Banmali S. Rawat

DGS based SIR filters for wireless communication on anisotropic substrate

Low pass (LP) and band pass (BP) filters using stepped impedance resonator (SIR) utilizing band-reject behavior of defected ground structure (DGS) for wireless applications are proposed. These new configurations of DGS filters are fabricated on both isotropic and anisotropic substrates. Improvement in cut-off characteristics for both LP filter and BP filter, and fractional bandwidth improvement of BP filter using anisotropic substrate over isotropic substrate are reported. A size reduction of up to 67.7% using the DGS configuration over the conventional three-pole SIR- BPF is achieved.

Effect of optical beat interference on channel spacing in DWDM optical systems

The information capacity of dense wavelength division multiplexing (DWDM) optical systems is reviewed. The effect of optical beat interference of closely spaced optical carriers sets the limit on the allowed channel spacing even in the absence of nonlinear effects. Present DWDM networks operating at 10.7 Gb/s in the C and L bands region have channel spacing no less than 25 GHz. We show that this limit is a constraint and smaller spacing may not be allowed without further optical and electrical pulse shaping.

Effect of laser source nonlinearity on optical heterodyne interferometry

In this paper, an optical heterodyne interferometric detection model with a frequency-ramped laser diode (LD) has been analyzed. The effect of the nonlinearity of the LD source on the optical heterodyne interferometry has been investigated in two different ways, which are the power-distortion Fourier series analysis and the harmonic distortion analysis. The general formulation between the tangent of the tested phase and the interference fringe have been presented with the analysis of the beat signal in the frequency domain by each methodology. The numerical results of these formulations have been presented.

Peculiarities of the Spatial Power Spectrum of Scattered Electromagnetic Waves in the Turbulent Collision Magnetized Plasma

General dispersion equation is obtained at arbitrary inclination angles of the external magnetic field and wave vector of an incident EM wave. Statistical characteristics of the phase fluctuations of scattered high frequency EM waves in the collision magnetized plasma caused by electron density and external magnetic field fluctuations taking into account polarization coefficients for both ordinary and extraordinary waves are calculated analytically. The influence of collision frequency, anisotropy factor and angle of inclination of prolate irregularities of electron density fluctuations with respect to the geomagnetic field of lines on the broadening of the spatial power spectrum is analyzed. Phase portraits of the phase fluctuations caused by the geomagnetic field fluctuations are constructed at different spatial parameters characterizing magnetic field and electron density fluctuations. Numerical calculations are carried out for the ionospheric F -region parameters using experimental data.

Analysis of three-dimensional acousto-optic cell array (AOCA) system based on generalized equaitons

The acousto-optically tuned devices are becoming quite popular in dense wavelength division multiplexing (DWDM) applications due to low insertion loss, less cross talk and freedom from the grating wavelength drift due to thermal variations. Acousto-optic cell diffracts the optical beam depending on the wavelengths and acoustic frequency. This property is used to exploit acousto-optic cell array (AOCA) for multiplex/demultiplex (MUX/DEMUX) and cross-connect applications in DWDM in optical communication. Acousto-optic diffraction grating is preferred over other systems as the directions of the deflected light beams can be controlled by changing the frequency of the drive signal and the light intensity of the beams can be adjusted by changing the power of the drive signal. This paper presents the analysis and performance of three-dimensional acousto-optic cell array system based on generalized equations. Numerical results have been obtained for optical wavelengths vs deflection angles, incident angles vs deflection angles in different directions for several stages. The wavelengths under consideration range between 1500-1600 nm and the effects of acoustic wave velocity variations have also been considered.

Analysis of two dimensional multistage acousto-optic cell array system based on generalized equations for different parameters

Two dimensional multistage AOCA system based on generalized equations has been analyzed. Numerical results for Bragg angle as a function of acoustic frequency, deflection angles for different wavelengths, normalized power and diffraction efficiency with and without phase shift between consecutive arrays having different channel spacing based on generalized equations have been obtained.

Analsysis of soliton interaction with local defects in fiber Bragg grating

The interaction of a fiber Bragg grating point like soliton with local defects has been thoroughly analyzed. The stability of trapped solitons has also been discussed. The main finding reveals the reversal of the sign of interaction from attraction to repulsion. It is also observed that the attraction depends on the accuracy of the numerical simulations.

Analysis of a Tunable Asymmetrical Nonlinear Directional Coupler Using Laser Beam Interaction with Semiconductor Medium

A tunable asymmetrical nonlinear directional coupler (NLDC) having interaction of a laser beam with the semiconductor medium of the coupler has been thoroughly analyzed. The analysis is based on the coupled-mode theory for coupled lines. Laser beam is used for achieving optical control over the nonlinear directional coupler. The effects of various parameters such as plasma density, waveguide width, laser beam frequency and laser spot position on the coupling of power, on an asymmetric coupler have been investigated and presented.

Analysis of a laser beam controlled nonlinear directional coupler for optical signal processing

One of the most promising devices for high speed optical signal processing is the Nonlinear Directional Coupler (NLDC). In this paper an asymmetric nonlinear directional coupler controlled by an external laser beam focused on the surface of the coupler has been analyzed. The analysis is based on couple-mode theory using rigorous perturbation technique and enables one to obtain asymptotically correct coupled-mode equations. The effects of various parameters such as plasma density, waveguide width, laser beam frequency and laser spot position on the coupling of power have been investigated and presented.

Optical blackplane technology for a large sonnet multi-service switch

Current optical networks mainly serve very high data rates and long distances while short reach communication and low data rates is dominated by electrical interconnects. In this work, we examine and evaluate optical backplane technology based on substrate guided interconnects.