Q-switched Nd-doped depressed clad hollow optical fiber laser operating at 927 nm and its frequency doubling to blue light

This work utilizes a Nd-doped depressed clad hollow optical fiber (DCHOF) laser geometry. This allows for core area scaling of cladding pumped 930 nm fiber lasers. A DCHOF has a LP₀₁ mode cut-off at a finite wavelength, which makes the fiber act as a distributed wavelength filter that suppresses competing emission at 1060 nm. A peak power of 1.3 kW in 140 ns long pulses at 927 nm is achieved from a Q-switched Nd:Al-doped DCHOF laser. The pulses are then frequency doubled in a BiB₃O₆ crystal which results in 50 mW of average power at 463.5 nm.