Solving functional reliability issue for an optical electrostatic switch

TL;DR

This paper demonstrates that using AC signals in MEMS optical switches improves reliability by preventing charge injection and the pull-in effect, with experimental validation supporting the approach.

Contribution

It introduces the use of AC actuating signals as a novel method to enhance the reliability of MEMS optical switches by avoiding charge injection issues.

Findings

AC signals prevent charge injection in MEMS switches.

Grounded landing electrodes reduce electrostatic issues.

Long-term experiments confirm reliability improvements.

Abstract

In this paper, we report the advantage of using AC actuating signal for driving MEMS actuators instead of DC voltages. The study is based upon micro mirror devices used in digital mode for optical switching operation. When the pull-in effect is used, charge injection occurs when the micro mirror is maintained in the deflected position. To avoid this effect, a geometrical solution is to realize grounded landing electrodes which are electro-statically separated from the control electrodes. Another solution is the use of AC signal which eliminates charge injection particularly if a bipolar signal is used. Long term experiments have demonstrated the reliability of such a signal command to avoid injection of electric charges.