A computer controlled narrow bandpass optical tunable filter using a Fourier diffraction grating in the range of 1.3-1.55 mu m

A novel tunable filter using a Fourier grating is studied and discussed. It consists of a Fourier grating, a collimator lens, single-mode fibers, and a computer Controlled rotary actuator. It has very low polarization dependence df less than 0.3 dB, an insertion loss of less than 3 dB, and a narrow bandwidth of 1.5 nm. Wavelength selection was realized by rotating the grating, which was controlled by a computer. The device is able to select the light at the desired wavelength from more than 100 WDM optical data streams with 2 mn spacing in the range of 1.3-1.55 mu m.