Javier Martí

Ultrafast All-Optical Switching in a Silicon-Nanocrystal-Based Silicon Slot Waveguide at Telecom Wavelengths

We demonstrate experimentally all-optical switching on a silicon chip at telecom wavelengths. The switching device comprises a compact ring resonator formed by horizontal silicon slot waveguides filled with highly nonlinear silicon nanocrystals in silica. When pumping at power levels about 100 mW using 10 ps pulses, more than 50% modulation depth is observed at the switch output. The switch performs about 1 order of magnitude faster than previous approaches on silicon and is fully fabricated using complementary metal oxide semiconductor technologies.

Single Bandpass Photonic Microwave Filter Based on a Notch Ring Resonator

A novel tunable single bandpass photonic microwave filter is proposed. It is based on optically filtering one of the sidebands of a phase-modulated optical carrier by means of the notch response of a silicon-on-insulator ring resonator. The filter response can be tuned by changing the laser wavelength. Experimental results to prove the concept are provided.

Dual-Wavelength DFB Erbium-Doped Fiber Laser With Tunable Wavelength Spacing

A novel tunable dual-wavelength distributed-feedback fiber laser is presented. It is based on the optical resonances induced by two local phase shifts introduced in the periodic structure of an erbium-doped fiber Bragg grating. A dynamic control of the phase shifts, which are generated by piezoelectric transducers, permits the tunability of the wavelength spacing between the optical harmonics of the laser signal. The wavelength spacing is continuously tuned from 0.128 to 7 GHz. Moreover, a microwave carrier is created within such frequency tuning range by the heterodyne photodetection of the dual-wavelength laser signal.

Tailoring the dispersion behavior of silicon nanophotonic slot waveguides

We investigate the chromatic dispersion properties of silicon channel slot waveguides in a broad spectral region centered at ~1.5 μm. The variation of the dispersion profile as a function of the slot fill factor, i.e., the ratio between the slot and waveguide widths, is analyzed. Symmetric as well as asymmetric geometries are considered. In general, two different dispersion regimes are identified. Furthermore, our analysis shows that the zero and/or the peak dispersion wavelengths can be tailored by a careful control of the geometrical waveguide parameters including the cross-sectional area, the slot fill factor, and the slot asymmetry degree.

Photonic Technique for the Measurement of Frequency and Power of Multiple Microwave Signals

An optical approach to simultaneously measure the frequency and power of several microwave signals is presented and demonstrated. The system is based on the processing of an interferogram generated by integrating the microwave power over the measurement band at the output of a tunable photonic microwave notch filter. Experimental results to demonstrate the principle of operation are provided showing a resolution of 15 MHz.

Group-index engineering in silicon corrugated waveguides.

We present experimental measurements of the group index in tailored silicon corrugated waveguides. Nearly constant group index as high as ng=14 ±0.5 in a 13 nm range was measured in a 50 µm long waveguide.

Tunable Photonic Microwave Filter With Single Bandpass Based on a Phase-Shifted Fiber Bragg Grating

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.

Multiple extraordinary optical transmission peaks from evanescent coupling in perforated metal plates surrounded by dielectrics

We study numerically and theoretically the optical transmission of nanostructured gold films embedded in dielectric claddings. We show how multiple transmission peaks appear as the claddings thickness increases. These transmission peaks come not only from surface plasmon polariton excitations but also from the excitation of Fabry-Perot modes sustained at the claddings, coupled through the metal, as long as a periodic pattern is milled in the metal film. We propose that this structure could be used as an ultracompact all-optical switch by surrounding the metal film with Kerr nonlinear dielectric layers.

Group index engineering in silicon corrugated waveguides

We present experimental measurements of the group index in tailored silicon corrugated waveguides. Nearly constant group index as high as ng=14 ±0.5 in a 13 nm range was measured in a 50 µm long waveguide.