High Speed Electronically Tunable Fiber-Optic Filter

摘要

During phase I, two main areas of the tunable filter were investigated intensively. The first and the most important subject was increasing the tunability of the LPG based filter device in order to enable tuning over the required wavelength range (>50nm, in C-band). The second was how to create a tunable filter device with acceptable strength and narrow bandwidth for 100 GHz DWDM applications. Tunability over a range of 50nm was successfully demonstrated during this period with the parallel configuration with electro-optic polymer composites containing nanosized ZnS crystallites. For fabricating filter device, the direct writing of the LPG through the etched optical fiber with ITO layer coated was successfully achieved. This technique eliminates the several critical uncertainties such as peak shifting coming due to chemical etching of the fibers and the peak shifting resulting from the ITO coating. Together with this approach, considerable effort was made to determine the optimal conditions of LPG writing (such as the grating period, grating length and cladding layer thickness) to yield a strong stable spectral transmission peak in the C-band.