Investigation of core compositions for efficient 976 nm lasing from step index large-mode-area fiber

• Main Authors: Li, Huizi, Chen, Shaoxiang, Sidharthan, Raghuraman, Ma, Jie, Xia, Nan, Chang, Chen Jian, Kim, Jaesun, Yoo, Seongwoo
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2022
• Subjects: Engineering::Electrical and electronic engineering; Optical Fiber Amplifiers; Optical Fiber Devices
• Online Access: https://hdl.handle.net/10356/161055
• Institution: Nanyang Technological University

We present an efficient 976 nm fiber laser achieved in a step index large-mode-area (LMA) fiber by 915 nm diode pumping. The 976 nm lasing was enabled using spectroscopic engineering in a fiber design that helps suppress the competing 1030 nm gain. Our study shows, alumino-phospho-silicate (Al:P) is advantageous for shaping a gain spectrum in favor of 976 nm compared to other widely used compositions, hence facilitating otherwise the challenging 976 nm lasing. In addition, a germanium (Ge)-cladding was introduced to achieve LMA and low numerical aperture step-index fiber, permitting a wavelength selective bending technique. By applying the bending technique, an efficient 976 nm lasing was achieved with up to 15 W output power (pump power limited) with 28% slope efficiency in the step-index LMA fiber.