is attributed to the resonance between the polar nanoregions (PNRs) and the electric field, induced by the field-driven reorientation of free dipoles on the boundary of the PNRs. In addition, the order of EO effect depending on the frequency of electric field was attributed to the motion modes of the PNR. This finding improves the understanding of how the EO effect is caused by field-driven PNR dynamics, but also provides a basis for the development of EO devices.

Broad temperature range ferrielectric liquid crystal as a highly sensitive quadratic electro-optical material.

A chiral smectic liquid crystal in which a ferrielectric phase with a helix pitch p0 less than 125 nm exists over a temperature range of at least from -3°C to +36°C has been developed. Such a wide temperature range (including room temperatures) of the ferrielectric phase with a subwavelength helix pitch has been achieved for the first time, to the best of our knowledge, which creates opportunities for the practical use of ferrielectric liquid crystals. A quadratic electro-optical effect caused by deformations of the helix in an electric field is observed in the ferrielectric phase, and the Kerr coefficient, which reaches almost 200 nm/V2, is significantly higher than the same coefficient for the blue phase and for the smectic C* phase, which means a higher sensitivity of the developed ferrielectric liquid crystal to the electric field. The electro-optical response time does not exceed 300μs at room temperatures for this ferrielectric liquid crystal.

Vortex Solitons on Partially $\mathcal{PT}$-symmetric Azimuthal Lattices in a Medium with Quadratic Nonlinear Response

Vortex solitons in parity-time ($\mathcal{PT}$) symmetric and partially $\mathcal{PT}$ (p$\mathcal{PT}$) symmetric azimuthal lattices are demonstrated for a media with quadratic nonlinear response. Stability properties of the vortices are investigated comprehensively by linear spectra and nonlinear evolution of the governing equations, and it is shown that, although the existence domain of the $\mathcal{PT}$-symmetric and p$\mathcal{PT}$-symmetric lattices are identical, the stability region of $\mathcal{PT}$-symmetric lattice is narrower than that of the p$\mathcal{PT}$-symmetric lattice. It is also observed that deeper real part in the azimuthal potentials supports stability of vortex solitons, whereas deeper imaginary part and strong quadratic electro-optic effects impoverish stability properties of the vortices. Moreover, it is shown that there are different stability properties of vortices in p$\mathcal{PT}$-symmetric azimuthal potentials for different vorticity values, while there is no such difference for vortices in $\mathcal{PT}$-symmetric potentials.

Effect of ansatz on soliton propagation pattern in photorefractive crystals

Soliton propagation and some related parameter in a photorefractive crystal are considered. This study analyzes the soliton propagation on a photorefractive crystal having both linear and quadratic electro-optical effects through a time-dependent model of nonlinear dynamics equation using the numerical split-step Fourier method. In conducting analysis, we apply various models of ansatz as initial conditions of the optical beam envelope. Based on the studies conducted, ansatz influences the soliton propagation pattern in the photorefractive crystals. Besides, we found ansatz in secant-hyperbolic and Gaussian functions as the most appropriate model for realizing solitons in crystals. Finally, the photorefractive effect supports the evolution of soliton before it achieved a level of stability.

Large Quadratic Electro-Optic Effect of the PLZT Thin Films for Optical Communication Integrated Devices

Developing large electro-optic (EO) effect material is crucial technology for developing current levels of optical communication, and the lanthanum-modified lead zirconate titanate (PLZT) transpare...

Precise Method for Measuring the Quadratic Electro-Optic Effect in Noncentrosymmetric Crystals in the Presence of Natural Birefringence.

The application of the improved dynamic polarimetric method for the measurement of the quadratic electro-optic effect in NH4H2PO4 (ADP) crystal with the light beam propagating perpendicularly to its optical axis is presented. This technique can be applied in noncetrosymmetric crystals in the presence of natural birefringence even when the fast and slow rays diverge slightly, causing them to only partially interfere. The method allows for minor errors in cutting and orientation of the crystal samples, resulting in deviations from configurations in which the crystal symmetry vetoes the linear electro-optic effect. The occurring contribution of the linear effect, if it is not too large, not only does not exclude the measurement of the quadratic effect, but increases its accuracy. The method does not require any prior compensation for the natural birefringence. Its sensitivity allows for quadratic electro-optic effect measurements in ferroelectrics in temperatures significantly different from the phase transition temperature or in paraelectric crystals, for which this effect is relatively small.

Gap solitons supported by an optical lattice in biased photorefractive crystals having both the linear and quadratic electro-optic effect

Abstract We investigate the existence and stability of gap solitons supported by an optical lattice in biased photorefractive (PR) crystals having both the linear and quadratic electro-optic effect. Such PR crystals have an interesting interplay between the linear and quadratic nonlinearities. Gap solitons are predicted for the first time in such novel PR media. Taking a relevant example (PMN-0.33PT), we find that the gap solitons in the first finite bandgap are single humped, positive and symmetric solitons while those in the second finite band gap are antisymmetric and double humped. The power of the gap soliton depends upon the value of the axial propagation constant. We delineate three power regimes and study the gap soliton profiles in each region. The gap solitons in the first finite band gap are not linearly stable while those in the second finite band gap are found to be stable against small perturbations. We study their stability properties in detail throughout the finite band gaps. The interplay between the linear and quadratic electro-optic effect is studied by investigating the spatial profiles and stability of the gap solitons for different ratios of the linear and quadratic nonlinear coefficients.

Electroabsorption in Metallic Nanoparticles within Transparent Dielectric Media

Electroabsorption in metallic nanoparticles within transparent dielectric media has been measured. In particular, gold nanoparticles in glass and subnanometer-size metallic domains in iodine doped nonconjugated conductive polymer have been studied. Measurements have been made for applied ac fields at 4 kHz, at a wavelength close to the onset of the surface plasmon resonance. The measured electroabsorption (imaginary part of χ(3) or Kerr coefficient) has a quadratic dependence on electric field. Its magnitudes were compared for different sizes of the metallic nanoparticles down to the subnanometer-size particles in iodine-doped nonconjugated conductive polymer. As in the case of quadratic electro-optic effect reported earlier, electroabsorption has approximately a 1/d3 dependence, d being the diameter of nanoparticle. This is consistent with existing theories on confined metallic systems.

Coupling of separate solitons in a series circuit of two photon photorefractive crystals exhibiting simultaneous quadratic and linear nonlinearities

Separately coupled optical spatial solitons are shown to exist in a biased series two-photon photorefractive(TPPR) crystal circuit consisting of two TPPR crystals which have the quadratic and linear electro-optic(EO) effect present simultaneously. The space charge field in each photorefractive(PR) crystal in the circuit has been derived. We find that the space charge field in each crystal is coupled with the space charge field in the other crystal. We consider the cases of separately coupled bright, dark and grey solitons and obtain the numerical solutions for the spatial solitons’ profile. The coupling effect due to the soliton peak intensity in each crystal and the gating beam intensity is studied in detail. The light induced current causes a change in the spatial profile of the dark or grey soliton in one of the crystal which results in a change in the spatial profile and propagation of the soliton in the other crystal. We also find that the bright soliton intensity in one crystal does not affect the soliton in the other crystal. A change in the gating beam intensity in one crystal influences the soliton in the other crystal and this is true for all the three cases of dark, grey and bright separate soliton pairs.