Temperature insensitive micromachined GaAlAs/GaAs vertical cavity wavelength filter

A novel temperature insensitive wavelength filter consisting of GaA1As/GaAs distributed Bragg reflectors (DBRs) has been demonstrated. This micromachi ned DBR is mechanically tuned by differential thermal expansion. The strain -induced displacement of one mirror can generate wavelength tuning and trim ming functions with an adjustable temperature dependence. We succeeded in t he control of temperature dependence in this micromachined semiconductor fi lter by properly designing a vertical cavity structure. The achieved temper ature dependence was as small as +0.01 nm/K, which is one-tenth of that of conventional semiconductor based optical filters. Also, a wavelength trimmi ng of over 20 nm was demonstrated after completing the device fabrication. In addition, we demonstrated a 4 x 4 multiple wavelength micromachined vert ical cavity filter array. The multi-wavelength filter array with a waveleng th span of 45 nm was fabricated by partially etching off a GaAs wavelength control layer loaded on the top surface of device.