Series in Quantum Electronics
Vol. 27

This thesis presents investigations on compact, pulsed laser sources. Two approaches are explored, yielding lasers with properties covering a wide range of parameters. In both cases, we have taken care to use techniques suitable for practical applications. Consequently, the lasers are diode pumped and semiconductor saturable absorber mirrors (SESAMs) are used for the pulse formation. A microchip laser emitting around 1.5 µm is passively Q-switched, producing sub-nanosecond pulses with peak powers exceeding 10 kW at a repetition rate of ‰ 1 kHz. Such laser properties are required for applications using the pulses in a time-of-flight configuration for distance measurements (e.g. three-dimensional imaging or geodesy). For gigahertz repetition rates, a high-power passively mode-locked semiconductor laser is presented. An optically pumped vertical-external-cavity surface-emitting laser (VECSEL) is used to achieve a diffraction-limited beam with high average power. Design, growth and fabrication of the gain element with a low thermal impedance and a smooth gain spectrum are discussed and a thermal model for the device is derived. Under mode-locked operation a performance is reached with up to 950 mW average power with 15 ps pulse duration at a repetition rate of 6 GHz. Nearly chirp-free pulses with 4 ps duration are achieved at 530 mW. These are the highest average powers reported from a mode-locked semiconductor laser, making it very attractive for many applications such as commercial printing, improved schemes for data transmission or even laser display systems requiring efficient nonlinear frequency conversion.

Reto Häring received his diploma degree in experimental physics from the Swiss Federal Institute of Technology (ETH) Zürich, Switzerland, where he joined the Institute of Quantum Electronics in 1997. His research focused on compact, diode-pumped, passively mode-locked and passively Q-switched lasers, and on the design and characterization of semiconductor gain structures used for vertical-external-cavity surface-emitting lasers.

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