British Telecommunications Public Limited Company

British Telecommunications Corporation

Bt&d Technologies Limited

Colin A Millar

Michael Charles Brierley

Stephen R Mallinson

Timothy J Whitley

Jonathan R Armitage

Stephen A Cassidy

Michael H Hunt

David J Potter

David Talbott

Thomas D Wood

Loudon T Blair

William P Urquhart

Paul Urquhart

Optical sensor/actuator communication system with common control site

A laser has a resonant cavity defined by a pair of mirrors (6, 10) butted to respective ends of a 3 m fluorozirconate optical fibre (14). The fibre (14) has a .DELTA.n of 0.014 and a cut-off wavelength of around 790 nm and is doped to about 500 ppm (weight) with erbium ions. An optical pump source (12) provides a pump signal at 971 nm which excites the erbium ions into the .sup.4 S.sub.3/2 energy level to provide lasing at about 546 nm. The laser may alternatively be pumped by a pump signal in the band 791 nm to 812 nm, preferably 801 nm. The pump source is preferably a high power semiconductor laser (16).

Optical amplifier and laser

Laser and an amplifier

A laser has a resonant cavity defined by a pair of mirrors (6, 10) butted to respective ends of a 3 m fluorozirconate optical fibre (14). The fibre (14) has a .DELTA.n of 0.014 and a cut-off wavelength of around 790 nm and is doped to about 500 ppm (weight) with erbium ions. An optical pump source (12 ) provides a pump signal at 971 nm which excites the erbium ions into the .sup.4 S.sub.3/2 energy level to provide lasing at about 546 nm. The laser may alternatively be pumped by a pump signal in the band 791 nm to 812 nm, preferably 801 nm. The pump source is preferably a high power semiconductor laser (16).

A laser amplifier having an improved pump efficiency for a given pump power comprises a pump source (46) longitudinally coupled at a plurality of coupling points (47, 48, 49) to an optical fibre (41). By thus coupling the pump power into the fibre (41), a fraction of the pump power is applied to the fibre (41) at each of the coupling points (47, 48, 49). A significant improvement in pump efficiency may be achieved in this way.

Laser amplifier

Laser systems

Optical device

Optical coupler

Dielectric optical Fabry-Perot waveguide device and method for making

Cleaving apparatus and method

Features of the endface of a dielectric member are assessed by means of a reflected diffraction pattern. A plurality of light beams 6, 7 which intersect in a region containing the endface 8 can be used to generate a diffraction pattern 10 which subtends an angle of at least 180.degree. at the endface 8. Such a diffraction pattern 10 contains information about the endface 8 and may be used, in particular, to locate the plane in which the endface 8 lies. Embodiments of the invention find particular application in the measurement of endface angles of optical fibres.

Endface assessment

Growing community of inventors

Suffolk, United Kingdom

Colin A Millar