国产部分掺杂光纤实现3 kW全光纤激光振荡输出

Home-made confined-doped fiber with 3-kW all-fiber laser oscillating output

模式不稳定效应和非线性效应成为光纤激光器输出功率和光束质量进一步提升的主要限制因素.采用改进的化学气相沉积工艺结合溶液掺杂技术制备33/400μm部分掺杂掺镱双包层光纤,镱离子掺杂直径比为70%,折射率剖面近似阶跃型.利用主振荡功率放大系统验证部分掺杂光纤光束质量优化作用,种子光束质量为1.53,随着泵浦功率增长,输出激光光束质量逐渐优化至1.43.搭建915 nm反向泵浦全光纤结构激光振荡器.实验中,在泵浦光功率约为4.99 kW时,获得3.14 kW中心波长为1081 nm的激光输出,3 dB带宽为3.2 nm,且未出现模式不稳定和受激拉曼散射现象,这是目前基于国产部分掺杂光纤实现的最高输出功率.以上结果表明,部分掺杂光纤在实现高功率且高光束质量光纤激光输出中具有潜力.

Ytterbium doped fiber lasers(YDFLs)with small volume,good beam quality,good heat dissipation performance and high conversion efficiency are widely used in industrial processing,military,medical and other fields.In past decades,with the development of high-performance double cladding gain fiber and fiber devices,the output power of YDFLs increases rapidly.However,nonlinear effects(NLEs),such as stimulated Brillouin scattering(SBS),stimulated Raman scattering(SRS),are produced,which limits the further enhancement of the output power of fiber laser.Large mode area ytterbium-doped fiber(LMAYDF)can effectively increase the nonlinear effect threshold.However,increasing the core diameter will support more high-order modes(HOMs),which may lead the beam quality to deteriorate and induce the mode instability(MI)effect to occur in fiber lasers.Thus,MI and NLEs have become the main limiting factors for the further improving of output power and beam quality in fiber lasers.The confined-doped ytterbium-doped double-clad fiber(CDYDF),by reducing the doping diameter of gain ions in the fiber core,makes the fundamental mode(FM)dominate in mode competition and HOM suppressed to achieve LMAYDF gain control for different modes,thus improving the output power of the fiber laser and maintaining good beam quality.The 33/400μm confined-doped ytterbiumdoped double-clad fiber(CDYDF)is fabricated by modifying the chemical vapor deposition(MCVD)process with solution doping technology(SDT).The Yb^3+doping diameter ratio is 70%and refractive index profile is close to step-index.Utilizing the master oscillator power amplifier(MOPA)system the beam quality optimization effect of confined-doped fiber is verified and optimized to 1.43 as the power increases while the M2 of seed laser is 1.53.An all-fiber structure counter-pumped fiber oscillator is constructed to test the laser performance of home-made confined-doped fiber.When the pump power is^4.99 kW,laser power of 3.14 kW with a central wavelength of 1081 nm and line width of 3.2 nm at 3 dB is obtained.Moreover,there is no MI nor SRS in the whole experiment.We demonstrate that it is the highest output power based on home-made confined-doped fiber.The above results indicate that confined-doped fibers have the potential to achieve highpower and high-beam-quality fiber laser output.