M. Chi¹, A. Müller², A.K. Hansen¹, O.B. Jensen¹, P.M. Petersen¹, and B. Sumpf²

Published in:

Appl. Opt., vol. 59, no. 26, pp. 7836-7840 (2020).

Abstract:

We investigate microsecond pulse-mode operation of a micro-integrated high-power diode laser based on volume Bragg grating external-cavity feedback around 808 nm. The laser system contains a tapered amplifier consisting of a ridge-waveguide section and a tapered section with separated electrical contacts. Thus, the diode laser system can be pulsed by modulating the injected current either to the ridge waveguide section (I_RW) or to the tapered amplifier section (I_TA). With a trigger signal of a 50 µs pulse width and a 10 kHz repetition rate, comparing the modulation depth, peak output power, beam propagation factor, and spectral bandwidth, we conclude that the pulse-mode operation achieved by modulating the I_TA gives better results than by modulating the I_RW due to the decreased thermal effect. At a constant I_RW of 0.2 A and a modulated I_TA of 6.0 A, 4.3 W of peak output power is obtained with an emission spectral bandwidth with an upper bound of 0.2 nm, and a beam propagation factor in the slow axis, M²_slow, of 2.6 (1/e²). The modulation depth is almost 100%. The results show that the tapered diode laser system may be a good candidate for microsecond pulse-mode solid-state lasers.

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