In the quest for inexpensive but ever more powerful lasers, and more exotic colors, I have had the opportunity to test many diode makes and models. In doing so, and after several lifetime tests there are a few things that have become clear that aid in determining maximum safe operating current of the lasers. First off, the die length of the diode resonator is related to its maximum output power, voltage drop, and lasing threshold. Longer die diodes typically have a higher lasing threshold, lower voltage drop, and a higher sustainable maximum current before entering dangerous territory. In the current ramp plot of a diode, you will see a smooth ramp after the lasing threshold has been reached, eventually followed by dips and bumps that indicate you are driving the diode past its safe long-term operating point. TEC cooling can extend the smooth ramp range somewhat, but there are hard limits that even cooling cannot overcome.
All tests were performed at room temperature 21-25C using aixiz modues with multi-element glass lenses for the red diodes and aperture-opened plastic lenses for the 405nm diodes. Plastic lenses were used for 405nm because the AR coating of the glass lenses tended to decrease output. All diodes were 5.6mm mount packages.
The current winners are the LG GGW-H20L in the 405nm camp with its laser etched bar code on its back, followed by the old xbox 360 hd-dvd add on drive laser (phr-803t pickup) of the same manufacturer. In the red camp, the Long-die open can diode from the sony NEC opticarc 20x dvd burners and Pioneer 112D, 115D burner. These diodes have been tested for weeks continuously at over 200mW and currently represent the best available 658-660nm diode tech in 5.6mm mounts.