Igor Ayesta

Amplified spontaneous emission in graded-index polymer optical fibers: theory and experiment.

In this work we analyze experimentally and theoretically the properties of amplified spontaneous emission (ASE) in a rhodamine-6G-doped graded-index polymer optical fiber. A theoretical model based on the laser rate equations describes the ASE features successfully. The dependence of the ASE threshold and efficiency on fiber length is analyzed in detail.

Computational Analysis of the Power Spectral Shifts and Widths Along Dye-Doped Polymer Optical Fibers

Polymer optical fibers doped with organic dyes can be used as efficient optical amplifiers and lasers in the visible region. We computationally analyze the spectral features of both their fluorescence and their amplified emission for different amounts of overlap between the emission and absorption spectra of the dyes employed. Representative cases are compared by calculating the respective evolutions along the doped fiber of the average wavelength, peak wavelength, and full-width at half-maximum of the output power obtained.

Analysis of the Emission Features in Graded-Index Polymer Optical Fiber Amplifiers

Organic dye-doped polymer optical fiber amplifiers (POFAs) are suitable for achieving high gains in short distances in the visible region. This paper presents a computational analysis of the optimum pump power and signal wavelength as a function of fiber length, numerical aperture, and radial distribution of dopant, for the case of a graded-index POFA doped with rhodamine B.

Laser-Like Performance of Side-Pumped Dye-Doped Polymer Optical Fibers

Mirrorless graded-index polymer optical fibers doped with the organic dye rhodamine 6G result in very compact broadband fiber lasers in the visible region when pumped from the side. The emission spectrum, threshold, and efficiency obtained on both fiber ends depend on the lengths of the directly illuminated region and of the non-excited ones. The paper analyzes such parameters both experimentally and theoretically for the first time.

Optical Characterization of Doped Thermoplastic and Thermosetting Polymer-Optical-Fibers

The emission properties of a graded-index thermoplastic polymer optical fiber and a step-index thermosetting one, both doped with rhodamine 6G, have been studied. The work includes a detailed analysis of the amplified spontaneous emission together with a study of the optical gains and losses of the fibers. The photostability of the emission of both types of fibers has also been investigated. Comparisons between the results of both doped polymer optical fibers are presented and discussed.

Luminescence Study of Polymer Optical Fibers Doped With Conjugated Polymers

The characterization of the spectral emission and of the photostability of polymer optical fibers (POFs) doped with conjugated polymers has been carried out taking into account the distribution of the dopant in the fiber core. Four different conjugated polymers embedded in the matrix of the typical POF material have been analyzed. Measurements include, among others, evolutions of the emission with excitation wavelength and time, spectral changes for different excitation irradiances, and the influence of the propagation distance along the fiber.

Two-Photon-Excited Emission in Polymer Optical Fibers Doped With a Conjugated Polymer

In this paper, the two-photon-excited emission spectra of polymer optical fibers doped with the conjugated polymer Poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) have been measured pumping the fibers transversely to their symmetry axis. Measurements include evolutions of the emission spectra with excitation wavelength and with propagation distance, together with an analysis of emission photostability. Comparisons with results for one-photon-excited emission are also presented and discussed.

Characterization of Chromatic Dispersion and Refractive Index of Polymer Optical Fibers

The chromatic dispersion and the refractive index of poly(methyl methacrylate) polymer optical fibers (POFs) have been characterized in this work by using a tunable femtosecond laser and a Streak Camera. The characterization technique is based on the measurement of the time delays of light pulses propagating along POFs at different wavelengths. Polymer fibers of three different lengths made by two manufacturers have been employed for that purpose, and discrepancies lower than 3% have been obtained in all cases.

Adaption of the Michelson interferometer for a better understanding of the temporal coherence in lasers

In this work, we show a design of a laboratory exercise in which a digital camera has been coupled to a Michelson interferometer based on free-propagation arms. By using the camera, our students measure the evolution of the interference patterns as a function of the difference between the optical paths of the arms. In this way, they obtain the corresponding reduction of the contrast of the fringes. The analysis of the results allows one to calculate the coherence length, and also to relate the temporal coherence of the employed laser with its spectral line profile. The exercise has been carried out with two lasers, which present different coherence lengths.