High efficiency gallium nitride laser diode pumped CW ruby laser

The design and performance of a laser diode pumped ruby laser is reported. The laser consists of a 5 mm long 0.05% doped ruby crystal placed within a hemispherical laser resonator. A single mode gallium nitride laser diode, operating at 405 nm provided up to 320 mW of pump power. Beam shaping optics were used to circularize the pump beam and a 150 mm focal length lens produced a ~20 μm waist in the crystal. The laser produced up to 44 mW of output power with a slope efficiency of 17%.