An electrically pumped photonic-crystal surface-emitting laser, the epitaxy structure has a first mesa, the first mesa has multiple air holes and forming a photonic crystal structure, the epitaxy structure further has a second mesa, the second mesa and photonic crystal structure is facing the same direction; a first metal electrode arranged on the insulating layer, and covering the photonic crystal structure; a second metal electrode arranged on the second mesa and protruding out of the groove, making the first metal electrode and the second metal electrode face the same direction; and further make the first metal electrode connect to the first connecting metal and make the second metal electrode connect to the second connecting metal for making the photonic crystal structure become flip chip.

Semiconductor Quantum Cascade Lasers (QCLs), in particular mid-IR lasers emitting at wavelengths of about 3-50 μm, are often designed as deep etched buried heterostructure QCLs. The buried heterostructure configuration is favored since the high thermal conductivity of the burying layers, usually of InP, and the low losses guarantee devices high power and high performance. However, if such QCLs are designed for and operated at short wavelengths, a severe disadvantage shows up: the high electric field necessary for such operation drives the operating current partly inside the insulating burying layer. This reduces the current injected into the active region and produces thermal losses, thus degrading performance of the QCL. The invention solves this problem by providing, within the burying layers, effectively designed current blocking or quantum barriers of, e.g. AIAs, InAIAs, InGaAs, InGaAsP, or InGaSb, sandwiched between the usual InP or other burying layers, intrinsic or Fe-doped. These quantum barriers reduce the described negative effect greatly and controllably, resulting in a QCL operating effectively also at short wavelengths and/or in high electric fields.

A quantum cascade laser includes a substrate including first and second regions arranged along a first axis; a stacked semiconductor layer disposed in the second region, the stacked semiconductor layer having an end facet located on a boundary between the first and second regions, the stacked semiconductor layer including a core layer and a cladding layer that are exposed at the end facet thereof; and a distributed Bragg reflection structure disposed in the first region, the distributed Bragg reflection structure including a semiconductor wall and a covering semiconductor wall that covers the end facet of the stacked semiconductor layer. The semiconductor wall and the covering semiconductor wall are made of a single semiconductor material. The semiconductor wall has first and second side surfaces. The covering semiconductor wall has an end facet that is located away from the first and second side surfaces of the semiconductor wall.

Provided is a light-emitting device that includes a first electrode layer, a first conduction type layer, a second conduction type layer, an active layer, and a second electrode layer. The first conduction type layer includes a current injection region formed by the first electrode layer and a current non-injection region. A waveguide structure included in the first conduction type layer, the active layer, and the second conduction type layer includes a first region and a second region. The first region has a first waveguide that is the current injection region and the current non-injection region and has a first refractive index difference. The second region has a second waveguide arranged to be extended from the first waveguide to the first end and has a second refractive index difference greater than the first refractive index difference. The second waveguide has a region narrowing toward the first end.

An electrically pumped photonic-crystal surface-emitting laser, the epitaxy structure has a first mesa, the first mesa has multiple air holes and forming a photonic crystal structure, the epitaxy structure further has a second mesa, the second mesa and photonic crystal structure is facing the same direction; a first metal electrode arranged on the insulating layer, and covering the photonic crystal structure; a second metal electrode arranged on the second mesa and protruding out of the groove, making the first metal electrode and the second metal electrode face the same direction; and further make the first metal electrode connect to the first connecting metal and make the second metal electrode connect to the second connecting metal for making the photonic crystal structure become flip chip.

In a semiconductor laser device, a n-type cladding layer, a multi-quantum well active layer, and a p-type cladding layer are sequentially laminated on an n-type substrate, and a stripe structure is provided on this semiconductor laminated section. The n-type cladding layer has a first n-type cladding layer configured of Al.sub.x1Ga.sub.1-x1As (0.4<x11), and a second n-type cladding layer configured of (Al.sub.x2Ga.sub.1-x2).sub.1-y2In.sub.y2P (0x21, 0.45y20.55). The p-type cladding layer is configured of (Al.sub.x3Ga.sub.1-x3).sub.1-y3In.sub.y3P (0x31, 0.45y30.55). The width of the stripe structure is 10 m or more, and the refractive index with respect to the laser oscillation wavelength of the first n-type cladding layer is less than or equal to the refractive index with respect to the laser oscillation wavelength of the second n-type cladding layer.

Semiconductor Quantum Cascade Lasers (QCLs), in particular mid-IR lasers emitting at wavelengths of about 3-50 m, are often designed as deep etched buried heterostructure QCLs. The buried heterostructure configuration is favored since the high thermal conductivity of the burying layers, usually of InP, and the low losses guarantee devices high power and high performance. However, if such QCLs are designed for and operated at short wavelengths, a severe disadvantage shows up: the high electric field necessary for such operation drives the operating current partly inside the insulating burying layer. This reduces the current injected into the active region and produces thermal losses, thus degrading performance of the QCL. The invention solves this problem by providing, within the burying layers, effectively designed current blocking or quantum barriers of, e.g. AIAs, InAIAs, InGaAs, InGaAsP, or InGaSb, sandwiched between the usual InP or other burying layers, intrinsic or Fe-doped. These quantum barriers reduce the described negative effect greatly and controllably, resulting in a QCL operating effectively also at short wavelengths and/or in high electric fields.

In a semiconductor laser device, a n-type cladding layer, a multi-quantum well active layer, and a p-type cladding layer are sequentially laminated on an n-type substrate, and a stripe structure is provided on this semiconductor laminated section. The n-type cladding layer has a first n-type cladding layer configured of Al.sub.x1Ga.sub.1-x1As (0.4<x11), and a second n-type cladding layer configured of (Al.sub.x2Ga.sub.1-x2).sub.1-y2In.sub.y2P (0x21, 0.45y20.55). The p-type cladding layer is configured of (Al.sub.x3Ga.sub.1-x3).sub.1-y3In.sub.y3P (0x31, 0.45y30.55). The width of the stripe structure is 10 m or more, and the refractive index with respect to the laser oscillation wavelength of the first n-type cladding layer is less than or equal to the refractive index with respect to the laser oscillation wavelength of the second n-type cladding layer.

[Object] To provide a light-emitting device and a display apparatus that high-output can be achieved without enlarging a light confinement width, i.e., without enlarging a beam spot size. [Solving Means] A light-emitting device includes a first electrode layer, a first conduction type layer, a second conduction type layer, an active layer, and second electrode layer. The first conduction type layer includes a current injection region formed by the first electrode layer and a current non-injection region. A waveguide structure included in the first conduction type layer, the active layer, and the second conduction type layer includes a first region and a second region. The first region has a first waveguide that is the current injection region and the current non-injection region and has a first refractive index difference. The second region has a second waveguide arranged to be extended from the first waveguide to the first end and has a second refractive index difference greater than the first refractive index difference. The second waveguide has a region narrowing toward the first end.

A heterogenous device includes a passive waveguide structure and an active waveguide structure. The passive waveguide structure is attached to a substrate and includes a dielectric layer. The active waveguide structure is attached to a top surface of the passive waveguide structure and includes a quantum well layer overlying an InGaP layer. The InGaP layer provides n-contact functionality.

A heterogenous device includes a passive waveguide structure and an active waveguide structure. The passive waveguide structure is attached to a substrate and includes a semiconductor layer. The active waveguide structure is attached to a top surface of the passive waveguide structure and includes a quantum well layer overlying an InGaP layer. The InGaP layer provides n-contact functionality.