21 research outputs found
Orientation of Nd dipoles in yttrium aluminum garnet: A simple yet accurate model
We report an experimental study of the 1064nm transition dipoles in neodymium
doped yttrium aluminum garnet (Nd-YAG) by measuring the coupling constant
between two orthogonal modes of a laser cavity for different cuts of the YAG
gain crystal. We propose a theoretical model in which the transition dipoles,
slightly elliptic, are oriented along the crystallographic axes. Our
experimental measurements show a very good quantitative agreement with this
model, and predict a dipole ellipticity between 2% and 3%. This work provides
an experimental evidence for the simple description in which transition dipoles
and crystallographic axes are collinear in Nd-YAG (with an accuracy better than
1 deg), a point that has been discussed for years.Comment: Accepted for publication in Physical Review
Laser à état solide bi-fréquence sans bruit d’antiphase
National audienceUne réduction de plus de 20 dB du bruit d'antiphase a été obtenue dans un laser bi-fréquence mono-axe sans aucun asservissement d'intensité. Ce résultat repose sur l'utilisation d'un cristal de Nd :YAG taillé selon le plan cristallographique (001) et l'alignement des deux états de polarisation du laser avec deux des axes cristallographiques du Crystal
Mode coupling control in a resonant device: application to solid-state ring lasers
A theoretical and experimental investigation of the effects of mode coupling
in a resonant macro- scopic quantum device is achieved in the case of a ring
laser. In particular, we show both analytically and experimentally that such a
device can be used as a rotation sensor provided the effects of mode coupling
are controlled, for example through the use of an additional coupling. A
possible general- ization of this example to the case of another resonant
macroscopic quantum device is discussed
Experimental demonstration of a dual-frequency laser free from anti-phase noise
A reduction of more than 20 dB of the intensity noise at the anti-phase
relaxation oscillation frequency is experimentally demonstrated in a
two-polarization dual-frequency solid-state laser without any optical or
electronic feedback loop. Such a behavior is inherently obtained by aligning
the two orthogonally polarized oscillating modes with the crystallographic axes
of a (100)-cut neodymium-doped yttrium aluminum garnet active medium. The
anti-phase noise level is shown to increase as soon as one departs from this
peculiar configuration, evidencing the predominant role of the nonlinear
coupling constant. This experimental demonstration opens new perspectives on
the design and realization of extremely low noise dual-frequency solid-state
lasers
Symmetric microwave potentials for interferometry with thermal atoms on a chip
International audienceA trapped atom interferometer involving state-selective adiabatic potentials with two microwave frequencies on a chip is proposed. We show that this configuration provides a way to achieve a high degree of symmetry between the two arms of the interferometer, which is necessary for coherent splitting and recombination of thermal (i.e., noncondensed) atoms. The resulting interferometer holds promise to achieve high contrast and long coherence time, while avoiding the mean-field interaction issues of interferometers based on trapped Bose-Einstein condensates
Oscillation regimes of a solid-state ring laser with active beat note stabilization : from a chaotic device to a ring laser gyroscope
We report experimental and theoretical study of a rotating diode-pumped
Nd-YAG ring laser with active beat note stabilization. Our experimental setup
is described in the usual Maxwell-Bloch formalism. We analytically derive a
stability condition and some frequency response characteristics for the
solid-state ring laser gyroscope, illustrating the important role of mode
coupling effects on the dynamics of such a device. Experimental data are
presented and compared with the theory on the basis of realistic laser
parameters, showing a very good agreement. Our results illustrate the duality
between the very rich non linear dynamics of the diode-pumped solid-state ring
laser (including chaotic behavior) and the possibility to obtain a very stable
beat note, resulting in a potentially new kind of rotation sensor
Suppression of Nonlinear Interactions in Resonant Macroscopic Quantum Devices : the Example of the Solid-State Ring Laser Gyroscope
We study the suppression of nonlinear interactions in resonant macroscopic
quantum devices in the case of the solid-state ring laser gyroscope. These
nonlinear interactions are tuned by vibrating the gain medium along the cavity
axis. Beat note occurrence under rotation provides a precise measurement of the
strength of nonlinear interactions, which turn out to vanish for some discrete
values of the amplitude of vibration. Our theoretical description, in very good
agreement with the measured data, suggests the use of a higher vibration
frequency to achieve quasi-ideal rotation sensing over a broad range of
rotation speeds. We finally underline the analogy between this device and some
other macroscopic quantum rotation sensors, such as ring-shaped superfluid
configurations, where nonlinear interactions could be tuned for example by the
use of magnetically-induced Feschbach resonance