I have a laser diode and photo diode in a single three-pins package like this one https://im0-tub-ru.yandex.net/i?id=c97eaabd28f722612d05403d21a519c2-l&n=13

The laser radiation will be supposed to be modulated at a frequency of no more than 150 Hz. One friend of mine said to me that maybe there would be a proceess of self-heating in my laser diode. It might cause the variations in brightness of a lightspot from the laser but its brightness is important for me. I would like to ask in this connection whether that is truth? If it is then what is the characterisic time of selfheating? When does the brightness become homogeneous? Will it change at a low frequency that equals 150 Hz?

  • $\begingroup$ Slight changes in temperature and power output may well exist due to self-heating. But the important question for you is how much power output variation is unacceptable for your application? Do you even care if the power output varies by, say, 0.01% due to self-heating? $\endgroup$ – Samuel Weir Oct 6 '17 at 3:40
  • $\begingroup$ I think if there are just 0.01% variations in power emitted it will be ok. Is it actually so small? Does this power deviation you mentioned concern the case when the laser turns on and turns off frequently? I mean whether it has time to chill sufficiently at that mode? $\endgroup$ – Jacob. St Oct 6 '17 at 11:17
  • $\begingroup$ I don't know if typical power variations due to self-heating are as small as 0.01%. I'm simply pointing out the fact that you need to quantify your question. From a practical standpoint, the question isn't whether any self-heating power variations exist at all (they almost certainly do), but whether they are large enough to be a practical concern for your application. $\endgroup$ – Samuel Weir Oct 6 '17 at 15:37
  • $\begingroup$ I got you. Thanks. I'll see in an experiment how strong my camera's sensitivity is $\endgroup$ – Jacob. St Oct 6 '17 at 21:04

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