Yuri Chamorovskii

Russian Academy of Sciences, Moskva, Moscow, Russia

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Publications (9)12.17 Total impact

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    ABSTRACT: We have experimentally investigated fundamental mode propagation in few-meter-long adiabatic step-index tapers with high numerical aperture, core diameter up to 117μm (V=38), and tapering ratio up to 18. We confirmed single fundamental mode guiding in tapers with uniform core index profile by several experiments. We observed an annular near field distribution and degraded beam quality for large output core diameters, found to occur due to intrinsic mechanical stress in the fibers. We expect that eliminating the stress would prevent the mode deformation and allow constructing single-mode, diffraction-limited tapered large-mode-area amplifiers with a good beam shape.
    Proc SPIE 03/2013;
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    ABSTRACT: We have studied the recently demonstrated concept of fiber lasers based on active tapered double-clad fiber (T-DCF) in copropagating and counterpropagating configurations, both theoretically and experimentally, and compared the performance to fiber lasers based on conventional cylindrical fibers in end-pumped configurations. Specific properties of T-DCFs were considered theoretically using a rate-equation model developed for tapered fibers, and a detailed comparative study was carried out experimentally. Furthermore, we have studied mode coupling effects in long adiabatic tapers due to coiling and local bending. The results allow us to conclude that, with proper fiber design, the T-DCF technology offers a high-potential alternative for bright, cost-effective fiber devices.
    Applied Optics 10/2012; 51(29):7025-38. · 1.69 Impact Factor
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    ABSTRACT: We have performed a detailed comparative analysis of the main configurations of fiber lasers based on tapered double-clad active fiber (T-DCF). The most prospective fields of application are proposed and discussed.
    05/2011;
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    ABSTRACT: In this work, we have constructed an actively Q-switched T-DCF laser with an acousto-optic modulator (AOM). Actively Q-switched laser with T-DCF generated stable emission at 1065 nm over a wide repetition rate range of 0 Hz - 150 kHz, with the highest measured pulse energy of 1.6mJ limited by stimulated Brillouin scattering (SBS). We attribute the robust operation at low duty cycles to the intrinsically low amplified spontaneous emission (ASE), provided by the tapered fiber shape. In addition to the advantage of the large mode area at the output end of the fiber, the T-DCF provides several other attractive features. First, the vignetting of co-propagating ASE results in ASE power loss in wide-to-narrow end propagation. Second, the low-mode nature of counter-propagating spontaneous emission, arising from mode selection in the narrow part of the fiber, leads to weaker amplification of the spontaneous emission. These two effects contribute to the low ASE background. Finally, fiber diameter modulation is a known method for SBS suppression, and another inherent property of the T-DCF. These characteristics allowed for generation of 1.6mJ, 64 ns pulses at very low duty cycles, up to single shot operation, illustrating the potential of the T-DCF for high-energy pulse generation and amplification.
    Proc SPIE 01/2011;
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    ABSTRACT: We have demonstrated an actively Q-switched tapered double-clad fiber laser capable of single-shot generation of 1.6-mJ, 64-ns pulses. The active medium based on tapered double-clad fiber is shown to exhibit a reduced level of amplified spontaneous emission which allows for high-energy pulse extraction at extremely low repetition rates.
    Optics Express 08/2010; 18(18):18543-9. · 3.55 Impact Factor
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    ABSTRACT: The results of theoretical and experimental studies of active tapered double-clad fibers, intending the optimization of its imperative parameters--tapering ratio, longitudinal profile, core/cladding diameters ratio, are presented. Using a refined taper geometry we have demonstrated power scaling of a ytterbium fiber laser pumped by low-brightness, cost-effective laser diodes up to 750 W, with 80% efficiency.
    Optics Express 06/2010; 18(12):12499-512. · 3.55 Impact Factor
  • Article: LASE
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    ABSTRACT: We report the theoretical and experimental study of the properties of an active tapered double clad fiber (T-DCF). Optimization of the most important parameters of T-DCF such as tapering ratio, longitudinal profile, core/clad ratio and absorption have been considered. Using optimized T-DCF design we have demonstrated a high-power (750W) and highly efficient (80%) ytterbium fiber laser.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
    02/2010;
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    ABSTRACT: We report the theoretical and experimental study of the properties of an active tapered double clad fiber (T-DCF). Optimization of the most important parameters of T-DCF such as tapering ratio, longitudinal profile, core/clad ratio and absorption have been considered. Using optimized T-DCF design we have demonstrated a high-power (750W) and highly efficient (80%) ytterbium fiber laser.
    Proc SPIE 02/2010;
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    ABSTRACT: With a tapered double-clad all-glass ytterbium fiber as a gain medium, a maximum output power of over 200 W at 1079 nm and a slope efficiency of over 70% were demonstrated. The tapered double-clad fiber concept allows for using low-brightness diode bars and results in cost-effective and efficient high-power fiber lasers. The adiabatic conical fiber gain waveguide combines improved pump absorption owing to enhanced mode mixing in the pump cladding, low-noise single fundamental mode operation with M(2)< or =1.02, and strong potential for significant power scaling.
    Optics Letters 08/2008; 33(13):1416-8. · 3.39 Impact Factor

Publication Stats

19 Citations
12.17 Total Impact Points

Top Journals

Institutions

  • 2008–2012
    • Russian Academy of Sciences
      • Fiber Optics Research Center
      Moskva, Moscow, Russia
  • 2008–2010
    • Tampere University of Technology
      • Optoelektroniikan tutkimuskeskus
      Tampere, Western Finland, Finland