High Brightness Laser Diode Bars

Based on the most recent generation of Bookham's laser diode bars in the 9xx nm wavelength range which are able to deliver in excess of 250 W of output power from 50% filling factor 2.4 min cavity length design, we have developed low 20% fill-factor bar devices for high brightness applications. Close to 200 W of output power has been achieved in CW mode from actively cooled micro-channel cooler devices without signs of damage. Mounted on conductively cooled copper blocks, still more than 130 W (CW) has been obtained, indicating the high conversion efficiency of > 60% reducing the thermal load on the mounting assembly. Based on extensive reliability testing in excess of 5000 h and at power densities ranging up to 36mW / um and beyond, highly reliable operation of 20% fill-factor bars is expected.To facilitate fiber coupling into wide-core multi-mode fibers a further reduction of the emitter aperture has been realized. From a single 3.6 mm cavity length by 800 um wide emitter design ("MaxiChip") about 50 W output power has been obtained in CW mode from devices mounted on standard conductively cooled 1x1 inch copper blocks. While CW operation has been thermally limited, extremely high peak power operation can be expected in qCW operation. Due to the narrow aperture of this MaxiChip efficient and easy coupling into wide aperture multimode fibers can be achieved.