Brief Experience and Interests
His area of interest is coherent control of optical phenomenon
in semiconductors.
He is looking at ways of controlling wavepacket
dynamics in semiconductor quantum wells and other heterostructures.
The study includes various effects involving
coherent tera-hertz radiation, trapping and tunneling dynamics,
effects of dephasing in these systems, role of dimensionality and
nonlinear signal generation.
A recent work involved a proposal to realize trapping of excitonic
population and also its motion using chirped pulses.
We also showed effects of quasi-adiabatic population transfer in this
system. These studies were undertaken for a two-band semiconductor
quantum well system.
This work is published in Physical Review B.
Another recent work involved harmonic generation in quantum well systems
using simultaneous excitation by optical and a tera-hertz field.
We put forth an exactly solvable model and brought out an
explicit relation between harmonic generation and
the time-dependent resonant tunneling structure.
This work is published in Physical Review B.
Wanare has worked in frontier areas of Quantum optics,
dealing specifically with the subject of
coherent manipulation of optical properties of atoms using ideas of
quantum interference. His work involved modeling
realistic systems and presenting calculations of phenomenon which can be
observed in experiments. He has worked closely with his colleagues
involved in experimental laser physics.
Wanare has published detailed papers in
prestigious international journals.
He has been invited to give seminars and talks in various
forums and international conferences.
Following are details of some of his
contributions.
Control of Optical Bistability and Multistability
All optical switching devices have suffered from various
limitations, one main limitation being the efficiency
of switching at low power levels of light.
We have shown that using the effects of Quantum Interferences
and Electromagnetic Field Induced Transparency one can
substantially overcome this limitation.
We have demonstrated that by
using a control field which couples the excited state of
the usual two-state atomic system to another level, one can
obtain substantial decreasein the threshold intensity required in an
all-optical bistablesystem, to switch from the off state to the on state.
We have proposed two schemes using a collection of atoms in
( i) ladder or ( ii ) $\Lambda $ configuration
in an unidirectional ring cavity.
We studied both the absorptive and dispersive kind of bistability.
We also took into account the temporal evolution and
observed that the rate of critical slowing down is dependent on the
We also took into account the temporal evolution and
observed that the rate of critical slowing down is dependent on the
control field.
We have also demonstrated the possibility
of control field induced multistable behavior.
This multistability is achieved at much
lower intensity levels than conventionally possible.
This work was published as a full length article in Physical Review A.
Control of Two-Photon Absorption:
The phenomenon of Two-photon absorption has wide range of
applications from study of microscopic samples to
analysis of astrophysical phenomenon. We proposed
a mechanism to effectively control this phenomenon.
We used a control field to create another pathway for thea mechanism to effectively control this phenomenon.
We used a control field to create another pathway for the
two-photon absorption, the evolution along these two pathways
interferes destructively (or constructively),
to provide transparency against (or enhancement of) two-photon absorption.
We also predicted
considerable enhancement of
two-photon absorption even in presence of Doppler broadening.
Detailed absorption profiles under different conditions of the control
laser were studied.
This work was published in Physical Review Letters.
Enhancement of Nonlinear Optical Effects:
In nonlinear optics one of the goals has been - how to improve the
efficiency of signal generation. It is also well known that the
atomic coherence is maximized in a coherentefficiency of signal generation. It is also well known that the
atomic coherence is maximized in a coherent
population trapping (CPT) state,
between the ground states in a three-level $\Lambda$ system.
We predicted
the enhancement of nonlinear signal by
utilizing the maximal coherence of the CPT state.
We have proposed enhancement of $\omega_1 + \Omega$ generated by the
nonlinear process $(\omega_1 + \Omega) = \omega_1 - \omega_2 + (\omega_2 +
\Omega)$, under Coherent Population Trapping conditions created by the pumps
$\omega_1$ and $\omega_2$.
In this process $\omega_1$ and $\omega_2 +\Omega$
are absorbed and $\omega_2$ is emitted, to generate the field at
$\omega_1 +\Omega$.
We have obtained enhancement of the order of $\sim 10^2$ in the
intensity of the generated field.
We developed non-perturbative and exact
treatment of the wave-mixing phenomenon.
treatment of the wave-mixing phenomenon.
This work was published as a full length article in Physical Review A.
New Trapping States:
The trapping phenomenon in atomic systems occupies a very special
place in Quantum Optics. The CPT phenomenon in three-level $\Lambda$
system driven by two monochromatic fields is well known.
The trapping phenomenon we
discovered is quite different from the CPT phenomenon.
We demonstrated new states that exhibit trapping of
population, in the semiclassical regime, in a two-level system
in presence of a frequency modulated field.
We have shown explicitly the conditions
under which such states can be produced and also demonstrated
tunneling of population due to level crossing.
The trapping of population in a two-level system is akin to localizationgtunneling} of population due to level crossing.
The trapping of population in a two-level system is akin to localization
in a double-well potential. We demonstrated a method
for coherent control of quantum tunneling.
Recently this prediction was experimentally realized by
M.W. Noel et al. Phys. Rev. A {\bf 58}, 2265 (1998).
This work was published as a rapid communication in the Physical Review A.
Trapping in Multilevel Systems and its application:
We have also demonstrated the possibility of similar
trapping states in
multilevel systems. We studied the effects of phase in
population transfer after multiple
crossings, and studied quantum interference effects.
We proposed a new method of inverting
the population across multiple levels. In our scheme
the population in the intermediate state remains unaffected.
The method we proposed would be experimentally more attractive than the
conventional Rapid Adiabatic Passage method.
We also proposed the possibility of experimentally
realizing these features using Optical Atoms,
where the atomic levels are simulated as various classical modes
of electromagnetic radiation in an em optical cavity.
As of now there has been no scheme to simulate the three-level
system in optical atoms. We have demonstrated
a novel scheme using coupled cavities that would simulate
the three-level atom and this could open up a whole range of
parameter space which is inaccessible in atomic experiments.
This work was published as a full length article in Physical Review A.
Research Experience in Experimental Laser Physics
During his stay at the Physics department,
Indian Institute of Science (IISc), Bangalore,
he worked as a Project Assistant
in the project ``Laser Application Programme - Phase
II". He conducted extensive experiments in Stimulated Bruillion
Scattering on $SF_6$ molecule in high pressure (140 Bar) gas cell with
$\mbox{Nd-YAG}$ pulsed laser (100 Joules), and observed very high conversion
efficiency $\sim 85\%$ of the
fundamental into the nearly phase conjugated signal.
He was also involved in the fabrication of the high pressure gas cell.
He set up various experiments using both Bulk and Fiber Optic elements. Particularly dealing with various applications of interferometers like the Michelson, Mach-Zehnder and the Sagnac interferometers. Extensive experiments in Fabry-Perot interferometer
were undertaken as part of the the Laser Laboratory course for the M.Tech Programme, which he supervised.
Computational Experience
Wanare has extensive computational experience, particularly in high-precision large scale scientific computing using Fortran. His work involved solving numerically the algebraic equations, coupled ordinary and partial differential equations, integral tra
nsforms, integrals, digonalization of matrices for eigenvalues and eigenvectors determination and programming efficient matrix continued fraction techniques to solve large tridiagonal relations which govern temporal dynamics of various systems. He also
worked on visualization of large output data after computation.
He has extensively worked with IBM RISC 6000/580, Digital AlphaStation 400,
and to a lesser extent HP9000/735 workstations. He has also worked
on a supercomputer the CRAY T90 system at the San Diego Supercomputing
facility. He is familiar with both the DOS and UNIX operating systems.
He has used many specialized mathematical and statistical
computational packages like
MATHEMATICA, MATLAB, NAG, IMSL, LAPACK etc.
Teaching experience
Wanare is presently assigned to teach a complete
undergraduate course "Physics-105" - titled Fundamentals of Physics
at the Illinois State University in the Spring semester of 2000. The course also involves planning and teaching of the associated laboratory work.
Wanare has taught an undergraduate course "Physics-202" - a
calculus based course dealing with fundamentals
of electricity and magnetism at the Physics department of Washington State University
in the Spring semester of 1999. The class enrollment was 84 and the
students were primarily from engineering background.
Wanare has taught Laser Physics Laboratory Course for
the Masters programme (M. Tech.)
at the Indian Institute of Science, Bangalore, India.