200 research outputs found
Coherent population trapping in ruby crystal at room temperature
Observation of coherent population trapping (CPT) at ground-state Zeeman
sublevels of -ion in ruby is reported. The experiments are performed
at room temperature by using both nanosecond optical pulses and nanosecond
trains of ultrashort pulses. In both cases sharp drops in the resonantly
induced fluorescence are detected as the external magnetic field is varied.
Theoretical analysis of CPT in a transient regime due to pulsed action of
optical pulses is presented.Comment: 4 pages, 4 figures, submitted to PR
Generation of coherent terahertz pulses in Ruby at room temperature
We have shown that a coherently driven solid state medium can potentially
produce strong controllable short pulses of THz radiation. The high efficiency
of the technique is based on excitation of maximal THz coherence by applying
resonant optical pulses to the medium. The excited coherence in the medium is
connected to macroscopic polarization coupled to THz radiation. We have
performed detailed simulations by solving the coupled density matrix and
Maxwell equations. By using a simple -type energy scheme for ruby, we have
demonstrated that the energy of generated THz pulses ranges from hundreds of
pico-Joules to nano-Joules at room temperature and micro-Joules at liquid
helium temperature, with pulse durations from picoseconds to tens of
nanoseconds. We have also suggested a coherent ruby source that lases on two
optical wavelengths and simultaneously generates THz radiation. We discussed
also possibilities of extension of the technique to different solid-state
materials
Superradiance in media with a near-zero refractive index
The dependence of the efficiency of collective spontaneous emission in a spherical medium on the modulus of a complex refractive index approaching zero and on the ordering of optical centers is studied. © Allerton Press, Inc., 2012
Storage and recall of single-photon states in systems with controlled phase matching
The possibilities of cavity-assisted quantum storage based on control-field angular manipulation during off-resonant Raman interaction between a single-photon pulse and a strong control field in a polyatomic system are discussed. © 2014 Allerton Press, Inc
Infrared generation in low-dimensional semiconductor heterostructures via quantum coherence
A new scheme for infrared generation without population inversion between
subbands in quantum-well and quantum-dot lasers is presented and documented by
detailed calculations. The scheme is based on the simultaneous generation at
three frequencies: optical lasing at the two interband transitions which take
place simultaneously, in the same active region, and serve as the coherent
drive for the IR field. This mechanism for frequency down-conversion does not
rely upon any ad hoc assumptions of long-lived coherences in the semiconductor
active medium. And it should work efficiently at room temperature with
injection current pumping. For optimized waveguide and cavity parameters, the
intrinsic efficiency of the down-conversion process can reach the limiting
quantum value corresponding to one infrared photon per one optical photon. Due
to the parametric nature of IR generation, the proposed inversionless scheme is
especially promising for long-wavelength (far- infrared) operation.Comment: 4 pages, 1 Postscript figure, Revtex style. Replacement corrects a
printing error in the authors fiel
Ultraslow light in inhomogeneously broadened media
We calculate the characteristics of ultraslow light in an inhomogeneously
broadened medium. We present analytical and numerical results for the group
delay as a function of power of the propagating pulse. We apply these results
to explain the recently reported saturation behavior [Baldit {\it et al.}, \prl
{\bf 95}, 143601 (2005)] of ultraslow light in rare earth ion doped crystal.Comment: 4 pages, 5 figure
Multimode electromagnetically-induced transparency on a single atomic line
We experimentally investigate electromagnetically-induced transparency (EIT)
created on an inhomogeneously broadened 5S_1/2-5P_1/2 transition in rubidium
vapor using a control field of a complex temporal shape. A comb-shaped
transparency spectrum enhances the delay-bandwidth product and the light
storage capacity for a matched probe pulse by a factor of about 50 compared to
a single EIT line [D. D. Yavuz, Phys. Rev. A 75, 031801 (2007)]. If the
temporal mode of the control field is slowly changed while the probe is
propagating through the EIT medium, the probe will adiabatically follow,
providing a means to perform frequency conversion and optical routing
Coherent resonant interactions and slow light with molecules confined in photonic band-gap fibers
We investigate resonant nonlinear optical interactions and demonstrate
induced transparency in acetylene molecules in a hollow-core photonic band-gap
fiber at 1.5m. The induced spectral transmission window is used to
demonstrate slow-light effects, and we show that the observed broadening of the
spectral features is due to collisions of the molecules with the inner walls of
the fiber core. Our results illustrate that such fibers can be used to
facilitate strong coherent light-matter interactions even when the optical
response of the individual molecules is weak.Comment: 5 pages, 4 figure
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