D. Pastor

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

We present a novel and simple technique for obtaining transversal filters with negative coefficients by using uniform fiber Bragg gratings. We demonstrate a wide tuning range, good performance, low cost, and easy implementation of multitap filters in an all-optical passive configuration in which negative taps are obtained by use of the transmission of a broadband source through uniform Bragg gratings.

Automatic tunable and reconfigurable fiberoptic microwave filters based on a broadband optical source sliced by uniform fiber Bragg gratings.

We demonstrate an automatic tunable transversal notch filter based on uniform fiber Bragg gratings and a broadband optical source. High tunability can be performed by stretching the fiber with the gratings written in series. Also, high sidelobe supression can be achieved by introducing tunable attenuators in a parallel configuration of the gratings.

Multiwavelength single sideband modulation for WDM radio-over-fiber systems using a fiber grating array tandem device

We demonstrate the generation of high-quality multiwavelength single sideband (SSB) signals for wavelength-division-multiplexing radio-over-fiber systems using a tandem of two identical arrays of fiber Bragg grating devices placed in a serial arrangement. SSB is confirmed by spectral measurements and also by the simultaneous cancellation of the radio-frequency fading effect in three different wavelengths. The results show a considerable improvement both in terms of insertion losses, carrier supression effect, and bandwith (extensible from the millimeter to the whole microwave band) over the previously reported configuration based on arrayed-waveguide grating devices.

Tunable radio-frequency photonic filter based on an actively mode-locked fiber laser

We propose the use of an actively mode-locked fiber laser as a multitap optical source for a microwave photonic filter. The fiber laser provides multiple optical taps with an optical frequency separation equal to the external driving radio-frequency signal of the laser that governs its repetition rate. All the optical taps show equal polarization and an overall Gaussian apodization, which reduces the sidelobes. We demonstrate continuous tunability of the filter by changing the external driving radio-frequency signal of the laser, which shows good fine tunability in the operating range of the laser from 5 to 10 GHz.

High-Q microwave photonic filter with a tuned modulator

We propose the use of tuned electro-optic or electroabsorption external modulators to implement high-quality (high-Q) factor, single-bandpass photonic filters for microwave signals. Using this approach, we experimentally demonstrate a transversal finite impulse response with a Q factor of 237. This is to our knowledge the highest value ever reported for a passive finite impulse-response microwave photonic filter.

Reconfigurable fiber-optic delay line filters incorporating electrooptic and electroabsorption modulators

The authors propose and demonstrate experimentally a novel class of flexible and fastly reconfigurable fiber optic delay line filters for microwave signal processing that incorporate electrooptic and electroabsorption modulators as weighting elements.

Reconfigurable RF photonic filter with negative coefficients and flat-top resonances using phase inversion in a newly designed 2 /spl times/ 1 integrated Mach-Zehnder modulator

We report novel results for the implementation of incoherent radio-frequency (RF) photonic filters with negative coefficients using a newly developed 2 /spl times/ 1 Mach-Zehnder modulator device featuring /spl pi/-shifted RF modulation over the lightwave signals entering the device at complementary input ports. The characteristics of the novel device are described and the device used to implement an eight-tap (positive and negative) transversal RF photonic reconfigurable filter with square-type resonances.

Dynamic optical transversal filters based on a tunable dispersion fiber Bragg grating

We demonstrate a fibre optic radio frequency notch filter with continuous tuning by using a uniform fibre Bragg grating. The uniform grating is dynamically chirped by using a magnetic field and a magnetostrictive transducer.

Tunable dispersion device based on a tapered fiber Bragg grating and nonuniform magnetic fields

We present a new variable dispersion device based on tuning the chirp of a tapered fiber Bragg grating by means of a magnetic transducer. By using a nonuniform magnetic field, we demonstrate a 188-472-ps/nm dispersion tuning range, suitable for tunable radio-frequency filters and dispersion compensation, among others.

Continuous tuning of photonic transversal filter based on the modification of tapped weights

We propose and experimentally demonstrate a novel technique to tune the microwave photonic filter which is based on the sinusoidal modulation superimposed to the envelope of the filter coefficients. This configuration overcomes the use of tunable optical sources and optical dispersive devices. To the best of our knowledge, these are the first experimental results where the resonances of the cited filters are shifted by changing the weight of the optical taps