Temperature insensitive micromachined GaAlAs/GaAs vertical cavity wavelength filter

A novel temperature insensitive wavelength filter consisting of GaAlAs/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 o f conventional semiconductor based optical Alters. Also, a wavelength trimm ing of over 20 nm was demonstrated after completing the device fabrication. In addition, we demonstrated a 4 x 4 multiple wavelength micromachined ver tical cavity Alter array. The multi-wavelength Alter array with a wavelengt h span of 45 nm was fabricated by partially etching off a GaAs wavelength c ontrol layer loaded on the top surface of device.