Laser diode structures with a saturable absorber for high-energy picosecond optical pulse generation by combined gain-and Q-switching

Abstract

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

A range-gated CMOS SPAD array for real-time 3D range imaging

“…This work allowed the laser pulse energy to be increased from 1 nJ [8] to over 6 nJ by increasing the active volume of the laser diode [9]. The pulsing rate used in the experimental result was 700 kHz, but a lower pulsing rate, e.g.…”

Theoretical studies of the generation of picoseconds pulses with two-section blue-violet semiconductor lasers

“…However, diode lasers compete with other lasers such as solid state and fibre lasers regarding pulse energy and peak power. Therefore, during the last years experimental and theoretical efforts have been undertaken by several groups to improve the performance of pulsed diode lasers in the red and near-infrared spectral region [1][2][3][4][5].…”

Ultrashort pulse generation in a semiconductor laser with strong coherent optical feedback

“…Semiconductor laser (SL) sources of ultrashort optical pulses are needed in optical communications systems as pulse sources for high-speed data transmission and all-optical signal processing [1]. To produce such sources, several techniques have been explored, such as gain switching [2][3][4][5][6][7] and different types of mode locking [8][9][10][11][12][13][14][15].…”