US 5,287,377 A · Coupled quantum well tunable laser

Abstract

The present invention is the use of coupled quantum wells in the active region of a semiconductor laser to modulate the frequency and amplitude of the light output of the laser. In a particular embodiment of the present invention the coupled quantum wells are contained in a graded index of refraction semiconductor double heterostructure laser. The active region of this tunable laser consists of two quantum wells having a width of approximately 50 Angstroms or less which are separated by a barrier layer having a width of approximately 20 Angstroms or less. The quantum well material is intrinsic GaAs and the barrier layer is Al.sub.x Ga.sub.1-x As wherein x=0.23. The active region is surrounded by the double heterostructure in which one side is doped p-type and the second side is doped n-type. The resulting laser is a p-i-n type structure. A reverse bias with respect to the flat band voltage of the p-i-n structure is applied across the p-i-n structure which modulates both the frequency and the intensity of the laser output. The tunable laser is pumped with a variety of conventional means, including both electrical and optical pumping. The modulation of the wavelength is approximately linear over a 1.5 volt operating range. A tunable laser, such as the present invention, having an output wavelength modulated by an electric field is useful in the field of optical communications and computing.

Claims16

Dependent claims

A semiconductor laser for producing light, comprising:

a longitudinal cavity formed by a longitudinal active region interposed between at least two reflective facets formed substantially perpendicular to said longitudinal cavity;
said longitudinal active region consisting of two coplanar quantum well layers forming two quantum wells, said quantum well layers having a thickness of less than approximately 60 Angstroms, and said longitudinal active region having a barrier layer interposed between said quantum well layers, said barrier layer having a thickness of less than approximately 35 Angstroms, said barrier layer being coplanar with said quantum well layers;
said longitudinal active region being interposed between an N-type and a P-type contact layer, said N-type and P-type contact layers creating a built-in electric field substantially perpendicular to said longitudinal active region and corresponding to a built-in voltage, said N-type contact layer being coupled to a first voltage and said P-type contact layer being coupled to a second voltage, said first voltage having a value greater than said second voltage minus said built-in voltage.

A semiconductor laser for producing light, comprising:

a longitudinal cavity formed by a longitudinal active region interposed between at least two reflective facets formed substantially perpendicular to said longitudinal cavity;
said longitudinal active region comprising a plurality of coupled quantum well regions, each of said plurality of coupled quantum well regions consisting of a barrier layer interposed between two quantum well layers;
each of said quantum well layers having a thickness of less than approximately 60 Angstroms, each of said barrier layers having a thickness of less than approximately 35 Angstroms;
and each of said plurality of coupled quantum well regions separated from an adjacent coupled quantum well region by at least one isolation region having a thickness of at least approximately 100 Angstroms;
said longitudinal active region being interposed between an N-type and a P-type contact layer, said N-type and P-type contact layers creating a built-in electric field substantially perpendicular to said longitudinal active region and corresponding to a built-in voltage, said N-type contact layer being coupled to a first voltage and said P-type contact layer being coupled to a second voltage, said first voltage having a value greater than said second voltage minus said built-in voltage.

2 more elements

Dependencies are inferred from the claim text.

Coupled quantum well tunable laser

Life of this patent

Coupled quantum well tunable laser

Life of this patent

Abstract

Claims16