# How does a pulsed laser diode driver circuit work

So i am looking at pulsed laser diodes, and i want to build a circuit for it to work. https://www.osram-os.com/Graphics/XPic7/00054198_0.pdf/Standard%20Pulsed%20Laser%20Diode.pdf This is the article im using for my diode. I understand that the laser stores its electrical pulses in the capacitor but thats all i understand, maybe you guys can point me in a better direction of how the pulsed laser diode works and what it needs to drive. Also does the laser actually pulse or is it continuous wave with pulses of evergy in it?

• Laser diodes are CW devices, they have a laser threshold current which once exceeded results in a continuous optical wave output. Pulsed lasers are simply laser diodes used where pulses are generated externally to turn the Laser diode on/off rapidly ...hence 'pulsed'. – Jack Creasey Nov 17 '17 at 18:51
• @JackCreasey, First generations of new laser diode designs tend to not be "CW" in the sense that they'll burn themselves up if operated CW. Making a CW laser diode requires getting the design efficient enough (and heatsinking well enough) to avoid this. While an integraged laser diode doesn't contain any mechanism for self-pulsation, it's also possible to make an external cavity diode laser that does. (note "diode laser" rather than "laser diode"). – The Photon Nov 17 '17 at 19:24
• The key to this question is more about understanding the operation of the avalanche transistor than understanding the laser diode. – The Photon Nov 17 '17 at 19:27
• @ThePhoton. The laser diode IS definitely CW (look at the datasheet). it has no other operating mode. You are saying you can't operate it continuously (which is different to CW) ...I agree with that. But the if the laser outputs a single frequency/wave length continuously for the length of a pulse on time..... It's still CW light. – Jack Creasey Nov 17 '17 at 19:40
• So the avalanche transistor is what i need to look at for sure. So is the diode cw with pulses in energy or is it actually pulsed like light for 10ns no light for 10ns ect ect – Reese Houseknecht Nov 17 '17 at 19:45