Wavelength‐stabilized ns‐pulsed 2.2 kW diode laser bar with multiple active regions and tunnel junctions

Abstract

The improvement of the performance of a distributed Bragg reflector laser bar emitting near 905 nm through the use of multiple epitaxially stacked active regions and tunnel junctions is reported. The bar consisting of 48 emitters (each having an aperture of 50 µm) emits an optical power of 2.2 kW in 8 ns long pulses at an injection current of 1.1 kA. This corresponds to an almost threefold increase of the pulse power compared to a bar with lasers having only a single active region. Due to the integrated surface Bragg grating, the bar exhibits a narrow spectral bandwidth of about 0.3 nm and a thermal tuning of only 68 pm/K.

High brightness nanosecond-pulse operation of 905 nm distributed Bragg reflector tapered-ridge-waveguide lasers with multiple active regions

“…While the 1-AZ-TRWL features a slope and power of only 0.17 W/A and 6.1 W pulse power at 20 A, respectively, the 3-AZ-TRWL features a 3.4-fold increase in slope (0.57 W/A) and 2.6-fold increase in pulse power (15.6 W) at 20 A. This is in good agreement with the values determined with our DBR broad area laser bar [9]. The slow onset of saturation shown by the 3-AZ-TRWL allows for a further increase of pulse power up to about 21 W at a pulse current of about 33 A.…”

“…A means to achieve high output power of a diode laser is to epitaxially stack N independent diode lasers where each diode laser features its own vertical waveguide [4][5][6][7][8]. Alternatively, as we introduced previously, multiple active regions alternating with tunnel junctions can be epitaxially stacked in a common higher-order vertical waveguide where the mode order N-1 is determined by the number of active regions N [9,10]. While this concept allows to increase the output power roughly by a factor of N compared to a device with a single active region, it is typically employed in devices with a wide stripe width (w ≥ 50 µm) where the lateral beam propagation ratio M² is larger than 10.…”

2kW pulse power from internal wavelength stabilized diode laser bar for LiDAR applications

“…As expected from the single lasers discussed above, the DBR laser bar with 3 active regions achieves a factor of 2.9 higher pulse power than a DBR laser bar with only one active region. Another challenge we previously found was an inhomogeneous power distribution across the laser bar (with one active region) due to an inhomogeneous current distribution resulting from parasitic inductances and impedance mismatch to the electronic driver board as well as a temporal delay of the injection of current pulses in the laser center [1,7], see also Figure 14(right). There, the emitters situated at the center of the laser bar achieved only about 40% of the power of the lasers at the edge of the laser bar.…”