Tunable chirped fiber Bragg grating based on the D-shaped fiber

A novel tunable chirped fiber Bragg grating is realized by bending a piece of D-shaped fiber Bragg grating into a specific shape like the character ‘Ω’. The principle of tuning is demonstrated by numerical simulation. The dispersion of the grating can be tuned while the center wavelength is kept nearly no shift. The experimental results match well with the numerical analysis. The influence from D-shaped fiber’s birefringence and polarization dependent loss is discussed theoretically and experimentally as well. This proposed tuning technique has potential applications in the optical communications and other fiber optics systems.