Date of Award
Master of Applied Science (MASc)
Electrical and Computer Engineering
Tunable fiber optic filter has extensive applications in telecommunications, spectroscopy, and fiber optic sensing. Many research attempts have been devoted to develop a filter with a wide tuning range, a fast tuning speed, a fine tuning resolution, and high reliability. Despite of the progress made so far, a tunable fiber optic filter that combines all these qualities is still a subject of intensive research. This thesis describes the design, fabrication and test results of a high performance tunable fiber optic filter. The filter is piezo-driven using a flexural hinge structure for displacement magnification and an axial strain of a fiber Bragg grating. Finite element analysis was used to design the mechanical structure to achieve the required displacement magnification and reaction force for grating compression. A passive thermal compensation design was implemented with two spacers of different coefficients of thermal expansion to compensate the thermal-induced wavelength drift. A feedback control system with a linear variable differential transformer was employed to control the displacement and to achieve the designed tuning accuracy. A tuning range of 13.7 nm, a maximum closed loop switching time of 17.3 ms, and a wavelength drift of 1.4 pm/C were achieved. The flexural-hinge structure, that offers noise-free motion, no need of lubricants and no wear, ensures its long-term reliability.
Zu, Wen, "Piezo drive tunable optic filter" (2005). Theses and dissertations. Paper 416.