RESUMO
LP(01)-LP(02) mode converters based on UV-written intracore gratings have been fabricated for chromatic-dispersion compensation. The mode converters operate in transmission at wavelengths near 150 nm with spectral bandwidths of 14-25 nm and coupling efficiencies of as much as 90%. A large negative dispersion of -335 ps/(nm km) is obtained for a compensator consisting of the mode converter and a 1490-m-long few-mode fiber. The compensator shows negative dispersion over a wavelength region of 5 nm. Its figure of merit is estimated to be 370 ps/(nm dB).
RESUMO
The influence of drawing tension on the formation of Bragg gratings in B-Ge- and Sn-Ge-codoped core fibers is investigated by transmission and stress measurements. With increasing drawing tension, the axial stress is reduced in the B-Ge-codoped core but increased in the Sn-Ge-codoped core. A higher drawing tension leads to a photosensitivity enhancement and an increase of the core stress during the grating formation in B-Ge-codoped fibers. For Sn-Ge-codoped fibers, increased drawing tension results in an UV-induced stress decrease accompanied by a reduction of the photosensitivity. The results are discussed on the basis of an UV-induced compaction of the core network.
RESUMO
It is theoretically demonstrated that a succession of four unchirped gratings, ~20 mm long, induces a negative chromatic dispersion in transmission of -100 ps/nm over a 0.2-nm bandwidth, with a power loss below 1 dB. The stability of the proposed arrangement is also considered and found to be within today's technology.
RESUMO
A strong axial tension increase induced by UV laser radiation is observed in the cores of single-mode optical fibers containing Bragg gratings, independently of the initial core stress. The induced index modulation of the gratings is linearly correlated to stress changes with a slope of (0.8 +/- 0.2) x 10(-4) mm(2)/kg. The phenomenon can be explained by a structural change of the glass in the fiber core into a more compact configuration.
RESUMO
Standard single-mode communication fibers have been characterized with respect to their mode-preservation capability in the dual-mode regime. For a 1300-nm single-mode fiber working at 830 nm, the equivalent h parameter for its LP(01) and LP(11) modes is shown to be as good as that for the best polarization-maintaining fibers, i.e., better than -20 dB-km.
RESUMO
A method is presented that gives the thickness, both the ordinary and the extraordinary refractive indices, and the angle between the c axis and the surface of a thin dielectric film by measuring the effective index of TE and TM propagating modes.
