DOI QR코드

DOI QR Code

스펙클 이미지의 푸리에 공간 분석을 통한 결맞음 빔결합 상태 모니터링 변수 도출

Study of Monitoring Parameters for Coherent Beam Combination through Fourier-domain Analysis of the Speckle Image

  • 박재덕 (아주대학교 에너지시스템학과) ;
  • 최윤진 (아주대학교 에너지시스템학과) ;
  • 염동일 (아주대학교 에너지시스템학과)
  • Park, Jaedeok (Department of Energy Systems Research, Ajou University) ;
  • Choe, Yunjin (Department of Energy Systems Research, Ajou University) ;
  • Yeom, Dong-Il (Department of Energy Systems Research, Ajou University)
  • 투고 : 2020.10.13
  • 심사 : 2020.11.04
  • 발행 : 2020.12.25

초록

레이저 빔이 산란 매질에서 반사될 때 발생하는 스펙클 패턴을 모니터링함으로써 산란 매질에 입사하는 레이저 빔들의 결맞는(coherent) 결합 상태를 분석하고자 하였다. 이를 위하여 가간섭성이 높은 3개의 시준 레이저 광원을 자유공간에서 렌즈를 이용하여 무작위 표면특성을 가진 산란목표물(scattering target)에 집속한 후, 되돌아오는 빔의 스펙클 패턴을 푸리에 영역에서 살펴보았다. 목표물에 입사하는 단일 레이저 빔의 크기변화 및 3개 결맞는 레이저 빔 간의 공간적인 빔결합 정도에 따라 스펙클 패턴의 평균적인 크기가 변하게 되는데, 이를 푸리에 영역에서 분석함으로써 결맞음 빔결합의 효율을 판별할 수 있는 단일 모니터링 변수를 도출할 수 있었다.

We analyze the characteristics of the coherent beam combination of lasers by monitoring the speckle pattern of the beam reflected from a scattering medium. Three collimated laser sources with high coherence are focused on a scattering target using a lens, and we then examine the speckle pattern of the returned beam in the Fourier domain. We observe that the size of the speckle pattern changes, depending on the focused-beam size or degree of spatial overlap of the three beams. Furthermore, through Fourier-domain analysis of the speckle pattern we obtain the monitoring variable to qualify the efficiency of the coherent beam combination.

키워드

참고문헌

  1. B. He, Q. Lou, J. Zhou, J. Dong, Y. Wei, D. Xue, Y. Qi, Z. Su, L. Li, and F. Zhang, "High power coherent beam combination from two fiber lasers," Opt. Express 14, 2721-2726 (2006). https://doi.org/10.1364/OE.14.002721
  2. V. Jolivet, P. Bourdon, B. Bennai, L. Lombard, D. Goular, E. Pourtal, G. Canat, Y. Jaouen, B. Moreau, and O. Vasseur, "Beam shaping of single-mode and multimode fiber amplifier arrays for propagation through atmospheric turbulence," IEEE J. Sel. Top. Quantum Electron. 15, 257-268 (2009). https://doi.org/10.1109/JSTQE.2009.2011141
  3. N. R. Van Zandt, S. J. Cusumano, R. J. Bartell, J. E. McCrae, and S. T. Fiorino, "Comparison of coherent and incoherent laser beam combination for tactical engagements," Opt. Eng. 51, 104301 (2012). https://doi.org/10.1117/1.OE.51.10.104301
  4. H. Tian, Y. Song, F. Meng, Z. Fang, M. Hu, and C. Wang, "Long-term stable coherent beam combination of independent femtosecond Yb-fiber lasers," Opt. Lett. 41, 5142-5145 (2016). https://doi.org/10.1364/OL.41.005142
  5. T. Y. Fan, "Laser beam combining for high-power, high-radiance sources," IEEE J. Sel. Top. Quantum Electron. 11, 567-577 (2005). https://doi.org/10.1109/JSTQE.2005.850241
  6. H. Bruesselbach, S. Wang, M. Minden, D. C. Jones, and M. Mangir, "Power-scalable phase-compensating fiber-array transceiver for laser communications through the atmosphere," J. Opt. Soc. Am. B. 22, 347-353 (2005). https://doi.org/10.1364/JOSAB.22.000347
  7. M. A. Vorontsov, G. Filimonov, V. Ovchinnikov, E. Polnau, S. Lachinova, T. Weyrauch, and J. Mangano, "Comparative efficiency analysis of fiber-array and conventional beam director systems in volume turbulence," Appl. Opt. 55, 4170-4185 (2016). https://doi.org/10.1364/AO.55.004170
  8. M. A. Vorontsov and V. Kolosov, "Target-in-the-loop beam control: basic considerations for analysis and wave-front sensing," J. Opt. Soc. Am. A 22, 126-141 (2005). https://doi.org/10.1364/JOSAA.22.000126
  9. X. L. Wang, Y. X. Ma, P. Zhou, H. T. Ma, X. X. Xu, and Z. J. Liu, "Coherent beam combining of two W-level fiber amplifiers in turbulence atmospheric environment based on stochastic parallel gradient descent algorithm," Laser Phys. 19, 984-988 (2009). https://doi.org/10.1134/S1054660X09050168
  10. T. Weyrauch, M. A. Vorontsov, G. W. Carhart, L. A. Beresnev, A. P. Rostov, E. E. Polnau, and J. J. Liu, "Experimental demonstration of coherent beam combining over a 7 km propagation path," Opt. Lett. 36, 4455-4457 (2011). https://doi.org/10.1364/OL.36.004455
  11. E. Polnau, M. A. Vorontsov, and R. Gudimetla, "Experimental demonstration of target-in-the-loop remote sensing of laser beam and atmospheric turbulence characteristics," J. Opt. 21, p095602 (2019). https://doi.org/10.1088/2040-8986/ab3876
  12. M. A. Vorontsov and G. W. Carhart, "Adaptive phase distortion correction in strong speckle-modulation conditions," Opt. Lett. 27, 2155-2157 (2002). https://doi.org/10.1364/OL.27.002155
  13. M. A. Vorontsov, T. Weyrauch, S. Lachinova, M. Gatz, and G. Carhart, "Speckle-metric-optimization-based adaptive optics for laser beam projection and coherent beam combining," Opt. Lett. 37, 2802-2804 (2012). https://doi.org/10.1364/OL.37.002802