Tunable photodetectors and light-emitting diodes for wavelength division multiplexing

The authors propose and analyse a hybrid device structure which extends the dynamic tuning range of vertical-cavity photodiodes and emitters. The device consists of a conventional epitaxial PIN junction quantum-well diode grown on a quarter-wave mirror stack. The upper mirror is attached to the underside of a micromachined membrane fabricated on top of the epilayer. This configuration allows the upper mirror to be electrostatically deflected towards the episurface, reducing the overall vertical cavity length which tunes the resonance wavelength over the entire free spectral range of the cavity. Simulations of the device indicate that eight-channel operation between 900 and 1000 nm can be achieved with low crosstalk. It is expected that this device will find use in wavelength-division-multiplexing applications.