We show for the first time that multi-ten Watt operation of an Alexandrite laser can be achieved with direct red diode-pumping and with high efficiency. An investigation of diode end-pumped Alexandrite rod lasers demonstrates continuous-wave output power in excess of 26W, more than an order of magnitude higher than previous diode end-pumping systems, and slope efficiency 49%, the highest reported for a diode-pumped Alexandrite laser. Wavelength tuning from 730 to 792nm is demonstrated using self-seeding feedback from an external grating. Q-switched laser operation based on polarization-switching to a lower gain axis of Alexandrite has produced ~mJ-pulse energy at 1kHz pulse rate in fundamental TEM(00) mode.

Satellite-based remote sensing using laser-based lidar techniques provides a powerful tool for global 3-D mapping of atmospheric species (e.g. CO 2 , ozone, clouds, aerosols), physical attributes of the atmosphere (e.g. temperature, wind speed), and spectral indicators of Earth features (e.g. vegetation, water). Such information provides a valuable source for weather prediction, understanding of climate change, atmospheric science and health of the Earth ecosystem. Similarly, laser-based altimetry can provide high precision ground topography mapping and more complex 3-D mapping (e.g. canopy height profiling). The lidar technique requires use of cutting-edge laser technologies and engineered designs that are capable of enduring the space environment over the mission lifetime. The laser must operate with suitably high electrical-to-optical efficiency and risk reduction strategy adopted to mitigate against laser failure or excessive operational degradation of laser performance.

We present an investigation of a versatile pulsed laser source using a low power, gain-switched diode laser with independently variable repetition rate and pulse duration to seed an ultra-high gain Nd:YVO4 bounce geometry amplifier system at 1064nm. Small-signal gain as high as 50dB was demonstrated in a bounce geometry pre-amplifier from just 24W pumping, with good preservation of TEM00 beam quality. The single amplifier is shown to be limited by amplified spontaneous emission. Study is made of further scaling with a second power amplifier, achieving average output power of ~14W for a pulsed diode seed input of 188μW. This investigation provides some guidelines for using the bounce amplifier to obtain flexible pulse amplification of low-power seed sources to reach scientifically and commercially useful power levels.

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