| 摘要 |
PURPOSE: To obtain chirped fiber gratings which are easily producible by forming continuous changes of waveguide structures in the longitudinal direction of an optical fiber and forming the gratings in these changing parts. CONSTITUTION: The waveguide structures, such as fiber diameter, core diameter, refractive index and refractive index distribution, of the optical fiber are previously continuously changed in the longitudinal direction of the fiber and the gratings and the gratings of the specified period by a conventional method are formed at this fiber. The wavelength (in-tube wavelengthλg) of the light propagating therein changes corresponding to these changes when the waveguide structures of such optical fibers are changed. Then, the wavelength of the light propagating in the fiber is changed by previously forming the gratings of the specified period and, therefore, reflection characteristics similar to the reflection characteristics of the chirped fiber gratings continuously changed in the grating periods are eventually obtd. The reflection wavelength region is widened by continuously changing the waveguide structures of the fiber and in addition, the determination of the band of the reflection wavelength region corresponding to the change quantity of the waveguide structures is made possible. |
