Soumya Gupta

Homi Bhabha National Institute

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D. Bhattacharya

Inter-University Centre for Astronomy and Astrophysics

V. Bhalerao

Indian Institute of Technology Bombay

S. Vadawale

Physical Research Laboratory

Tanmoy Chattopadhyay

Kavli Institute for Particle Astrophysics and Cosmology

Tajinder Singh Arora

Aligarh Muslim University

Divita Saraogi

Indian Institute of Technology Bombay

N. P. S. Mithun

Physical Research Laboratory

Shabnam Iyyani

Indian Institute of Science Education and Research Thiruvananthapuram

Abhay Kumar

Rajendra Institute of Medical Sciences

A. R. Rao

Tata Institute of Fundamental Research

Cooperative Institutions

Inter-University Centre for Astronomy and Astrophysics

Aryabhatta Research Institute of Observational Sciences

Tata Institute of Fundamental Research

Instituto de Astrofísica de Andalucía

Indian Institute of Technology Bombay

Russian Academy of Sciences

Physical Research Laboratory

Vorago Technologies (United States)

Lomonosov Moscow State University

Goddard Space Flight Center

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Advances and improvements in VCSEL designing

Priyanka Goyal Soumya Gupta Gurjit Kaur

In 50 years of research and development, VCSEL (Vertical-cavity surface-emitting lasers) photonics opened up number of applications in various fields. VCSEL being inexpensive, reliable, and readily manufacturable is one of the most compact laser light sources for generation of high intensity coherent light in — free space, optical fibers, board to board, on-chip optical interconnects, module to module and other information related system networks. This paper reviews the efficiency, thermal stability and temperature stability of VCSEL. Change in wavelength of VCSEL or VCSEL arrays is caused by changing the properties of periodic mirrors, cavity length and substrate material. Such changes enable us to manipulate the speed of light. Optical interconnects in data centers and supercomputers are the most attracting site of interest. VCSEL shows higher coupling efficiency into fibers due to having a circular beam cross section and a low output beam divergence angle. Due to high quality vertical light emission by the device, number of VCSEL lasers can be implemented on a single chip. A review of the potential of the device and the challenges faced in the functioning of VCSEL are also presented.

Vertical-cavity surface-emitting laser

10.1109/iceeot.2016.7755518

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Citations (4)

Realization of lossy inductor employing current feedback operational amplifier and its applications

Tajinder Singh Arora Soumya Gupta

A grounded lossy inductor realization, with minimum number of active and passive components along with its various applications such as filter implementation, oscillator, is the motive of this manuscript. The proposed synthetic inductor utilities single current differencing buffered amplifier as an active device. The circuit comprises of two resistors and one grounded capacitor. Voltage mode high pass and low pass filter and single resistance controlled oscillator have also been demonstrated as application examples of implemented inductor. PSPICE simulation software has been used for verifying the designs along with its various applications.

Realization (probability)

Current-feedback operational amplifier

Lossy compression

Electronic component

10.1109/spin.2017.8049971

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A New Electronically Tunable CM/VM Oscillator Using All Grounded Components

Advances in intelligent systems and computing (2018)

Soumya Gupta M. Abdullah Sandhu Manish Gupta Tajinder Singh Arora

Oscillation (cell signaling)

Electronic component

Realization (probability)

Component (thermodynamics)

10.1007/978-981-13-1822-1_13

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Citations (7)

A Detailed Time-resolved and Energy-resolved Spectro-polarimetric Study of Bright Gamma-Ray Bursts Detected by AstroSat CZTI in Its First Year of Operation

The Astrophysical Journal (2024)

Rahul Gupta S. B. Pandey Soumya Gupta T. Chattopadhayay D. Bhattacharya

Abstract The radiation mechanism underlying the prompt emission remains unresolved and can be resolved using a systematic and uniform time-resolved spectro-polarimetric study. In this paper, we investigated the spectral, temporal, and polarimetric characteristics of five bright gamma-ray bursts (GRBs) using archival data from AstroSat CZTI, Swift Burst Alert Telescope, and Fermi/GBM. These bright GRBs were detected by CZTI in its first year of operation, and their average polarization characteristics have been published in Chattopadhyay et al. In the present work, we examined the time-resolved (in 100–600 keV) and energy-resolved polarization measurements of these GRBs with an improved polarimetric technique such as increasing the effective area and bandwidth (by using data from low-gain pixels), using an improved event selection logic to reduce noise in the double events and extend the spectral bandwidth. In addition, we also separately carried out detailed time-resolved spectral analyses of these GRBs using empirical and physical synchrotron models. By these improved time-resolved and energy-resolved spectral and polarimetric studies (not fully coupled spectro-polarimetric fitting), we could pin down the elusive prompt emission mechanism of these GRBs. Our spectro-polarimetric analysis reveals that GRB 160623A, GRB 160703A, and GRB 160821A have Poynting flux-dominated jets. On the other hand, GRB 160325A and GRB 160802A have baryonic-dominated jets with mild magnetization. Furthermore, we observe a rapid change in polarization angle by ∼90° within the main pulse of very bright GRB 160821A, consistent with our previous results. Our study suggests that the jet composition of GRBs may exhibit a wide range of magnetization, which can be revealed by utilizing spectro-polarimetric investigations of the bright GRBs.

Gamma-Ray Astronomy

10.3847/1538-4357/ad5a92

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A Broadband LNA and Sub-Harmonic Mixer Based Multi-Mode RX in 22nm CMOS

Soumya Gupta Benjamin Jann Mostafa Essawy Kareem Rashed Arun Natarajan

The paper describes a mm-wave receiver architecture that uses a low noise amplifier (LNA) and subharmonic mixer with a reconfigurable LO generation system based on a phase interpolator (PI). The receiver is fabricated in 22nm CMOS and operates in two modes: lx mode from 15-25 GHz and 3x mode from 20-37 GHz. The LO path of the receiver is power-efficient due to the multi-mode operation. The proposed receiver achieves a peak gain of 40 dB in lx mode and 30 dB in 3x mode, with a total power consumption of S7 mW and 94 mW, respectively. The LO path consumes 27 mW at 25 GHz in lx mode and 15 mW at 25 GHz in 3x mode. The receiver has an IF bandwidth of 2 GHz in both modes.

10.23919/eumic58042.2023.10288916

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Investigating Polarization characteristics of GRB200503A and GRB201009A

arXiv (Cornell University) (2024)

Divita Saraogi Suman Bala J. Joshi Shabnam Iyyani V. Bhalerao

We present results of a comprehensive analysis of the polarization characteristics of GRB 200503A and GRB 201009A observed with the Cadmium Zinc Telluride Imager (CZTI) on board AstroSat. Despite these GRBs being reasonably bright, they were missed by several spacecraft and had thus far not been localized well, hindering polarization analysis. We present positions of these bursts obtained from the Inter-Planetary Network (IPN) and the newly developed CZTI localization pipeline. We then undertook polarization analyses using the standard CZTI pipeline. We cannot constrain the polarization properties for GRB 200503A, but find that GRB 201009A has a high degree of polarization.

10.48550/arxiv.2411.00410

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High average power density (0.2-0.65 kW/cm/sup 2/) diode laser stacks for 808 nm, 915 nm & 940 nm wavelengths

Soumya Gupta A. Garcia Sudharsanan Srinivasan Xiaolong He S. Wilson

Combining developments in high-power (/spl sim/100 W) laser diode arrays and high heat flux (kW/cm/sup 2/) water-cooled Cu-'mini-channel' heatsinks, we demonstrate record average power density operation of diode laser stacks. Using advanced die attachment, record CW power levels of 180 W and 108 W has been demonstrated at 915 nm & 808 nm, respectively, from 1 cm wide laser arrays on such heatsinks.

Power density

Laser diode

10.1109/islc.1998.734133

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Citations (2)

A detailed time-resolved and energy-resolved spectro-polarimetric study of bright GRBs detected by AstroSat CZTI in its first year of operation

arXiv (Cornell University) (2024)

Rahul Gupta S. B. Pandey Soumya Gupta Tanuka Chattopadhayay D. Bhattacharya

The radiation mechanism underlying the prompt emission remains unresolved and can be resolved using a systematic and uniform time-resolved spectro-polarimetric study. In this paper, we investigated the spectral, temporal, and polarimetric characteristics of five bright GRBs using archival data from AstroSat CZTI, Swift BAT, and Fermi GBM. These bright GRBs were detected by CZTI in its first year of operation, and their average polarization characteristics have been published in Chattopadhyay et al. (2022). In the present work, we examined the time-resolved (in 100-600 keV) and energy-resolved polarization measurements of these GRBs with an improved polarimetric technique such as increasing the effective area and bandwidth (by using data from low-gain pixels), using an improved event selection logic to reduce noise in the double events and extend the spectral bandwidth. In addition, we also separately carried out detailed time-resolved spectral analyses of these GRBs using empirical and physical synchrotron models. By these improved time-resolved and energy-resolved spectral and polarimetric studies (not fully coupled spectro-polarimetric fitting), we could pin down the elusive prompt emission mechanism of these GRBs. Our spectro-polarimetric analysis reveals that GRB 160623A, GRB 160703A, and GRB 160821A have Poynting flux-dominated jets. On the other hand, GRB 160325A and GRB 160802A have baryonic-dominated jets with mild magnetization. Furthermore, we observe a rapid change in polarization angle by $\sim$ 90 degrees within the main pulse of very bright GRB 160821A, consistent with our previous results. Our study suggests that the jet composition of GRBs may exhibit a wide range of magnetization, which can be revealed by utilizing spectro-polarimetric investigations of the bright GRBs.

10.48550/arxiv.2406.13755

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Single-resistance-controlled quadrature oscillator employing two current differencing buffered amplifier

Diksha Kalra Soumya Gupta Tajinder Singh Arora

Among various active building blocks, current differencing buffered amplifier (CDBA) is coming up as a novel device in designing analog circuits. Realization of single-resistance-controlled oscillator (SRCO) employing CDBA is the purpose of this manuscript. The main focus is on utilization of minimum active and passive components, keeping the maximum possible z-terminals grounded through capacitor so as to avoid the parasitic effect of the terminal. The proposed oscillator circuit involves independent control of frequency of oscillations and condition of oscillation. All appropriate analysis, ideal and non-ideal, have been taken into consideration. Theoretical and practical validation of the circuit has been done and PSPICE simulation software has been used for the latter.

Realization (probability)

Quadrature (astronomy)

Oscillation (cell signaling)

10.1109/ic3i.2016.7918050

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Citations (5)

Investigation of the Gamma-Ray Bursts prompt emission under the relativistically expanding fireball scenario

arXiv (Cornell University) (2024)

Soumya Gupta S. Sahayanathan

The spectral properties of a composite thermal emission arising from a relativistic expanding fireball can be remarkably different from the Planck function. We perform a detailed study of such a system to explore the features of the prompt emission spectra from the gamma-ray bursts (GRBs). Particularly, we address the effect of optical opacity and its dependence on the density profile between the expanding gas and the observer. This results in a nontrivial shape of the photospheric radius which in combination with the constraints derived from the equal-arrival-time can result in a mild broader spectrum compared to the Planck function. Further, we show the time-integrated spectrum from the expanding fireball deviates significantly from the instantaneous emission and is capable of explaining the observed broad spectral width of the GRBs. We also show, that the demand of the spectral width of the order of unity, obtained through statistical analysis, is consistent with the scenario where the dynamics of the expanding fireball are governed predominantly by the energy content of the matter.

10.48550/arxiv.2407.02841

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