1×2、1×4與2×2微/奈米機械式光開關之研製
Development of 1×2, 1×4 and 2×2 Micro/Nano Mechanical Optical Switches
Date Issued
2006
Date
2006
Author(s)
Lin, Wu-Lang
DOI
zh-TW
Abstract
This research is to develop micro/nano mechanical optical switches including 1×2, 1×4 and 2×2 switches which features small size, simple structure and high reliability. We have adopted precision positioning and MEMS technologies to accomplish the development of those switches. These switches assume the advantages of MEMS technology while omitting the disadvantage of high manufacturing cost. The fiber holder and ultra thin mirror are fabricated by MEMS technology; they functions as an output fibers holder and optical signal reflector. By applying the two stages geometry error reduction principle, the switching position error of the input fiber can be reduced and the position resolution can reach micro/nano degree.
For the 1×2 optical switch, we adopt fiber-to-fiber configuration and use a fiber holder to hold the two output fibers. Using two stages geometry error reduction principle, the precision of the input fiber switching position can be adjusted to reach 0.18μm. Experimental results showed the insertion loss can be controlled to ch1: 0.8dB, ch2: 1.4dB with switching time 5ms, and crosstalk≦80dB. The reliability tests demonstrated the variation of the insertion losses are ch1: 0.04dB, ch2: 0.02dB after 10,000 cycle times, and ch1: 0.024dB, ch2: 0.006dB throughout 100 switch times after 1,000,000 cycle times. The switch size is only 7.5×16×20mm .
For the 1×4 optical switch, we apply the previously successfully developed 1×2 opical switch technology. This switch uses two relays as the two actuators whose switching direction is perpendicular to each other by orthogonal arrangement. Due to the use of a fiber holder, the fiber position errors could be reduced to less than 0.27μm. The experimental test results show that after an initial 100 cycles test run the insertion losses of the four channels are ch1: 0.68dB, ch2: 1.49dB, ch3: 0.71dB, ch4: 0.97dB. The reliability tests of the insertion losses of the four channels after 10,000 cycles are ch1: 1.67dB, ch2: 1.63dB, ch3: 0.75dB, ch4: 0.98dB. The switch size is only 20×20×25mm .
This 2×2 switch utilizes four collimators arranged 90° to each other on a common plane, and use an ultra thin mirror as the reflector whose thickness is less than 1.8μm and roughness 5.721nm to allow double-sided reflection. We apply the advantage of high precision of MEMS process, and omit the disadvantage of all MEMS-based type switches which is high in cost and dramatically increase the insertion loss when the lens-fiber lateral misalignment occurs. In addition, compared to the traditional prism type 2×2 optical switch, our switch will reduce alignment steps leading to a simpler switch structure. Experimental results show that the best insertion loss of two output channels at transmission state are: ch3: 0.281dB, ch4: 0.547dB and at reflection state: ch3: 0.545dB, ch4: 0.571dB, respectively. In order to test for the long-term reliability we continue to switch 10,000 cycle times. The best insertion loss of two output channels at transmission state are found to be: ch3: 0.31dB, ch4: 0.52dB and at reflection state: ch3: 0.61dB, ch4: 0.62dB respectively.
To overcome the bottleneck of mass production of optical switches, we have successfully developed an automatic light tracing alignment technology (ALTA), which comprise of CCD image processing module, PZT motion control module and the light detection module, and is edited in the LabVIEW environment and applied to our 1×2 optical switch. With the aid of the CCD module the ALTA program calculates the initial position of the input fiber, which is then moved by the PZT module close to the ch1 output fiber. The program will carry out quadratic estimation algorithm and hill-climbing algorithm for ch1 and ch2, and terminate when the insertion losses are below 1dB individually. The program will run the DSA and BSA process until the ch1 and ch2 insertion losses and difference are below 1dB and 0.1dB, simultaneously. The results show the best insertion loss of ch1, ch2 are 0.47dB, 0.51dB, respectively and the total alignment took only 383 seconds. The difference between the ch1 and ch2’s insertion loss is 0.04dB. This technology could be save manual assembly and alignment time, and overcome the bottleneck of the so called "last-mile" in fiber-optics communication development.
Subjects
光開關
精密定位技術
光纖直接對位
光纖夾持器
幾何縮小定位誤差
自動尋光對位
Optical switch
Precision positioning technology
Fiber-to-fiber
Fiber holder
Geometry error reduction
Automatic light tracing alignment
Type
thesis
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