The performance of gain-switched Fabry-Perot asymmetric-waveguide semiconductor lasers with a large equivalent spot size and an intracavity saturable absorber was investigated experimentally and theoretically. The laser with a short (~ 20 m) absorber emitted highenergy afterpulse-free optical pulses in a broad range of injection current pulse amplitudes; optical pulses with a peak power of about 35 W and a duration of about 80 ps at half maximum were achieved with a current pulse with an amplitude of just 8 A and a duration of 1.5 ns. Good quality pulsations were observed in a broad range of elevated temperatures. The introduction of a substantially longer absorber section lead to strong spectral broadening of the output without a significant improvement to pulse energy and peak power. Introduction: Picosecond-range (~100 ps) high energy optical pulse generation with semiconductor lasers has attracted significant attention recently, with a view for obtaining compact optical sources for applications such as high-precision laser radars (the most immediate intended application in our studies) three-dimensional (3-D) time imaging, spectroscopy and lifetime studies. Pulses of such duration, or shorter, have been reported by a large number of authors since the early days of laser diode technology (see e.g. [1,2] for an overview). The main techniques used are gain switching (pumping the laser with a current pulse of a nanosecond duration or somewhat shorter, but still significantly longer than the desired optical pulse), active or passive Q-switching (using a laser incorporating an active voltage-controlled modulator or a saturable absorber respectively), or a combination of these techniques. The general principles of all these regimes have been relatively well understood
Abstruct-The transit times of light pulses as functions of temperature in nylon and acryl-coated fibers and hard-clad silica fibers were analyzed theoretically and compared with the measured results. The effect of temperature on the transit time can be explained in terms of generally known models and the physical and thermal coefficients of the materials. Increased non-homogeneities at lower temperatures will cause increasing attenuation and longer transit times for light pulses in hardclad silica (HCS) fibers, in contrast to the situation in silica fibers.
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