Tomasz Swietlik

Next generation 8xx nm laser bars and single emitters

Semiconductor lasers with emission in the range 790 - 880 nm are in use for a variety of application resulting in different laser designs to fulfill requirements in output power, operation temperature and lifetimes. The output power is limited by self heating and catastrophic optical mirror damage at the laser facet (COMD). Now we present data on bars fabricated with our new facet technology, which enables us to double the maximum facet load. We present q-cw laser bar with 80% fill factor with increased power level to 350W in long term operation at 200μs and 100Hz. The COMD limit of the bar is as high as 680W. Using Quantels optimized packaging stacks with 11 bars of 5mm widths are tested at up to 120A resulting over 66% power conversion efficiency at 1600W output power. Laser bars for continuous wave operation like 50% fill factor bars had an COMD limit of approx. 250W with conventional facet technology, the value is equivalent to 10W per 200μm emitter (conditions: 200μs). The new facet technology pushes the facet stability to 24W/emitter. The new process and an improved design enable us to shift continuous wave operation at 808nm from 100W to 150W/bar with lifetimes of several thousand hours at 30°C using DILAS mounting technology. Higher power is possible depending on lifetime requirements. The power conversion efficiency of the improved devices is as high as 62% at 200W cw. The next limitation of 8xxnm lasers is high temperature operation: Values of 60-80°C are common for consumer applications of single emitters. Therefore Osram developed a new epitaxial design which reduced the generation of bulk defects. The corresponding Osram single emitters operate at junction temperatures up to 95°C, a value which corresponds to 80°C heat sink temperature for lasers soldered on C-mount or 65°C case temperature for lasers mounted in TO can. Current densities of the single emitter broad area lasers are as high as 1.4kA/cm2 at 850nm emission wavelength.

IR lasers optimised for high-temperature operation in frequency-doubled green module for mobile laser projection

The above presented data of a green laser module regarding output power of 100mW based on an 850nm pump laser, 1060nm VECSEL and intra-cavity second-harmonic generation prove an excellent performance of the whole module with the overall WPE of as high as 10% at 40°C. It is the highest value of all cutting edge technologies enabling green lasing achieved up to date with capability of high-speed modulation in MHz range. Reliability and WPE of a pump die at high temperatures are of crucial importance for this kind of device. We demonstrate reliable operation up to 90°C junction temperature of the pumping IR laser diode at current density of 1.4kA/cm2, which is also used as a single emitter delivering 0.5–1W output power after being mounted in TO-can under the same junction temperature and current load.