We report on a 2.3 m long air-clad ytterbium-doped large-mode-area photonic crystal fiber laser generating up to 80 W output power with a slope efficiency of 78%. Single transverse mode operation is ...achieved with a mode-field area of 350 /spl mu/m/sup 2/. No thermo-optical limitations are observed at the extracted /spl sim/35 W/m, therefore such fibers allow scaling to even higher powers.
We observe that changing the surrounding material from air to a low refractive index polymer can considerably alter the transmission spectrum of a microfiber knot around a given wavelength. We report ...on a silica microfiber knot resonator about 180 m in diameter. Using a supercontinuum source, we study its transmission when air and when a low index polymer are used as cladding. The resonator shows similar extinction ratio and Q-factor for both cladding materials. However, embedding the resonator in the polymer down-shifts the optimal operating wavelength by about 20%.
For development of hollow-core transmission fibers, the realizable fibers lengths, bandwidth, characterization, and compatibility with standard technology are important issues. We report ...record-length air-guiding fiber, spectral properties, splicing, and optical time domain reflectometer (OTDR) measurements. Furthermore, spectral macrobending loss measurements for two different designs of air-core photonic bandgap fibers are presented. While bending loss is observed, it does not limit operation for all practical bending diameters (>5 mm).
We characterize the propagation of infrared light inside a silica glass microfiber laid on a magnesium fluoride substrate, using both numerical simulations and near-field experiments. Propagation ...constants and cut-off diameter are computed by finite-element analysis, while near-field measurements reveal the evanescent tails of the modes. The microfibers display an excellent surface quality since very low scattering levels are measured, and the field distribution is in good agreement with simulations. Finally, dust scattering and coupling structure are investigated.
Hybrid metamaterials comprising split-ring resonator (SRR) structures with different gap dimensions are fabricated on polyethylene naphthalate (PEN) films by parallel laser micro-lens array (MLA) ...lithography and a liftoff process. The unit cell of hybrid metamaterials consists of four SRRs with the same SRR core side length but different gap sizes. The different-gap-size SRRs in each unit cell correspond to different but successive resonance dips, which are coupled to form a significantly broader band with enhanced resonance. The hybrid SRRs design is numerically and experimentally demonstrated, showing a much broader bandwidth to cover all narrowband induced by each SRR and enhanced resonance as compared with a uniform SRR design.
The phenomenon of pulse bunching was analyzed to study the stabilization of modelocking in fibre ring laser. The bunching characteristics of a stretched-pulse dispersion-managed ring laser were ...studied using equally spaced pulses in a simple ring cavity design. The laser output gave pedestal-free sech-profiled pulses bunched with regular spacing in 50 GHz range. It was observed that adjustment of wave plates created new pulses located far apart from the bunch. The autocorrelation results showed that the time position of the new pulse was unstable until it joined the equally spaced pulse train bunch.
We demonstrate a new class of hollow-core Bragg fibers that are composed of concentric cylindrical silica rings separated by nanoscale support bridges. We theoretically predict and experimentally ...observe hollow-core confinement over an octave frequency range. The bandwidth of bandgap guiding in this new class of Bragg fibers exceeds that of other hollow-core fibers reported in the literature. With only three rings of silica cladding layers, these Bragg fibers achieve propagation loss of the order of 1 dB/m.
Nanofibres can be produced with diameters smaller than the wavelength of the light they guide. In this regime, the guided mode presents a strong evanescent field well adapted to the excitation of ...“evanescent nonlinearities”. We theoretically investigate such an evanescent nonlinearity: the Raman interaction between the evanescent field and a liquid surrounding the nanofibre. Our calculations demonstrate that the Raman conversion is obtained with nanofibre lengths an order of magnitude lower than those required for liquid core photonic crystal fibres.
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