2,570 research outputs found
Is there a linewidth theory for semiconductor lasers?
Semiconductor laser generation begins at a critical injection when the gain
and loss spectra touch each other at a singular frequency. In the framework of
the standard (Schawlow-Townes-Lax-Henry) theory, the finite linewidth results
from the account of fluctuations associated with the random spontaneous
emission processes. This approach is based on the assumption that in the
mean-field approximation the singular frequency generation persists for
injection levels higher than critical. We show that this assumption in the
framework of the Boltzmann kinetic equation for electrons and photons is
invalid and therefore the standard description of semiconductor laser linewidth
lacks theoretical foundation. Experimental support of the standard theory is
also questionable
Transport in Two Dimensional Electronic Micro-emulsions
In two dimensional electron systems with Coulomb or dipolar interactions, a
direct transition, whether first or second order, from a liquid to a
crystalline state is forbidden. As a result, between these phases there must be
other (microemulsion) phases which can be viewed as a meso-scale mixture of the
liquid and crystalline phases. We investigate the transport properties of these
new electronic phases and present arguments that they are responsible for the
various transport anomalies that have been seen in experiments on the strongly
correlated 2DEG in high mobility semiconductor devices with low electron
densities
Mesoscopic effects in superconductor-ferromagnet-superconductor junctions
We show that at zero temperature the supercurrent through the superconductor
- ferromagnetic metal - superconductor junctions does not decay exponentially
with the thickness of the junction. At large it has a random
sample-specific sign which can change with a change in temperature. In the case
of mesoscopic junctions the phase of the order parameter in the ground state is
a random sample-specific quantity. In the case of junctions of large area the
ground state phase difference is .Comment: 4 pages, 1 figur
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