Integrated bi-directional focusing and tracking actuators in a monolithic device for a MEMS optical pick-up head

This work presents a miniaturized two-degree-of-freedom (2-DOF) optical pick-up head implemented using MEMS technology. This device contains novel bi-directional vertical comb-drive actuators to act as the focusing positioner, and V-beam thermal actuators to serve as the tracking positioner. In addition, a UV-cured polymer droplet is used for an objective lens. Particularly, the focusing and tracking actuators are monolithically fabricated and integrated in a single device. Electrical routing and isolation is also available by poly-Si and Si 3 N 4 multi-layers for 2-DOF operation. In applications, the proposed device has been successfully fabricated and characterized. The upward and downward displacements of the focusing optical pick-up head are 4.6 µm and 4.1 µm, respectively, at a 30 V driving voltage. And the in-plane displacement of the tracking optical pick-up head is ±16.3 µm, at a 5 V driving voltage. The resonant frequencies of the focusing and tacking systems are 1.9 kHz and 4.1 kHz, respectively.