Techniques to improve speed and efficiency of photodetectors

Techniques for simultaneously realizing broad bandwidth, high efficiency, and high power photodetectors are discussed. Resonant cavity techniques circumvent the usual bandwidth-efficiency limitations associated with photodetectors. An InGaAsP/GaAs device with responsivity of 0.34 A/W at 800 nm wavelength, for 410 nm of absorbing material, is demonstrated. Coherent summation of the signals in an impedance-matched photodetector array circumvents tradeoffs between bandwidth and power-handling capability. Design of coplanar waveguide based arrays on InP is discussed, along with their applications in fibre networks.