Development of Optical Switches Using MEMS-based Technology
Date Issued
2009
Date
2009
Author(s)
Liao, Bo-Ting
Abstract
In this work, novel MEMS-based optical switches, which include 2?2 optical switch and N?N hybrid optical switches, are presented. The proposed novel optical switches possess advantages over traditional optical switches. novel 2?2 MEMS optical switch using the proposed split cross-bar (SCB) design is demonstrated. When compared with the cross-bar switches, the SCB switch does not have the constraint on mirror thickness which affects fiber alignment significantly. When compared with the mirror-array switches, the SCB switch requires less movable mirrors and thus potentially gives better fabrication yield. The SCB switch consists of two fixed mirrors, two movable mirrors, and two actuators. Two types of actuators, including electrostatic comb-drive actuators and electrothermal V-beam actuators, are utilized. Furthermore, the electrothermal V-beam actuators are integrated with the bi-stable mechanism to move and latch the movable mirrors. Thus, the power consumption of the SCB switch can be greatly reduced.he SCB device is easily realized by using inductively-coupled-plasma (ICP) etching on a silicon-on-insulator (SOI) wafer with one photo-mask. The comb-drive actuators and electrothermal V-beam actuators can move the movable mirrors with a displacement of 60 m under a driving voltage of 40V. The optical performance and the dynamic response of the SCB switch are also investigated. The measured insertion losses are between -1.1dB and -1.4dB and the measured switching time is less than 10 ms.lthough the SCB design can eliminate the drawbacks of traditional designs for 2?2 optical switches, it is not suitable to be utilized in N?N optical switch designs. Thus, the novel N?N hybrid optical switches, which include 4?4 and 8?8 hybrid switches, are presented in this work. The proposed hybrid switches comprising a MEMS-based micro-mirror array and a mini-actuator array possess the advantages of high precision, high yield, low cost, and low power-consumption. The micro-mirror array, which includes vertical mirrors, cantilevers, and light-path trenches, can be monolithically realized by using single-step KOH anisotropic etching process. The micro-mirrors can be naturally self-aligned and thus reduces the complexity of the packaging process. For 4?4 hybrid switch, commercially-available bi-stable actuators integrated with L-shape arms are used in the mini-actuator array. For 8?8 hybrid switch, smaller-footprint solenoid-based bi-stable actuators integrated with pushing arms are used in the mini-actuator array. Each micro-mirror of the mirror array can be individually actuated by the bi-stable actuator, and thus the power consumption of the system can be greatly reduced.e also develop a driving circuit and a Window-based program for controlling the hybrid switches. Device characterizations and optical performance are also investigated. The driving voltage of the mini-actuator array is about 5 ~ 6 volt. The typical surface roughness of the fabricated mirrors is about 78nm. For 4?4 hybrid switch, the measured insertion losses are between -1.6dB and -2.3dB and the measured switching time is less than 13 ms. For 8?8 hybrid switch, the measured insertion losses are between -2.2dB and -3.3dB and the measured switching time is less than 12 ms.
Subjects
Optical switch
optical communication
MEMS
wet anisotropic etching
bi-stable actuator
Type
thesis
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