Experimental investigation of nanosecond pulsed tapered-waveguide lasers obtaining extremely high brightness values

Diode lasers generating nanosecond-long optical pulses with high output powers and a good beam quality are used for various applications, such as light detection and ranging (LiDAR) systems needed for autonomous driving or robotics [1] . To achieve a high brightness, i.e. the combination of a high optical output power and a good beam quality, under pulsed operation we investigate a laser design that is based on [2] where 2 W continuous-wave (cw) operation was obtained with an excellent beam quality factor of M 2 < 1.1 at a wavelength of λ = 970 nm. A 23 µm ridge at the front facet is combined with a narrow 5 µm ridge at the rear facet by means of a tapered section, see Fig. 1(a) . The narrow ridge section inhibits excitation of higher-order lateral modes, whereas the broader front section reduces facet load and maintains a low series resistance compared to smaller ridges. For lateral current and optical confinement index-guiding trenches are etched next to the injection stripe, light grey areas in Fig. 1(a) , so that here a built-in effective refractive index step of approximately ∆ n 0 = 2•10− 3 is obtained. Under pulsed operation the requirements of the lateral design differ compared to cw operation, which will be experimentally investigated in this contribution. A theoretical analysis of the investigated laser structures employing a traveling-wave based simulation model can be found in Ref. [3] .