If microstructured optical fibers are to find widespread use in photonics technology, they will have to be easily cleavable using mechanical cleavers, since more sophisticated cleaving techniques add complexity. Conventional mechanical cleavers are the preferred laboratory and production tools because they are both simpler to use and more time- and cost-effective compared to techniques such as laser cutting. When designing complex microstructured fibers (MSF) with exciting novel optical characteristics, it is therefore important to favor those geometries that allow high-quality cleavage using standard mechanical cleavers. In this paper, we present an analytical model for fracture propagation during the cleaving process in a complex MSF. The model is based on experimental observations. Three samples of high air-fraction double-clad MSFs were used. Although that they all feature the same structural profiles (but differing in certain geometrical dimensions), they give totally different cleavage patterns. The cleaved surfaces were studied and analyzed. Analysis of the cleaved surfaces allowed to establish a criterion for smooth fracture propagation in a high air-fraction double clad MSF and to suggest a novel design approach for these specific structures.
Agile optical amplifiers must preserve constant gain and flatness over a wide range of input conditions to meet the needs of reconfigurable optical networks. Though routers and switches used to perform system protection or network reconfiguration feature slow transition times, reported theoretical and experimental analyses of the dynamics of agile EDFAs have focused on fast, sub-microsecond input-signal transitions. As a result, only low population inversion, one- or two-stage baseline amplifiers practically provide acceptable transient performance over the entire dynamic and wavelength range of operation. On the other hand, advanced, versatile optical amplifiers, which are highly desirable to perform system-level controls such as gain adjustment or reconfigurable wavelength add-drops at mid-stage, feature large excursions in these input conditions. In this paper, we discuss the line-transient times in view of today's switching technologies and Standards and provide experimental evidence of the suitable performance of advanced agile amplifiers at system switch speeds. The amplifier used is a very high-performance, agile device, which relies on a 3 μs feedback loop. Input transients up to 15 dB were studied, showing excursions smaller than 1 dB and steady-state gain errors no larger than 0.2 dB.
We report on fabrication and characterization of channel waveguide lasers, operating near 1.06 micrometers and made in a commercial neodymium-doped glass using thermal silver ion exchange. The slope efficiency and threshold are measured as a function of waveguide width. The waveguide structure with a 7.5 micrometers width shows the best laser characteristics in terms of threshold and slope efficiency. The emitted wavelength, while close to the peak emission wavelength of the bulk glass at 1.059 micrometers , varies with the waveguide width. This behavior is interpreted in terms of the birefringence and the dichroism of the waveguides.
The progress in fabrication of rare-earth doped glass waveguides using two different techniques, ion exchange in a doped glass and sol-gel processing, is reported. A study of the effect of postbake on the coupling efficiency of the pump beam in silver ion-exchanged waveguides made in a commercially available neodymium-doped silicate glass is presented. Upconversion is reported for the first time in a silver ion-exchanged phosphate glass waveguide. A new ion-exchanged glass fabrication process in conjunction with rare-earth-doped sol-gel layers is proposed.
Experiments on supercontinuum generation in high pressure CO2 (1 - 40 atm) by 1 ps pulses at 593 nm are described. While changing the gas pressure and the laser power we observed self-focusing and optical breakdown in the gas. Their influence on the supercontinuum spectral width evolution is experimentally demonstrated and discussed. Threshold powers for optical breakdown and supercontinuum generation have been measured under different focusing conditions. The relation between these phenomena is analyzed.