A novel optical fiber evanescent-wave (EW) sensing platform combining a taper and a refractive index (RI) gel residue is proposed. It includes two identical large core multimode fibers that are positioned perpendicularly to each other with one for excitation light delivery (i-fiber) and one for EW fluorescent signal collection (r-fiber). One end of the r-fiber is decladded to expose a segment of a cylindrical fiber core terminated with a taper. A small drop of rhodamine 6G (R6G) solution sample is distributed in such a way that it surrounds the side wall of the cylindrical portion of the core and covers the i-fiber end face. The fluorescent signal is recorded under the following conditions: 1. the entire taper is exposed to the air; 2. the entire taper is immersed into a large gel block; 3. the taper is covered with a gel residue. A dramatic rise of the fluorescence signal is observed in the third case, which is over 20 times more than the level achieved from the first two cases. We reveal that the combination of the end-face-TIR and the mode mixing accounts for this phenomenon, which will be discussed in detail.

This paper focuses on the principles and phenomena of the overlap pattern of the linear grating and zone plate. Deriving from the describing equations, it has been proved theoretically that the pattern also consists of zone plates, which are called moiré zone plates. The locations of the centers and the radius of the moiré zone plates are determined by the pitch of the linear grating, the first radius of the original zone plate and the phase of both of them. The fringe visibility is affected by the fill factor of linear grating and 0.5 results in the best visibility. Magnification, which is defined as the ratio of the change in area to the displacement in the x-axis direction, can be as large as 500. Furthermore, both AutoCAD and Matlab software were employed to verify the hypothesis.

The multi-channel dispersion compensator by using chirped fiber Bragg gratings(CFBGs) has been one of the key technologies of high speed optical fiber communication system. The characteristics of reflection spectrum, time delay and dispersion of CFBGs with different connection forms are studied. By stress modulating and UV post-exposure, the uniform characteristics of the reflection spectrum of CFBGs are increased, and the influence of superposition effect caused by the parallel connection of CFBGs is decreased greatly. At the same time, the interference length is used to optimize the position of the cascaded CFBGs, and the cross talk can be decreased. By using the above optimized CFBGs connection forms,13 different wavelength CFBGs are cascaded in each dispersion compensator, and 20 CFBGs are parallel connected in each channel, a 13×10Gb/s 3100km ultra long G.652 fiber transmission system is successfully implemented without electric regenerator. The power penalty of the carrier-suppressed return-to-zero (CSRZ) code transmission system is only 2.5dB.

In recent years, optical fiber sensors have developed rapidly in Singapore. Nanyang Technological University, National University of Singapore and several research institutes under Agency for Science, Technology and Research (A*STAR) are studying on various types of optical fiber sensing devices for different applications. In this talk, we would like to briefly introduce the research work on optical fiber sensors area in Singapore. We will mainly present the contributions of Institute for infocomm Research (I2R) in A*STAR and Network Technology Research Center (NTRC) in Nanyang Technological University, including optical fiber sensors in aircraft health monitoring and medical care applications and optical fiber cavity ring-down sensors in the chemical and bio-sensing applications. Finally, based on our current work, the future work on optical fiber sensing area will be described as well.

In this paper, we investigate in detail the characteristics of a LPG written in an endlessly-single-mode (ESM) solid silica core PCF both theoretically and experimentally. By use of a dispersion factor, a deeper understanding of the behavior of LPG in the ESM-PCF is achieved. Our analysis clearly reveals the significant effect of the waveguide dispersive characteristics of the cladding modes on the strain and temperature characteristics of the LPG in the ESM-PCF. By selecting an appropriate grating period, a LPG with approximately zero temperature sensitivity but large strain sensitivity is realized. By utilizing the properties of LPGs in the PCF, we realize a simple temperature-insensitive strain sensor, a stable demodulator of a fiber Bragg grating temperature sensor, and others.