Dr. Pramod KUMAR, M.Phil., Ph.D. (Laser Tech.)

University of Exeter, QuantLase Research and Development Center, UAE, Faculty Member

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My multidisciplinary research interest crosses the borders of scientific disciplines which cover various fundamental and practical applications aspects in the field of Ultrafast Laser physics and Natural Photonics for paving the way towards Photonic Integration technology on chip scale. However for real life applications, the exploitation, understanding, and control of complex optical processes for determining the performance of photonics devices like optical multi-functionality of Photonic structures, Optical parametric oscillators, Quantum nano-structure based mode-locked semiconductor lasers for broadband optical frequency comb need to be understood. In addition, I am very much interested in nature inspired photonic structures fabrication through biomimetic technology for biophotonic applications. My focus is on coherent manipulation
and control light through Natural photonic structures. Currently, I am dealing with quantum nano-structure based semiconductor laser for the generation of ultra-short and ultra-fast optical pulses via optical pumping for the applications in telecommunications, Bio-imaging . Moreover, I am dealing with the Prime factorization issue using light for Quantum computing.
Supervisors: Prof. John Gerard McInerney, PhD, Rupamanjari GHOSH, Ph.D., and Dr. Jacopo Bertolotti
Address: Dr. Pramod KUMAR
M.Phil. (Inst. Physics), Ph.D. (Laser Tech.)
Principal Scientist of Quantum Photonics
Team Lead, QuantLase Lab. Abu Dhabi, U.A.E.
Email: pramod.kumar@quantlase.ae
http://quantlaselab.com/

Ultrafast Laser Group,
Optoelectronics and Nonlinear Optics Lab.
Department of Physics/Tyndall National Institute
Kane Building, University College Cork (UCC)
Western Road, Cork, Ireland
Mobile No. :353-892468055
Email: pramod.kumar@ucc.ie
*********************************************
Ph.D Thesis Supervisor
***************************************
Rupamanjari GHOSH, Ph.D.

Professor of Physics
School of Physical Sciences
Jawaharlal Nehru University (on leave)
New Delhi 110 067, India.
http://www.jnu.ac.in/Faculty/rghosh/
http://www.jnu.ac.in/FacultyStaff/ShowProfile.asp?SendUserName=rghosh

Director, School of Natural Sciences
Dean of Research & Graduate Studies
Shiv Nadar University
Adjoining Greater Noida
Dist. Gautam Budh Nagar
UP 203 207, India.
http://www.snu.edu.in/naturalsciences/natural_sciences_overview.aspx
http://www.snu.edu.in/naturalsciences/Rupamanjari_Ghosh_profile.aspx

E-mail: rghosh.jnu@gmail.com
rupamanjari.ghosh@snu.edu.in
rghosh@mail.jnu.ac.in

Tel: (+91-120) 2663 840 (SNU office direct), 841 (Executive Assistant to the Director),
(+91-11) 2670 4636 (JNU office direct), 2674 1004 (residence)
Fax: (+91-11) 2674 2891 (SPS, JNU)

http://jnu.academia.edu/RGhosh/Papers
***************************************************
Post Doctoral Research Associate
with
Prof. Sudeshna Sinha (Dean)
Professor (Physics) , IISER Mohali
Knowledge city, Sector 81, SAS Nagar,
Manauli PO 140306
http://www.imsc.res.in/~sudeshna/, http://www.iisermohali.ac.in/html/faculty/sudeshna.html

&
Dr. Kamal P. Singh (Femtolaser Lab)
Assistant Professor (Physics)
Knowledge city, Sector 81, SAS Nagar,
Manauli PO 140306
http://www.iisermohali.ac.in/html/faculty/kpsingh.html
******************************************************************
John Gerard McInerney, PhD

Professor of Physics and Head of Department
Department of Physics/Tyndall Institute
University College, Cork, Ireland

Adjunct Professor of Optical Sciences
University of Arizona
Tucson AZ 85721 USA

tel +353 21 490 2468/2327
fax +353 21 427 6949
mcinerney@ucc.ie
www.physics.ucc.ie/opto/ or www.tyndall.ie

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Videos by Dr. Pramod KUMAR, M.Phil., Ph.D. (Laser Tech.)

03:30

Ultrafast Laser based DPI mass screening technology for the Corona 19 detection

The equipment, which uses a CMOS detector, will enable mass-scale screening with results made ava... more The equipment, which uses a CMOS detector, will enable mass-scale screening with results made available in seconds,” said Dr Pramod Kumar, who leads the team of researchers at the lab which has been studying the change in cell structure of the virus-infected blood. In fact, our laser-based DPI [Diffractive Phase Interferometry] technique, based on optical-phase modulation, is able to give a signature of infection within a few seconds. What’s more, it is user-friendly, non-invasive and low-cost. We believe it will be a game-changer in tackling the spread of the coronavirus.

4 views

02:57

UAE Develops a Rapid Coronavirus Laser Testing Technology

The equipment, which uses a CMOS detector, will enable mass-scale screening with results made ava... more The equipment, which uses a CMOS detector, will enable mass-scale screening with results made available in seconds,” said Dr Pramod Kumar, who leads the team of researchers at the lab which has been studying the change in cell structure of the virus-infected blood.
“In fact, our laser-based DPI [Diffractive Phase Interferometry] technique, based on optical-phase modulation, is able to give a signature of infection within a few seconds. What’s more, it is user-friendly, non-invasive and low-cost. We believe it will be a game-changer in tackling the spread of the coronavirus.”

11 views

02:56

United Arab Emirates develops technology for rapid coronavirus laser testing

QuantLase Imaging Lab, the medical research arm of International Holdings Company (IHC) listed on... more QuantLase Imaging Lab, the medical research arm of International Holdings Company (IHC) listed on the Abu Dhabi Stock Exchange, announced that it has developed novel devices that enable mass exams to be performed much faster, with test results available in seconds and testing at a larger scale enable. This breakthrough will enable “mass-scale screening” and thus change the entire dimension of traceability.

18 views

Papers by Dr. Pramod KUMAR, M.Phil., Ph.D. (Laser Tech.)

Stable phase-locking of an external-cavity diode laser subjected to external optical injection

Journal of Physics B: Atomic, Molecular and Optical Physics, 2008

We analyse the locking phenomena arising when an external-cavity diode laser is subjected to opti... more

Optical functionality of natural photonic structures on the transparent insect wings for bio-mimetic applications

Electroactive Polymer Actuators and Devices (EAPAD) 2014, 2014

ABSTRACT We experimentally and numerically probe the natural quasi-ordered complex structures in ... more ABSTRACT We experimentally and numerically probe the natural quasi-ordered complex structures in the transparent insect wings by a simple, non-invasive, real time optical diffraction technique using monochromatic cw lasers and broadband femtosecond laser pulses. A complex diffraction pattern in transmission unveils the signature of long range spatial correlation in structural arrangement (symmetry) at various length scales on the whole wing surface for a variety of insect wings. A quantitative analysis analysis of the Fast Fourier transform (FFT) angular spectrum reveals a direct link between the structural organization and optical transmitted diffraction patterns. Our findings directly demonstrate how the diffraction pattern through the transparent insect wings is spatially and functionally correlated with its structural origination at various length scales. The methodology of the studies developed in this paper is applicable to a wide class of disordered photonic structures.

Optical probing of long-range spatial correlation and symmetry in complex biophotonic architectures on transparent insect wings

Laser Physics Letters, 2015

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Sub-picosecond pulse stability of passively mode-locked two- section quantum dash laser at ~ 1550 nm subject to single and dual optical feedback

by Haroon Asghar, Dr. Pramod KUMAR, M.Phil., Ph.D. (Laser Tech.), and John Gerard McInerney

Conference on Lasers and Electro-Optics (CLEO), San Jose, California, USA, 2016

We report effects of varying feedback ratios and phases in dual-loop external optical feedback o... more

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Dynamical Complexity Induced by Frequency- dependent Optical Feedback in Dual-section Passive Mode-locked Quantum-dash Laser at ~ 1.55 µm

by Haroon Asghar and Dr. Pramod KUMAR, M.Phil., Ph.D. (Laser Tech.)

Chaotic Modeling and Simulation International Conference (CHAOS), London, UK, 2016

In this work, we present experimental studies of complex nonlinear dynamics in mode- locked quan... more In this work, we present experimental studies of complex nonlinear dynamics in mode-
locked quantum-dash lasers subject to frequency dependent optical feedback with fixed
filtering. Filtered or dispersive optical feedback offers advantages over conventional
optical feedback as its provides specific controllable spectral content of feedback to
manipulate the laser dynamics, specifically by varying the filter bandwidth and detuning
from the free running mode-locked frequency, without introducing attenuating optics in
the feedback loop. In addition, we discuss how the various dynamical regimes of the
mode-locked laser with filtered optical feedback depend on the filter bandwidth and
frequency and also how the presence of particular dynamical states can induce a
significant change in the timing jitter of a mode-locked pulse train. We suggest that the
dynamics are manipulated and controlled by changes in phase-amplitude coupling, and
thus strong carrier dependence of the index on carrier density and varying with dispersive
optical feedback. Physically, when the free running mode-locking frequency is on the
blue side of the filter center frequency then the feedback induces a red-shift in frequency
with reduced phase-amplitude coupling factor α. Our technique provides a simple and
low cost way to effectively control the Rf dynamics of the mode-locked laser diode and
here its uses as an optical clock, lidar or frequency comb.

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Stabilization of self-mode-locked quantum dash lasers by symmetric dual-loop optical feedback

by Haroon Asghar and Dr. Pramod KUMAR, M.Phil., Ph.D. (Laser Tech.)

Optics Express, 2018

We report experimental studies of the influence of symmetric dual-loop optical feedback on the RF... more We report experimental studies of the influence of symmetric dual-loop optical feedback on the RF linewidth and timing jitter of self-mode-locked two-section quantum dash lasers emitting at 1550 nm. Various feedback schemes were investigated and optimum levels determined for narrowest RF linewidth and low timing jitter, for single-loop and symmetric dual-loop feedback. Two symmetric dual-loop configurations, with balanced and unbalanced feedback ratios, were studied. We demonstrate that unbalanced symmetric dual loop feedback, with the inner cavity resonant and fine delay tuning of the outer loop, gives the narrowest RF linewidth and reduced timing jitter over a wide range of delay, unlike single and balanced symmetric dual-loop configurations. This configuration with feedback lengths of 80 and 140 m narrows the RF linewidth by ∼ 4-67x and ∼ 10-100x, respectively, across the widest delay range, compared to free-running. For symmetric dual-loop feedback, the influence of different power split ratios through the feedback loops was determined. Our results show that symmetric dual-loop feedback is markedly more effective than single-loop feedback in reducing RF linewidth and timing jitter, and is much less sensitive to delay phase, making this technique ideal for applications where robustness and alignment tolerance are essential. "Quantum dash mode-locked lasers for data centre applications ," IEEE J. Sel. Top. Quantum Electron. 21(6), 53-60 (2015). 2. J. P-Cetina, S. Latkowski, R. M-.Basilio, and P. Landais, "Wavelength tunability of all-optical clock-recovery based on quantum-dash mode-locked laser diode under injection of a 40-Gb/s NRZ data stream," IEEE J. Sel. Top. Quantum Electron.

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Optical choas: dynamical complexity of delay-coupled semiconductor lasers system

M utually delay-coupled semiconductor lasers system show a plethora of dynamical complexity in th... more M
utually delay-coupled semiconductor lasers system show a plethora of dynamical complexity in the emitted radiation due to phase-amplitude coupling factor alpha, α that make them ideal candidate for fundamental studies of coupled oscillators
as well as for practical applications ranging from optical communications to computing. On the one hand these dynamical instabilities are undesired features and disturb the many applications where one needs the constant stable high power but
on the other hand they may allow for new methods for secure communications using chaos synchronization. The variety of optical complexity in these systems which we have investigated theoretically as well as experimentally is well behaving, well
understandable, well classifiable in terms of complex nonlinear dynamics. So the systematic study and control of these nonlinea dynamics provides fundamental insight into the underlying physics of the system, on the basis of which one can redesign the device in order to stabilize the working point against environmental fluctuations or improve the processing, or simply exploit the dynamical performance of a system to one’s advantages.

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Stabilization of self-mode-locked quantum dash lasers by symmetric dual-loop optical feedback

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Manipulation of phase-amplitude coupling in a delay-coupled semiconductor lasers system for the high power technology

We numerically demonstrate the effect of optical injection induced modulation of the phase-amplit... more We numerically demonstrate the effect of optical injection induced modulation of the phase-amplitude coupling (factor) on power spectra and optical characteristics in mutually coupled lasers system with finite delay. We observed the signature of tunable phase locked laser emission (coherent In-phase and Anti-phase) by directly controlling the nonlinearity via manipulating phase-amplitude coupling. In addition, we predict the occurrence of frequency discretization and multistability near the phase transitions regimes, which could be useful in guiding the design of both experimental setup and compact photonic integrated practical devices for the generation of higher power laser system with the aid of optical phase control.

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Optimum Stabilization of Self-Mode-Locked Quantum Dash Lasers Using Dual Loop Optical Feedback

IEEE , 2017

We have experimentally investigated the RF linewidth and timing jitter in self-mode-locked two-se... more We have experimentally investigated the RF linewidth and timing jitter in self-mode-locked two-section quantum dash lasers emitting at ~1.55 µm and operating at ~21 GHz repetition rate, subjected to single and dual loop optical feedback into the gain section, over a wide range of feedback delay. Various feedback conditions are investigated and optimum levels determined for narrowest linewidth and reduced timing jitter for both single and dual-loop configurations. We demonstrate that dual-loop feedback with the shorter feedback cavity tuned to be fully resonant, followed by fine tuning of the phase of the longer feedback cavity, gives stable narrow RF spectra across the widest delay range, 10 – 50× better than single-loop feedback. In addition, for dual-loop configurations, under fully resonant conditions, phase noise is reduced to 295 fs [10 kHz – 100 MHz], the RF linewidth narrows to < 1 kHz, with more than 30 dB fundamental side-mode suppression. We show that dual-loop optical feedback with separate fine tuning of both external cavities is far superior to single-loop feedback, with increased system tolerance against phase delay mismatch, making it a robust and cost-effective technique for developing practical, reliable and low-noise mode-locked lasers, optoelectronic oscillators and pulsed photonic circuits.

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A Novel Symmetric Dual Loop Feedback Scheme Insensitive to Phase Tuning Using Self-Mode-Locked Two-Section Quantum Dash Laser

We demonstrate a symmetric dual loop feedback scheme, insensitive to delay phase tuning, for a se... more We demonstrate a symmetric dual loop feedback scheme, insensitive to delay phase tuning, for a self-mode-locked quantum dash laser emitting at ~ 1.55 µm and operating at ~ 21 GHz repetition rate. These lasers are subjected to single and dual loop optical feedback into the gain section. Various feedback conditions are studied and optimum levels determined for narrowest linewidth and reduced timing jitter for both single and symmetric dual loop configurations. We demonstrate that symmetric dual loop with the inner cavity fully resonant and the outer one slightly offset, produces narrowed RF spectra across the widest delay range. In general, symmetric dual loop feedback is far more effective than single loop feedback in reducing RF linewidth and timing jitter, across a much wider range of delay phase. Resonant conditions for dual loop feedback are nearly independent of delay, making it ideal for practical applications where robustness and tolerance to misalignment are essential.

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Narrow RF linewidth and low timing jitter performance of self-mode-locked quantum dash laser on full delay phase subject to feedback ratio controlled symmetric dual-loop configuration

arXiv, 2017

We investigate the influence of symmetric dual-loop feedback (loops with equal length) as a funct... more We investigate the influence of symmetric dual-loop feedback (loops with equal length) as a function of full delay tuning on the RF linewidth and timing stability of ~ 21 GHz self-mode-locked quantum dash laser. Various feedback scenarios are investigated and optimum levels determined for narrowest linewidth and reduced timing jitter for both feedback schemes. Two symmetric dual-loop configurations, subject to balanced (equal feedback strength through either feedback cavity) and unbalanced feedback ratio (~ 4x more power through loop-I relative to other) are presented here. We demonstrated that unbalanced symmetric dual-loop, with the inner cavity fully resonant (at higher feedback intensity) and fine delay tuning of the outer loop (at lower feedback intensity), gives narrow RF linewidth and reduced timing jitter over a wide range of delay detuning, unlike single and balanced symmetric dual-loop configurations. This study reveals that unbalanced symmetric dual-loop with feedback delay lengths 80 and 140 m narrows the RF linewidth by ~ 4-67x (~ 2-9x timing jitter reduction) and ~ 10-100x (~ 2.5-10x timing jitter reduction), respectively, across the widest delay range, compared to free-running condition. The influence of symmetric dual-loop with balanced and unbalanced feedback ratio on the stability of the laser device is further discussed. These results suggests that symmetric dual-loop feedback with controlled feedback strength over each loop and without additional delay time in external feedback loops is significantly more effective than single loop feedback in reducing RF linewidth and timing jitter, across full range of delay phase tuning. Wider resonant feedback regime as a function of full delay tuning achieved with symmetric dual-loop configuration makes this technique ideal for practical applications where robustness and tolerance to misalignment are essential.

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Optimum stabilization of self-mode-locked quantum dash lasers using dual optical feedback with improved tolerance against phase delay mismatch " Quantum-dot mode-locked lasers With dual-mode optical injection

Opt. Express 25, 15796-15805 (2017)

We experimentally investigate the RF linewidth and timing jitter over a wide range of delay tunin... more We experimentally investigate the RF linewidth and timing jitter over a wide range of delay tuning in a self-mode-locked two-section quantum dash lasers emitting at ~ 1.55µm and operating at ~ 21 GHz repetition rate subject to single and dual optical feedback into gain section. Various feedback conditions are investigated and optimum levels determined for narrowest linewidth and reduced timing jitter for both single and dual loop configurations. We demonstrate that dual loop feedback, with the shorter feedback cavity tuned to be fully resonant, followed by fine tuning of the phase of the longer feedback cavity, gives stable narrow RF spectra across the widest delay range, unlike single loop feedback. In addition, for dual loop configurations, under fully resonant conditions, integrated timing jitter is reduced from 3.9 ps to 295 fs [10 kHz-100 MHz], the RF linewidth narrows from 100 kHz to < 1 kHz, with more than 30 dB fundamental side-mode suppression. We show that dual loop optical feedback with separate fine tuning of both external cavities is far superior to single loop feedback, with increased system tolerance against phase delay mismatch, making it a robust and cost-effective technique for developing practical, reliable and low-noise mode-locked lasers, optoelectronic oscillators and pulsed photonic circuits.

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A novel dual-loop feedback scheme to reduce spurious tones in self-mode-locked two-section quantum Dash laser emitting at ≈ 1.55 µm

CLEO: Science and innovation 2017, May 19, 2017

We demonstrate a novel dual-loop scheme to suppress external cavity side-bands and modal overlaps... more

Unraveling the phase-amplitude coupling modulation in a delay-coupled diode lasers functionality

Proc. SPIE 10086, High-Power Diode Laser Technology XV, 100860Q (22 February 2017)

We numerically investigate the effect of phase-amplitude coupling modulation on power spectra in ... more We numerically investigate the effect of phase-amplitude coupling modulation on power spectra in semiconductor lasers subject to optical injection in a face to face configuration, when a non-negligible injection delay time is taken into account. We find that as phase-amplitude coupling factor α varies, the system goes through a sequence of phase transactions between In-phase locking states to anti-phase locking states via phase-flip bifurcation. Moreover, we observed the signature of frequency discretization (Frequency Island) and uncovered the physical mechanism for the existence of multi-stability near the phase transitions regimes. Within the windows between successive anti-phases to in-phase locking regions, optical injection induced modulation in alpha, unveiling a remarkable universal feature in the various dynamics of coupled lasers system which could be useful in controlling the chirp or pulse repetition rate of a photonic integrated compact device with the aid of phase control.

Broadband femtosecond laser pulse interaction with natural photonic structures: Manipulation and control

We probed the natural quasi-ordered complex photonics structures on the transparent insect wings ... more We probed the natural quasi-ordered complex photonics structures on the transparent insect wings of rainfly (Termite) by a simple, non-invasive, real time transmission optical diffraction technique using monochromatic CW lasers and broadband femtosecond laser pulses. Our observations directly demonstrate the coherent manipulation and control of light in these photonic systems and detail understanding of our observation could provide a platform for the development of novel photonic devices for biomimetic technological applications.

Sub-kHz RF linewidth of quantum-dash mode-locked laser by self-injection from symmetric dual-loop feedback and fiber delay

by Dr. Pramod KUMAR, M.Phil., Ph.D. (Laser Tech.) and Declan Marah

Sub-kHz RF-linewidth was demonstrated in two-section quantum-dash mode-locked lasers emitting nea... more

Sub-picosecond pulse stability of passively mode-locked two-section quantum dash laser at ~ 1550 nm subject to single and dual optical feedback

by Dr. Pramod KUMAR, M.Phil., Ph.D. (Laser Tech.) and Declan Marah

CLEO: Science and Innovations 2016 San Jose, California United States 5–10 June 2016, Jun 3, 2016

We report effects of varying feedback ratios and phases in dual-loop external optical feedback on... more

Pulse Characteristics of Passively Mode-locked Dual-section Quantum-dash Laser Subjected to Optical Feedback

by Dr. Pramod KUMAR, M.Phil., Ph.D. (Laser Tech.), Sanjay Kumar Keshri, and Raju KUMAR

We present an experimental investigation of the influence of biasing conditions on the mode-locki... more We present an experimental investigation of the influence of biasing conditions on the
mode-locking of a dual-section quantum dash laser in the presence of Gain–to-Absorber optical
feedback. Our investigations reveal that variations in the forward bias gain current and reverse bias absorbing voltage have a direct impact on the pulse duration, variability in RF linewidth and repetition frequency tunability. Our observation of optimal biasing conditions opens the way to applications requiring high stable, low noise pulses and unavoidable reflections from optical components in photonic integrated circuit.

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Researchers from Indian Institute of Science Report Details of New Studies and Findings in the Area of Environmental Monitoring

by Dr. Pramod KUMAR, M.Phil., Ph.D. (Laser Tech.) and Danish Shamoon

News of Science. NewsRX. 2015. HighBeam Research. 4 Aug. 2015 , Mar 15, 2015

By a News Reporter-Staff News Editor at News of Science -- Investigators discuss new findings in ... more By a News Reporter-Staff News Editor at News of Science -- Investigators discuss new findings in Laser Physics. According to news reporting originating from Punjab, India, by VerticalNews correspondents, research stated, "We experimentally probe the structural organization of complex bio-photonic architecture on transparent insect wings by a simple, non-invasive, real-time optical technique. A stable and reproducible far-field diffraction pattern in transmission was observed using collimated cw and broadband fs laser pulses."

Dr. Pramod KUMAR, M.Phil., Ph.D. (Laser Tech.)

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Videos by Dr. Pramod KUMAR, M.Phil., Ph.D. (Laser Tech.)

Papers by Dr. Pramod KUMAR, M.Phil., Ph.D. (Laser Tech.)

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