Class 4 Laser
| | Re: Liquid Nitrogen Cooled Oclaro 638nm Laser Diode??
The shift is directly related to the temperature of the semiconductor material. In is an inherit property where the bandgap depens on temperature. How large this variation is depends on the actual semiconductor material, but for a simple silicon diode (like a 1n4148) is it large and reliable enough to use these as course temperature sensors.
As far as current handling: Obviously there is plenty of cooling at cryo temperatures so that's not much of a concern. This still does not mean that you can push power up that far though, as the facets remain sensitive to optical failure. Also you might want to be careful at what rate you increase and decrease currents as i can imagine thermal cracks would become a problem if you ran a diode from zero to full power instantly under cryo conditions.