Long-wavelength optical telecommunication systems require receivers of optimal sensitivity at optical wavelengths of 1.3 μm and, increasingly, 1.55 μm, to take advantage of the low loss and dispersion of currently-available optical fibre at these wavelengths(1).
K L Monham,
J W Burgess,
P G McTiernan,
"The Development Of Long-Wavelength Optical Receivers", Proc. SPIE 0468, Fibre Optics '84, (15 August 1984); doi: 10.1117/12.941640; https://doi.org/10.1117/12.941640