Angular and spectral selectivity of resonant cavity light emitting diodes used as resonant cavity photodetectors

摘要

We have explored the operation of resonant cavity light-emitting diodes (RC-LEDs) used as resonant cavity photodetectors (RC-PDs). Our experiments were conducted using a variety of components, operating in diverse wavelength ranges and having different structural characteristics (different distributed Bragg reflector mirror reflectivities, different detuning, etc.). The measurements show a clear and systematic angular and spectral dependence of the RC-PD photodetected signal. The angular and spectral photosensitivity is derived not only from the quantum well absorption but largely from the microcavity enhancement factor and from the photodetection efficiency condition, which both are dependent on angle and wavelength. The detuning of the microcavity and the extension of the distributed Bragg reflector (DBR) stopband control the extension of the photosensitivity spectral window and the front/top DBR mirror reflectivity controls the angular wavelength selectivity. The fact that the RC-PDs' angular and spectral selectivity can be controlled by proper microcavity design, together with their high bandwidth, opens the possibility of using the same RC-PD device for detecting different WDM channels.