Tunable all-optical negative multitap microwave filters based on uniform fiber Bragg gratings

Instituto de Ciencia de los Materials, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassort, Valencia, Spain.
Optics Letters (Impact Factor: 3.29). 09/2003; 28(15):1308-10. DOI: 10.1364/OL.28.001308
Source: PubMed


A novel and simple technique for obtaining transversal filters with negative coefficients by using uniform fiber Bragg gratings was presented. A wide tuning range, good performance, low cost and easy implementation of multitap filters in an all-optical passive configuration in which taps were obtained by use of the transmission of a broadband source through uniform Bragg gratings was demonstrated. It was found that the spurious term that the filters generate was limited to a low-frequency bandwidth and can be electrically filtered in the system's receiver.

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Available from: José Mora
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    • "One straightforward approach to generating negative coefficients is to perform differential detection using a balanced photodetector (PD) [3]. Other techniques to generate negative coefficients include the use of crossgain modulation (XGM) [4] or cross polarization modulation (XPolM) [5] in a semiconductor optical amplifier (SOA), carrier depletion effect in a distributed-feedback laser diode (LD) [6] or in a Fabry–Pérot LD [7], and the use of the transmission of a broadband source through uniform fiber Bragg gratings (FBGs) [8]. Negative coefficients can also be generated by biasing a pair of Mach–Zehnder modulators (MZMs) at the opposite slopes of the transfer functions to achieve amplitude inversion [9], or by using a single dual-output MZM with a double-pass modulation [10]. "
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    • "Note that the lasing wavelength of the DFB laser diode should be slight different from the injection wavelength sent to the photodetector through an FBG. Negative coefficients can also be generated by using an EDFA amplified spontaneous emission (ASE) source cascaded with uniformed FBGs [45]. The transmission spectrum at the output of FBGs is altered which is used to generate negative taps. "
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