Micro-opto-mechanical 2x2 switch for single-mode fibers based on plasma-etched silicon mirror and electrostatic actuation

This paper reports on a new optical 2 x 2 switch for single-mode fibers. Th e switching principle is based on a vertical micro-mirror which can be move d into the optical path to switch light between two pairs of fibers. The mi cromirror switch is designed for by-pass applications. When power is turned off the mirror springs back into its rest position and brings the switch i nto its bar state. This operation is very reliable, since the moving parts do not get into contact. Fabrication is based on the silicon micromachining technology, which allows to integrate the switching: mirror, its electrost atic actuator and the alignment grooves for the fibers on the same chip. Th e mechanical switching principle brings with it a number of optical advanta ges such as a high crosstalk attenuation above 50 dB and wavelength and pol arization insensitivity. At a wavelength of 1310 nm a minimum insertion los s of 0.6 dB was measured in the bar state, i.e. when the mirror is out of t he optical path. In the cross state the light is reflected on the gold coat ed micro-mirror which has a reflectivity of about 80%. The insertion loss o f the bar state was thus higher and a minimum value of 1.6 dB could be obta ined. The switching time was well below 1 ms.