22 research outputs found
Dynamics of platicons due to third-order dispersion
Dynamics of platicons caused by the third-order dispersion is studied. It is
shown that under the influence of the third-order dispersion platicons obtain
angular velocity depending both on dispersion and on detuning value. A method
of tuning of platicon associated optical frequency comb repetition rate is
proposed.Comment: 11 pages, 5 figure
Impact ionization fronts in Si diodes: Numerical evidence of superfast propagation due to nonlocalized preionization
We present numerical evidence of a novel propagation mode for superfast
impact ionization fronts in high-voltage Si -- structures. In
nonlinear dynamics terms, this mode corresponds to a pulled front propagating
into an unstable state in the regime of nonlocalized initial conditions. Before
the front starts to travel, field-ehanced emission of electrons from deep-level
impurities preionizes initially depleted base creating spatially nonuniform
free carriers profile. Impact ionization takes place in the whole high-field
region. We find two ionizing fronts that propagate in opposite directions with
velocities up to 10 times higher than the saturated drift velocity.Comment: 3 pages, 4 figure
Platicon Stability in Hot Cavities
The stability of platicons in hot cavities with normal group velocity at the
interplay of Kerr and thermal nonlinearities was addressed numerically. The
stability analysis was performed for different ranges of pump amplitude,
thermal nonlinearity coefficient and thermal relaxation time. It was revealed
that for the positive thermal effect, the high-energy wide platicons are
stable, while the negative thermal coefficient provides the stability of narrow
platicons.Comment: 4 pages, 8 figure
Ultra high-Q WGM microspheres from ZBLAN for the mid-IR band
The advantages of high-quality-factor whispering gallery mode microresonators
can be applied to develop novel photonic devices for the mid-IR range. ZBLAN
(glass based on heavy metal fluorides) is one of the most promising materials
to be used for this purpose due to low optical losses in the mid-IR. We
developed original fabrication method based on melting of commercially
available ZBLAN-based optical fiber to produce high-Q ZBLAN microspheres with
the diameters of 250 to 350 m. We effectively excited whispering gallery
modes in these microspheres and demonstrated high quality factor both at 1.55
m and 2.64 m. Intrinsic quality factor at telecom wavelength was
shown which is defined by the material losses in ZBLAN.
In the mid-IR at 2.64 m we demonstrated record quality factor in ZBLAN
exceeding which is comparable to the highest values of the Q-factor
among all materials in the mid-IR
Theory of superfast fronts of impact ionization in semiconductor structures
We present an analytical theory for impact ionization fronts in reversely
biased p^{+}-n-n^{+} structures. The front propagates into a depleted n base
with a velocity that exceeds the saturated drift velocity. The front passage
generates a dense electron-hole plasma and in this way switches the structure
from low to high conductivity. For a planar front we determine the
concentration of the generated plasma, the maximum electric field, the front
width and the voltage over the n base as functions of front velocity and doping
of the n base. Theory takes into account that drift velocities and impact
ionization coefficients differ between electrons and holes, and it makes
quantitative predictions for any semiconductor material possible.Comment: 18 pagers, 10 figure