一种基于反谐振结构的三能级掺钕激光光纤设计OA北大核心CSTPCD

900-nm Nd-doped fiber laser can find widespread applications including biomedical diagnosis,laser detection,and spectral analysis.The four-level gain competition of Nd3+around 1060 nm severely constrains the laser power scaling of the 900-nm three-level Nd-doped fiber laser.In this work,we propose a large-mode-area Nd-doped double-layer solid-core anti-resonant fiber with a core diameter of 27 μm for generating a high-power 900-nm laser based on the resonant and anti-resonant conditions of anti-resonant fiber.The transmission properties and mode profiles of the designed fiber are analyzed theoretically by using the full-vector finite-element method combined with an optimized mesh size.By introducing the double-layer anti-resonant elements into the active fiber and optimizing the fiber structure parameters and refractive index distribution,the high-order modes are well coupled with cladding modes.Finally,the designed fiber exhibits a confinement loss below 0.1 dB/m for fundamental mode and the confinement losses of all high-order modes are greater than 10 dB/m in 880-913 nm band.More importantly,around 1060 nm,the confinement losses of all modes can reach up to 100 dB/m,which enables the designed Nd-doped fiber to effectively suppress parasitic lasing and even amplified spontaneous emission.The Nd-doped solid-core anti-resonant fiber proposed in this study shows broad application prospects in the fields of 900-nm high-power fiber laser and amplifier.The developed chemical vapor deposition process combined with stack-and-draw technology can be adopted for the fabrication of the designed fiber.In order to ensure the optical performance of the anti-resonant fiber,it is necessary to accurately control the thickness of all anti-resonant tubes,the glass composition of the active core and background area in actual fabrication.