What is the difference between responsivity and sensitivity in photodiodes?

[phy_optics]

Hello frnds!

Nice to meet you all here.

Can anybody help me in understanding the exact differences between responsivity and sessitivity of a photodiode or photodetector?

 

[Manchot]

Responsivity measures the amount of output swing produced by a specified input swing. For example, if you had a photodetector that produced a voltage output proportional to incident power, responsivity would be measured in V/W.

However, note that this is not enough information to tell you how "sensitive" a detector truly is, because you can always take an electrical signal and boost it with an low-noise amplifier. If you did this, your responsivity would go up, but the noise intrinsic to the detector would also be boosted (i.e., your signal-to-noise ratio would remain the same). There are multiple definitions for sensitivity; one common one is the noise-equivalent power, which is the amount of power required on the photodetector to produce a signal-to-noise ratio of 1.

 

[phy_optics]

Thank you Manchot. :)