Romeo Selvas-Aguilar

Compact high-energy Q-switched cladding-pumped fiber laser with a tuning range over 40 nm

We describe a compact Q-switched diode pumped double-clad ytterbium-doped fiber laser. The fiber laser was bidirectionally pumped by two laser diodes (2 W of output power each) via two side-injecting pump-couplers. We used a large multimode core of 15 /spl mu/m diameter to increase the laser gain volume and thus to achieve higher pulse energy. Experimentally this laser produced pulses with energy up to 170 /spl mu/J with a peak power of 2 kW (at a low repetition rate of 500 Hz) and was tunable from 1060 to 1100 nm.

Single-polarization narrow-linewidth wavelength-tunable high-power diode-pumped double-clad ytterbium-doped fiber laser

Cladding-pumped ytterbium-doped fiber lasers operating in the wavelength region 1–1.1 µm offer a superior combination of high output power and wall-plug efficiency as well as reliability and compactness, and have consequently seen a rapid commercial development [1].

Novel optical mux-demux module for fiber-optic communication applications

We demonstrated a novel design for a multi channel optical MUX/DEMUX module, which uses the principle of a Cassegrain-telescope. We carried out some optical simulations to show the feasibility to build up a multiplexer or de-multiplexer module for Dense Wavelength Division Multiplexing (4 channels). The set-up consists of a concave mirror that receives different beams which are then focused at the centre. For the case of a MUX-module, different radial positions enable injecting the system different wavelength inputs as the concave mirrors concentrates all the beams in one point (collector fibre). Moreover, for the case of a DEMUX-module, a bulk grating is positioned at one point between the concave mirror and the focal point of it, and when a stream of pulses with different wavelengths reaches this point, it automatically distributes the incoming signal in different radial positions (several collector fibers).

Intracavity absorption gas sensor in the near-infrared region by using a tunable erbium-doped fiber laser based on a Hi-Bi FOLM

We report an experimental study erbium-doped fiber laser for gas pressure detection in the L-band wavelength region by laser intracavity absorption spectroscopy. By using a high-birefringence fiber optical loop mirror as spectral filter within the ring cavity laser, the wavelength of the generated laser line is finely selected and tuned in a range of ~10 nm in order to select the wavelength where the gas absorption line is exhibited. Experimental results for detection of CO2 pressure with absorption at 1573.2 nm are shown and discussed. The proposed fiber laser sensor exhibits reliability and stability for gas detection with absorption in the L-band such as CO2, CO, and H2S.

Novel photonics devices for optical communications systems

In this work, we propose a set of photonics devices that can be employed as part of optical communications systems. These devices consist of an isolator, a circulator, a multiplexer and a pump concentrator, and are based on the functionality of an optical paraboloidal mirror. The devices were first studied using software for optical modeling and then were experimentally tested. For the cases of the isolator and the circulator, we obtained numerically roughly 50 dB of isolation. Furthermore, we proposed a simple and a novel multi channel multiplexing device, and finally, we asses the alternative and elegant way of the combination of high power multimode diode laser to increase the power capability of diode laser systems that are commonly used in high power fiber laser. In all the cases, the design showed the advantage of the easiness of alignment and the simplicity to implement.

Second harmonic generation in a ppln crystal pumped by an ytterbium doped fiber laser

We report the second-harmonic generation of light using a periodically poled lithium niobate (PPLN) crystal pumped by a diode-pumped, broadband Yb-doped fibre laser. Generation of visible (green) continuous-wave radiation around 545 nm is demonstrated by the second harmonic generation of a free-running high efficient Yb-doped cladding-pumped fibre laser. The output power handling and conversion efficiency are also reported.

Modeling and optimization of the coupling efficiency for double-clad fiber

In this work, we simulate the efficiency of optical power transfer between a 915 nm diode laser, and a double-clad fiber optic. A lenses array allows collimating and focusing the pump energy to the fiber. This model was made using the optical design software OSLO. The result shows a high coupling efficiency of roughly 84%, which can increase the optical input power in fiber optics lasers.

Bistability, chirping, and switching in a nonlinear and partially nonlinear photonics crystal

The study of nonlinear photonics crystals is quite complex and cumbersome, because of their inherent architectural complexity and, in addition, because of the nonlinearity that couples propagating and counterpropagating waves. However, they are quite attractive because of their potential capabilities, and that has lead to use different approximated methods. In a one dimensional stack, it has been successfully demonstrated that they show switching, bistability and chirping as nonlinear characteristics. Band gap solitons are a well established feature of the coupled wave equations. We have extended a method that have previously shown its success for a stack with a Kerr nonlinearity, to a much more complex structure such as an omniguide fiber, as part of our suggestion that such method could be applied to numerical or analytical methods as long as the linear solution were available. Such a restriction, hinder our ability of getting analytical solution beyond their enabling approximations, however, it is completely adequate for the purpose of to develop devices. A comparative numerical analysis of a one dimensional photonic crystal and an omniguide fiber, made of a dielectric and stratified linear and nonlinear media, has been carried out. They were considered as multilayer arrangements with a finite numbers of periods: linear-linear, nonlinear-linear and nonlinear- nonlinear in order to study and isolate those features. Finally, a comparison of multilayer systems with variations in the diffraction indexes profiles is presented.

Superfluorescence three-level neodymium-doped fiber source

We report on a new type of cladding-pumped neodymium-doped fiber which enables strong ASE emission at the wavelength region of 940 nm with a highly reduced emission in the four-level transition at 1060 nm when is pumped by an 806 nm source. This ASE source delivers a total emission power of 60 mW from 500 mW of absorbed pump power. The arrangement setup consisted in a pump diode emitting at 806 nm with a total output power of 1.5 W, a collimated and focused lenses and a dichroic mirror. The broadband of the neodymium source was measured to be 25 nm. Moreover, a numerical simulation for the ASE source is also discussed.

Scattered data beam analyzer

We provide an analysis of a data beam fitting method of N data points on a circular pupil that corresponds to its best rms fit that uses an orthogonal vectorial basis of the N data points. The solutions of many physical problems often result on finding specific solutions of basic functions Fnl(ρ,θ) with polar symmetries that also can be easily treated numerically. Unfortunately, in some other cases, the analytical solution loss its orthogonality by the experimental data discretization, therefore become inadequate for a best rms fit data. On the other hand, by introducing the Schmidt orthogonalization, we can get the best rms fit for the solution in the coefficients of the expansion and in Fnl(ρ,θ). In these cases, where the Fnl(ρ,θ) has a cumbersome convergence, we develop the rms fit based on Zernike like Polynomials and establish the proper transformation. We illustrate in more detail the method by developing a beam analyzer as an application.