A 1x20 MEMS mirror array with large scan angle and low driving voltage for optical wavelength-selective switches

Wavelength-selective switches (WSSs) are the core devices for reconfigurable optical add-drop multiplexers (ROADMs) that are essential in all-optical networks. WSSs based on microelectromechanical (MEMS) mirror arrays exhibit high potential due to their high switching speed and large port counts, but there still exist challenges to achieve large optical scanning angle at low voltage. This paper presents a 1x20 MEMS mirror array (MMA) design that can scan over 10 degrees in both axes at less than 5 V. The MMA is based on an unique electrothermal bimorph actuator design that can perform 2D scanning and its fill factor reaches 96 %. The 1x20 MMA design has been successfully fabricated using a combined bulk-and surface-micromachining process. The size of each mirror plate is 240 mu m by 500 mu m. The measured maximum optical scan angles in the x-axis and y-axis are 29.3 degrees and 11.8 degrees, respectively, at 3 V. The measured response time is about 3.7 ms. The thermal crosstalks between adjacent electrothermal actuators are about 10 %. Long-term stability tests show that the angular drifts of the individual mirrors are about 0.002 degrees/h. (C) 2021 Elsevier B.V. All rights reserved.