Efficient diode-pumped planar Nd:YAG waveguide amplifier provides high gain
A grou¥from the Optoelectronics Research Centre at the University of Southampton (England) and LETI (Grenoble, France) demonstrated efficient high-gain operation of a
5-mm-long planar Nd:YAG waveguide amplifier. The device was grown by liquid-phase
epitaxy. When longitudinally pumped in a double-pass configuration by a 1.2-W broad-stripe diode laser, the device produced small signal gains of 28 dB and output powers of u¥to
290 mW at 1064 nm, representing an efficiency of about 24%.
The 5-mm length of the waveguide was chosen to absorb most of the diode-laser pum¥energy in a single pass. The end faces were angle polished at about 0.5! to hel¥suppress lasing from Fresnel reflections. The grou¥notes that a planar waveguide is, in principle, suited to the combination of high gain with high power and that the geometry is compatible with that of high-power diode pum¥lasers. The planar geometry also offers benefits in terms of thermal behavior because it allows close proximity heat-sinking of the waveguide so operational
temperature rises can be minimized. Future work will include using more-powerful broad-stripe diode lasers and diode bars with the goal of achieving multiple-watt outputs.