Wavelength and polarization multiplexed vertical cavity surface emitting lasers
AssigneeXerox Corporation
InventorRobert L. Thornton
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Abstract
The present invention relates to a vertical cavity surface emitting laser device comprising a plurality of semiconductor layers formed upon a substrate and capable of emitting a laser beam of a selected wavelength and a selected polarization, wherein said polarization is established by the presence of stress inducing elements disposed on said free surface of the laser device which induce a stress in the active layers of the laser device. The stress inducing elements are made of a material having a higher coefficient of thermal expansion than the material which comprises the surface layer of the laser device.
Claims16
A vertical-cavity surface-emitting laser device comprising:
- a substrate;
- a plurality of semiconductor layers disposed upon said substrate including
- a first reflector;
- a series of active layers, disposed on said first reflector;
- and
- a second reflector disposed on said active layers, wherein at least one of said first and second reflectors allows transmission of light energy;
- means for defining a laser emitting aperture in said plurality of active layers and for controlling current flowing through said active layers;
- a first electrode disposed on one side of said substrate
- a second electrode disposed on the surface of said plurality of semiconductor layers, whereby said first and second electrodes enable electrical biasing of said active layers;
- and
- stress inducing elements comprising a plurality of parallel stripes of a material having a long dimension and a short dimension disposed on the surface of said plurality of semiconductor layers which impart a selected polarization to a laser beam emitted from said laser device in the direction parallel to said long dimension of said stripe.
A dual-beam vertical-cavity surface emitting laser array comprising a first laser device capable of emitting a laser beam of a first polarization from a free surface thereof and a second laser device capable of emitting a laser beam of a second polarization from a free surface thereof, wherein said polarizations are established by the presence of stress inducing elements disposed on said free surfaces of said laser devices, said stress inducing elements comprising a plurality of parallel stripes and wherein said stripes disposed on the free surface of said first laser device are at a non-zero angle with respect to said stripes disposed on the free surface of said second laser device.
A quad-beam vertical-cavity surface emitting laser array comprising a first laser device capable of emitting a laser beam of a first wavelength and a first polarization from a free surface thereof, a second laser device capable of emitting a laser beam of a second wavelength and a second polarization from a free surface thereof, a third laser device capable of emitting a laser beam of said second wavelength and said first polarization from a free surface thereof, and a fourth laser device capable of emitting a laser beam of said first wavelength and said second polarization from a free surface thereof, wherein said polarizations are established by the presence of stress inducing elements disposed on said free surfaces of said laser devices, said stress inducing elements comprising a plurality of parallel stripes and wherein said stripes disposed on the free surface of said first laser device are orthogonal to said stripes disposed on the free surface of said fourth laser device.
Dependencies are inferred from the claim text.