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Chizhevsky V.N.,B. I. Stepanov Institute of Physics
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2010

An efficient method for enhancement of a random bit generation rate from a physical source of randomness is proposed. It is based on the repeated application of the operation of symmetrization of random data. This procedure allows one to transform asymptotically any nonsymmetrical distribution into a perfectly symmetrical one. As a result, one can extract up to 46 uncorrelated and unbiased bits from each variate, increasing an effective rate up to 46 times with respect to the mean frequency of random events. The method was tested with spontaneous switchings in a bistable vertical cavity laser. A statistical analysis of the generated random bit sequences which passed the standard randomness tests (ENT, NIST Statistical Test Suites, and Diehard) is presented. © 2010 The American Physical Society.


Chizhevsky V.N.,B. I. Stepanov Institute of Physics
Optics Letters | Year: 2012

It is experimentally demonstrated that the response of a bistable vertical-cavity surface-emitting laser at a selected polarization to the effect of the modulated optical feedback at the orthogonal polarization can be considerably enhanced by the additional periodic current modulation via vibrational resonance. It shows up as a nonmonotonic dependence of the response at the frequency of the modulated optical feedback as a function of the amplitude of the current modulation. In such conditions the laser response can be amplified more than 80 times for a weak optical feedback. At the optimal amplitude of the current modulation a complete synchronization of optical switchings between polarization states with modulated optical feedback is observed. The effect of asymmetry of a bistable quasi-potential is also experimentally demonstrated. © 2012 Optical Society of America.


Khilo N.A.,B. I. Stepanov Institute of Physics
Optics Communications | Year: 2013

As shown previously, the propagation of a Bessel light beam along the optical axes of a biaxial crystal results in conversion of the order of a Bessel function. The Bessel beam changes its order by one due to the effect of the crystal anisotropy, which results in the generation of a vortex beam. In this work we demonstrate a simple derivation of the equations describing the conversion and propagation of the vortex field. These equations are applied to study the conversion of a strongly truncated Bessel beam. The results can be used for developing crystal-based Bessel beam converters and generating vortex optical fields. © 2012 Elsevier B.V. All rights reserved.


Novitsky D.V.,B. I. Stepanov Institute of Physics
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

We solve the problem of ultrashort pulse propagation in a two-level medium beyond the rotating-wave (RWA) and slowly varying-envelope approximations. The method of solution is based on the Maxwell-Bloch equations represented in the form that allows one to switch between RWA and general (non-RWA) cases in the framework of a single numerical algorithm. Using this method, the effect of a subcycle pulse (containing less than a single period of field oscillations) on the two-level medium was analyzed. It is shown that for such short pulses, the clear breakdown of the area theorem occurs for the pulses of large enough area. Moreover, deviations from the area theorem appear to be strongly dependent on the pulse shape that cannot be observed for longer few-cycle pulses. © 2012 American Physical Society.


Novitsky D.V.,B. I. Stepanov Institute of Physics
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

We study inelastic collisions of counterpropagating self-induced transparency solitons in a homogeneously broadened two-level medium. The energy of the pulse can be almost totally absorbed in the medium due to asymmetric collision with a properly chosen control pulse. The medium state thus prepared demonstrates the property of an all-optical diode which transmits pulses from one direction and blocks from another. The saturation process of a controlled absorption effect, local-field correction influence, and the parameter ranges for the diode action are studied as well. © 2012 American Physical Society.

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