Higher brightness laser diodes with smaller slow axis divergence

摘要

The slow axis (SA) divergence of 20% fill-factor, 980nm, laser diodes (LDs) have been investigated under short pulsed (SP) and continuous (CW) operation. By analyzing the data collected under these two modes of operation, one finds that the SA divergence can be separated into two components: an intrinsic divergence and a thermally induced divergence. At low injected current and power, the intrinsic SA divergence is dominant while at high power their magnitudes are approximately equal. The thermal gradient across the broad stripe is negligible under SP operation and, the SA divergence increased at a much slower rate as a function of injected current, thereby increasing the brightness of the LD by 2X. SRL has redesigned microchannel coolers that remove the thermal gradient under CW operation thereby eliminating the thermally induced SA divergence resulting in LDs that are 2X brighter at 300W/bar.