OPTICAL FIBRE Russian patent published in 2011 - IPC G02B6/36 

FIELD: physics.

SUBSTANCE: fibre includes at least: a central part of the core, having maximum refraction index N₁ and external diametre 2a, a depressed part on the periphery of the central part of the core having minimum refraction index N₂ and external diametre 2b, and part of the cladding on the outside of the depressed part, having maximum refraction index N₃. Said refraction indices satisfy the inequality: N₁>N₃>N₂.The relative difference Δ₁ between the refraction index of the central part of the core and that of the said part of the cladding is greater than 1.0%. The relative difference Δ₂ between the refraction index of the depressed part and that of the part of the cladding is less than -0.3%. At wavelength 1.05 mcm, the second derivative β₂ of the propagation coefficient β relative the frequency ω is positive. The third derivative β₃ of the propagation coefficient β relative the frequency ω is negative and the ratio (β₃/β₂) of the third derivative β₃ to the second derivative β₂ is equal to or less than -0.002.

EFFECT: high efficiency of stretching a light pulse with a short fibre and reduction of loss on bends of the fibre.

9 cl, 22 dwg