Semiconductor diode laser having smaller beam divergence
Patent 5170405 Issued on December 8, 1992. Estimated Expiration Date: February 6, 2011. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
A distributed feed back semiconductor diode laser comprising a substrate of n-type conductivity gallium arsenide having a channel along one surface thereof between its end surfaces. A first clad layer of n-type gallium aluminum arsenide is on the surface of the substrate. The first clad layer fills the channel and has a planar surface. A thin active layer of undoped aluminum gallium arsenide is on the first clad layer and a spacer layer of p-type conductivity aluminum gallium arsenide is on the active layer. A grating layer of p-type conductivity aluminum gallium arsenide is on the spacer layer and has a second order grating therein which extends across the channel in the substrate. A second clad layer of p-type conductivity aluminum gallium arsenide is on the grating layer and a cap layer of n-type conductivity gallium arsenide is on the second clad layer. A p-type conductivity contact region extends through the cap layer to the second contact layer and is over the channel in the substrate. Conductive contacts are on the contact region and a second surface of the substrate. The composition and thicknesses of the active layer, spacer layer and grating layer are such as to provide the output beam of the diode laser with a relatively low divergence angle of about 27°.
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