2×2 bi-reflection optical add-drop module with variable attenuation using four 45° micromirrors

We propose a micromachined 2x2 optical switch with variable optical attenuation. The proposed optical switch features expandability and integration utilizing four 45° micromirrors driven by four electrostatic comb actuators. These four micromirrors can move independently to reflect and/or partially block the optical signal. In order to reduce the insertion loss caused by long optical path length, the optical module employed anti-reflection coated lensed fibers. Two pairs of optical fibers were aligned in each single trench at both sides for cost-effective packaging. The device was fabricated using SOI (Silicon-On-Insulator) process with one photo-mask, and its experimental IL (Insertion Loss) and attenuation range were less than 1.53 dB and over 60 dB, respectively. Also the PDL (Polarization Dependent Loss) was less than 0.25 dB in the range of 30 dB.