No abstract

No abstract

Fiber Bragg gratings (FBGs) are key elements in modern telecommunication and sensing applications. In optical communication, with the advancement of the Erbium doped fiber amplifier (EDFA), there is a great demand for devices with wavelength tunability over the Erbium gain bandwidth (in particular, for wavelength division multiplexing (WDM) networks). The center wavelength of a FBG can be shifted by means of change of temperature, pressure or mechanical axial strain. The axial strain approach is the best method among all other techniques because it allows relatively large wavelength shifts with high speed. Axial strain of up to 4% will be required to cover the whole EDFA region (more than 40 nm of central wavelength shift). The formation of Bragg grating results in significant reduction in mechanical strength of optical fibers especially in tension. As a result, axial strain of only about 1% can be achieved by mechanical stretching of FBGs. In order to achieve the remaining 3% strain compression of FBGs has to be applied.In this thesis, the design and analysis of a novel device for achieving central wavelength shift are presented. In particular, the device has achieved, for a fiber with Further, using the piezoelectric transducer (PZT) actuator as a driver, tuning speed of around 1.5nm/ms was achieved.-iii - ACKNOWLEDGMENTSUpon the completion of this thesis, I would like to express my sincere gratitude and appreciation to my supervisors Professor Chris W.

No abstract

A numerical procedure to compute nonsingular, time-optimal solutions for nonlinear systems, which have fixed initial and final states, and are linear and bounded in control, is presented. Using the Pontryagin’s Minimum Principle, the corresponding nonlinear two-point boundary-value problem is formulated and solved by combination of the forward-backward and the shooting methods. The forward-backward procedure generates a good guess of the initial costates, which is crucial for the convergence of the shooting method. Numerical example of a two-link manipulator illustrates the proposed approach and the convergence of the procedure.