Backside-Supported Electrothermal Actuation for 25,000 <i>g</i>-Survivable Optical Switches

Electrothermal actuation micro-electro-mechanical systems (MEMS) optical switches have found widespread applications in optical fields owing to their compact size, low power consumption, and continuous tunability. However, the low survivability of optical switches in high-<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</i> overload significantly impedes its application in military and aerospace. Here, we propose a MEMS optical switch based on a backside-supported electrothermal actuation mechanism to enhance its high-<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</i> survivability. A double-sided deep reactive ion etching process is developed to fabricate the backside-supported MEMS optical switch. Experimental results show that the MEMS optical switch can survive under overloads as high as 25,<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$000~g$</tex-math> </inline-formula>. The survival mechanism of the backside-supported MEMS optical switch under high-<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</i> inertial loading is investigated. It is the out-of-plane displacement limitation function of backside-supported beams that enhances the overload resistance. In addition, the electrothermal actuation mechanism of the backside-supported beams-incorporated optical switch is investigated. Experimental results show that the optical switch actuator fabricated demonstrates a displacement of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$38.65~\mu $</tex-math> </inline-formula>m at 1.05 W, which coincides well with the proposed electrothermal actuation model. We believe this work is significant for providing reliable photonic switching capabilities under extreme mechanical shocks in military/aerospace systems. [2025-0090]