Scalable electrothermal MEMS actuator for optical fibre alignment

A new geometry of high-force electrothermal actuator is demonstrated using microelectromechanical systems technology. The actuator consists of two sets of inclined, parallel, suspended beams, which are tethered at one end and linked together at the other. The first set is divided into two halves, which are connected in series and heated electrically. The second set acts as a tether for the first, so that differential thermal expansion gives rise to a lateral deflection. The design can be scaled easily to increase the actuation force, which is sufficient to deflect a cantilevered optical fibre. A bi-directional fibre alignment device is formed from two opposed actuators, which are designed to grip the fibre, and a set of fixed mounting features. Prototype devices are demonstrated by deep reactive ion etching of bonded silicon-on-insulator, and in-plane alignment of single-mode fibre is demonstrated.