What is the cut-off wavelength of InGaAs photodiodes ?

The long end of the spectral response of InGaAs photodiodes is limited by the bandgap energy of InGaAs which is 0.75eV at room temperature (corresponding to about 1620nm). Hence incoming light with a wavelength beyond that limit (i.e. light with a larger wavelength) will not be absorbed as InGaAs is transparent for such wavelengths. In the wavelength region from  1260nm to 1620nm Albis’ InGaAs photodiodes have an excellent quantum efficiency. Below 1260nm the quantum efficiency decreases gradually due to recombination losses at the semiconductor surface.