Power Scaling of SM Fiber Lasers toward 10kW

Abstract

In this paper, we report the mode area scaling of a rare-earth doped step index fiber by using low numerical aperture. Numerical simulations show the possibility of achieving an effective area of ~700um 2 (including bend induced effective area reduction) at a bend diameter of 32cm from a 35μm core fiber with a numerical aperture of 0.038. An effective single mode operation is ensured following the criterion of the fundamental mode loss to be lower than 0.1dB/m while ensuring the higher order modes loss to be higher than 10dB/m at a wavelength of 1060nm. Our optimized modified chemical vapor deposition process in conjunction with solution doping process allows fabrication of an Yb-doped step index fiber having an ultra-low numerical aperture of ~0.038. Experimental results confirm a Gaussian output beam from a 35μm core fiber validating our simulation results. Fiber shows an excellent laser efficiency of ~81% and a M 2 less than 1.1. 2015 Optical Society of America OCIS codes: (060.2280) Fiber design and manufacturing; (140.3510) Fiber lasers.

Demonstration of ultra-low NA rare-earth doped step index fiber for applications in high power fiber lasers

“…Our studies show that addition of ring significantly enhances the suppression of HOMs by delocalizing the HOMs [24][25]. Our detailed studies ensure that the effective area larger than 1,000μm 2 , while offering HOMs losses to be larger than 10dB/m and FM loss to be lower than 0.1dB/m and a more than 30% difference in power fraction of FM and HOMs in core region can be achieved at 20cm bend radius and at 1060nm wavelength [24][25]. STF offers a number of advantages over other competitive fiber designs.…”

“…Good beam quality and flexibility offered by optical fibers are also very attractive features for high power beam delivery. Conventional step index fiber (SIF), where core is doped with rare-earth ions has been used as a gain medium in fiber lasers and output power level in the range of kWs has been reported using these fibers [2]. However, non-linear effects often found to be the primary limiting factors for power scaling in fiber lasers and amplifiers [3].…”

High-power double-cladding fiber lasers: A 30-year overview

“…激光 器发明后的第二年(1961年), 来自America Optical公司 的Snitzer [1,2] 就在掺钕玻璃波导中观察到了激光现象, 不久后又实现了光纤激光放大 [3] . 20世纪70年代, Bell 实验室的Stone和Burrus [4,5] [15,16] , 合束后的光 纤激光输出功率已达100 kW级 [17] . 出功率提升至1 W [24] , 5 W [25] 和9.2 W [26] .…”

“…需要说明的是, 除了掺镱双包层光纤之外, 研究人 员也基于掺杂其他稀土离子的光纤实现了较高功率输 出, 其中最具有代表性的就是千瓦级掺铥光纤激光 (2010年) [35] 、600 W级掺铒光纤激光(2018年) [36] 和 400 W级掺钬光纤激光(2013年) [37] . 不同掺杂光纤使 得激光器的中心波长等参数有较大差别, 但单从输出 功率这一项而言, 掺镱光纤激光无疑是最具有代表性 的, 单束掺镱光纤激光输出功率已经突破了万瓦级 (2009年) [15,16] , 比其他类型的掺杂光纤激光功率高出 了1个量级.…”

Impact of Phase Perturbation on Passive Phase-Locking Coherent Beam Combination

“…In 2009, IPG demonstrated 9.6 kW of output power in a single-mode through a single fiber [1]. However, the output power from a single fiber can not be infinitely improved due to fiber nonlinear effects and thermal limitations [2].…”