Meha Sharma

Qualitative analysis of gain spectra of InGaAlAs/InP lasing nano-heterostructure

This paper deals with the studies of lasing characteristics along with the gain spectra of compressively strained and step SCH based In0.71Ga0.21Al0.08As/InP lasing nano-heterostructure within TE polarization mode, taking into account the variation in well width of the single quantum well of the nano-heterostructure. In addition, the compressive conduction and valence bands dispersion profiles for quantum well of the material composition In0.71Ga0.21Al0.08As at temperature 300 K and strain ~1.12% have been studied using 4 × 4 Luttinger Hamiltonian. For the proposed nano-heterostructure, the quantum well width dependence of differential gain, refractive index change and relaxation oscillation frequency with current density have been studied. Moreover, the G–J characteristics of the nano-heterostructure at different well widths have also been investigated, that provided significant information about threshold current density, threshold gain and transparency current density. The results obtained in the study of nano-heterostructure suggest that the gain and relaxation oscillation frequency both are decreased with increasing quantum well width but the required lasing wavelength is found to shift towards higher values. On behalf of qualitative analysis of the structure, the well width of 6 nm is found more suitable for lasing action at the wavelength of 1.55 μm due to minimum optical attenuation and minimum dispersion within the waveguide. The results achieved are, therefore, very important in the emerging area of nano-optoelectronics.

Design and implementation of TDPC sleep scheduling algorithm for energy efficient networks

The key point for successful operation of routing based sensor networks is to save power consumption and thus utilize the energy efficiently. Researchers have been working on the same by following standard Type I, II and III sleep scheduling algorithms. In this paper we have proposed a new approach Traffic Dependent Power Conservation, which proactively measures and models the traffic of the network and the sleep window size is estimated by considering the entire traffic of network as a cumulative flow instead of individual patterns. Authors are successful in modeling the proposed approach TDPC (Traffic Dependent Power Conservation) to provide enhanced capability to achieve power conservation.

Performance Modeling of Unified TDPC in IEEE 802.16e WiMAX

One of the major concerns in wireless networks is optimization of power as mobile devices are battery operated. Researchers have been constantly focusing on standard Type I or Type II power saving classes. In our previous work, limitation of standard Type I and Type II power saving classes in IEEE 802.16e was discussed and the idea of TDPC was suggested. In this paper, authors have proposed a new enhanced method of Traffic Dependent Power Conservation, in which each MSS is considered as a single member group initially and then groups are iteratively combined until reasonable sleep schedule is maintained. Authors have successfully modeled the suggested approach, Unified-TDPC to attain desired power optimization. Results clearly illustrates that Unified-TDPC, improve upon TDPC-cum and TDPC-divide and shows better power conservation at the cost of small delay in highly varying load.

A novel traffic dependent sleep scheduling method for energy conservation

Power conservation is a critical issue in wireless networks as the mobile devices are battery constrained and therefore researchers have been constantly working for saving power by following standard Type I, II and III sleep scheduling algorithms. In this paper we have proposed a new improved algorithm of Traffic Dependent Power Conservation, which proactively divides the MSSs(Mobile Subscriber Stations) into several groups and for each group assign a distinct awake time frame. Authors are successful in modeling the proposed approach TDPC-divide (Traffic Dependent Power Conservation-divide) to provide enhanced ability to achieve power conservation. Results demonstrate that TDPC-divide outperforms TDPC-cum and help conserving more power at the cost of slightly more delay in higher variation in load.

A comparative simulation based analysis of DSR and DSDV routing protocols

This paper reports a simulation based comparative analysis of Dynamic Source Routing On Demand Distance Vector (DSR) and Destination Sequenced Distance Vector (DSDV) protocol on the basis of parametric specifications like packet delivery ratio, packet lost, packet arrival rate and end to end delay. The information elicited from the simulation studies show that DSR has a consistent and uniform performance as compared to DSDV. We have also studied the behavior of both the protocols with increase in the node mobility. In addition to it the studies also report that DSR achieves significantly higher packet arrival rate, throughput, end to end delay and packet delivery ratio and lower packet lost rate as compared to DSDV. The simulation results assure the suitability of DSR for real time networking applications requiring higher throughput and lower packet drop rate.

Carrier dependent gain characteristics of InGaP/GaAs nano-heterostructure

This paper reports the lasing characteristics of SCH based InGaP/GaAs nano-heterostructure such as anti-guiding factor (a substantial parameter for optical gain), material gain, mode gain, and carrier induced refractive index change. The simulation studies also cover the variation in material gain and mode gain with respect to lasing wavelength and photonic energy. Furthermore, gain calculations have also been reported for different carrier concentrations. The theoretical results achieved reveal that maximum gain of 2921.535 /cm appears at wavelength 0.625 μm and corresponding photonic energy is 1.98 eV. In addition, the analysis also shows that the proposed nano heterostructure provides more optical gain in TE polarization mode than TM mode. A significant gain achieved at lasing wavelength promises the utility of proposed structure in optical fibre communication systems.

Gain investigation on strained InGaA1As/InP lasing nano-heterostructure

In this paper we have reported various lasing characteristics of strained InGaAlAs/InP nano-heterostructure. Under the effect of strain, behavior of material gain with lasing wavelength and current density has been studied and reported. In addition, differential gain and refractive index change with carriers has also been calculated. The maximum material gain for compressive strained heterostructure appears at the wavelength of 1.55 μm while for tensile strained heterostructure, it appears at the wavelength of 1.70 μm, The achieved results show that compressive strained structure is very important in the optical fiber based communication systems due to low attenuation.