초정밀 다축 스테이지를 이용한 광소자 정렬 특성 향상에 관한 연구

Abstract

The communication through optical fiber is taking an important role in the expansion of communication network with excellent transmitting rate and quality. The optical communication is introduced to the backbone network at first and becomes a general communication method of network. In recent years, as the demands of VBNS(Very high speed Backbone Network Service) and VDSL(Very high-data rate Digital Subscriber Line) increase, the development of kernel parts of optical communication such as PLC(Planar Light Circuit), Coupler, and WDM(Wavelength Division Multiplexing) elements increases. The alignment and the attachment technology are very important in the fabrication of optical elements. In this thesis, a mechanism of precision multi-axis stage for optical alignment is studied. The major researches are as follows. At first, the driving unit mechanism of precision stage is studied with the aim of optimal design of stage. The driving unit consists of piezoelectric actuator and flexure guide. The strain of flexure due to the actuating force and the stress distribution for the output displacement are analyzed with FEM. The precision multi-axis stages are fabricated based on the result of analysis. This travel and the resolution of stage are evaluated from the view of optical element alignment. The hysteresis of the stage is generated due to PZT actuator. The hysteresis and the inverse hysteresis are modeled with the experiments in X, Y, and Z-axis motion. The input data of desired displacement of the stage according to input voltage is obtained from the inverse hysteresis equation. In the result of experiments with the input data, the error due to hysteresis is well compensated. The alignment algorithm is studied for applying it to the precision multi-axis stage. The field search and peak search algorithms are used for the optical alignment algorithm. The 2-D profile with 5 ㎛ grid of the optical power is obtained with field search alignment. After the field search, peak search alignment is performed for the precise position of the maximum optical power. The precision accuracy of peak search is 0.5 ㎛. To automate the process of optical element alignment, the automation program of optical element alignment is developed by using LabView programming and composed of three tabs that are field search tab, plotting tab, and peak search tab. The process of the optical element alignment is performed by pushing the related buttons using event function. Between 1 ch. input and 8 ch. output PLC stack are performed for the alignment evaluation.