O'Reilly logo

Microwaves Photonic Links: Components and Circuits by Anne-Laure Billabert, Catherine Algani, Christian Rumelhard

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

Chapter 4

Photodetectors

4.1. Photodetector definition

Regarding photodetectors, it is possible to speak of current response in units of incident optical power.

In the first English texts concerning optoelectronics, current response as a function of optical power (A/W) of a photodetector was called sensitivity. This significant term was gradually replaced by responsivity, which more specifically describes the sensitivity of a photodetector. This nomenclature will be adopted in this text.

For photodetectors, it is also possible to speak of quantum efficiency, expressed as:

[4.1] Equation 4.1

with:

np= number of electron-hole pairs generated per second;

-φ = number of incident photons per second.

The relation between quantum efficiency and responsivity Rpd in A/W is:

[4.2Equation 4.2

with:

q= electron charge = 1.602×10-19 C;

h = Planck’s constant = 6.626×10-34 J/s;

ν= light wave frequency in hertz.

Responsivity takes into account the frequency of the light wave. Consequently, by referring to Table 5.1, it should be noted that for a quantum efficiency of 100%, the responsivity of an optical photodetector at 1.55 µm is 1.25 A/W, whereas to obtain identical quantum efficiency the responsivity of a photodetector at 0.8 µm is only 0.64 A/W.

In the sections below, quantum efficiency notion is used for photodiodes, ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required