Simple MOPA fiber laser achieved 2 kW near-single-mode output at 1035 nm

The 1035 nm short-wavelength-band fiber laser serves as a critically important light source with extensive and growing applications across numerous advanced technological fields. Its unique spectral properties make it highly suitable for spectral beam combining (SBC), nonlinear frequency conversion, and high-resolution lidar systems. However, the power scaling of 1035 nm fiber lasers has long been constrained by the amplified spontaneous emission (ASE) effect. This phenomenon has historically impeded significant progress, with the output power from conventional master oscillator power amplifier (MOPA) configurations remaining confined below 2 kW, creating a bottleneck for higher-performance applications.

To realize high-power, high-brightness laser output in the 1035 nm band, we designed and constructed a counter-pumped MOPA fiber laser.

The system’s performance was enhanced through multi-parameter optimization, including optimizing the temporal characteristics of the fiber seed source, the bending and coiling parameter of the gain fiber in the amplifier stage, and refining the backward pump scheme.

Finally, when the seed laser power was 24 W and the total pump power was 2.9 kW, a maximum output power of over 2 kW was reached, and the corresponding optical-to-optical conversion efficiency of the amplifier stage was approximately 69.5%. At the maximum output power, the ASE suppression ratio was measured to be around 32 dB, indicating effective control over noise. Furthermore, the beam quality factors were measured to be M_x^2 =1.33 and M_y^2 =1.22, confirming near-diffraction-limited, single-mode operation, and high spatial beam quality.

The results represent a significant stride forward in the power scaling of high-brightness 1035 nm fiber lasers. Next research will focus on further elevating the output power and beam quality by implementing seed source with more stable temporal characteristics and optimizing the overall fiber laser structure to mitigate ASE and other nonlinear effects.