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Dayton, OH, United States

Vorontsov M.A.,University of Dayton | Lachinova S.L.,Optonicus
Optics InfoBase Conference Papers | Year: 2014

A new target-in-the-loop (TIL) atmospheric sensing concept for in-situ remote measurement of major atmospheric parameters is discussed. The proposed technique is based on utilization of integral relationships between complex amplitudes of the counter-propagating waves, whose values are preserved along the propagation path, for atmospheric turbulence characterization. We show that these relationships, referred to here as the remote sensing invariants, can be directly measured using a TIL sensor composed of a single-mode fiber-based optical transceiver and a remotely located small-size retro-reflector. The measured signals allow retrieval of key turbulence characteristics along the target line of sight, including refractive index structure parameter and scintillation index. The discussed concept allows practical development of a compact TIL atmospheric sensor that does not require installation of an additional transmitter/receiver device at the other end of the laser beam propagation path. © 2014 OSA. Source


Vorontsov M.A.,Optonicus | Vorontsov M.A.,University of Dayton | Lachinova S.L.,Optonicus | Majumdar A.K.,U.S. Navy
Applied Optics | Year: 2016

A new target-in-the-loop (TIL) atmospheric sensing concept for in situ remote measurements of major laser beam characteristics and atmospheric turbulence parameters is proposed and analyzed numerically. The technique is based on utilization of an integral relationship between complex amplitudes of the counterpropagating optical waves known as overlapping integral or interference metric, whose value is preserved along the propagation path. It is shown that the interference metric can be directly measured using the proposed TIL sensing system composed of a single-mode fiber-based optical transceiver and a remotely located retro-target. The measured signal allows retrieval of key beam and atmospheric turbulence characteristics including scintillation index and the path-integrated refractive index structure parameter. © 2016 Optical Society of America. Source


Lachinova S.L.,Optonicus | Vorontsov M.A.,Optonicus | Vorontsov M.A.,University of Dayton
Journal of Optics (United Kingdom) | Year: 2013

A new approach for engineering a variety of unconventional laser beams with complex spatio-temporal characteristics using coherent (coherently combinable) fiber-array laser transmitter systems is proposed and analyzed through numerical simulations. These laser beams, referred to here as exotic beams, include beams with periodic, quasi-periodic, and stochastic spatio-temporal phase modulation. We show that exotic laser beams can be generated in fiber arrays using feedback control systems of different architectures based on a network of beam-tail interference sensors and fiber-integrated phase shifters. Due to the extremely short (nanosecond time scale) response time of these phase shifting elements, the proposed technique permits generation of laser beams with controllable spatial coherence which can be used for mitigation of speckle effects in various applications including directed energy, laser communications, active imaging, and wavefront sensing. Results of analyses and computer simulations of exotic beams are presented for the fiber-array system with seven subapertures. © 2013 IOP Publishing Ltd. Source


Lachinova S.L.,Optonicus | Vorontsov M.A.,Optonicus | Vorontsov M.A.,University of Dayton
Journal of Optics (United Kingdom) | Year: 2016

In the wave-optics numerical simulations of laser beam propagation in volume atmospheric turbulence, we observe irregular appearance of giant intensity spikes with amplitudes exceeding the diffraction-limited intensity value by a factor of ten or even more. The presence of giant spikes may explain the existing significant difference between the scintillation index theoretical prediction and the results obtained in numerical simulation and experimental measurements. The giant spikes' physics-based origin, probability of appearance, and impact on irradiance scintillation index are analyzed. © 2016 IOP Publishing Ltd. Source


Filimonov G.A.,University of Dayton | Filimonov G.A.,Zuev Institute of Atmospheric Optics | Vorontsov M.A.,University of Dayton | Lachinova S.L.,Optonicus
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

The phase noise that originates in the multi-channel master-oscillator power amplifier (MOPA) system of a coherent tiled fiber-array beam director may drastically impact the efficiency of laser beam projection on a remotely located target in the atmosphere. The recently proposed near-field phase locking (NFPL) technique mitigates the MOPA-induced phase noise and gives an opportunity for programmable control of local (on-subaperture) piston and tip/tilt phases of the outgoing fiber-array beams (beamlets). In the present paper, we evaluate the influence of both NFPL and programmable phase control on the beam director performance for different laser beam propagation paths and atmospheric turbulence conditions. Our analysis is based on wave-optics numerical simulation. © 2014 SPIE. Source

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