Ultradispersive adaptive prism based on a coherently prepared atomic medium Page: 2
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SAUTENKOV, LI, ROSTOVTSEV, AND SCULLY
FIG. 1. (Color online) (a) Refraction of light by the prism.
(b) Configuration of the probe and control laser beams inside the
cell of Rb vapor. One can see that our setup can be viewed as an
ultradispersive prism. (c) Simplified scheme of the energy levels of
cell, which serves as the frequency reference. Another part
of the laser output is used to study the ultradispersive optical
prism. The beam is split into two beams, and the X/2 wave
plate rotates the linear polarization of one beam by 90. After
passing through a polarizing beam splitter (PBS) and the
X/4 wave plate, the laser beams are sent to the glass cell
with rubidium atomic vapor. The configuration of the laser
beams in the cell is shown in Fig. 1(b). The orthogonally
polarized beams, control (P = 0.5 mW) and probe (PP =
0.2 mW), create coherence between the ground-state Zeeman
sublevels as shown in Fig. 1(c). Two-photon detuning is
accomplished by applying the longitudinal magnetic field B.
The magnitude of Zeeman splitting is given by 0.7 B MHz/G.
The heated rubidium cell (1 = 7.5 cm, N = 3 x 101" cm3) is
I A/4 oA/4e
I - - - D oSOJ
S PBS PBS
Reference beam to CCD
FIG. 2. (Color online) Experimental setup: ECDL, external cavity
diode laser; PBS, polarizing beam splitter; GP, parallel glass plate;
X/2 and X/4, retardation wave plates, PSD, position-sensitive
detector; DSO, the digital storage oscilloscope; CCD, linear CCD
PHYSICAL REVIEW A 81, 063824 (2010)
corresponds to the maximum angle deviation in Fig. 4(a) (8 =
0.5 mrad) and curve 2 in Fig. 3(b) corresponds to the minimum
installed inside of a two-layer magnetic shield, and two-
photon detuning is varied by changing the magnitude of the
longitudinal magnetic field. The transmitted optical beams
with the orthogonal polarizations are separated using a second
X/4 wave plate and another PBS. Then the probe beam is sent
to the data acquisition part of the setup.
We employ two independent techniques to measure the
probe beam position and the angle of deviation. Measurements
by both techniques are consistent with each other. The first
technique is based on using a charge-coupled device (CCD)
camera and a removable mirror in front of the cell to measure
the positions of the control and probe beams. The CCD
camera is used to record an optical field distribution for
selected two-photon detuning. In the second method, we
use a position-sensitive detector (PSD)  to accurately
measure the beam direction versus the two-photon detuning.
The distance from the center of the cell to PSD is 1 m, and that
to the CCD camera is 2.3 m. The influence of air currents
on the beams around the heated cell is negligible due to
the small variation of temperature inside the magnetic shield
(L = 0.4 m). In addition, the optical paths are protected by
To study the frequency dependence of the probe beam
deflection, we record a signal from the PSD. The output voltage
from the PSD is proportional to the transverse shift of the
beam. The relation between the shift of the probe beam and
the signal from the PSD is calibrated by using a translation
stage. Before the cell, the control and probe beams are parallel
to each other. The control beam can be adjusted to the left
or to the right side of the probe beam profile by tilting a
parallel glass plate. The profiles of the beams are shown in
Fig. 3(a) for the case when the probe beam is shifted to the
right side of the control beam. The profiles have been recorded
by the CCD camera. Dependence of the angle of the probe
beam refraction on two-photon detuning for the probe beam is
presented in Fig. 4(a) as curve 1. The curve is dispersion-like
and it has a maximum and minimum at 0.5 and -0.2 mrad,
respectively. In addition, we have recorded the transmission
of the probe beam by using a removable mirror and a usual
photo detector. The EIT resonance is presented in Fig. 4(a) as
curve 2. Then we shift the probe beam to the left side of the
control beam profile. Frequency dependence of the angle and
EIT resonance is presented in Fig. 4(b). The dispersion-like
curve 1 has a maximum and minimum at 0.05 and -0.45 mrad.
The widths (FWHMs) of EIT resonances are 0.5 MHz for the
both cases. The different offset for dispersion-like curves in
Figs. 4(a) and 4(b) can be attributed to single-photon saturation
of rubidium atoms. Near zero detuning, the dependences are
practically linear. They can be characterized by slopes dO/dy,
which can be estimated using the preceding parameters to be
of the order of 1 mrad/MHz. By using the obtained values
of the slopes at zero detuning, we can estimate dO/dX as
5 x 102 rad/nm.
The profiles of the probe beam after the rubidium cell are
recorded by the CCD camera. For the case when the probe
beam is on the right side of the pump beam the profiles of
the probe beams before the cell for two different two-photon
detunings are presented in Fig. 3(b). Curve 2' in Fig. 3(b)
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Sautenkov, Vladimir A.; Li, Hebin; Rostovtsev, Yuri V. & Scully, Marlan O. (Marlan Orvil), 1939-. Ultradispersive adaptive prism based on a coherently prepared atomic medium, article, June 23, 2010; [College Park, Maryland]. (digital.library.unt.edu/ark:/67531/metadc103269/m1/2/: accessed April 28, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT College of Arts and Sciences.