摘要：In this paper I describe research activities in the field of optical fiber sensing undertaken by me after leaving the Applied Optics group at the University of Kent. The main topics covered are long period gratings, neural network based signal processing, plasmonic sensors, and polymer fiber gratings. Ⅰ also give a summary of my two periods of research at the University of Kent, covering 1985-1988 and 1991-2001.

摘要：A 2 × 2 optical waveguide coupler at 850 nm based on the multimode interference （MMI） structure with the polysilsesquioxanes liquid series （PSQ-Ls） polymer material and the imprint technique is presented. The influence of the structural parameters, such as the single mode condition, the waveguide spacing of input/output ports, and the width and length of the multimode waveguide, on the optical splitting performance including the excess loss and the uniformity is simulated by the beam propagation method. By inserting a taper section of isosceles trapezoid between the single mode and multimode waveguides, the optimized structural parameters for low excess loss and high uniformity are obtained with the excess loss of -0.040 dB and the uniformity of-0.007 dB. The effect of the structure deviations induced during the imprint process on the optical splitting performance at different residual layer thicknesses is also investigated. The analysis results provide useful instructions for the waveguide device fabrication.

摘要：The use of near infrared, high intensity femtosecond laser pulses for the inscription of long period fiber gratings in photonic crystal fiber is reported. The formation of grating structures in photonic crystal fiber is complicated by the fiber structure that allows wave-guidance but that impairs and scatters the femtosecond inscription beam. The effects of symmetric and asymmetric femtosecond laser inscriptions are compared and the polarization characteristics of long period gratings and their responses to external perturbations are reported.