Birefringent Optical Waveguides Research Articles

Analytical investigations of propagation of ultra-broad nonparaxial pulses in a birefringent optical waveguide by three computational ideas

This paper mainly concentrates on obtaining solutions and other exact traveling wave solutions using the generalized G-expansion method. Some new exact solutions of the coupled nonlinear Schrödinger system using the mentioned method are extracted. This method is based on the general properties of the nonlinear model of expansion method with the support of the complete discrimination system for polynomial method and computer algebraic system (AS) such as Maple or Mathematica. The nonparaxial solitons with the propagation of ultra-broad nonparaxial pulses in a birefringent optical waveguide is studied. To attain this, an illustrative case of the coupled nonlinear Helmholtz (CNLH) system is given to illustrate the possibility and unwavering quality of the strategy utilized in this research. These solutions can be significant in the use of understanding the behavior of wave guides when studying Kerr medium, optical computing and optical beams in Kerr like nonlinear media. Physical meanings of solutions are simulated by various Figures in 2D and 3D along with density graphs. The constraint conditions of the existence of solutions are also reported in detail. Finally, the modulation instability analysis of the CNLH equation is presented in detail.

Propagation of the ordinary and extraordinary modulated optical pulses in a nonlinear Kerr-type birefringent optical waveguide: Analytical description

The purpose of this work is to describe theoretically the behavior of modulated pulses in nonlinear birefringent optical waveguides and particularly in the optical fibers, by taking into account the anisotropy of the medium as well as the orientation of the optical axis with respect to the propagation direction of an incoming pulse. Firstly, the multiple times scale method is used to describe the behavior of an optical pulse in the waveguide whose optical axis is perpendicular to the direction of propagation of the pulse. It appears that in the nonlinear regime, the optical pulse splits into two different modes in propagation namely an ordinary mode and an extraordinary mode which propagate with different group velocities. These modes are described by the different nonlinear Schrodinger (NLS) equations involving nonlinear Kerr-like responses. Next, we turn attention to the waveguide whose the optical axis is parallel to the direction of propagation of an incoming pulse and found that the two modes continue to exist, and are also described by different NLS equations. In addition, we show that for some parameter regime, the two modes become identical and described by the same NLS equation.

Nonparaxial solitons and their interaction dynamics in coupled nonlinear Helmholtz systems

It is well-known that the nonparaxiality plays an important role in the fabrication of nanoscale devices. In this paper, we study the existence of nonparaxial solitons in a dimensionless coupled nonlinear Schrödinger system with cross-phase modulation (XPM), which enables the propagation of ultra-broad nonparaxial pulses in a birefringent optical waveguide. Despite the fact that the system is a nonintegrable one (Tamilselvan et al., 2020), we obtain a bright soliton solution analytically by employing the standard Hirota’s bilinearization method. Subsequently we numerically investigate the scattering dynamics of two and three bright solitary waves using the general solution as the seed one by adopting the split-step Fourier method based on the Feit-Flock algorithm. We explain how the soliton parameters such as separation distance and relative phase influence the interaction between the nonparaxial bright solitons. In particular, we report a bunch of interesting phenomena of soliton interactions, which include oscillating bound solitons when the phase of the two solitary waves are equal and parallel propagation as the phase is changed to out-of phase with a zig-zag pattern. Similarly the in-phase three solitary waves also exhibit a novel interaction which mimics a triple knot structure which has never been observed before in the framework of coupled nonlinear Helmholtz systems. We believe that our results would pave a way for future research generating optical memories based on the nonparaxial solitons.

Remotely biasing the electro-optic response of an electric field sensing-detection system using LiNbO3 asymmetric Mach–Zehnder optical retarders

Lithium niobate (LiNbO3) electro-optic birefringent optical waveguides or electro-optic Mach-Zehnder interferometers have been proposed as electric field sensors in recent years. Electrode-less sensing using LiNbO3 devices is an active research domain, as they do not perturb the measurands. Asymmetric LiNbO3 Mach-Zehnder interferometers can be used as electrode-less electric field sensors. However, as an electrode-less sensor cannot be electrically adjusted in the linear region of its electro-optic transfer function, the measurand is imprinted anywhere on such a characteristic. With a view toward achieving a linear response of the sensing-detection process, a simple technique for remotely biasing the electro-optic response, based on two cascaded LiNbO3 AMZI optical retarders, is described in this paper.

Photonic Filters Using Optical Retarders Based on Birefringent Optical Media

Photonic filters can be used for filtering the spectrum of wide-band optical sources such as light emitting diodes (LED) or multimode laser diodes(MMLD). In this work the use of birefringen optical media such as polarization maintaining fiber (PMF) or birefringent optical waveguides on Lithium Niobate (LiNbO3) crystal, perform as optical filters.

Equivalence principle and quantum mechanics: quantum simulation with entangled photons.

Einstein's equivalence principle (EP) states the complete physical equivalence of a gravitational field and corresponding inertial field in an accelerated reference frame. However, to what extent the EP remains valid in non-relativistic quantum mechanics is a controversial issue. To avoid violation of the EP, Bargmann's superselection rule forbids a coherent superposition of states with different masses. Here we suggest a quantum simulation of non-relativistic Schrödinger particle dynamics in non-inertial reference frames, which is based on the propagation of polarization-entangled photon pairs in curved and birefringent optical waveguides and Hong-Ou-Mandel quantum interference measurement. The photonic simulator can emulate superposition of mass states, which would lead to violation of the EP.

On the Design of Video-Bandwidth Electric Field Sensing Systems Using Dielectric ${\rm LiNbO}_{3}$ Electro-Optic Sensors and Optical Delays as Signal Carriers

As the measurement of wide-band (multi-megahertz) electric fields is often of practical interest in industrial and commercial environments, in this paper, a methodology of design and implementation of a wide-band electric field sensing scheme, using optical delays as information carriers is described. The scheme is based on a lithium niobate (LiNbO3) birefringent optical waveguide that performs simultaneously as an optical retarder and as a dielectric (electrode-less) sensor. In this scheme, the LiNbO3 sensor introduces an optical delay and simultaneously senses an on-air electric field and imprints it around an optical delay. At the receiver, the sensed electric field is detected when the sensor and demodulator are optically matched, i.e., when both introduce identical optical delays. An important aspect, when sensing electric fields using LiNbO3 dielectric sensors, is that the optically sensed field is weaker than the external field by a factor given by the ratio of the permittivity of the surrounding dielectric media over the LiNbO3 permittivity (boundary condition for normal electric fields). When the surrounding media is air, the optically sensed electric field is 35 times weaker than the external field, as described in this paper. Another practical issue is that a birefringent optical waveguide is highly sensitive to optical polarization variations. Such a sensitivity implies that the output dc component of the received light changes with time (dc-drift). The dc-drift performance of the proposed electric field sensing scheme is measured and reported in this paper. The dc-drift can be minimized using polarization-insensitive LiNbO3 unbalanced Mach-Zehnder interferometers.

Electric Field Sensing Scheme Based on Matched $ \hbox{LiNbO}_{3}$ Electro-Optic Retarders

In this paper, a wideband-electric-field-sensing scheme that uses optically matched integrated optics electrooptic devices and coherence modulation of light is described. In a coherence modulation scheme, the integrated optics sensor detects the electric field and imprints it around an optical delay. The optical delay is generated by a birefringent optical waveguide in a lithium niobate (LiNbO3) integrated optics two-wave interferometer. The modulated optical delay, acting as an information carrier, is transmitted through an optical fiber channel. At the receiver, light is demodulated by a second integrated optics two-wave interferometer, which also introduces a second optical delay. The optical delays on the sensor and demodulator are matched at the same value. The integrated optics demodulator measures the autocorrelation of light around the optical delay value, and the imprinted electric field is recuperated as a linear variation of the received optical power. The matching of the sensor and demodulator allows a direct detection of the electric field, giving a unique feature to this fiber-integrated optics scheme. The experimental setup described here uses two pigtailed LiNbO3 electrooptic crystals: one acting as the electric field sensor and the other acting as the optical demodulator. The wideband sensing range on the experimental setup corresponds to frequencies between 0 and 20 kHz.

Polarization instability, steering, and switching of discrete vector solitons

We study the dynamics of discrete vector solitons in arrays of weakly coupled birefringent optical waveguides with cubic nonlinear response. We start with a modulational instability analysis, followed by approximate analytical solutions in the form of strongly localized modes. Next, we compute the effective Peierls-Nabarro potential for these modes and obtain the spatial average of the power transfer between both polarizations modes as a function of their relative phase. Finally, we combine the concepts of polarization mode instability with discreteness-induced beam trapping by the array, and demonstrate numerically the amplification of a weak signal by a strong pump of the other polarization, combined with simultaneous discretized all-optical switching.

Analysis of a novel stress-sensing technique based on light scattering by an array of birefringent optical waveguides

We propose a new stress-sensing technique based upon measurement of light scattering produced by an array of birefringent waveguides. When external stress is applied to the array of waveguides, their optical properties are modified via the photoelastic effect. Specifically, the intensity of light scattered by the optical waveguides is significantly affected by stress. In this work we analyse theoretically this stress-induced change. Our numerical simulations show that this effect provides a means to assess the strength and direction of the external force.

Light scattering by an array of birefringent optical waveguides: theoretical foundations

We develop a computational method for calculating the spatial profile of the electromagnetic field after scattering by an array of waveguides. Our formalism is very general and includes chromatic dependence, the influence of the array arrangement, and other effects such as the effect of stress. Our calculations of the amplitude and phase of scattered light provide valuable information about the features of the waveguides. These results can be applied to different areas of study, such as biological waveguides and fiber sensing.