162 research outputs found
Phase-dependent Supermode Excitation in Photonic Molecules
A photonic molecule (PM) is a miniature diffractive optical structure
composed of resonance microcavities called atoms (e.g., cylinders or spheres)
supporting a set of high-quality eigenmodes. All atoms in a PM are coupled by
the electromagnetic fields of eigenmodes, which form collective supermodes of
the whole PM. We consider a particular type of mirror-symmetric PMs being
optically excited simultaneously via two light channels (tapered fibers). Based
on the numerical simulations, we show that the spectral composition of
supermodes in such PM can be effectively manipulated by changing the phase
detuning between the optical channels. For a seven-atom silicon microcylinder
cyclic-PM is demonstrated the possibility to achieve tenfold intensity
amplification/suppression of several supermodes from the Stokes and anti-Stokes
bands of PM spectrum
Toward high-speed effective numerical simulation of multiple filamentation of high-power femtosecond laser radiation in transparent medium
High-power femtosecond laser radiation during the propagation in air (and
other transparent media) experiences multiple filamentation. Filamentation is a
unique nonlinear optical phenomenon, which is accompanied by a wealth of
nonlinear optical effects such as formation of extended plasma channels in the
beam wake, generation of higher harmonics and supercontinuum, generation of THz
radiation. The manifestations of laser filamentation can be useful for solving
atmospheric optics problems related to remote sensing of the environment as
well as directed transmission of laser power. The classical numerical methods
used for simulating the nonlinear long-range atmospheric propagation of
high-power radiation with a sufficiently large laser beam aperture have almost
reached their limit regarding the acceleration of calculations. To solve this
problem and speed-up the numerical simulations of laser filamentation, we
propose an improved numerical technique based on a modified method of phase
screens constructed on a sparse spatial grid. Within the framework of this
technique, we seek for optimal ansatz (substitution function) to the governing
equations using the machine learning technology, which provides for the best
correspondence to the numerical solution of the test problem using a denser
spatial gri
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