Measuring the Optical Power of a Pulsed Source

[narra]

Hi. I was wondering if someone can provide me with some advice on the proper way for measuring the optical power of a pulsed laser system?

My optional methods are: - Photodiode detector: measuring average power
- Oscilliscope with optic-electric converter: measuring temporal power as voltage magnitude.
- Optical spectrum analyser: measuring spectral power


Thanks

 

[chrisbaird]

In all honesty, people tend to use whatever method gives them the highest numbers to publish. ;) There is no "proper way". If your purpose is just to have some metric of performance, pick whatever method is easiest and most reliable, and then use it consistently. If you have a specific application in mind, you have to think through the physical requirements of the application.

 

[narra]

Hi Chrisbaird, I do agree with that to some extent, but for my circumstances I firstly want to accurate actual optical power (not a relative or value for indication); something that I can believe in.

Secondly, since I am working with a pulsed system at say 1-10kHz repetition rate then how do I know that my measurement tool is responding in the right way (ie, can I believe an average power measurement on a photodiode power meter or should I turn to an oscilloscope where I can observe my pulse in time?).

Thirdly, if I'm interested in a narrow optical band (1550 +/- 2nm in my case) then should I rely on an optical spectrum analyser to offer me a spectral peak power or should I use a narrow band filter (@1550nm) on my photodiode detector/ oscilloscope?

Thanks

 

[johnbbahm]

It depends on how accurate you want to be. I think the right answer is an integrating sphere, but a one liter thermos bottle of water and a good thermometer would get you close.

 

[narra]

Actually my question is more what measurement domain is best suitable, time, averaged time or spectral. Since I'm concerned with single mode fibre optics then I am able to capture much of my light I believe.