Phys.org November 27, 2020
Fiber fabrication technology have led to an exponential increase in the output power of CW fiber lasers. However, with further scaling the output power, photodarkening (PD) is the critical limit factor for long-term laser reliability under multi kW level output power. Researchers in China demonstrated stable performance in fiber fabricated the Yb/Ce codoped aluminosilicate laser. The molar ratio of Ce/Yb was designed and optimized to be 0.58 for low background loss, effective photodarkening suppression, and no additional thermal load. The background loss of was 4.7 dB/km and its photodarkening loss at equilibrium was as low as 3.9 dB/m at 633 nm. The fiber showed uniform core composition devoid of clustering and central ‘dip’ of refractive index profile. Based on a master oscillator power amplifier laser setup, 5.04 kW laser output at 1079.80 nm was achieved. Stabilized at 5kW-level laser for over 60 minutes, the output power presented almost no power degradation, directly confirming a noticeable photodarkening mitigation…read more. TECHNICAL ARTICLE
Schematic diagram of MOPA configuration. Credit: XIOPM