A distributed Bragg reflector (DBR) tapered diode laser with a record optical output power of 12 W and a conversion efficiency of about 44% is presented. The device has a sixth-order surface grating and shows single longitudinal mode emission at 979 nm as well as a nearly diffraction limited beam. At 11.4 W the laser has a lateral beam propagation factor of M 2 1/ e 2 =1.1 with 72% of the power in the central lobe.

12 W high-brightness single-frequency DBR tapered diode laser

1 W tunable near diffraction limited light from a broad area laser diode in an external cavity with a line width of 1.7 MHz

We demonstrate spectral beam combining of a 980 nm tapered diode laser bar. The combined beam from 12 tapered emitters on the bar yielded an output power of 9.3 W at 30 A of operating current. An M2 value of 5.3 has been achieved along the slow axis. This value is close to that of a free running single tapered emitter on the bar at the same current level. The overall spectral beam combining efficiency was measured to be 63%.

https://orbit.dtu.dk/files/9906436/9F965d01.pdf

Spectral beam combining of a 980 nm tapered diode laser bar.

A review about second harmonic generation using edge emitting diode lasers and nonlinear crystals to obtain laser radiation in the blue-green spectral range is presented. Therefore, pump laser radiation with high brightness and narrow bandwidth is necessary. Thus, this review gives an overview of the advances made with distributed feedback and Bragg reflector lasers, tapered lasers and amplifiers as well as external cavity diode lasers and master oscillator power amplifier schemes to achieve high brilliance emission. Since periodically poled materials have enabled high second harmonic conversion efficiencies with low and moderate pump powers, the review is focused on frequency doubling using those materials. The most commonly used materials, their properties and limitations are discussed briefly. Single pass and resonant SHG setups with waveguide and bulk nonlinear crystals are discussed and an emphasis on building compact and integrated devices is made.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/lpor.200900023

Blue-green light generation using high brilliance edge emitting diode lasers

Strained triple-quantum-well, large-optical-cavity GaInSb/AlGaAsSb/GaSb diode lasers emitting at 1.98 μm at 300 K are investigated with regard to their high-power capability. As the heating of the active region is a limiting factor for these devices, a quantitative model is derived to simulate the performance of these lasers including thermal effects. The standard laser parameters, deduced from measurements on ridge waveguide lasers, and the measured thermal resistance of the mounted devices were then taken as input parameters. The output power and power efficiency of the lasers calculated using the presented model. Good agreement was found between calculated data and the measurements for different heatsink temperatures as well as for different laser geometries and mounting techniques. The maximum output power achieved for p-side down mounted 1000×150 μm2 broad-area laser was 1.7 W at 300 K in cw operation.

Comprehensive modeling of the electro-optical-thermal behavior of (AlGaIn)(AsSb)-based 2.0 μm diode lasers

High-efficiency tapered diode lasers with ridge-waveguide structure emitting at 976 nm have been realised. High wall-plug efficiencies of more than 57% result in output powers of more than 12 W for a single emitter with 3.5 mm resonator length. A nearly diffraction limited behaviour has been demonstrated up to 8.3 W CW.

Tapered diode lasers at 976 nm with 8 W nearly diffraction limited output power

InGaAs/AlGaAs large optical cavity (LOC) single quantum well (SQW) lasers emitting at 980nm were grown incorporating an AlGaAs/GaAs short-period superlattice layer next to the quantum well in order to improve the carrier confinement and thus high-temperature operation. Symmetric and asymmetric structures have been realized. High characteristic temperatures T0 above 300K between 20#C and 50#C operating temperature were measured for the symmetric structures without deterioration of the internal quantum efficiencies (> 90%) and low intrinsic losses (about 1cm-1). The improvement in the characteristic temperature is mainly attributed to the reduced thermionic emission of the carriers out of the quantum well due to the large effective barrier height of the short-period superlattice. Caused by the incorporation of the short-period superlattice the devices showed a higher series resistance, which could be lowered by switching to asymmetric structures. These asymmetric devices had unchanged high internal quantum efficiencies and low intrinsic losses but lower characteristic temperatures of about 250K.

G. Bihlmann

Papers

Tapered diode lasers at 976 nm with 8 W nearly diffraction limited output power

Improved high-temperature operation of InGaAs/AlGaAs LOC SQW diode lasers by incorporation of short-period superlattice quantum-well barriers