Search

Your search keyword '"Jayaraman, V."' showing total 1,179 results
Start Over Author "Jayaraman, V."
1,179 results on '"Jayaraman, V."'

17. Midwave infrared resonant cavity detectors with >70% quantum efficiency.

Author

Jackson, E. M., Kim, C. S., Kim, M., Canedy, C. L., Juarez, X. G., Ellis, C. T., Nolde, J. A., Aifer, E. H., Iversen, C., Burgner, C., Kolasa, B., Vurgaftman, I., Jayaraman, V., and Meyer, J. R.

Abstract

We report resonant cavity infrared detectors with a peak wavelength of 4.54–4.58 μm that combine external quantum efficiency (EQE) exceeding 70% with spectral bandwidth 20–40 nm and ≤2% EQE at all non-resonance wavelengths between 4 and 5 μm. A 300-nm-thick absorber assures that most of the radiation propagating in the cavity produces photocurrent rather than parasitic loss. The cavity is formed by heterogeneously bonding a midwave infrared (MWIR) nBn detector chip to a GaAs/AlGaAs distributed Bragg reflector, etching away the GaSb substrate, forming mesas with diameter ≈100 μm, depositing a Ge spacer, and then depositing a single-period Ge-SiO2 top mirror. At all temperatures between 125 and 300 K, the responsivity at 150 mV bias exceeds 2.2 A/W and the EQE exceeds 61%. When the thermal background current for a realistic system scenario with f/4 optic that views a 300 K scene is derived from the observed EQE spectra, the resulting specific detectivity D* of 7.5 × 1012 cmHz½/W at 125 K operating temperature is 4.5 times higher than for a state-of-the-art broadband MWIR HgCdTe device. Simulations of the cavity performance indicate that EQE > 90% may be feasible following minimization of parasitic optical loss and maximization of the photocarrier collection efficiency. Potential applications include free space optical communication, chemical sensing, on-chip spectroscopy, and hyperspectral imaging. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

33. Clustering of Complex Networks and Community Detection Using Group Search Optimization

Author

Kumar, G. Kishore and Jayaraman, V. K.

Subjects
Computer Science - Neural and Evolutionary Computing, Computer Science - Data Structures and Algorithms
Abstract

Group Search Optimizer(GSO) is one of the best algorithms, is very new in the field of Evolutionary Computing. It is very robust and efficient algorithm, which is inspired by animal searching behaviour. The paper describes an application of GSO to clustering of networks. We have tested GSO against five standard benchmark datasets, GSO algorithm is proved very competitive in terms of accuracy and convergence speed., Comment: 7 pages, 2 figures

Published
2013

47. Rapid separation, purification of 90Sr and feasibility studies for the preparation of 90Y resin microsphere brachytherapy source from FBTR irradiated fuel dissolver solution.

Author

Saha, Debasish, Vithya, J., Kalaiarasu, T., Bola Sankar, D., Rajeswari, S., Arulkumari, A., Manoravi, P., Sundararajan, K., Jayaraman, V., Sivaraman, N., and Venkatraman, B.

Subjects
RADIOISOTOPE brachytherapy, ION exchange chromatography, RADIOISOTOPES, LIQUID scintillation counting, ION exchange resins, FAST reactors, FUEL cells
Abstract

Presently several beta emitting radionuclides are in use as brachytherapy sources, due to their inherent advantages of short-range radiation dose delivery compared to their gamma emitting counterparts. 90Y is one of the well-known hard beta-emitting radioisotopes for the therapeutic application of radioactivity. Among various other modalities, 90Y resin microsphere as a brachytherapy source has its application for liver cancer. In the present study, 90Y was recovered from 235,238U,239Pu(nfast,f)90Sr(β−)90Y using Sr selective crown ether followed by quick purification using the Ion Chromatography technique. The purified 90Y was labelled in strong cation exchange resin to form 90Y resin microsphere. Various quality control parameters, e.g., water solubility, chemical, radionuclidic purity, and half-life, were verified using Gamma spectrometry, Cerenkov, and Liquid Scintillation Counting techniques. The obtained half-life was 64.05 h, which is in excellent agreement with the literature and is indirect evidence of the very high radionuclidic purity of the sample. A rapid method for the synthesis of 90Y resin microsphere brachytherapy source is being reported for the first time after its recovery from irradiated fast reactor fuel dissolver solution. After the separation of 90Sr along with trace level impurities inside the hot cell, simultaneous purification of parent 90Sr and daughter 90Y using single-stage Ion Chromatography step takes 15–25 min only in comparison to 24 h or more time using multistage conventional Ion exchange chromatography column, which saves the separation time and in turn, increase the yield of 90Y per separation campaign. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

49. High-power 1320-nm wafer-bonded VCSELs with tunnel junctions

Author

Jayaraman, V, Mehta, M, Jackson, A W, Wu, S, Okuno, Y, Piprek, J, and Bowers, J E

Subjects
long wavelength, semiconductor lasers, tunnel diodes, vertical cavity, vertical-cavity surface-emitting laser (VCSEL), wafer bonding
Abstract

A new long-wavelength vertical-cavity surface-emitting laser structure is described that utilizes AlGaAs-GaAs mirrors bonded to AlInGaAs-InP quantum wells with an intracavity buried tunnel junction. This structure offers complete wavelength flexibility in the 1250-1650 nm fiber communication bands and reduces the high free-carrier losses and bonded junction voltage drops in previous devices. The intracavity contacts electrically bypass the bonded junctions to reduce threshold voltage. N-type current spreading layers and undoped AlGaAs mirrors minimize optical losses. This has enabled 134 degreesC maximum continuous-wave lasing temperature, 2-mW room-temperature continuous-wave single-mode power, and 1-mW single-mode power at 80 degreesC, in various devices in the 1310-1340 nm wavelength range.

Published
2003

Catalog

Books, media, physical & digital resources
See catalog results