Should I choose InGaAs or Germanium?
The choice of detector is affected by several parameters: beam size, power and wavelength. In general a photodiode will give best results when used at wavelengths below the wavelength of peak sensitivity. Although the head may operate at higher wavelengths, the sensitivity of the photodiode will be strongly temperature dependant. Thus, for wavelengths beyond 1550nm, InGaAs will be the material of choice.
Also, at wavelengths below 800nm, our visible enhance InGaAs exhibits markedly higher responsivity than Germanium.
However, since Germanium is much less expensive than InGaAs, photodiodes of larger sensitive area can be manufactured cost effectively, thus allowing measurement of larger beam sizes. Our G3 fibre receptacle detectors can handle larger fibre cores with larger numerical aperture (NA) than the respective InGaAs detectors.