Low power, high extinction electrothermal MEMS iris VOA

Abstract

ABSTRACT Electrothermalactuationpr ovidesthe longdisplacement requiredby anincreasingnumber ofMEMS applications.However, its high power consumption is a limiting factor, especially for applications in which multiple actuatorsare required. An iris type variable optical attenuator (VOA), 5 which was recently introduced by our group, is anexample of such an application. In this paper we introduce an improved single sided electrothermal design, whichreduces the power consumption by a factor of 70%, while at the same time removing an undesired mechanicalresonance. The optical performance is also improved by the introduction of a novel aperture shape which provideshigher extinction, independent of the process technology. 1. INTRODUCTION Electrothermal actuatorsar e commonly used in MEMS devices due to their simple structure and large mechanicalde”ection. Compared to elect rostatic actuators, they have a much sim pler suspension, which results in a morecompact design. Electrothermal devices require lower drive voltages which are more suitable for integration withthe control electronics. In contrast, comb drives generally require voltages of 20 V or more, which is incompatiblewith some IC processes. The main drawback of electroth ermal drives is their high power consumption. Hence, alow power electrothermal act uator would be a promising device for applications where a compact actuator withhigh displacement is required.Amongst these applications, the variable optical attenuators (VOA) is a key element in high capacity opticalcommunication systems. VOAs are employed in quantity in DWDM networks, to reduce the power of signalsfrom various sources to the levels required by netwo rk elements such as optica l ampli“ers and ADD/DROPnodes. Various technologies have already been used to implement VOAs. The majority of existing devices arebased on sliding shutters,