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67 results on '"Honzatko, Pavel"'

62. Optimization of genetic algorithm for reconstruction of cross-phase modulation frequency-resolved optical gating data.

Author

Vrany, Boleslav, Honzatko, Pavel, and Kanka, Jiri

Subjects
*OPTICAL fibers, *GENETIC algorithms, *MATHEMATICAL optimization, *PHASE modulation, *MICROSTRUCTURE, *ALGORITHMS, *OPTICAL polarization
Abstract

We implemented a frequency-resolved optical gating (FROG) measurement method using cross-phase modulation in a highly birefringent microstructure optical fiber. The standard FROG data reconstruction algorithm of generalized projection failed for this setup and we successfully used the genetic algorithm (GA) instead which is less prone to get stuck to local minima. GA has several parameters that must be set up to suitable values. We describe the experimental setup and the algorithm and present our findings on what GA parameters are crucial and what are their optimal values. A single run of the algorithm takes 7 min on contemporary CPUs, making the algorithm suitable for routine laboratory work. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Published
2011
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66. Preparation and characterization of highly thulium- and alumina-doped optical fibers for single-frequency fiber lasers

Author

Honzatko, Pavel, Dhar, Anirban, Kasik, Ivan, Podrazky, Ondrej, Matejec, Vlastimil, Peterka, Pavel, Blanc, Wilfried, and Dussardier, Bernard

Abstract

Thulium-doped fibers suitable for core-pumped single-frequency lasers were fabricated by the modified chemical vapor deposition (MCVD) method. Refractive index profile, doping profile and spectral absorption was measured. High doping concentration of thulium ions should be achieved to allow for high absorption of light at a pump wavelength while the thulium ions clustering should be avoided to prevent the cooperative upconversion and quenching processes. The fabricated fibers featured pump absorption up to 70dB/m at a pump wavelength of 1611nm. The single-frequency master oscillator with a resonator composed of a pair of fiber Bragg gratings and a thulium-doped fiber was demonstrated with predominantly single ended operation. We achieved a slope efficiency of 22\% and a threshold of 22mW at a lasing wavelength of 1944nm.

Published
2011
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67. Retrieval of the pulse amplitude and phase from cross-phase modulation spectrograms using the simulated annealing method.

Author

Honzatko P, Kanka J, and Vrany B

Abstract

The simulated annealing method is used for retrieving the amplitude and phase from cross-phase modulation spectrograms. The method allows us to take into account the birefringence of the measurement fiber and resolution of the optical spectrum analyzer. The influence of the birefringence and analyzer resolution are discussed.

Published
2004
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