Abstract: Techniques for driving a directly modulated laser whilst correcting non-linearities an optical output waveform, based on generating a modulating current waveform that approximates an ideal modulating current that produces a linear optical output waveform. The techniques enable useful, practical approximations to the ideal modulating current to be determined.

Abstract: A method and an apparatus are provided for launching light into an entrance facet of a MMF of an optical MMF link in a way that excites one or more targeted higher-order mode groups in the MMF. The light is launched into the entrance facet of the MMF as a line of phase-modulated spots, referred to herein as a “line launch”. The line launch causes one or more targeted higher-order mode groups to be excited in the MMF. The use of the line launch to excite one or more higher-order mode groups in the MMF increases the bandwidth of the link and allows overall link lengths to be increased. In addition, the use of the line launch is reliable and robust despite defects in the MMF and despite connector offsets. Thus, the use of the line launch ensures that a sufficient increase in link bandwidth will be achieved despite the existence of defects in the MMF and even if there is some amount of optical misalignment due to the connector being offset relative to the corresponding receptacle.

Abstract: A fiber optic link is provided that uses a relatively low-cost transceiver that incorporates relatively inexpensive low bandwidth optical and electrical components to achieve high data rate operations. The data rate of the fiber optic link can be greater than the data rate of the laser of the transceiver provided the laser meets certain noise requirements; in particular, the relative intensity noise (RIN) of the laser must be low enough to ensure low bit error rate (BER) operation of the link.

Abstract: A fiber optic link is provided that uses a relatively low-cost transceiver that incorporates relatively inexpensive low bandwidth optical and electrical components to achieve high data rate operations. The data rate of the fiber optic link can be greater than the data rate of the laser of the transceiver provided the laser meets certain noise requirements; in particular, the relative intensity noise (RIN) of the laser must be low enough to ensure low bit error rate (BER) operation of the link.

Abstract: A method and apparatus is provided for connecting an optical source to a multimode optical fibre in a multimode optical fibre communications system. A single mode fibre length is provided such that optical radiation admitted from an optical source at one end of the single mode fibre length is provided to a multimode optical fibre at the other end of the single mode fibre length. This method and apparatus is used in a duplex patchcord for connecting an optical transceiver to a pair of installed multimode fibres. The second fibre in the patchcord is a multimode fibre for passing optical signals to the optical receiver of the transceiver.

Abstract: In a method for encoding payload bits for transmission over communications link, data and control information are assembled into n-bit data words, where n is an even number and words for control information are constrained to have zero disparity (equal numbers of binary zero and one digits). The n-bit data words are then encoded into n+2-bit code words by adding a two-bit label; for words carrying control information the label has a value of 10. For other data words the disparity is evaluated; if it is zero, the label bits are 01; if the disparity is non-zero and opposite in sense to the running digital sum of the code words transmitted already, the label bits are 11; otherwise, the data word is inverted, and the label bits are 00.

Abstract: A method and apparatus is provided for connecting an optical source to a multimode optical fibre in a multimode optical fibre communications system. A single mode fibre length is provided such that optical radiation admitted from an optical source at one end of the single mode fibre length is provided to a multimode optical fibre at the other end of the single mode fibre length. This method and apparatus is used in a duplex patchcord for connecting an optical transceiver to a pair of installed multimode fibres. The second fibre in the patchcord is a multimode fibre for passing optical signals to the optical receiver of the transceiver.

Abstract: A method and apparatus is provided for connecting an optical source to a multimode optical fibre in a multimode optical fibre communications system. A single mode fibre length is provided such that optical radiation admitted from an optical source at one end of the single mode fibre length is provided to a multimode optical fibre at the other end of the single mode fibre length. This method and apparatus is used in a duplex patchcord for connecting an optical transceiver to a pair of installed multimode fibres. The second fibre in the patchcord is a multimode fibre for passing optical signals to the optical receiver of the transceiver.

Abstract: A method and apparatus for increasing the operational bandwidth of a multimode optical fiber communications system is provided. The method comprises launching optical radiation into the core of the multimode fiber away from the center of the core so as to strongly excite mid order modes of the multimode fiber, but to only weakly excite low order and high order modes of the multimode fiber. The mid order modes excited are predominately within a small number of mode groups and thus have similar propagation constants. This leads to a reduction in modal dispersion and thus to a significant increase in bandwidth compared to an overfilled launch. The offset launch of the invention is tolerant both to the launch conditions and to any imperfections in the fiber refractive index profile. Modal noise performance is also enhanced. Embodiments of the invention employ a singlemode fiber, a multimode fiber or a lens to illuminate an end face of a multimode fiber with a small spot offset from the optical axis of the fiber.