Person:
González Cano, Agustín

First Name

Agustín

Last Name

González Cano

URI

https://hdl.handle.net/20.500.14352/79943

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Óptica y Optometría

Department

Óptica

Area

Optica

Identifiers

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Search Results

Now showing 1 - 10 of 20

Generation of Surface Plasmons at Waveguide Surfaces in the Mid-Infrared Region
(Plasmonics, 2012) Díaz Herrera, Natalia; González Cano, Agustín; Esteban Martínez, Óscar; Navarrete Fernández, María Cruz; Mizaikoff, Boris
A technique is proposed to extend the application of surface-plasmon-based spectroscopy into the mid-infrared spectral regime, which is of substantial interest in the field of chemical analysis and biosensing. Surface plasmons can be excited for wavelengths of the order of 6 μm at corrugated waveguides for a given combination of materials and thicknesses, and for refractive indices of the surrounding medium corresponding to those of organic solvents. This approach can easily be extrapolated to other values of any of these parameters. Based on these considerations, a new generation of mid-IR SPR sensors can be developed with a diverse range of potential applications in chem/bio sensing.
Measurement of the degree of salinity of water with a fiber-optic sensor
(Applied Optics, 1999) Esteban Martínez, Óscar; Navarrete Fernández, María Cruz; González Cano, Agustín; Bernabeu Martínez, Eusebio
A fiber-optic sensor based on surface-plasmon resonance for the determination of the refractive index is used for measuring the degree of salinity of water. The transducing element consists of a multilayer structure deposited on a side-polished monomode optical fiber. Measuring the attenuation of the power transmitted by the fiber shows that a linear relation with the refractive index of the outer medium of the structure is obtained. The system is characterized by use of a varying refractive index obtained with a mixture of water and ethylene glycol. Experimental results show that the sensor can be used as a salinity-degree measurement device with environmental applications.
Simple model of compound waveguide structures used as fiber-optic sensors
(Optics and Lassers in Engineering, 2000) Esteban Martínez, Óscar; Navarrete Fernández, María Cruz; González Cano, Agustín; Bernabeu Martínez, Eusebio
In this work we present an application of a simple quasi-geometrical model to analyze the behavior of compound waveguide structures used as fiber-optic sensors. This theoretical model is based on the adjustment of the parameters of the structure from the experimental measures to predict the observed behavior of the device. It also takes into account the non-monocromaticity of the used source. In this way, it can be used as a design criterion for this kind of structures. It is applied to a refractive index fiber-optic sensor based on the excitation of surface plasmon in a metal layer by the light guided by a monomode fiber.
Selectivity of SPR fiber sensors in absorptive media: An experimental evaluation
(Sensors and Actuators B - Chemical, 2011) Navarrete Fernández, María Cruz; Díaz Herrera, Natalia; González Cano, Agustín; Esteban Martínez, Óscar; Leite, Ivo
Conventional surface plasmon resonance (SPR) fiber sensors show selective behavior when resonance wavelengths are tuned to absorption peaks of the surrounding medium, as it is experimentally shown and evaluated in this paper by using a doubly-deposited uniform-waist tapered optical fiber (DLUWT) and a dye as a test material. This behavior is clearly distinguishable from the usual response to nonabsorbing media and can be used to develop a new concept of SPR transducers. At the same time, the obtained results, which are in accordance with the theoretical predictions permit to increase the basic knowledge on surface plasma waves excitation in optical fibers.
Theoretical method for the study of plasmon generation in hybrid multilayer-optical fiber structures
(IEEE Sensors Journal, 2005) Esteban Martínez, Óscar; Navarrete Fernández, María Cruz; González Cano, Agustín
A theoretical method is presented for the determination of the behavior of devices based on the deposition of multilayer structures on polished optical fibers. Plasmon generation in metallic layers is modeled. The method is based on the Rayleigh expansion of the electric fields and permits us to determine their distribution over the whole structure by an application of boundary conditions. Once the distribution is known, the power transmitted by the fiber can be computed as a function of the geometrical and refractive parameters of the device. The method is versatile and can be used as a theoretical tool for the design of devices of that type used for many different purposes. We present real experimental results obtained with an operative sensor that agree with the theoretical predictions of our technique and prove its suitability.
Surface plasmon resonance sensors based on uniform-waist tapered fibers in a reflective configuration
(Applied Optics, 2006) Esteban Martínez, Óscar; Díaz Herrera, Natalia; Navarrete Fernández, María Cruz; González Cano, Agustín
We present a configuration for surface plasmon resonance sensors based on uniform-waist tapered optical fibers and reflective elements. Once the fiber is tapered fulfilling the adiabatic criterion, a multilayer including a metallic medium is asymmetrically deposited on the uniform waist of the fiber. This feature provides the resonant excitation of multiple surface plasma waves. In addition, a mirror is produced at the fiber tip by a chemical Tollens reaction. In this way, the sensor operates in a reflective mode, more convenient for dip probes. When these sensors are spectrally interrogated, a high sensitivity of 10^4 refractive index units per nanometer is attained. These devices can be advantageously used for any kind of chemical sensing and biosensing.
Multiple surface-plasmon resonance in uniform-waist tapered optical fibers with an asymmetric double-layer deposition
(Applied Optics, 2005) González Cano, Agustín; Bueno Guillén, Francisco Javier; Esteban Martínez, Óscar; Díaz Herrera, Natalia; Navarrete Fernández, María Cruz
Novel devices consisting of uniform-waist tapered optical fibers with asymmetric double-layer (metal plus dielectric) depositions have been recently proposed as refractive-index sensors. We study the properties of light transmission by use of this kind of devices, and we specifically perform a detailed study of the generation of surface-plasma waves in the structures. We show that multiple surface plasmons are excited for specific combinations of the constructive parameters of the devices and for specific ranges of the refractive index of the surrounding medium. The behavior also depends on the wavelength and the state of polarization of the incident light. The use of uniform-waist tapers allows for control of constructive parameters and an increase in the interaction length with the outer medium. We show how the plasmons are excited in the region of the taper waist by a coupling with the cladding modes guided in that area. This characterization shows the importance of the presence of a dielectric layer for selection of the operating range of the device. The results are useful for the design of new sensors.
Plasmonic sensor based on tapered optical fibers and magnetic fluids for measuring magnetic fields
(Sensors and actuators A - Physical, 2017) Rodriguez Schwendtner, E.; Díaz Herrera, Natalia; Navarrete Fernández, María Cruz; González Cano, Agustín; Esteban Martínez, Óscar
We present a new sensor based on the combination of Surface Plasmon Resonance (SPR) with magneto-refractive materials. We use doubly-deposited uniform-waist tapered optical fibers (DLUWTs), that have shown their good performance and versatility as refractometers, and magnetic fluids as transducers to measure magnetic fields in an all-optical-fiber configuration. We experimentally show the feasibility of our approach, by demonstrating the physical principle of the device and characterizing the performance of the sensors, which show very good sensitivity and resolution. In this way, we propose a new field of development for SPR optical fiber sensors to extend the field of application of the plasmonics-based technologies.
Surface plasmon resonance in the visible region in sensors based on tapered optical fibers
(Sensors and Actuators B - Chemical, 2014) Navarrete Fernández, María Cruz; Díaz Herrera, Natalia; González Cano, Agustín; Esteban Martínez, Óscar
Doubly deposited uniform-waist tapered optical fibers (DLUWTs) have shown their versatility and good performance as basis for surface plasmon resonance (SPR) sensors for a variety of wavelength ranges. In this work we experimentally show how these devices can be employed to extend the technology of SPR fiber sensors to the visible region, down to about 530 nm, with remarkable results in terms of sensitivity, plasmon definition and the availability of multiple plasmon resonances for each configuration. In this way, DLUWTs can be used to cover a range of more than 1000 nm for aqueous media only by changing the thickness of the deposits. Also, it is shown how these results can be used with the so-called absorption method to make selective the response of the sensors and a study is made on the influence of the taper waist in the performance of the devices. The number of SPR fiber sensors working in the visible region, of great interest in biological research, that have been depicted in the literature is very small, and the sensors that we present here notably improve their performance.
Microfiber as light source for exciting fluorescence in a polymer optical fiber
(Sensors and Actuators B - Chemical, 2016) Rodriguez Schwendtner, E.; Navarrete Fernández, María Cruz; Díaz Herrera, Natalia; Esteban Martínez, Óscar; González Cano, Agustín
We present a new technique for exciting and collecting fluorescence with all-fiber devices, consisting of two different tapered fibers, a microfiber used as illuminating source and a polymer optical fiber where a fluorophore has been deposited and where the fluorescence takes place. We depict the fabrication of the device, characterize its performance and show the feasibility of our approach, the good performance obtained and the possibility of using the flexibility of the illuminating fiber to increase this performance and the compactness of the device.