Semiconductor laser amplifiers
AssigneeBritish Telecommunications plc
InventorsWilliam J. Devlin, David M. Cooper, Paul C. Spurdens, Simon Cole, Ian F. Lealman, Joseph J. Isaac
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Abstract
A semiconductor laser amplifier includes both a waveguide layer and an active layer. In use, an optical wave in the active layer interacts with the waveguiding layer to reduce the polarisation sensitivity of the amplifier. A short, thick active layer is not required, typical dimensions being 250 or 500 .mu.m long, by 0.2 .mu.m high. The mesa is typically about 2 .mu.m wide, but may be wider.
Claims21
A semiconductor laser amplifier which does not include a grating, which amplifier comprises:
- an active layer provided by a first epitaxial layer,
- a substantially flat waveguiding layer separated from the active layer and provided by a second epitaxial layer, and
- an input facet and an output facet,
- wherein said waveguiding layer and said active layer each extend to both said facets and are separated from each other by a distance of less than one micron, the arrangement being such that, in use, an optical wave in the active layer interacts with the waveguiding layer to reduce the polarisation sensitivity of the amplifier.
A method of amplifying variable polarisation optical signals, which method comprises:
- supplying optical signals to be amplified to a facet of a semiconductor laser amplifier, the laser amplifier comprising an active layer and a separate substantially flat waveguiding layer which each extend as far as said facet and which are separated by not more than 1 .mu.m, and
- the input optical signals to be amplified impinging on both the waveguiding layer and the active layer at said facet.
A semiconductor laser amplifier having no feedback grating therein and comprising:
- an input facet for receiving optical signals to be amplified;
- an output facet for providing amplified optical signals therefrom;
- an active layer having ends thereof respectively forming parts of said input and output facets of the amplifier;
- and
- an inactive waveguide layer having substantially flat surfaces and having ends thereof also respectively forming parts of said input and output facets of the amplifier;
- said active and waveguide layers being separated but closely disposed between their respective ends sufficient to optically interact and reduce polarisation sensitivity of the amplifier less than 2 dB.
Dependencies are inferred from the claim text.