did some test runs the last couple of days to see at which power level something happens to the device performance.
Current devices are the old, already very noisy 3mm GTRAN diodes.
Devices are mounted in OMC heatsink using prototype of OMC invac preamp (100R fixed resistance) and the higher bias voltage of 12V (originally 5V).
DC current on PD before pulsing is adjusted to 30mA, pulse comes on top of that. No additional current limit for bias voltage. Spot size ~1mm.
I measure the following device parameters before each new cycle
time for each cycle: about 28min.
I started with the following parameters about a week ago
As nothing changed i increased the peak power step by step until i reached the following parameters today:
so far no visible changes in measured parameters. Also didn't visually damage a device so far. So if i don't see anything tomorrow i will try to physically damage one diode to see where the damage threshold is.
I probably don't see changes in noise performance as the excess noise of these 3mm diodes is about three orders of magnitude higher as the good EG&G ones. Unfortunately we sent all diodes to the sites.