Search

A microwave photonic filter, which can be switched between a high-Q bandpass filter and a notch filter, is proposed and experimentally demonstrated. It is based on a recirculating delay line loop with a reflective semiconductor optical amplifier, and negative taps are generated employing wavelength conversion. The filter can be also tuned by adjusting an optical variable delay line. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:198–201, 2014

A four-tap microwave photonic filter with tunable center frequency and reconfigurable transfer function is proposed.It is based on two Mach-Zehnder interferometers (MZIs) cascaded with a variable optical coupler (OC) in between. By simultaneously adjusting the variable optical delay line incorporated in each MZI, center frequency of the filter can be tuned continuously. Reconfiguration of the filter is achieved by changing the coupling ratio of the variable OC. Experimental result demonstrates a tunable four-tap filter with sidelobe suppression in excess of 25 dB. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1740–1743, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26877

Frequency equalization is essential for radio-over-fiber (RoF) applications due to the degraded performance at higher frequencies.In this article, an easily implemented scheme for tunable frequency equalization in RoF link is proposed. A tunable and reconfigurable microwave photonic filter is used in this method, which is realized through variable optical tilt filter. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2456–2459, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25505

New structures that can realize single and triple output coherence-free microwave photonic filter are presented. They are based on a Sagnac loop interferometer containing a single drive intensity modulator and a 3 × 3 collinear coupler, and no non-reciprocal bias unit is required. Notch responses are obtained by modulating the clockwise and counterclockwise propagating waves inside the Sagnac loop at different times. Theoretical analysis is obtained for both DFB laser source and broad-band source. Measured results verify the theoretical expressions and demonstrate robust notch filter responses. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 744–747, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23218

We propose a novel bandpass microwave photonic multitap filter configuration using a section of Hi-Bi fiber in a round-trip configuration. The configuration makes use of a chirped FBG both as a mirror and a dispersive device. Measured results are presented to show a two-tap and three-tap filter response, with a notch rejection greater than 35 dB and tunability of the level of secondary sidelobes by adjusting a polarization controller. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1181–1184, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23330

Continuously tunable incoherent microwave photonic filter using a tunable Mach-Zehnder interferometer as the slicing filter

A simple coherence-free microwave photonic filter configuration is presented. It is based on an electroabsorption modulator in a double pass configuration, modulating the optical signal at different times. The configuration is free from the velocity mismatch and polarization dependence problems of elecro-optic modulator. Measured results confirm the theoretical expressions and demonstrate a robust notch filter response without phase-induced intensity noise. Application of the filter in suppressing the second harmonic of modulating radio frequency signal is also demonstrated. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 226–229, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23039