Fabrication and evaluation of a 500 W cladding-light stripper

Abstract

Fiber lasers have reached kW levels of output power. To achieve this level it is necessary to use reliable high-power components that sustain these power levels. Double-clad fibers (DCFs) are often used in high-power fiber lasers. Cladding-light strippers (CLSs) are used to remove unwanted light from the inner cladding of the DCF. This unwanted light consists of residual pump light or signal light that leaked into the cladding, thus requiring that the CLS removes both high-NA (>0.4) and low-NA (<0.1) light. Often high-index polymers are used to remove the unwanted light from DCFs1,2,3. Because the CLS has to be able to withstand several 100W and most polymers are not capable of exceeding temperatures more than 200°C, we investigated a CLS without polymers, based on an etching process. We present results from a CLS that was tested up to 500W of stripped power. We determined the angle dependency of the stripping efficiency by launching both high- and low-NA light into the fiber and evaluating the NA attenuation. Furthermore, we measured the dependency of the stripping efficiency on the length of the etched area and the etching time. With optimized parameters an attenuation of more than 20 dB when launching high-NA light and 6 dB with low-NA light was achieved. The CLS did not show any degradation in terms of attenuation or thermal behavior in a six-hour stability test

Study and design of cladding power stripper for high power fiber laser systems

“…Removing the original fluoroacrylate jacket and recoating the exposed fiber with a high index polymer coating can strip over more than hundred watts of residual light [3] . Fabricated using an etching technique successfully tested that it has good behavior in stability and thermal so it can be used for higher power laser systems [4] . Corroding the inner cladding layer into special shape can strip the power of cladding light uniformly over the length of the fiber rather than other previous methods [5] .…”

Combined method for the fabrication of high-power cladding light stripper using a buffered oxide etchant

“…Various approaches were utilized in the formation of the high-power CLS. These are (i) hydrofluoric acid (HF) etching with acidic fluorides [1,2], (ii) cascaded coating of the fibers using UV-curable polymers with various RIs [3,4], (iii) soft metal coating, (iv) surface texturization using lasers [5,6], and (v) high-index capillary coating [7,8].…”

“…All these methods have their advantages and disadvantages as follows: (i) Working with HF and acidic fluorides requires a great deal of attention, but this method appears to be successful at attenuating 27 dB of the pumped light with the NA of 0.44 [1]. Furthermore, the etched fiber can be tapered despite the fact that the term "tapering" is generally used upon applying the heat-pull method but can also be referred to for acidic tapering [9].…”

“…Many groups have demonstrated CLSs fabricated by coating and/or etching methods. These include [5] the high-index polymer with 18 dB loss [4], the soft metal coating with 20 dB loss [10], an interesting study on high-power CLS preparation with 20 dB using recoating fiber surface with a capillary glass [8], and chemical etching methods with 27 dB and 16.7 dB loss [1,7,9]. However, no detailed studies on the precise information about the optimum etching conditions and utilizing different chemical etching methods, including chemical stain etching and vapor-phase etching were reported on the performance of CLSs.…”

Research advance on the key technology of high-power fiber laser materials and components

“…此外, 国内能够研 [17] 过3 kW的光纤光栅产品. 包层光剥离器方面目前国外 公开报道的结果较少, 一般认为已经达到千瓦量级水 平 [18] . [31] ; 美国Teradiode 公司于2011年报道了功率1040 W(光纤芯径200 μm, 数 值孔径0.18)的单波长966 nm光纤耦合输出模块 [32] , 而…”