We report the design, fabrication and characterization of a lead-silicate glass highly nonlinear W-type fiber with a flattened and near-zero dispersion profile in the 1.55 microm region. The fiber was composed of three types of commercial lead silicate glasses. Effectively single-mode guidance was observed in the fiber at 1550 nm. The nonlinear coefficient and the propagation loss at this wavelength were measured to be 820 W(-1)km(-1) and 2.1 dB/m, respectively. Investigations of the Brillouin threshold revealed no evidence of stimulated Brillouin scattering for continuous wave signal powers up to 29 dBm in a 2m sample of the fiber. A broadband dispersion measurement confirmed the near-zero dispersion values and the flat dispersion profile around 1550 nm, in good agreement with our simulations. Efficient four-wave-mixing, tunable across the whole C-band, was demonstrated in a 2.2m length of the fiber.
We review our recent progress in the development of lead silicate glass fibers with high nonlinearity and tailored near-zero dispersion at telecommunication wavelengths, encompassing holey, all-solid microstructured and W-type fiber designs. The fabrication techniques and relative merits of each fiber design are described in detail. The optical properties of the fabricated fibers are assessed both experimentally and through accurate numerical simulations. The significant potential of lead silicate highly nonlinear fibers for all-optical signal processing at telecommunication wavelengths is shown via a number of key experimental demonstrators.
We investigate a novel approach to obtain highly nonlinear fibers with a tailored group velocity dispersion around a desired wavelength region of interest. Rather than exploiting longitudinal holes to control the average refractive index of the cladding and hence the fiber's waveguide dispersion, as in holey fibers, we propose using an all-solid cladding with a suitably chosen refractive index difference relative to the core. We demonstrate numerically that this solution allows a large freedom in the manipulation of the overall fiber dispersive properties, while enabling, in practice, a much more accurate control of the fiber's structural properties during fabrication. Effectively single mode guidance over a broad wavelength range can be achieved through the use of a second outer cladding forming a W-type index profile. We derive simple design rules for dispersion controlled fibers, based on which an algorithm for the automatic dispersion optimization is proposed, implemented and used to design various nonlinear fibers for all-optical processing and supercontinuum generation. Fabrication of a lead silicate fiber with flattened dispersion at telecoms wavelengths confirms the potential of these new fibers.
Abstract:We report on a method to obtain accurate dispersion measurements from spectral-domain low-coherence interferograms, which enables high accuracy (~ps/nm/km), broadband measurements and the determination of very dense (up to 20 points/nm over 500 nm) datasets for both dispersion and dispersion slope. The method exploits a novel phase extraction algorithm which allows the phase associated with each sampling point of the interferogram to be calculated and provides for very accurate results as well as a fast measurement capability, enabling close to real time measurements. The important issue of mitigating the measurement errors due to any residual dispersion of optical elements and to environmental fluctuations was also addressed. We performed systematic measurements on standard fibers which illustrate the accuracy and precision of the technique, and we demonstrated its general applicability to challenging problems by measuring a carefully selected set of fibres: a lead silicate microstructured fiber with a flat, near-zero dispersion profile; a hollow core photonic bandgap fiber with strongly wavelength-dependent dispersion and dispersion slope; a small core, highly birefringent index guiding microstructured fiber, for which polarization resolved measurements over an exceptionally wide (~1000 nm) wavelength interval were obtained.
2013 Optical Society of America
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