Power scaling for narrow linewidth C-band pulsed fiber lasers using a highly Er/Yb co-doped phosphate glass fiber

Abstract

ABSTRACT Power scaling of nanosecond fiber laser pulses with narrow linewidth has been demonstrated by using a new single-mode (SM) large-core polarization maintaining (PM) highly Er/Yb co-doped phosphate glass fiber (EYPhF). We used an optimized length of 12 cm of the EYPhF fiber in the power amplifier of the all-fiber MOPA chain. The pulse energy can reach 0.11 mJ for the amplified pulsed fi ber laser, which correspond s to a peak power of 51.5 KW with pulse duration of 2.1 ns and repetition rate of 5 KHz. This high power pulse d fiber laser has an estimated linewidth of < 500 MHz. Keywords: Fiber laser, fiber amplifier, pulses, phosphate glass fiber, terahertz 1. INTRODUCTION Fiber lasers pumped by commercially available semiconductor lasers successfully produce high brightness, highly coherent, frequency agile lasers with a high quality of diffraction-limited beam. Fiber lasers are taking more important roles in laser applications, and creating new opportunities due to their unique advantages of compactness, robustness, efficiency, and significantly reduced-maintenance. Recently, high-energy pulses with nanosecond-order duration at retina-safe wavelength of ~1.55 P m have attracted intense interest for a range of practical applications, such as lidar and laser marking. At 1 P m the pulse energy for fiber-based lasers have been scaled to several mJ with multimegawatt peak power and single-transverse-mode (SM) operation, by using an Yb-doped, rodlike photonic crystal fiber, pumped by laser diodes [1]. However, due to the low absorption of Er