All-solid highly nonlinear singlemode fibers with a tailored dispersion profile

Abstract

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.

Highly Nonlinear and Dispersion-Flattened Fiber Design for Ultrafast Phase-Sensitive Amplification

“…This fiber has a group velocity dispersion D = 0.14 ps −1 nm −1 km −1 and nonlinear coefficient γ = 1099 W −1 km −1 , respectively at the telecoms wavelength of 1550 nm. Similar dispersion flattened nonlinear fibers have been fabricated recently [24], [25] showing the promise of highly nonlinear soft glass fiber designs for telecommunications applications [26], [27].…”

Dispersion management in soft glass all-solid photonic crystal fibres

“…The nonlinear properties and relatively low losses on the level of single dBs per meter of these fibres were confirmed in several designs [19,20]. In addition, the influence of the cross−section profile geometry on the single−mode operation and high nonlinearity was examined [17]. It is important to mention however, that LLF1 and SF57 glasses are not well suited for the stack− −and−draw technology because of their high crystallization behaviour and are better suited for fibre development using the extrusion processes.…”

“…Several successful exam− ples of the theoretical and practical development of all−solid photonic bandgap fibres with a low index core have also been reported in soft and pure silica glasses [11][12][13][14]. For index guided fibres different cross−section profiles are pro− posed, e. g., hexagonal lattice of microrods [1,12,13,15,16] W−type rings [17][18][19][20] and chirped Bragg−like geometry [21].…”

All-Optical Regeneration of Phase Encoded Signals

“…These glasses have invariably been used in either step-index [70][71][72][73] or photonic crystal fibre [74][75][76] designs, exhibiting up to three orders of magnitude higher nonlinearity than conventional silica singlemode fibres. Tapering of the waist diameter of such fibres has also been used to boost the nonlinear coefficient still further [77,78].…”