Bookham Technology Limited

Marconi Caswell Limited

Other

Oclaro Technology Limited

Imec

Universiteit Gent

David James Robbins

Andrew John Ward

William James Stewart

Michael C Wiltshire

Anthony J Holden

John B Pendry

Andrew Cannon Carter

Douglas Charles John Reid

Douglas Reid

Guy Towlson

Peter John Williams

Gert Jaak Anna Sarlet

Gert Jakk Anna Sarlet

The present invention concerns tunable distributed Bragg reflector (DBR) semiconductor lasers, in particular a DBR laser with a branched optical waveguidewithin which a plurality of differently shaped lasing cavities may be formed, and a method of operation of such a laser. The laser may comprise a phase control section (), gain section (), a sampled grating DBR () giving a comb-line spectrum and two tunable, chirped DBRs () for broadband frequency training and a coupling section ().

Tunable laser

A tuneable laser is disclosed, including a gain section with first and second comb reflectors to one side thereof. The two reflectors each provide combs with substantially uniform spacings, the spacings differing as between the combs. Each comb reflector can be tuned so as to shift the reflective peaks of the combs, thus allowing alignment of a single reflective peak at a chosen wavelength which is the same in both combs, forming a supermode. This supermode has an intensity greater than the threshold of the gain section and thus the laser produces an output at that selected wavelength.

Tuneable laser having comb reflectors producing combs of reflective wavelength peaks

A tuneable laser has a gain section bounded at one end by a first reflector in the form of a distributed Bragg reflector adapted to produce a comb of reflective peaks and on the other end by a second Bragg reflector, the second Bragg reflector adapted to reflect at a plurality of wavelengths and being capable of being varied selectively through discrete segments so that one or more segments of the Bragg reflector can be tuned to a lower wavelength to reflect with a segment reflecting at that lower wavelength to enhance the reflectivity at that lower wavelength.

Tuneable laser

A structure which exhibits magnetic properties when it receives electromagnetic radiation is formed from an array of capacitive elements each of which is smaller, and preferably much smaller, than the wavelength of the radiation. Each capacitive element has a low resistance conducting path associated with it and is such that a magnetic component of the received electromagnetic radiation induces an electrical current to flow around the path and through the associated element. The creation of internal magnetic fields generated by the flow of the induced electrical current gives rise to the structure's magnetic properties.

Structure with magnetic properties

The performance of a microwave antenna is improved by incorporating a fine wire dielectric material which has a dielectric constant &isin; of less than unity at microwave frequencies. The effect of the dielectric material is to refract microwaves so that the antenna appears to have a larger aperture than that of its physical size. Furthermore, by selecting the transmission cut off frequency of the dielectric material, two antenna elements which are intended to operate within different frequency bands can be mounted one behind the other.

Antenna arrangements

A multi-wavelength optical reflector comprises a diffraction grating structure ( ) which comprises a plurality of repeat grating units ( ) in which each grating unit ( ) comprises a series of adjacent diffraction gratings ( ) having the same pitch. The grating units ( ) and adjacent gratings within a grating unit are separated by a phase change ( ) of substantially pi (&pgr; radians). The lengths of the gratings ( ), which are different for each grating within a grating unit, are selected so as to provide a predetermined comb reflection spectrum which comprises a plurality of reflection maxima of substantially equal reflectivity.

Multi-wavelength optical reflector

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Towcester, United Kingdom

David James Robbins