Sara Mas

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.

Biconical Tapered Fibers Manipulation for Refractive Index and Strain Sensing Applications

Tapered fibers are used in multitude of applications due to its great versatility and functionality. In particular, this type of fibers is especially useful for sensing applications. For this purpose, tapered fibers must be adequately manipulated to avoid disturbances in the sensors response. In this paper, a guideline for the correct handling of biconical tapered fibers during refractive index and strain measurements is presented and analyzed considering several manipulation scenarios and its corresponding influence in the performance of the system.

Accurate Chromatic Dispersion Characterization of Photonic Integrated Circuits

An accurate technique to characterize chromatic dispersion and its slope versus wavelength is reported. The method is based on a heterodyne Mach-Zehnder interferometer, which is immune to thermal phase noise by using a counterpropagating reference beam. Chromatic dispersion profiles are obtained over a broad wavelength region even in short waveguides with considerable loss. Conventional strip silicon waveguides as well as slotted geometries are considered. Theoretical simulations are also presented for comparison, which show good agreement with the experimental results.

On-chip wireless silicon photonics: from reconfigurable interconnects to lab-on-chip devices

Photonic integrated circuits are developing as key enabling components for high-performance computing and advanced network-on-chip, as well as other emerging technologies such as lab-on-chip sensors, with relevant applications in areas from medicine and biotechnology to aerospace. These demanding applications will require novel features, such as dynamically reconfigurable light pathways, obtained by properly harnessing on-chip optical radiation. In this paper, we introduce a broadband, high directivity (>150), low loss and reconfigurable silicon photonics nanoantenna that fully enables on-chip radiation control. We propose the use of these nanoantennas as versatile building blocks to develop wireless (unguided) silicon photonic devices, which considerably enhance the range of achievable integrated photonic functionalities. As examples of applications, we demonstrate 160 Gbit s−1 data transmission over mm-scale wireless interconnects, a compact low-crosstalk 12-port crossing and electrically reconfigurable pathways via optical beam steering. Moreover, the realization of a flow micro-cytometer for particle characterization demonstrates the smart system integration potential of our approach as lab-on-chip devices.

All-fiber processing of terahertz-bandwidth signals based on cascaded tapered fibers.

Tapered single-mode fibers are employed to perform dynamic pulse shaping in a bandwidth of several terahertz. The transfer function of cascaded biconical tapers is controlled by introducing a phase shift into one of them through mechanical stretching. It is a simple and low-cost technique with potential to process signals with bandwidths as large as those allocated by standard optical fiber while introducing little degradation. Femtosecond pulses are shaped to prove the concept.

Optical Phase Characterization of Photonic Integrated Devices

We propose a relatively simple experimental setup, capable of accurately characterizing the optical phase response of an integrated photonic circuit. The setup is based on a phase-noise reduction scheme using an external heterodyne Mach-Zehnder interferometer. In particular, we characterize the phase response of different silicon photonic components: under- and over-coupled ring resonators, and a slow-light corrugated waveguide.

Accurate chromatic dispersion characterization of nanophotonic waveguides with thermal phase noise cancellation

We report an experimental technique for accurate characterization of chromatic dispersion and its slope versus wavelength. The system consists of a fiber-based heterodyne Mach-Zehnder interferometer with a counter-propagating beam which is used to cancel the thermal phase noise. Three different silicon-based waveguides are characterized, obtaining a good agreement with theoretical simulations.