Ultimate efficiency of spectral beam combining by volume Bragg gratings

Drachenberg, Derrek R.; Andrusyak, Oleksiy; Venus, George; Smirnov, Vadim; Lumeau, Julien; Glebov, Leonid

doi:10.1364/ao.52.007233

Cited by 24 publications

(15 citation statements)

References 26 publications

(36 reference statements)

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“…최근에 는 비선형 현상과 더불어 모드 불안정 현상 또한 광섬유 레 이저의 출력을 제한하는 요소가 될 수 있다고 보고되고 있는 데 [11,[40][41][42][43][44][45][46][47][48] , 이는 광신호의 평균 출력에 따라 출력 빔 모드 특 성이 심각하게 왜곡되는 현상으로, 특히 광섬유의 코어가 크 고 그 유효 개구수(Numerical Apeture)가 낮으며 상대적으로 펌프광 흡수율이 높은 막대형 이득 광섬유(Rod-Type Gain Fiber)에서 더욱 현저히 발생한다 [41][42][43][44][45][46][47] . [49][50][51][52][53][54][55][56][57] . 최종적으로 제5장 에서는 앞으로의 고출력 광섬유 레이저 기술에 대한 전망 및 발전 방향을 제시하며 본 논문의 논의를 마무리하고자 한다.…”

Section: 서 론unclassified

“…광학적 손상에 의한 광섬유 레이저의 가용 출력 임계값은 수식 (3)과 같이 표현 된다 [26] . [56] 가 더 높은 펌프 광원을 필요로 하게 됨을 이 미 예측할 수 있게 되는 것이다.…”

Section: 동일한 양의 Sbs가 발생하는 광섬유를 네 구간으로 나누어unclassified

“…따라서, 이러한 출력 증대의 한계성을 극복하기 위한 방안 중 하나로 이른바 다중 빔 결합 기술이 각광받고 있다 [49,50] . [여기서 휘도라함은 단위 입체각(Solid Angle)과 단위 면적당 발산되는 빔의 총 출력 광세기로 정의되며 [56] , 단일 파장 회 절 임계 빔(Diffraction-Limited Beam)의 경우, 휘도는 B = P/λ [49,50] . 반면, 분광형 빔 결합 방식, 즉, SBC 방식은 각 채널 빔들의 파장을 다르게 한 후, 파장 의존형 분광 소자를 이용하여 각 빔들을 중첩하 여 결합하는 방식을 취하게 되므로, 최종적으로 결합된 빔의 빔 발산 및 직경이 단일빔의 수준으로 유지됨과 동시에, 총 출력 광세기가 채널 수에 비례하여 증가되므로, CBC 수준의 빔 휘도 향상을 기대할 수 있다.…”

Section: 다중 빔 결합 기술의 현황unclassified

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Current Status and Prospects of High-Power Fiber Laser Technology (Invited Paper)

Kwon¹,

Park²,

Lee³

et al. 2016

Korean Journal of Optics and Photonics

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Over the past two decades, fiber-based lasers have made remarkable progress, now having reached power levels exceeding kilowatts and drawing a huge amount of attention from academy and industry as a replacement technology for bulk lasers. In this paper we review the significant factors that have led to the progress of fiber lasers, such as gain-fiber regimes based on ytterbium-doped silica, optical pumping schemes through the combination of laser diodes and double-clad fiber geometries, and tandem schemes for minimizing quantum defects. Furthermore, we discuss various power-limitation issues that are expected to incur with respect to the ultimate power scaling of fiber lasers, such as efficiency degradation, thermal hazard, and system-instability growth in fiber lasers, and various relevant methods to alleviate the aforementioned issues. This discussion includes fiber nonlinear effects, fiber damage, and modal-instability issues, which become more significant as the power level is scaled up. In addition, we also review beam-combining techniques, which are currently receiving a lot of attention as an alternative solution to the power-scaling limitation of high-power fiber lasers. In particular, we focus more on the discussion of the schematics of a spectral beam-combining system and their individual requirements. Finally, we discuss prospects for the future development of fiber laser technologies, for them to leap forward from where they are now, and to continue to advance in terms of their power scalability.

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Section: 서 론unclassified

Section: 동일한 양의 Sbs가 발생하는 광섬유를 네 구간으로 나누어unclassified

Section: 다중 빔 결합 기술의 현황unclassified

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Current Status and Prospects of High-Power Fiber Laser Technology (Invited Paper)

Kwon¹,

Park²,

Lee³

et al. 2016

Korean Journal of Optics and Photonics

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“…21 Induced scattering is the result of the precipitation of nanocrystals of sodium fluoride 18 and it is proportional to the concentration of those crystals. 22 The level of scattering in PTR glass containing a certain volume fraction of the crystalline phase is determined by the size of the crystals. The current technology results in a minimum size of crystals of about 15 nm; a further decrease of the crystal size would require the development of a new photosensitive material.…”

Section: Stretching and Compression Of Laser Pulsesmentioning

confidence: 99%

Volume-chirped Bragg gratings: monolithic components for stretching and compression of ultrashort laser pulses

et al. 2014

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Abstract. An innovative type of optical component-a volume Bragg grating-has recently become available commercially and has found wide applications in optics and photonics due to its unusually fine spectral and angular filtering capability. Reflecting volume Bragg gratings, with the grating period gradually changing along the beam propagation direction (chirped Bragg gratings-CBGs) provide stretching and recompression of ultrashort laser pulses. CBGs, being monolithic, are robust devices that have a footprint three orders of magnitude smaller than that of a conventional Treacy compressor. CBGs recorded in photo-thermo-refractive glass can be used in the spectral range from 0.8 to 2.5 μm with the diffraction efficiency exceeding 90%, and provide stretching up to 1 ns and compression down to 200 fs for pulses with energies and average powers exceeding 1 mJ and 250 W, respectively, while keeping the recompressed beam quality M 2 < 1.4, and possibly as low as 1.1. This paper discusses fundamentals of stretching and compression by CBGs, the main parameters of the gratings including the CBG effects on the laser beam quality, and currently achievable CBG specifications. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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“…Ранее уже неоднократно рассматривались мультиплексоры на данном материале, как на отдельно стоящих решетках под каждый лазер [2][3][4][5][6][7][8][9], так и на системах наложенных голограмм [10][11][12][13][14], однако все ранее рассмотренные методы использовали отражательные решетки для сложения пучков. В настоящей работе мы рассмотрим мультиплексор на основе пропускающих брэгговских решеток, а также особенно-сти записи наложенных голограмм в ФТР-стекле.…”

Section: Introductionunclassified