Pulse operation of CW LD

[a12b34c56]

I have CW AlGaAs multi mode injection 1W IR LD. According to Chinese vendor it can operate in pulse mode. I’m running it with microsecond long pulses and < 1kHz frequency. Should I expect a significant decrease in its lifetime?

 

[RedCowboy]

So on for 1 microsecond and off for 999 microseconds @ the factory rated CW current shouldn't hurt it at all or reduce the MTTF unless you have a noisy signal, but a square wave at the factory rating won't wear it out like a tungsten light bulb element, now there's something about a ramp up being a good idea when over-driving but pulsing is what they do sending data all day long, do you not have a data sheet ?

 

[a12b34c56]

I believe 0.1% duty cycle is typical for pulsed LDs but they are run at much higher currents than CW LDs. Are you saying that the same rule is applied to CW lasers operated in pulsed mode? I thought I could get away with higher duty cycle as long as my pulse current does not exceed factory rating. I know that you can overdrive LED but I did not think you can overdrive LD. How much current is safe to push over the factory rating?

 

[RedCowboy]

I have no idea, you need the data sheet, but yea, 0.1% duty cycle sounds safe to me, but I am not an expert.

https://www.newport.com/medias/sys_master/images/images/ha6/h59/8797049618462/AN11-Pulsing-a-Laser-Diode.pdf

 

[a12b34c56]

I’ve got the spec. It does not say anything about pulse operations. I bought some red lasers that according to the spec can be run in both CW and pulse mode and they are rated for higher current in pulse mode. I wander if my IR LD is not designed for pulse operations at all.

I did read Newport paper but it talks about testing CW laser so I’m not sure it is applicable to operations. The test time is minutes and operations are hundreds of hours.

 

[RedCowboy]

Your just turning it on and off very quickly, it won't reduce your MTTF.

The problem is when you try to drive a pulse laser in CW at it's pulse rated current and they overheat, but switching a CW on and off real fast won't reduce it's lifespan.