British Telecommunications Public Limited Company

The Post Office

E.i. Dupont De Nemours and Company

David R Smith

Peter Paul Smyth

Raymond C Hooper

Brian M MacDonald

Michael Robert Matthews

Michael J Hodgson

Kathleen S Abbott

Brian R White

David H Newman

Alan G Steventon

An optical fiber feedthrough comprising a glass seal for sealing the optical fiber within a metal sleeve. The fiber is held in a fixed position with respect to the sleeve while a glass solder, preferably an annular preform, is heated to its glass transition temperature and then cooled to form a glass to metal seal.

Optical fiber feedthrough

Optical demultiplexer

Optical receivers

A double heterostructure semiconductor laser having the configuration of its optical cavity arranged to impose a constraint on the lasing filament as the spatial distribution of the lasing filament changes from that occuring at the start of the lasing regime, so that the optical flux emitted by the laser has self-saturating properties. This protects the laser from catastrophic facet erosion and enables a simpler control circuit to be used to drive this laser when it is used as a light source for an optical communications system.

Self saturating semiconductor lasers

Apparatus for stabilizing the output characteristics of an injection laser has a device for producing an electrical pulse train representative of an optical pulse train of the laser. The electrical pulse train is fed to circuitry which monitors the switch-on delay of the laser and controls the bias current of the laser such that the switch-on delay is maintained constant. Alternatively the pulse length can be monitored. The pulse amplitude or mean pulse energy can also be monitored and maintained constant.

Injection laser stabilization

Growing community of inventors

Woodbridge, United Kingdom

David R Smith