Nowadays, nano-electro-mechanical systems (NEMS) actuators using electrostatic forces are facing the bottleneck of the electromagnetic interference which greatly degrades their performances. On the contrary, the hybrid circuits driven by optical gradient forces which are immune to the electromagnetic interference show prominent advantages in communication, quantum computation, and other application systems. In this paper we propose an optical actuator utilizing the optical gradient force generated by a hetero-structure photonic crystal cavity. This type of cavity has a longitudinal air-slot and characteristics of ultrahigh quality factor (Q) and ultra-small mode volume (V) which is capable of producing a much larger force compared with the waveguide-based structures. Due to the symmetry property, attractive optical gradient force is generated. Additionally, the optomechanical coefficient (g_om) of this cavity is two orders of magnitude larger than that of the coupled nanobeam photonic crystal cavities. The 2D hetero-structure cavity, comb drives, folded beam suspensions and the displacement sensor compose the whole device. The cavity serves as the optical actuator whilst the butt-coupled waveguide acts as the displacement sensor which is theoretically proved to be insensitive to the temperature variations. As known, the thermo-optic effect prevails especially in the cavity-based structures. The butt-coupled waveguide can be used to decouple the thermal effect and the optoemchanical effect (OM) with the aid of comb drives. The results demonstrate that the proposed optical gradient force actuator show great potential in the future of all-optical reconfigurable circuits.

Date Published: 13 March 2015
PDF: 9 pages
Proc. SPIE 9374, Advanced Fabrication Technologies for Micro/Nano Optics and Photonics VIII, 937405 (13 March 2015); doi: 10.1117/12.2078222

Published in SPIE Proceedings Vol. 9374:
Advanced Fabrication Technologies for Micro/Nano Optics and Photonics VIII
Georg von Freymann; Winston V. Schoenfeld; Raymond C. Rumpf; Henry Helvajian, Editor(s)