Francisco Prieto

An integrated optical interferometric nanodevice based on silicon technology for biosensor applications

Integrated optical sensors have become important in recent years since they are the only technology which allows the direct detection of biomolecular interactions. Moreover, silicon microelectronics technology allows mass production as well as the fabrication of nano-/macrosystems on the same platform by hybrid integration of sources, sensors, photodetectors and complementary metal-oxide semiconductor electronics.For the fabrication of an optical sensor nanodevice with an integrated Mach–Zehnder interferometric (MZI) configuration, the optical waveguides must have two main features: monomode behaviour and a high surface sensitivity. In this paper we present the development of a MZI sensor based on total internal reflection waveguides with nanometre dimensions. The aim is to use these sensors in environmental control to detect water pollutants by immunoassay techniques.

Second-order polarization mode dispersion: impact on analog and digital transmissions

Second-order polarization mode dispersion (PMD) is a major limitation to the transmission capabilities of analog systems and of high bit rate digital systems. Basically, the effect of second-order PMD is the same as that of chromatic dispersion. However, like all polarization effects in standard single-mode fibers, the effects of second-order PMD are stochastic, due to the random polarization mode coupling that occurs in such fibers. Hence, the effects of second-order PMD fluctuate with time. The purpose of this article is to present a description of the phenomenon and of its effects on analog and digital signals, to propose definitions, to discuss some orders of magnitudes and to present some numerical simulations and experimental results. Some general understanding of the phenomena of first-order PMD are assumed.

Integrated Mach-Zehnder interferometer based on ARROW structures for biosensor applications

Abstract The theoretical design, fabrication and characterisation of an evanescent field integrated optical (IO) sensor based on a rib anti-resonant reflecting optical waveguide (ARROW) structure are presented. The optical waveguides are designed to verify two conditions: mono-mode behaviour and high surface sensitivity. The sensor system is fabricated with ‘silicon microelectronics technology’ and it has been tested as a refractometer with glucose solutions of different refractive indices. The feasibility of applying the sensor for immunosensing is shown with antibody/antigen binding experiments.

Design and analysis of silicon antiresonant reflecting optical waveguides for evanescent field sensor

Silicon based antiresonant reflecting optical waveguides (ARROWs) have been designed in order to obtain a high sensitive optical transducer for sensing applications. The designed sensor has an integrated Mach-Zehnder interferometer configuration. The optical waveguides that form its structure have to verify two conditions: monomode behavior and high surface sensitivity. In this paper, we present a theoretical modeling of the propagation characteristics and surface sensitivity of the ARROW structure.

Optimized silicon antiresonant reflecting optical waveguides for sensing applications

The development of an evanescent field sensor with an integrated Mach-Zehnder interferometric (MZI) configuration requires the fabrication of optical waveguides with two main characteristics: (1) monomode behavior and (2) high surface sensitivity for sensing biomolecular interactions in a direct way (without labels). In this paper, we present an experimental study for the optimization of the different parameters of the waveguides that will be the basis of a highly sensitive optical sensor. After optimization, an MZI sensor has been fabricated and some sensing applications are shown. The designed waveguides are based on antiresonant reflecting optical waveguide (ARROW) structures and are fabricated with standard silicon technology.

Interferometric Biosensors for Environmental Pollution Detection

One important step in the development of biosensors is the design and fabrication of a highly sensitive physical transducer, that is, a device capable of transforming efficiently a chemical or biological reaction into a measurable signal. There are several physical methods to obtain this transducing signal such as those based on amperometric, potentiometric or acoustic systems. However, transducers that make use of optical principles offer more attractive characteristics such as immunity to electromagnetic interference, possible use in aggressive environments and, in general, a higher sensitivity.

Open-Cavity Spun Fiber Raman Lasers with Dual Polarization Output

Random distributed feedback fiber Raman lasers, where the feedback mechanism is provided by Rayleigh backscattering, have attracted a good deal of attention since they were first introduced in 2010. Their simple and flexible design, combined with good lasing efficiency and beam quality properties, comparable to those of standard cavity lasers, have led to multiple applications, particularly in the fields of fiber sensing and optical communications. In spite of these advances, the polarization properties of random fiber Raman lasers, which can strongly affect their performance in both sensing and communications, have barely been explored so far. In this article we experimentally and theoretically study the polarization properties of different open-cavity laser designs, based on either standard transmission fibers or low polarization-mode-dispersion spun fibers. By using high-power, highly-polarized pumps, we demonstrate controllable polarization-pulling and simultaneous lasing at close wavelengths with different output polarization properties in random distributed feedback fiber Raman lasers. These results advance our understanding of the polarization dynamics in ultralong lasers, and pave the way to the design of novel fiber laser sources capable of polarization-sensitive sensing and distributed amplification.

Open-cavity spun fiber Raman lasers with a polarized output

We experimentally study the polarization properties of the outputs of different open-cavity Raman fiber lasers based on spun fiber and a highly polarized pump, demonstrating controlled output polarization and improved threshold.

Applications of a femtocomb laser optically filtered by stimulated Brillouin scattering in an optical fiber

A frequency comb is the optical spectrum formed by a train of optical pulses and comprises a series of equally spaced spectral lines. Ytterbium and Erbium based fiber lasers can produce frequency combs in the region of 1.0 and 1.5 μm respectively. The frequency comb based on an Erbium doped fiber is especially interesting because it emission is centered in the spectral region of optical fiber communications. In this work we use a frequency comb based on an Erbium doped fiber optically filtered by stimulated Brillouin scattering in an optical fiber to generate optical reference frequency in the regions of optical fiber telecommunications and microwaves. The study of the stability of the isolated tooth are performed, resulting two orders of magnitude better than the stability of the pump laser used. This result is the calibration of telecommunication wavelength meters. Also, we analyze some applications based on the Brillouin filtering technique.