Northern Telecom Limited

Other

Nortel Networks Corporation

Bookham Technology Limited

David M Adams

Douglas James Beckett

Toshihiko Makino

Bruce A Richardson

Jozef Finak

Ian Woods

Paul J Paddon

George K Chik

Robert A Bruce

David Seniuk

Duane Brown

Joan E Haysom

Jean-Paul F Noel

Deck leveling saddle

An optical device, including a monolithically integrated diode laser and semiconductor optical amplifier, that has reduced linewidth and improved side mode suppression for a given output power target. In a preferred embodiment, the diode laser is detuned from a gain peak wavelength to an emission wavelength. The semiconductor optical amplifier has an active region that is bandgap shifted to move its gain peak towards the emission wavelength of the laser diode, thus reducing its linewidth enhancement factor. The diode laser is preferably either a gain-coupled or index-coupled distributed feedback laser. The bandgap shift can be effected by known bandgap shifting methods, such as ion implantation, dielectric cap disordering, and laser induced disordering.

Monolithically integrated high power laser optical device

Groove patterns on substrates coated with photoresist are made using the technique of photolithography by exposing photoresist via a reticle. In the instant invention, the pattern is provided on the reticle with a period larger than the final period to be printed on the photoresist. The complete pattern is obtained by subjecting the photoresist to two or more exposures and aligning the substrate relative to the reticle between exposures. In a further embodiment the slits on the reticle defining the line width of the grooves are larger than required and photoresist is subjected to multiple partial exposure. Both embodiments significantly reduce diffraction caused by the reticle and improve the resolution of the technique.

Methods for making patterns in radiation sensitive polymers

A semiconductor laser device structure comprising an active region provided by a quantum well of an indirect bandgap material, the quantum well being divided laterally to form an active region comprising a two dimensional array of localized cells. Preferably the quantum well of indirect band gap material is selected from group IV semiconductor materials and comprises a silicon-germanium alloy. A silicon/silicon-germanium alloy multi-quantum well (MQW) structure is described. In a preferred embodiment, a Si/SiGe alloy MQW laser diode comprises a coplanar double grating configuration etched through the MQW structure to provide distributed feedback. The double intersecting grating structure functions to define an array of 'cells' or regions of finite dimensions in the quantum well structure which 'localize' carriers within the cells thereby enhancing the radiative emission probability. The grating also provides for combined gain-coupled and index-coupled distributed feedback. The diode structure is preferably designed using a suitable Si/SiGe alloy composition and QW layer thicknesses, to provide for lasing at wavelengths compatible with fiber optic communication applications.

Laser diode and method of fabrication thereof

A Type II heterojunction formed of semiconductor material which normally forms a Type I heterojunction. The Type II heterojunction is created by using a carefully chosen stack of epitaxial semiconductor materials with modifications to the band structure through quantum mechanical confinement effects. This virtual type II heterojunction is incorporated adjacent to the active region in a single-quantum-well, ridge-waveguide laser structure. An anomalous 'Negative-T.sub.o ' region is observed in which threshold current decreases with increasing temperature. A reduction in the temperature sensitivity of the threshold current of the laser structure results.

Semiconductor laser structure for improved stability of the threshold

A method of reducing thermally-induced emission wavelength shift in laser diodes. In addition to the conventional ridge contact for supplying the modulation current to the laser diode a second ridge contact is formed on the device. A compensation current of substantially the same frequency as the modulation current but having an opposite phase is applied to the second contact. This compensation current is selected to substantially neutralize the transient temperature variations due to changes in the modulation signal and result in a generally steady state thermal situation.

Method of reducing the thermally-induced shift in the emission

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Gloucester, Canada

David M Adams