Juan Carlos Martin

University of Zaragoza | UNIZAR · Department of Applied Physics

The design and fabrication of a integrated symmetric directional coupler dependent o the pumping power and operating at a 1534 nm wavelength is reported. The twin-core waveguide was inscribed into Er3+/Yb3+ co-doped phosphate glass by a femtosecond laser direct writing technique. By optical pumping, the coupling ratio can be modulated due to the ch...

A method based on the photographic recording of the power distribution laterally diffused by cationic-network (CN) hydrogel waveguides is first checked against the well-established cut-back method and then used to determine the different contributions to optical power attenuation along the hydrogel-based waveguide. Absorption and scattering loss co...

Modal decomposition of light is essential to study propagation properties of waveguides and photonic devices. Modal analysis can be carried out by implementing a computer generated hologram acting as a match filter in a spatial light modulator. In this work, a series of aspects to be taken into account in order to get the most out of this method ar...

A method based on the photographic recording of the power distribution laterally diffused by cationic electroactive network (CN)-based hydrogel waveguides is first checked against the well-established cut-back method and then used to determine the different contributions to the optical power attenuation along the hydrogel-based waveguide. Absorptio...

We present a modal analysis of coupled two-core integrated waveguides fabricated by femtosecond laser writing as a function of the core-to-core distance, illuminating position and input light wavelength. In order to do that we use the correlation filter method, implementing the computer generated holograms in a phase-only spatial light modulator. D...

Modal decomposition of light is essential to study its propagation properties in waveguides and photonic devices. Modal analysis can be carried out by implementing a computer-generated hologram acting as a match filter in a spatial light modulator. In this work, a series of aspects to be taken into account in order to get the most out of this metho...

The output signal intensity distribution of several fs-laser written double-core active waveguides was registered. The ratio between cores output powers exhibited a strong dependence on the input pump power when both input pump and signal powers were directly coupled to one of the cores. A model based on the coupled-mode theory which incorporates n...

A method to calculate the optical transmission evolution of a ferrofluid after exposure to an external magnetic field is proposed. In the first part of this work, a simulation program is employed to simulate the nanoparticle rearrangement for different particle concentrations and different magnetic field intensities. In the second part, the simulat...

A new methodology to completely characterize active multicore waveguides is proposed. The method is applied to two-core waveguides written in an Er <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> /Yb <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"...

The influence of temperature on the ferrofluid magneto-optical response after magnetic field commutation is studied. Its contribution to the diffusion and mobility of the ferrofluid nanoparticles is considered by means of thermal agitation and the temperature-dependent viscosity of the fluid. Experimental responses after magnetic field switch on an...

The magneto-optical response in ferrofluids depends significantly on the orientation and intensity of an applied magnetic field. However, such essential dependence is far from being properly described by a model based on fundamental laws. In this work, the model proposed by Elmore as an extension of the Langevin theory of a paramagnetic gas is chec...

Optical transmission changes in ferrofluids when exposed to magnetic fields are difficult to predict: under similar conditions, exposure to a magnetic field may cause increasing, decreasing or even non monotonous optical transmission evolution in different samples. Absence or presence of coalescence has been conjectured as the key phenomenon that c...

A numerical method to simulate the ferrofluid particle distribution evolution is presented. Also, the optical transmission of the distributions obtained is calculated by two numerical methods. The first one consists on a numerical propagation of an electromagnetic wave through the sample. The second one analyzes the aggregates’ mean length to obtai...

This study includes the experimental both passive and active characterization of multicore waveguides written in phosphate glass codoped with erbium and ytterbium, with the aim of designing and optimizing photonic devices based on this type of structures.

Using a previously validated characterization method based on the careful measurement of the characteristic parameters and fluorescence emission spectra of a highly Yb-doped double-clad fibre, we evaluate the contribution of ion pair induced processes to the output power of a double-clad Yb-doped fibre ring laser. This contribution is proved to be...

Evolution of the optical transmission of a ferrofluid after magnetic field commutation is analyzed by means of an approach based on the so-called mixture laws: expressions which predict the effective permittivity of heterogeneous media as a function of their constituents' permittivities, their proportions and the way they are arranged. In particula...

We demonstrate a new scheme for realizing the Optical Bistability (OB) in an erbium-doped-fiber laser with an external control laser. It is found that the OB can be significantly modified by changing the power and the wavelength of the control laser. We give an explanation of the bistability phenomenon based on numerical simulations, which are agre...

The performance of a fiber-based modal interferometer as lateral stress sensor has been analyzed, both for static and periodic forces applied on it. The central fiber of the interferometer is a photonic crystal fiber. Forces are applied on it perpendicular to its axis, so that they squeeze it. In static situations, changes in the transmission spect...

We demonstrate a new scheme for realizing the Optical Bistability (OB) inside an all-fiber ring cavity with an external control field. In the absence of the external control field, the pump power is fixed below the threshold value of laser, and there is no laser in the cavity. However, when the control signal of 1505 nm to 1520 nm is injected into...

Las estructuras multinúcleo integradas son buenas candidatas para mejorar las prestaciones de los dispositivos ópticos activos [1]. Estamos trabajando en la caracterización de estas estructuras fabricadas mediante escritura por láser de femtosegundo [2]. Se presentan las dos técnicas de caracterización modal implementadas por nuestro grupo.

The performance of water-filled suspended-core fibers as key components of interferometric temperature sensors has been analyzed. Use of water is motivated by simplicity of use and by its thermo-optic and thermal expansion coefficients, which provide a good balance between sensitivity and wide temperature range (limited by the free spectral range o...

A characterization method based on the careful measurement of the characteristic parameters and fluorescence emission spectra of a highly Yb-doped double-clad fiber is presented. The method is successfully checked by numerically fitting experimental results of a ring laser based on highly doped double-clad Yb-doped silica fibers with different dopa...

Analizamos los interferómetros modales basados en fibra de cristal fotónico como sensores de presión. Bajo presión estática observamos cambios en la transmisión del interferómetro, con sensibilidad de ~0.2% por g/cm y comportamiento lineal para cargas inferiores a 30-40 g. Para presiones oscilantes el sistema muestra buena linealidad y comportamien...

A sine-wave-modulated erbium-doped-fiber laser with an external signal coupled into its cavity has been studied. In particular, an analysis on how the time-dependent laser emission changes as a function of the external signal power has been conducted. Under appropriate working conditions, different bistable behaviors have been found. In some cases,...

Application to a chaotic erbium-doped fiber laser of the digital encoding technique by control of its emitted symbolic dynamics is numerically tested. Criteria to select the better working conditions and the perturbation to be introduced in any control parameter are proposed. Once they are chosen, the procedure to prepare the system for control and...

The dynamic response after pump switch-on of a 980 nm pumped-ring laser based on an active photonic crystal fiber with an Er3+ ion concentration of ≈1020 ions cm−3 was registered. Then a numerical fitting procedure of a theoretical model was followed to the experimental values of the relaxation oscillation parameters as a function of the input pump...

We report on an experimental/numerical investigation into the use of methanol-filled Er-doped suspended-core fibres (SCFs) in temperature-sensing ring laser systems. We have adopted a ring laser configuration that includes an Er-doped SCF as a temperature-dependent attenuator (TDA) with a step-index Er-doped fibre (EDF) as the laser active medium....

Topological analysis is employed for the first time to our knowledge as a method of validation for a physical model describing a chaotic system. Topological analysis theory provides both a way to characterize the topological structure of chaotic attractors by means of a set of integer numbers and a method to obtain this set departing from a time se...

We report on a comparison of characterization techniques for high concentration erbium-doped photonic crystal fibres (PCFs). A highly erbium-doped-silica PCF was fabricated and an amplifier based on the PCF was built. Then, measurements on the amplifier output optical powers were carried out. To model the amplifier, three different formalisms were...

In this paper a simple theoretical model is presented where the energy conservation principle is used. The model is based on semi-analytical equations describing the behaviour of an erbium-doped photonic crystal fibre (PCF) inside a ring laser. These semi-analytical equations allow the characterisation of the erbium-doped PCF. Spectral absorption a...

An erbium-doped photonic crystal fiber laser has been designed, constructed and characterized in order to examine the feasibility of this kind of devices for secure communications applications based on two identical chaotic lasers. Inclusion of a tailored photonic crystal fiber as active medium improves considerably the security of the device becau...

Two erbium-doped fibre ring lasers are subject to different sine-wave pump modulation conditions, so that each of them may present periodic or chaotic response. For each working condition, the response of both lasers is analyzed for different coupling factors of their cavities. Many possible situations are found: as the coupling factor is swept fro...

We analyze the chaotic emission of an erbium-doped fiber laser with sine-wave pump power modulation for different modulation frequencies and modulation indexes. For each working condition considered, the template which summarizes the corresponding chaotic attractor has been determined by means of topological analysis techniques. The variety of temp...

We present a simplified treatment of templates used to summarize the topological properties of chaotic attractors bounded by a genus-1 torus. The reduction is based on determinism and flow continuity, which impose tight relations between torsions of each branch, rotations between pairs of branches and the order in which they join at the branch line...

We present experimental and numerical results of the correlation between the chaotic emissions of two coupled erbium-doped fibre ring lasers whose pump powers are modulated with a sine-wave signal. Experimentally, it is observed that correlation does not increase monotonously as the coupling becomes stronger: for certain intermediate coupling condi...

Time series obtained from the emission of an erbium-doped fiber ring laser with sine-wave pump modulation have been analyzed in order to determine the topological structure of the underlying chaotic attractor. With appropriate modulation conditions, topological structures not often observed in experimental systems have been found: the reverse horse...

We studied the erbium-doped fiber laser transient behavior dependence on the pump polarization state or on the cavity polarization eigenvalues. Several series of measurements are shown in which the changes in the transient laser response can be appreciated as the pump polarization state, or the cavity polarization eigenvalues are modified by means...

The transient of an erbium-doped fiber ring laser coupled to another one receiving CW pump power is studied. The transient signals experimentally obtained may present different profiles depending on several conditions (degree of coupling between both lasers, pump powers of each one, etc.). In particular, an appropriate choice of working conditions...

We study a characterization method for the active mean of an erbium-doped fibre laser in ring configuration. The method is based on a previously developed model and in the measurement of several laser transient characteristic magnitudes. We describe both the experimental setup and the procedure to be followed in order to obtain the doped fibre abso...

A numerical model of an erbium doped fibre laser (EDFL) is applied to the description of the system dynamic behaviour. In particular, the transient and steady regimes after pump power switch-on are analysed, studying the spatial and temporal evolution of the main parameters of the system. With this information, the applicability of the usual hypoth...

An analytical procedure is employed to account for the response of an erbium-doped fiber ring laser whose pump power is sinusoidally modulated. The approximations considered, only strictly valid for very low modulation indexes (of the order of some hundredths), reveal the origin of some relationships between resonances of the main harmonics present...

The dynamic behavior of the polarization eigenmodes in a ring erbium-doped fiber laser is experimentally studied as a function of the input pump polarization. It is found that the coupling factor between eigenmodes can be modified by choosing the pump polarization and, under pump sinusoidal modulation, it is shown how the antiphase dynamics changes...

In this article several characterization techniques developed by the authors for erbium-doped fibers and integrated waveguides are discussed. These techniques are used to obtain the input parameters in the theoretical models that have been developed, too. In this way optical amplifiers and lasers are studied and optimized for different applications...

A dielectric study is proposed in order to describe the behaviour of a composite polymer conductor such as the combination polypropylene-carbon black, as a function of the charge volume fraction in the range from direct current to 5 GHz by time domain reflectometry (TDR). A mixture law generalization leads to the dielectric characterization of the...

An EDF characterisation method, based on laser transient behaviour, is applied to 980 and 1480 nm pumped ring tunable fibre lasers. Absorption and emission coefficients at both, pump and laser frequencies, along the 1521–1561 nm spectral range, are obtained, as well as dopant concentration. Obtained parameters are introduced in EDF amplifier (EDFA)...

A simple mathematical function is introduced to describe a wide assortment of dopant profiles and study its influence on an erbium-doped fiber performance. Significant gain differences are observed in active fibers similar in every respect save for their erbium transversal distributions (ETD). It is found that a well-known overlapping parameter tur...

A new, simple EDF characterization method is presented. Departing from well-known equations, some approximations, applicable in WDM working conditions, are introduced. Thanks to them, the number of active parameters necessary to describe the EDF behaviour is sensibly reduced. Afterwards, a simple experiment to find such parameters is proposed. Fina...

A new, simple EDF characterization method is presented. Departing from well-known equations, some approximations, applicable in WDM working conditions, are introduced. Thanks to them, the number of active parameters necessary to describe the EDF behaviour is sensibly reduced. Afterwards, a simple experiment to find such parameters is proposed. Fina...

A procedure to extract spectroscopic information from erbium doped fibres (EDF), based on transient laser behaviour analysis, is presented. It achieves a complete characterisation of EDF on wavelengths corresponding to pump and laser emission, obtaining respective absorption and emission coefficients. In addition, it allows Co perform predictions o...

A comparison between theoretical and experimental results of gain and ASE obtained with erbium-doped fibers (EDFs) pumped at 980 nm is presented. Parameters used for the calculations were deduced from a completely different experiment based on the study of fluorescence dynamics. The deduced parameters are not only the emission coefficents (equivale...

The capacity of the erbium-doped fibre models to predict output signal and amplified spontaneous emission power in time-dependent situations is studied. In the initial stage, we demonstrate the usefulness of a model based on overlapping factors for time-dependent calculations, which allow one to save computation time, apart from other advantages. I...

A technique for erbium-doped fiber characterization is presented. Its foundation lies in the study of the transversal and copropagating fluorescence time evolution when pumping is switched on and off. A model that describes these phenomena is developed, and experimental results, in good agreement with the model, are shown. The stimulated emission c...

The accuracy in the measurement of gain and amplified spontaneous emission in an erbium-doped fibre amplifier is studied, when optical spectrum analysis combined with signal modulation and electrical signal analysis by a lock-in amplifier are used. This study has been made by computer simulation in the framework of the European project COST 241. Th...

Two fiber-based resonators are studied. Their properties of light confinement are examined as a function of their couplers' parameters. Conditions for optimum performance of these devices as frequency filters or as laser resonators for a given pump wavelength are found.