| 摘要 |
Optical filters, filter systems, and methods for filtering optical signals transmitted along optical fibers (12, 14) provide enhanced filter performing by combining the capabilities of different types of filters particularly for dense wavelength division multiplexed systems. More specifically, the spectral skirt or transition wavelength range between a pass band wavelength range and a blocked wavelength range of a thin film pass band or dichroic filter (16) is enhanced by arranging the thin film filter (16) in series with one or more Fiber Bragg Gratings (18, 20). The Fiber Bragg Gratings (18, 20) will generally reflect a portion of the signal within the spectral skirt or transition wavelength range of the thin film filter (16). Although short Fiber Bragg Gratings generally block a quite narrow range of signals, the steep spectral skirt of the grating, when combined with the broader wavelength response of a thin film bandpass or dichroic filter (16), results in a composite filter structure which exhibits the beneficial characteristics of each of its components.
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