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US 12,586,987 B2Granted
Weak index guiding of interband cascade lasers
AssigneeThe Government of the United States of America, as represented by the Secretary of the Navy
InventorsJerry R. Meyer, Alexander Spott, Chul Soo Kim, Mijin Kim, Chadwick L. Canedy, Charles D. Merritt, William W. Bewley, Igor Vurgaftman
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Abstract
Semiconductor laser architectures that provide weak index guiding of interband cascade lasers (ICLs) processed on a native III-V substrate and of ICLs grown on silicon or integrated on silicon by heterogeneous bonding. Weak index guiding of a ridge waveguide semiconductor laser can enhance the stability of lasing in the fundamental lateral mode, so as to allow a wider ridge to maintain stable single-lateral-mode operation.
Claims21
A weakly index-guided interband cascade laser (ICL), comprising:
- a silicon substrate;
- a high-index layer disposed on an upper surface of the silicon substrate;
- an n+ contact layer disposed on an upper surface of the high-index layer;
- and
- an inner laser ridge disposed on an upper surface of the n+ contact layer, the inner laser ridge comprising:
- a plurality of active ICL stages formed on an upper surface of the n+ contact layer;
- an n-type upper cladding layer formed on an upper surface of the active ICL stages;
- and
- an n+ top contact layer;
- wherein a refractive index of the n-type upper cladding layer is lower than a refractive index of the high-index layer;
- wherein the high-index layer is sufficiently thick that a sufficient fraction of a fundamental lateral optical mode profile lies below an etch depth of the inner laser ridge to impose weak index guiding on at least one predetermined optical mode in the weakly index-guided ICL;
- and
- wherein the inner laser ridge is not so wide that significant lasing occurs in higher-order lateral modes.
10 more elements
A weakly index-guided interband cascade laser (ICL) comprising:
- a Si-based substrate comprising a silicon layer and a high-index separate confinement layer (SCL) formed on top of the silicon layer;
- a III-V gain chip disposed epitaxial-side-down on top of the Si-based substrate, the III-V gain chip comprising:
- a GaSb or InAs substrate;
- an etch-stop layer disposed on an upper surface of the GaSb or InAs substrate;
- a sacrificial layer disposed on an upper surface of the etch-stop layer;
- a first n+ contact layer disposed on an upper surface of the sacrificial layer;
- an n-type cladding layer disposed on an upper surface of the first n+ contact layer;
- a plurality of active ICL stages disposed on an upper surface of the n-type cladding layer;
- and
- a second n+ contact layer;
- a portion of the GaSb or InAs substrate of the III-V gain chip, the etch-stop layer, and the sacrificial layer being removed by a combination of mechanical lapping and chemical etches, followed by etching of an inner laser ridge to a depth near to a bottom or below a bottom of the active ICL stages;
- wherein the active ICL stages have a refractive index higher than a refractive index of the n-type cladding layer;
- wherein the high-index SCL has a refractive index higher than that of the n-type cladding layer of the III-V gain chip and of at least one underlying layer in the Si-based substrate;
- wherein the high-index SCL is sufficiently thick that a sufficient fraction of a fundamental lateral optical mode profile lies below the active ICL stages to impose weak index guiding on at least one predetermined optical mode in the weakly index-guided ICL;
- and
- wherein the inner laser ridge is not so wide that significant lasing occurs in higher-order lateral modes.
13 more elements
A cascade laser comprising:
- a substrate comprising a silicon layer;
- a high-index layer on the silicon layer;
- a first n+ contact layer on the high-index layer, wherein the high-index layer is between the substrate and the first n+ contact layer;
- a laser ridge on the first n+ contact layer, wherein the first n+ contact layer is between the high-index layer and the laser ridge, wherein the first n+ contact layer extends beyond opposite sides of the laser ridge, and wherein the laser ridge includes,
- a plurality of active cascade laser stages on the first n+ contact layer, wherein the first n+ contact layer is between the high-index layer and the plurality of active cascade laser stages,
- an n-type cladding layer on the plurality of active cascade laser stages, wherein the plurality of active cascade laser stages is between the first n+ contact layer and the n-type cladding layer, and wherein a refractive index of the high-index layer is greater than a refractive index of the n-type cladding layer, and
- a second n+ contact layer, wherein the plurality of active cascade laser stages is between the n-type cladding layer and the second n+ contact layer.
4 more elements
Dependencies are inferred from the claim text.