Birefringence-Induced Trains of High-Rate Pulses in a Mode-Locked Fiber Laser

The output of a mode-locked erbium-doped ring fiber laser incorporating a section of a polarization-maintaining (PM) fiber is investigated in both numerical simulations and experiments. With proper inline polarization control, the laser can be set to emit a train of pulses, separated by the differential group delay of the PM section. Repetition rates as high as 500 GHz are experimentally observed. The results provide an added insight into the role of birefringence in mode-locked lasers based on nonlinear polarization rotation

Electro-opto-mechanical radio-frequency oscillator driven by guided acoustic waves in standard single-mode fiber

An opto-electronic radio-frequency oscillator that is based on forward scattering by the guided acoustic modes of a standard single-mode optical fiber is proposed and demonstrated. An optical pump wave is used to stimulate narrowband, resonant guided acoustic modes, which introduce phase modulation to a co-propagating optical probe wave. The phase modulation is converted to an intensity signal at the output of a Sagnac interferometer loop. The intensity waveform is detected, amplified and driven back to modulate the optical pump. Oscillations are achieved at a frequency of 319 MHz, which matches the resonance of the acoustic mode that provides the largest phase modulation of the probe wave. Oscillations at the frequencies of competing acoustic modes are suppressed by at least 40 dB. The linewidth of the acoustic resonance is sufficiently narrow to provide oscillations at a single longitudinal mode of the hybrid cavity. Competing longitudinal modes are suppressed by at least 38 dB as well. Unlike other opto-electronic oscillators, no radio-frequency filtering is required within the hybrid cavity. The frequency of oscillations is entirely determined by the fiber opto-mechanics

Incorporaciones a la prosopografía del archivo de Eanna

This article presents additional prosopographical data from the archive of the Eanna temple of Uruk (southern Babylonia). Most of the data are included in unpublished or little-studied Neo- and Late-Babylonian tablets mostly from the Knopf collection which has been housed until recently at the Claremont Graduate University (California). The pertinent tablets are either published or digested below. In addition, several unpublished tablets from the archive which belong to the Spurlock Museum of the University of Illinois in Urbana-Champaign are also included. This is mainly a prosopography of Eanna’s craftsmen. It completes and modifies previous studies on this subjectEl artículo presenta incorporaciones a los datos prosopográficos del archivo del templo del Eanna de Uruk (Sur de Babilonia). Muchos de los datos están incluidos en tablillas neoasirias y tardobabilónicas sin publicar o poco estudiadas, la mayor parte de ellas de la colección Knopf, que ha sido custodiada hasta hace poco en la Claremont Graduate University (California). Las tablillas correspondientes se publican o meditan a continuación. Además, varias tabillas no publicadas del archivo que pertenecen al Museo Spurlock de la University of Illinois in Urbana-Champaign están incluidas. Se trata principalmente de una prosopografía relativa a los artesanos del Eanna que completa y modifica los estudios previos en esta materi

Distributed opto-mechanical analysis of liquids outside standard fibers coated with polyimide

The analysis of surrounding media has been a long-standing challenge of optical fiber sensors. Measurements are difficult due to the confinement of light to the inner core of standard fibers. Over the last two years, new sensor concepts have enabled the analysis of liquids outside the cladding boundary, where light does not reach. Sensing is based on opto-mechanical, forward stimulated Brillouin scattering interactions between guided light and sound waves. In most previous works, however, the protective polymer coating of the fiber had to be removed first. In this work, we report the opto-mechanical analysis of liquids outside commercially available, standard single-mode fibers with polyimide coating. The polyimide layer provides mechanical protection but can also transmit acoustic waves from the fiber cladding towards outside media. Comprehensive analysis of opto-mechanical coupling in coated fibers that are immersed in liquid is provided. The model shows that forward stimulated Brillouin scattering spectra in coated fibers are more complex than those of bare fibers, and strongly depend on the exact coating diameter and the choice of acoustic mode. Nevertheless, sensing outside coated fibers is demonstrated experimentally. Integrated measurements over 100 meters of fiber clearly distinguish between air, ethanol and water outside polyimide coating. Measured spectra are in close quantitative agreement with the analytic predictions. Further, distributed opto-mechanical time-domain reflectometry mapping of water and ethanol outside coated fiber is reported, with a spatial resolution of 100 meters. The results represent a large step towards practical opto-mechanical fiber sensors

Some Physical Aspects of the Porcine Stress Syndrome

In recent years the number of porcine carcasses which show pale-watery muscle within 3-4 hours after slaughter has increased. Presently, this phenomenon is a serious economic problem in the pork industry. This phenomenon of pale-watery muscle may be encountered in the literature as Porcine Stress Syndrome (PSS) or Pale Soft Exudative Pork (PSEP)