Vishnu Priye

Analysis and design of a novel leaky YIG film guided wave optical isolator

A guided wave optical isolator using a four layered leaky yttrium iron garnet (YIG) waveguide with a YIG guiding layer is proposed and analyzed through a transfer matrix formulation. The dependence of isolation characteristics on different waveguide parameters are discussed. It is shown that for four layered structures an isolation ratio of about 24 dB can be achieved with YIG films having large gyrotropy. It is also shown that by replacing the single guiding YIG film with multilayers of YIG with compensated walls and proper permittivity, high isolation ratio can be achieved even with currently available YIG films having low gyrotropy.

Extended shortcut tree routing for ZigBee based wireless sensor network

Energy efficiency and network lifetime are main concerns in WSN. In order to improve these factors ZigBee plays an important role. Low cost, low data rate features of ZigBee results in low power consumption and makes it useful in wireless sensor networks, increasing life of small batteries of nodes in the network. Since tree routing in ZigBee does not require any routing tables to send the packet to the destination, it can be used in ZigBee end devices that have limited resources. Routing protocols such as AODV (Ad-hoc on demand distance vector routing), ZTR (ZigBee tree routing), and STR (Shortcut tree routing) are compared on the basis of different performance metrics (End to end delay, routing overload, throughput, packet delivery ratio). An extensive simulation in NS2 is carried out. The performance evaluation shows that STR achieves better performance as compared to other two routing protocols. But there are some limitations of the STR method. Performance of packet delivery ratio of STR is less as compared to AODV. Performance of end to end delay of STR is poor as compared to AODV. Hence ESTR is proposed. The main aim of proposed ESTR Extended STR is to present new ZigBee network routing protocol with goal of improving the performance of ESTR in terms of PDR and delay against STR and AODV.

All-Optical XOR Gate Based on XGM Properties of SOA

A new configuration of all-optical 2 input XOR Gate is proposed that incorporates two semiconductor optical amplifiers (SOAs). The proposed XOR Logic is numerically simulated by solving nonlinear coupled equations that explain cross gain modulation (XGM) effect in individual SOAs. In this paper we describe a novel all-optical binary all-optical 2 input XOR Gate that demonstrates the ability of all-optical digital processing to perform even more complex operations.

Multiple scale analysis of low index subwavelength slot waveguide electrooptic modulator

Multiple scale analysis of slot waveguide electrooptic modulator of few nanometer width and lower refractive index than the adjacent waveguides is presented for the first time to predict phase modulation due to variation in the refractive index in the slot by application of external voltage. The effect of different electrooptic coefficient pertaining to diverse polymers on voltage required for π phase change is investigated. Phase modulation and corresponding intensity modulation for practical waveguide configuration is theoretically demonstrated.

Power penalty in WDM system due to stimulated Raman crosstalk

Power penalty in N-channel WDM system due to stimulated Raman crosstalk is investigated in a typical configuration consisting of two periodically amplified single mode fibers (SMF) by Erbium-doped fiber amplifier (EDFA) and dispersion compensated by dispersion compensating fiber (DCF). Results show that minimum power penalty is in central wavelength region of WDM system and inclusion of EDFA and DCF increases power penalty. Power penalty in individual channels due to remaining N-1 channels has also been investigated. The dependence of power penalty due to stimulated Raman scattering (SRS) on average input power, interchannel separation and bit rate of the system has also been assessed.

Parametric Analysis of Silicon Nanowire Optical Rectangular Waveguide Sensor

A silicon nanowire optical rectangular waveguide (SNORW) on 220-nm silicon-on-insulator platform is proposed for optical sensing of gases. Analysis and interdependence of critical parameters of SNORW are evaluated. Overall performance in terms of power confinement, waveguide sensitivity, and compactness is compared with that of conventional slot and ridge slot waveguides. Exploratory results on SNORW application as methane sensor are also discussed.

Instantaneous microwave frequency measurement using dual drive Mach-Zehnder Modulator

A technique for instantaneous microwave frequency measurement using dual drive Mach-Zehnder Modulator is proposed and demonstrated. In the proposed technique a microwave signal for which frequency is to be use is phased modulated on the two optical carriers. These carrier wavelength are extracted from the side bands of dual drive LiNbO3 Mach-Zehnder Modulator, and this modulated signal passed through dispersive optical fiber and detected at two photo detector. Dispersive fiber provide the chromatic dispersion and two microwave signal will experience different power fading, which leads to different power level at different frequency. A fixed relation between power and unknown frequency is obtained. The microwave frequency is estimated by measuring the microwave power.

Rectangular Array Multicore Fiber Realizing Low Crosstalk Suitable for Next-Generation Short-Reach Optical Interconnects With Low Misalignment Loss

Toward the next-generation exa-scale short-reach optical interconnects (OIs) supporting large-capacity data transmission, a compact computer-compatible 8-core heterogeneous trench-assisted multicore fiber (TA-MCF) is proposed, in which cores are arranged in a rectangular array. To analyze the crosstalk (XT) between adjacent cores of TA-MCF OI, a rigorous full-vectorial H- field finite element method (FEM) and coupled power theory are applied. The impact of various trench design parameters on the mode-coupling coefficient Cmn and the coupling length Lc is discussed in detail. An accurate explicit condition for the achievement of low XT in an 8-core heterogeneous TA-MCF OI is obtained through numerical simulations. A rigorous modal solution approach based on the computationally efficient FEM and the least squares boundary residual method is employed to analyze the coupling loss caused by the misalignment to a butt-coupled TA-MCF OI.

Error probability performance of a short-reach multicore fiber optical interconnect transmission system.

A standalone module for rectangular array multicore fiber (MCF)-based optical interconnect (OI) is realized that includes inherent intercore crosstalk and provides space division multiplexed coupling/decoupling of optical power. The module is integrated in a short-reach communication system to provide bit error probability (BEP). Next, a closed-form equation for BEP applicable to MCF OI with intercore crosstalk is derived. For characteristic parameters of the module, results obtained by two approaches agree within 1% for 40 Gbps per channel and predict an error-free transmission of aggregated data rate of 2.5 Tbps through the MCF OI under consideration.

Performance analysis of an optically amplified add/drop wavelength division multiplexing fiber communication link

Abstract. The impact of power transients stemming from channel reconfiguration on erbium-doped fiber amplifier (EDFA) gain dynamics in wavelength division multiplexing (WDM) optical networks is investigated. The impact of power transients on EDFA gain dynamics leads to error bursts and impact on the network performance. First, we model an EDFA simulator with one-dimensional nonlinear differential equation that describes the time-dependent population density. For the model to show gain flattening multiplexed channels at different wavelengths, new function blocks are used. Next, to simulate the noise performance of EDFA, forward amplified spontaneous emission noise blocks are designed that add noise dynamically at signal wavelength. Finally, EDFA simulator is used as an in-line amplifier for amplitude shift keying-modulated WDM fiber communication link where the gain clamping facility is provided to protect power imbalance at the receiver. Next, we apply the mentioned model in the estimation on the link performance parameters, like signal-to-noise ratio and bit error rate, and variations in these values by channel add/drop results from variation in incremented signal output of EDFA. The variations are almost equal at different wavelengths in C- or L-band, which is due to flat gain and also the gain clamping facility of the present EDFA simulator.