Raynet Corporation

Pirelli Cavi E Sistemi S.p.a.

Lucjan Sniadower

The present invention relates to an optical fiber telecommunications system and more in particular to an optical telecommunications system having a high loss transmission line. The optical fiber telecommunications system includes a transmission station producing at least one transmission signal in a predetermined wavelength band carrying the information, a receiving station for receiving said transmission optical signal, an optical fiber line connecting the transmission station and the receiving station, and at least one optical fiber amplifier connected along the line for amplifying the transmission optical signal, the amplifier having a total optical output power greater than 20 dBm. The fiber optic amplifier for amplifying a transmission signal including a first stage and a second stage, an isolator placed between the first stage and the second stage where the second stage includes an erbium doped fiber, pump means including two pump sources at different wavelengths in a second stage pump wavelength band, A WDM coupling means coupling the different wavelengths as a composite second stage pump signal, and a coupler coupling the composite second stage pump signal and the transmission optical signal to the erbium doped fiber.

Optical fiber telecommunication system

An optical fiber network includes a single mode silica core/cladding optical fiber having a cutoff wavelength in the range of about 1000-1200 nanometers, and a plurality of optical couplers serially disposed on the optical fiber so as to form a bus network, with each optical coupler injecting its own unique optical signal into the optical fiber so as to be multiplexed in time, each optical signal injected having a dominant light intensity wavelength below the cutoff wavelength of the optical fiber. Each injected signal propagates initially via a plurality of modes. According to the invention the optical couplers are designed or other means are provided for preferentially attenuating all modes in each optical signal above that of the fundamental modes such that an optical receiver at an end of the optical fiber is capable of detecting signals at a data rate so as to result in a bandwidth far in excess of the multimode bandwidth normally associated with such a fiber at the dominant wavelength of the light emitters. An additional advantage is that an intensity of the fundamental mode is enhanced by mode shifting of optical power from the higher order modes of each optical signal initially supported by the optical fiber.

Filtering high order modes of short wavelength signals propagating in

An optical coupler for coupling light between a light emitter and an optical fiber includes a substrate for maintaining a bend in an optical fiber through which light can be coupled between an optical fiber core and the light emitter. The substrate includes a cavity which extends in a direction substantially perpendicular to a plane defined by the fiber bend so as to enable the light emitter to be secured to the substrate to minimize a propagation distance of light to be coupled through the substrate. The light emitter includes first and second substantially spherical lenses, one of which being disposed in the cavity so as to increase optical coupling efficiencies and result in a compact coupler design.

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Paris, France

Lucjan Sniadower