[SOLVED] Pulsed Laser diode vs pulse mode operation of CW laser

[chippevijaya]

Does Any one tell me what is the difference between the pulsed laser diode and cw single mode laser diode. Can i control the each and every pulse in order to generate them......

I have so many questions in my mind to use a laser diode in generating pulse.

 

[chuckey]

Its a heat thing. A pulsed laser, might be able to handle say 10W, but it over heats, so providing it is pulsed so the 10 W is only flowing for 1/10 of the time, the dissipation of the laser is 1W, which means it will not over heat. Conversely a CW laser will be able to dissipate its rated power all the time.
Frank

 

[chippevijaya]

That's cool,
What i understand is, when the Pulsed Laser Diode turned on it generates the pulses, let us say 100ns pulses continously, for example...
But in CW laser it will generate continuous on right?

But can i control the laser diode when to turn on and when to turn off to generate the pulses? in this case i am generating 100ns pulses from microcontroller to drive the PLD.

 

[keith1200rs]

A pulsed laser diode doesn't generate pulses - you have to generate them. So, you need a circuit which can turn a pulse from a microcontroller or FPGA of less than 100ns into a current pulse of several amps (up to 40A or more depending on the laser). Be careful of the duty cycle - they are typically 0.1% which means if you use a 100ns pulse you need 100us between pulses.

Keith

 

[chippevijaya]

Sure, I am generating a 100ns pulse and next pulse will come after 125us and 2nd pulse will come after 250us, like this randomly.

So i got clear that pulsed laser diode will not generate the pulses itself, if i supply pulses from microcontroller, it will drive.

 

[dick_freebird]

The dynamics of these lasers is key.

To get fast consistent operation of a pulsed laser diode
you use a bilevel pulse, set such that the "low" level is
still above lasing threshold and the high, is your desired
power level. Starting from dark, things can be inconsistent
and slow.

Whether a CW laser responds the way you'd like to fast
pulses, you'd have to spend some time researching and
challenging.

For things like material removal, a pulsed laser's peak
power will ablate while a CW laser's average power may
only warm up the workpiece. Like trying to pound a nail
by pushing on it with your hammer. Same hand, same
tool, different result.