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We report the development and demonstration of a long-period grating refractometer. The principle of operation is based on the using of a long-period grating that is structurally induced by a CO 2 laser, and where the resonance wavelengths are shifted as the refractive index of medium surrounding the cladding of the long-period grating. The different concentrations for three types of solutions (ethylene glycol, salt, and sugar) were experimentally measured, and results show that, as a refractometer, this fiber-based device not only can differentiate chemicals based on their refractive index, but it can also become a concentration indicator of a particular chemical solution, and applied in the oil and petroleum industry.

Splicing between single-mode fiber (SMF) and photonic crystal fiber (PCF) using a conventional electric-arc splicer is not easily achieved. It is reported, for the first time, that the condensation within the capillaries resulted in a bubble developed at the fiber ends in the midst of splicing. A novel and effective splicing technique using a CO/sub 2/ laser has successfully eliminated this limitation and a complete splicing process is achieved within 3-5 s. The splice losses have been recorded to be in the range of 1.3-2.8 dB; the high splice losses are possibly due to the field-mode discrepancy of the sampled PCF with a diameter of 100 /spl mu/m.

Silica photonic crystal fiber (PCF) is a new type of fiber that has an array of microscopic air holes running along its length. Splicing PCF to standard single-mode fiber (SMF) is a challenging task, but it is also important because of the potential broad applications. Proper splicing of SMF to PCF is imperative in order to avoid collapsing of the PCF on the air holes; however, the two types of fiber require different laser powers for melting. A laser splicing system is developed to demonstrate its effectiveness at splicing between the large-mode-area PCF and SMF with low splice loss.

Optical fiber is the medium of choice to meet the ever-increasing demand for huge information transmission and presently there is no technology that can match the information transmission speed and capacity of optical fiber communications systems. Developments and improvements in optical communications technology have been occurring with tremendous rapidity in parallel with its increasingly wide scale deployment. Potential advantages of optical fiber technology as engineering and economic considerations have stimulated a growing activity in the development of relevant devices and processes to exploit the maximum benefits of this technology. DOCTOR OF PHILOSOPHY (EEE)

Splicing between single mode fiber (SMF) and photonic crystal fiber (PCF) using conventional electric arc splicer is not easily achieved, the condensation within the capillaries resulted in bubble developed at the fiber-ends in the midst of splicing is observed. A novel and effective splicing technique using CO/sub 2/ laser has successfully eliminated this limitation and a complete splicing process is achieved within few seconds. The splice losses have been recorded to be in the range of 1.3-2.8 dB; the high splice losses are possibly due to the field mode discrepancy of the sampled PCF with a diameter of 100 /spl mu/m.

An effective, simple, and low cost fabrication of Long-period fiber gratings (LPFGs) using point-by-point method by CO/sub 2/ laser was investigated and demonstrated. The B-Ge codoped fiber was used to produce a peak attenuation loss of at least 20 dB with period number of 17. Monitoring on the variation of spectral responses with the change of temperatures in the range of 25/spl deg/C to 250/spl deg/C had been observed. Below 100/spl deg/C, the spectral response was nearly stable. An approximate sensitivity of 0.0186 nm//spl deg/C was obtained in 100/spl deg/C to 160/spl deg/C temperature range. It exhibited a double sensitivity response to approximately 0.0378 nm//spl deg/C in the 170/spl deg/C to 250/spl deg/C range.

We report the development and demonstration of a long-period grating refractometer. The principle of operation is based on in the use of a long-period grating that is structurally induced by a CO/sub 2/ laser, and where the resonance wavelengths are shifted by the refractive index of the medium surrounding the cladding of the long-period grating. The different concentrations for three types of solutions (ethylene glycol, salt, and sugar) were experimentally measured, and results show that, as a refractometer, this fiber-based device can not only differentiate chemicals based on their refractive index, but it can also become a concentration indicator of a particular chemical solution, and applied in the oil and petroleum industry.

An extremely short long-period grating (LPG) with strong resonance has been developed in a large-mode-area photonic crystal fiber (PCF) by use of the heat source of a CO2 laser. We believe that such a LPG in pure silica PCF is the first example to be obtained with the point-by-point technique. The fabrication method is simple and repeatable. The resulting LPG has 8 periods, written by a CO2 laser, within a 2.8-mm length of fiber, which yields a deep notch of core-cladding mode coupling of -31.5 dB at the telecommunication wavelength of 1529.2 nm, with a FWHM of approximately 0.7 nm. The principal advantages of this LPG are that it is practical, cost effective, and compact.