Applications of Nonlinear Fiber Optics
Book Author Govind P. Agrawal
DescriptionSilica fibers can change their optical properties permanently when they are exposedrnto intense radiation from a laser operating in the blue or ultraviolet spectralrnregion. This photosensitive effect can be used to induce periodic changesrnin the refractive index along the fiber length, resulting in the formation of anrnintracore Bragg grating. Fiber gratings can be designed to operate over a widernrange of wavelengths extending from the ultraviolet to the infrared region. Thernwavelength region near 1.5 μm is of particular interest because of its relevancernto fiber-optic communication systems. In this chapter on fiber gratings, the emphasisrnis on the role of the nonlinear effects. Sections 1.1 and 1.2 discuss thernphysical mechanism responsible for photosensitivity and various techniquesrnused to make fiber gratings. The coupled-mode theory is described in Sectionrn1.3, where the concept of the photonic bandgap is also introduced. Sectionrn1.4 is devoted to the nonlinear effects occurring under continuous-wave (CW)rnconditions. Time-dependent features such as modulation instability, opticalrnsolitons, and optical switching are covered in Sections 1.5 and 1.6. Section 1.7rnconsiders nonuniform and long-period gratings together with photonic-crystal fibers.