Should I choose InGaAs, Silicon 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 950nm, germanium will be the material of choice and for wavelengths beyond 1550nm, InGaAs will be the material of choice.
The photosensitive area of our Si and Ge fibre receptacle detector heads are very similar, the silicon detector being slightly larger.
Also, at wavelengths below 800nm, our visible enhance InGaAs exhibits markedly higher responsivity than Germanium.
On the downside, large area InGaAs detectors are prohibitively expensive. Thus, this material is generally limited to ø3mm sensitive area.
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.
Which detector ist best for measuring YAG-lsers at 1064nm?
The choice of detector is affected by several parameters: beam size, power and wavelength. For use at 1064nm there are two choices available: OPM150UVS and OPM150G10 (or G5).
The G10 version is more expensive than the UVS version. However, it is more accurate since the responsivity of the UVS detector is temperature dependant at wavelengths beyond 900nm – which includes 1064nm. The user must consider this price-to-performance aspect for the application.