Developments and performances of ultra-wide-band long-wavelength photo
detectors are outlined. Theoretical consideration shows the competence
of the waveguide p-i-n photodetector for ultra-wide-band long-wavelen
gth optical fibre communication. A newly proposed multimode waveguide
p-i-n photodetector with mushroom-mesa structure can relax the parasit
ic limits, and reaches a record performance of 110 GHz bandwidth and 5
0% external quantum efficiency at a 1.55 mu m wavelength. A high-speed
monolithically integrated photoreceiver using the waveguide p-i-n pho
todetector is also presented.