An object of the present invention is to provide a method for manufacturing an optical device having a laser diode, which method is suitable for mass production, and an optical device having a laser diode which allows accurate property evaluations thereof with small measurement errors. Specifically, the method includes: an etching process of etching a semiconductor lamination unit to form a mesa structure having a resonator end face, thereby forming a laser diode; and a reflecting layer forming process of forming a light reflecting layer such that the light reflecting layer covers entire side surfaces of the mesa structure, wherein the semiconductor lamination unit has a substate, a n-type clad layer including a nitride semiconductor layer having n-type conductivity, a light-emitting layer including at least one quantum well, and a p-type clad layer including a nitride semiconductor layer having p-type conductivity, laminated in this order.

A group-III nitride semiconductor laser device includes a GaN substrate, and an active layer provided on the GaN substrate, in which the GaN substrate has an oxygen concentration of 510.sup.19 cm.sup.3 or more, and an absorption coefficient of the GaN substrate with respect to an oscillation wavelength of the active layer is greater than an absorption coefficient of the active layer with respect to the oscillation wavelength.

To provide a high-quality group III nitride semiconductor. A group III nitride semiconductor including an n-GaN layer composed of Al.sub.xGa.sub.1-xN (0x<1), an InGaN layer disposed on the n-GaN layer and composed of InGaN, an n-AlGaN layer disposed on the InGaN layer and composed of n-type Al.sub.yGa.sub.1-yN (0y<1), and a functional layer disposed on the n-AlGaN layer, wherein the concentration of Mg in the n-GaN layer is higher than the concentration of Mg in the n-AlGaN layer.

A semiconductor vertical light source includes upper and lower mirrors with an active region in between, an inner mode confinement region, and an outer current blocking region that includes a common epitaxial layer including an epitaxially regrown interface between the active region and upper mirror. A conducting channel including acceptors is in the inner mode confinement region. The current blocking region includes a first impurity doped region with donors between the epitaxially regrown interface and active region, and a second impurity doped region with acceptors between the first doped region and lower mirror. The outer current blocking region provides a PNPN current blocking region that includes the upper mirror or a p-type layer, first doped region, second doped region, and lower mirror or an n-type layer. The first and second impurity doped region force current flow into the conducting channel during normal operation of the light source.

A semiconductor light emitting element includes: a GaN substrate; a first semiconductor layer located above the GaN substrate and including a nitride semiconductor of a first conductivity type; an active layer located above the first semiconductor layer and including a nitride semiconductor including Ga or In; an electron barrier layer located above the active layer and including a nitride semiconductor including Al; and a second semiconductor layer located above the electron barrier layer and including a nitride semiconductor of a second conductivity type. The electron barrier layer includes: a first region having an Al composition ratio changing at a first change rate; and a second region having an Al composition ratio changing at a second change rate larger than the first change rate. In the first second regions, the Al composition ratio monotonically increases at the first change rate in the direction from the active layer toward second semiconductor layer.

A semiconductor light-emitting device includes a layer structure of a nitride semiconductor, and the layer structure includes an n-type semiconductor layer, a p-type semiconductor layer, and an intermediate layer. The intermediate layer includes an active layer and is provided between the n-type semiconductor layer and the p-type semiconductor layer. The layer structure includes a residual donor in a region at least included in the intermediate layer, the region being situated between the active layer and the p-type semiconductor layer. The intermediate layer includes impurities in the region between the active layer and the p-type semiconductor layer, the impurities compensating the residual donor. Further, the intermediate layer is configured such that a concentration of the impurities in the region between the active layer and the p-type semiconductor layer is higher than a concentration of the impurities in the p-type semiconductor layer.

A vertical cavity surface emitting laser includes: a supporting base; and a post including an upper distributed Bragg reflecting region, an active layer, and a lower distributed Bragg reflecting region. The upper distributed Bragg reflecting region, the active layer, and the lower distributed Bragg reflecting region are arranged on the supporting base. The lower distributed Bragg reflecting region includes first semiconductor layers and second semiconductor layers alternately with each of the first semiconductor layers having a refractive index lower than that of each of the second semiconductor layers. The upper distributed Bragg reflecting region includes first layers and second layers alternately with each of the first layers having a group III-V compound semiconductor portion and a group III oxide portion. The group III-V compound semiconductor portion contains aluminum as a group III constituent element, and the group III oxide portion surrounds the group III-V compound semiconductor portion.

An optical semiconductor device includes a semiconductor multilayer structure, an active region interposed between a first facet on a light emitting side and a second facet opposing to the first facet, and a first electrode layer provided on a top of the semiconductor multilayer structure and a second electrode layer provided on a bottom of the semiconductor multilayer structure; and an electrical connection region connected to at least one of the first electrode layer and the second electrode layer of the optical semiconductor device and used for injecting a current to the active region, and > and >0 are satisfied where is the contact area included in a half region on the first facet side in a top area of the optical semiconductor device and is the contact area included in a half region on the second facet side.

A wireless communication device includes a quantum cascade laser (QCL) configured to generate a terahertz (THz) or microwave carrier signal. The QCL includes a laser waveguide, a laser optical gain medium incorporated in the laser waveguide, and at least one electrode. An antenna may be integrated with the electrode. The device may be a transmitter, the electrode configured to receive an input baseband signal, the QCL configured to couple the THz or microwave carrier signal and the input baseband signal into a THz or microwave communication signal, and the antenna configured to transmit the THz or microwave communication signal. The device may be a receiver, the antenna configured to receive a THz or microwave communication signal, and the QCL configured to de-couple the THz or microwave communication signal from the THz or microwave carrier signal into an output baseband signal.

A semiconductor vertical light source includes upper and lower minors with an active region in between, an inner mode confinement region, and an outer current blocking region that includes a common epitaxial layer including an epitaxially regrown interface between the active region and upper minor. A conducting channel including acceptors is in the inner mode confinement region. The current blocking region includes a first impurity doped region with donors between the epitaxially regrown interface and active region, and a second impurity doped region with acceptors between the first doped region and lower minor. The outer current blocking region provides a PNPN current blocking region that includes the upper minor or a p-type layer, first doped region, second doped region, and lower minor or an n-type layer. The first and second impurity doped region force current flow into the conducting channel during normal operation of the light source.