Tunable all-optical negative multitap microwave filters based on uniform fiber Bragg gratings
ABSTRACT 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.
Full-textDOI: · Available from: José Mora, Aug 20, 2015
- SourceAvailable from: Jianping Yao
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- "One straightforward approach to generating negative coefficients is to perform differential detection using a balanced photodetector (PD) . Other techniques to generate negative coefficients include the use of crossgain modulation (XGM)  or cross polarization modulation (XPolM)  in a semiconductor optical amplifier (SOA), carrier depletion effect in a distributed-feedback laser diode (LD)  or in a Fabry–Pérot LD , and the use of the transmission of a broadband source through uniform fiber Bragg gratings (FBGs) . 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 , or by using a single dual-output MZM with a double-pass modulation . "
ABSTRACT: A finite impulse response (FIR) filter for microwave signal processing implemented based on an optical delay-line structure with uniformly spaced taps has been extensively investigated, but the realization of such a filter with negative or complex tap coefficients to provide an arbitrary frequency response is still a challenge. In this paper, an overview of photonic microwave delay-line filters with nonuniformly spaced taps, by which an arbitrary bandpass frequency response can be achieved with all-positive tap coefficients, is presented. We show that the nonuniform time delays provide equivalent phase shifts to the tap coefficients, while the all-positive-coefficient nature simplifies greatly the filter realization. Based on the theory, a 50-tap flat-top bandpass filter with a quadratic phase response is designed and analyzed. A seven-tap nonuniformly spaced photonic microwave filter with a flat-top and chirp-free bandpass response is then demonstrated. The use of the proposed technique for advanced microwave signal processing is then discussed. The generation of a chirped microwave signal and a phase-coded microwave signal are discussed and demonstrated. The use of the proposed technique to design a FIR filter for microwave matched filtering is also discussed and experimentally demonstrated.IEEE Transactions on Microwave Theory and Techniques 12/2010; 58(11-58):3279 - 3289. DOI:10.1109/TMTT.2010.2074570 · 2.94 Impact Factor
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- "One of the most interesting areas where optical technology could provide benefits is photonic microwave filtering. Many different architectures have been proposed –, offering advantages such as low and frequency-independent loss or tunability and reconfiguration of the filter response. However, most optically implemented microwave filters exhibit periodic transfer functions, preventing their use in radio-frequency (RF) applications. "
ABSTRACT: A novel tunable photonic microwave single bandpass filter based on the optical resonance originated by a local phase shift introduced in the periodic structure of a fiber Bragg grating is proposed. Dynamic control of the phase shift is obtained employing a piezoelectric transducer in order to stretch the grating, thus changing the resonance wavelength. A photonic microwave filter is obtained by using an optical single-sideband modulation. Experimental results are provided in order to prove the concept.IEEE Photonics Technology Letters 11/2010; DOI:10.1109/LPT.2010.2063019 · 2.18 Impact Factor
- "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 . The transmission spectrum at the output of FBGs is altered which is used to generate negative taps. "
Article: Microwave Photonics[Show abstract] [Hide abstract]
ABSTRACT: Broadband and low loss capability of photonics has led to an ever-increasing interest in its use for the generation, processing, control and distribution of microwave and millimeter-wave signals for applications such as broadband wireless access networks, sensor networks, radar, satellite communitarians, instrumentation and warfare systems. In this tutorial, techniques developed in the last few years in microwave photonics are reviewed with an emphasis on the systems architectures for photonic generation and processing of microwave signals, photonic true-time delay beamforming, radio-over-fiber systems, and photonic analog-to-digital conversion. Challenges in system implementation for practical applications and new areas of research in microwave photonics are also discussed.Journal of Lightwave Technology 03/2009; 27(3-27):314 - 335. DOI:10.1109/JLT.2008.2009551 · 2.86 Impact Factor