A design for a highly tunable long-wavelength LED/photodetector has been investigated, The device consists of a GaAs-based distributed Bragg reflector (DBR) that is wafer-bonded to InP-based active layers, with a surface-micromachined tunable top DBR mirror to produce the wavelength shift, A 1.5-mu m device has been fabricated with a continuous tuning range of 75 nm, An extinction ratio of greater than 20 dB existed across the entire tuning range.