6,359 research outputs found
Microwave Optical Link In The Frequency Range Of 10-18 Gigahertz By Direct Modulation Of Injection Laser Diode
It is demonstrated that an ultra-high speed window buried heterostructure GaAlAs laser fabricated on semi-insulating substrate can be used as narrow band signal transmitters in the Ku-band frequency range (12-20GHz). The modulation efficiency can be increased over a limited bandwidth by a weak optical feedback. A stronger optical feedback enables one to actively mode-lock the laser diode at a very high repetition rate up to 17.5GHz, producing pulses of = 12ps long
Coherent microscopy by laser optical feedback imaging (LOFI) technique
The application of the non conventional imaging technique LOFI (Laser Optical
Feedback Imaging) to coherent microscopy is presented. This simple and
efficient technique using frequency-shifted optical feedback needs the sample
to be scanned in order to obtain an image. The effects on magnitude and phase
signals such as vignetting and field curvature occasioned by the scanning with
galvanometric mirrors are discussed. A simple monitoring method based on phase
images is proposed to find the optimal position of the scanner. Finally, some
experimental results illustrating this technique are presented
Quantum state protection using all-optical feedback
An all-optical feedback scheme in which the output of a cavity mode is used
to influence the dynamics of another cavity mode is considered. We show that
under ideal conditions, perfect preservation against decoherence of a generic
quantum state of the source mode can be achieved.Comment: 10 pages, 4 figures, to appear in the Dan Walls Memorial Volume,
edited by H. Carmichael, R. Glauber, and M. Scully, to be published by
Springe
All-optical versus electro-optical quantum-limited feedback
All-optical feedback can be effected by putting the output of a source cavity
through a Faraday isolator and into a second cavity which is coupled to the
source cavity by a nonlinear crystal. If the driven cavity is heavily damped,
then it can be adiabatically eliminated and a master equation or quantum
Langevin equation derived for the first cavity alone. This is done for an input
bath in an arbitrary state, and for an arbitrary nonlinear coupling. If the
intercavity coupling involves only the intensity (or one quadrature) of the
driven cavity, then the effect on the source cavity is identical to that which
can be obtained from electro-optical feedback using direct (or homodyne)
detection. If the coupling involves both quadratures, this equivalence no
longer holds, and a coupling linear in the source amplitude can produce a
nonclassical state in the source cavity. The analogous electro-optic scheme
using heterodyne detection introduces extra noise which prevents the production
of nonclassical light. Unlike the electro-optic case, the all-optical feedback
loop has an output beam (reflected from the second cavity). We show that this
may be squeezed, even if the source cavity remains in a classical state.Comment: 21 pages. This is an old (1994) paper, but one which I thought was
worth posting because in addition to what is described in abstract it has:
(1) the first formulation (to my knowledge) of quantum trajectories for an
arbitrary (i.e. squeezed, thermal etc.) broadband bath; (2) the prediction of
a periodic modification to the detuning and damping of an oscillator for the
simplest sort of all-optical feedback (i.e. a mirror) as seen in the recent
experiment "Forces between a Single Atom and Its Distant Mirror Image", P.
Bushev et al, Phys. Rev. Lett. 92, 223602 (2004
Distributed feedback X-ray lasers in single crystals
There are two main obstacles in the
way of obtaining laser action in the X-ray
region. The first involves the pumping
necessary to obtain the critical inversion.
The second one is that of the optical feedback
Discrete mode lasers for applications in access networks
Fast development of the modern telecommunication networks such as fiber-to-the-home or radio-over-fiber systems require an inexpensive yet reliable optical transmitter for electro-optic conversion. Such devices should be able to generate stable, single moded optical signals suitable for athermal operation. Discrete Mode Lasers (DMLs) are able to fulfill all the above-mentioned requirements with the added benefit of low sensitivity to optical feedback. DMLs are essentially Fabry-Perot lasers in which the refractive index is modified by introducing perturbations along very small sections of the laser cavity. These modifications result in a single mode laser output with a very narrow linewidth (order of 400 kHz). In this paper, we demonstrate how a DML can outperform the commonly used/commercially available DFB lasers in terms of linewidth, sensitivity to optical feedback and transmission performance in the presence of feedback
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