Fundamental mode operation in broad area quantum cascade lasers
First Claim
1. A broad area quantum cascade laser for emitting infrared light, comprising:
- an optical cavity comprised of an active region situated between a top cladding and a bottom cladding;
the cavity being fabricated from structure grown by gas source molecular beam epitaxy on an n−
InP(001) substrate;
the active region being fabricated in a plurality of stages, with multilayer GaInAs/AlInAs injector regions in each of the stages;
the top and bottom claddings having a cladding refractive index;
a concave excavation extending into the bottom cladding and having a refractive index less than the cladding refractive index; and
the excavation having a size and shape to suppress high order transverse modes of light in the cavity and favor a fundamental transverse mode, wherebythe laser generates a single-lobed light beam collinear with an optical axis.
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Abstract
A broad area quantum cascade laser subject to having high order transverse optical modes during operation includes a laser cavity at least partially enclosed by walls, and a perturbation in the laser cavity extending from one or more of the walls. The perturbation may have a shape and a size sufficient to suppress high order transverse optical modes during operation of the broad area quantum cascade laser, whereby a fundamental transverse optical mode is selected over the high order transverse optical modes. As a result, the fundamental transverse mode operation in broad-area quantum cascade lasers can be regained, when it could not otherwise be without such a perturbation.
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Citations
19 Claims
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1. A broad area quantum cascade laser for emitting infrared light, comprising:
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an optical cavity comprised of an active region situated between a top cladding and a bottom cladding; the cavity being fabricated from structure grown by gas source molecular beam epitaxy on an n−
InP(001) substrate;the active region being fabricated in a plurality of stages, with multilayer GaInAs/AlInAs injector regions in each of the stages; the top and bottom claddings having a cladding refractive index; a concave excavation extending into the bottom cladding and having a refractive index less than the cladding refractive index; and the excavation having a size and shape to suppress high order transverse modes of light in the cavity and favor a fundamental transverse mode, whereby the laser generates a single-lobed light beam collinear with an optical axis. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A broad area quantum cascade laser for emitting infrared light, comprising:
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an optical cavity formed from a top cladding, a bottom cladding and sidewalls, and including an active region situated between the top cladding and the bottom cladding; a concave excavation extending into the cavity from a sidewall, and having an excavation refractive index; the top and bottom claddings having a cladding refractive index less than the excavation refractive index; the excavation being configured to suppress high order transverse modes of light in the cavity and favor a fundamental transverse mode; the optical cavity being fabricated from structure grown by gas source molecular beam epitaxy on an n−
InP(001) substrate; andthe active region being fabricated in a plurality of stages, with multilayer GaInAs/AlInAs injector regions in each of the stages, whereby the laser emits a single-lobed light beam aligned with an optical axis. - View Dependent Claims (8, 9, 10)
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11. A method for making a broad area quantum cascade laser for emitting infrared light, comprising:
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fabricating an optical cavity from structure grown by gas source molecular beam epitaxy on an n−
InP(001) substrate;fabricating a strain compensated active region in a plurality of stages, with multilayer GaInAs/AlInAs injector regions in each of the stages; fabricating an InP top cladding including an approximately 3 μ
m thick layer with a carrier concentration rising from about 1016/cm3 to 1017/cm3, and an additional approximately 1 μ
m thick layer of n+ InP with a carrier concentration of approximately 1019/cm3;fabricating a bottom cladding; situating the active region between the top cladding and the bottom cladding, wherein the top and bottom claddings have a cladding refractive index; and extending a concave excavation into the bottom cladding;
whereinthe excavation has a refractive index less than the cladding refractive index, and a size and shape to suppress high order transverse modes of light in the optical cavity and favor a fundamental transverse mode, whereby the laser generates a single-lobed light beam collinear with an optical axis. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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Specification