How to calculate the photons/pulse of Laser diode?

[Pattarasak]

Hello everyone, I'm an Undergrad and I'm trying to set the Quantum key distribution experiment by using weak laser pulses(the laser diode with attenuated filter). but I don't know how to calculate the photon number per pulse. Can anyone tell me how to calculate the photon number per pulse?. Thank you for all answer.

 

[f95toli]

It is not entirely clear what you are asking. What information do you have? Do you have some way of measuring the energy/pulse (before the attenuators) directly?

I am not an expert in this field (I've done some work on single microwave photons, but that is a bit different) but presumably you could get a good estimate if you know the average power and duty cycle of your laser as well as the frequency of the generated light.

 

[Pattarasak]

It is not entirely clear what you are asking. What information do you have? Do you have some way of measuring the energy/pulse (before the attenuators) directly?

I am not an expert in this field (I've done some work on single microwave photons, but that is a bit different) but presumably you could get a good estimate if you know the average power and duty cycle of your laser as well as the frequency of the generated light.

Sorry about the Unclear question, I have only the data about average power of laser diode but have no idea to calculate the photon number per pulse in the experiment.
Can you guide me about some paper or book that I can learn about it?

 

[BvU]

I have only the data about average power of laser diode

I hope that is the output power, not the power consumed ?

You should also have (or measure) a pulse repetition rate and a pulse duration, so you can convert the average power to energy per pulse.

Photons per pulse is then energy per pulse divided by energy per photon.

Energy per photon is the famous $\ E= h \nu \$ with $\ \nu$ the frequency of the light.