Micromachined AlGaAs/GaAs vertical cavity filter with adjustable temperature dependence and wavelength trimming ability

Abstract

The authors present a novel micromachined vertical cavity filter which has an AlGaAs/GaAs distributed Bragg reflector (DBR), that can be mechanically tuned by differential thermal expansion. The strain-induced displacement of one of the mirrors potentially enables wavelength tuning and trimming to be carried out with an adjustable temperature dependence. A negative temperature coefficient has been achieved in a micromachined semiconductor filter for the first time, demonstrating the possibility of temperature insensitive operation. Also, wavelength trimming of > 20 nm was demonstrated after completion of the device fabrication.