An optimal refractive index profile of pure silica core optical fiber (PSCF) was designed, in combination with the characters of the modified chemical vapor deposition (MCVD) process. Techniques of preform fabrication by a new furnace round heating MCVD process and fiber drawing process were reviewed. Difficulties in doping fluorine in silica, widening the depressed-index cladding and maintaining the index of fiber core were discussed. Methods used to overcome these difficulties were given at the same time. Additionally, the optimal refractive index profiles of PSCF were presented.

In this paper, we demonstrate a chirped grating designed to compensate for both second-and third-order fiber dispersion. The fabrication technique of chirped gratings is the phase-mask beam scanning method by using a standard unchirped phase mask and by tapering a fiber in the region of the grating. We have made theoretical analysis on the chirp induced by linear and nonlinear taper profiles. The reflectivity and time delay curve of such fiber Bragg grating have been calculated.

The design criteria of the Panda-type erbium-doped polarization-maintaining fiber (EDPMF) are presented, which take into account the cutoff wavelength, mode field diameter, modal birefringence and background loss. The structural parameters are optimized in terms of the design criteria. A Panda-type EDPMF has been manufactured. The fabrication process and the parameter control of the Panda-type EDPMF are in detail described. Its refractive index profile, birefringence and absorption spectra are experimentally investigated.

In order to obtain high-concentration doped erbium ions in silica-based fiber, we manufactured Er3+-Bi3+-Ga3+ co-doped fiber using MCVD and solution doping technique. The concentration of Er3+ in the fiber was about 5.24×1025/m3. We described a new method to measure the degree of clustering in the Er3+-Bi3+-Ga3+ co-doped fiber using fiber transmission experiment. Compared with other methods, the new method is simpler and more accurate. By the new method, the degree of clustering in Er3+-Bi3+-Ga3+ co-doped fiber was determined. It was shown that co-doped Bi3+-Ga3+ strongly increased the Er3+ solubility in the silica-based fiber.

Bragg fibres have many special characteristics. Therefore this kind of fibre attracts more and more attention .In this paper, genetic algorithm is applied to design Bragg fibres to realise desired dispersion and attenuation characteristics.