Abstract: A sample is irradiated with terahertz light from a light source, so that an image (G1) is generated by capturing an image of a region (R1) including a point (S) of the sample, and an image (G2) is generated by capturing an image of a region (R2) including the point (S) and separated from the region (R1) by a distance (L). A single image (V) is generated by applying a predetermined binary operation to the images (G1) and (G2).

Abstract: In order to generate a two-dimensional image of a sample in a short time using THz waves, provided is a reflective imaging device including a sample holder, a THz wave light source, a THz wave camera, a rotation mechanism for rotating the holder and the camera, and a processing unit. A sample unit includes an incidence member, a sample, and a reflection member. The sample includes a first region of only a membrane and a second region including a biopolymer. The camera detects, with regard to respective incident angles, a THz wave in which interference occurs between a component reflected at an interface between the incidence member and the sample and a component reflected at an interface between the sample and the reflection member, of each portion of the sample unit, and outputs a signal.

Abstract: A sample is irradiated with terahertz light from a light source, so that an image (G1) is generated by capturing an image of a region (R1) including a point (S) of the sample, and an image (G2) is generated by capturing an image of a region (R2) including the point (S) and separated from the region (R1) by a distance (L). A single image (V) is generated by applying a predetermined binary operation to the images (G1) and (G2).

Abstract: In order to generate a two-dimensional image of a sample in a short time using THz waves, provided is a reflective imaging device including a sample holder, a THz wave light source, a THz wave camera, a rotation mechanism for rotating the holder and the camera, and a processing unit. A sample unit includes an incidence member, a sample, and a reflection member. The sample includes a first region of only a membrane and a second region including a biopolymer. The camera detects, with regard to respective incident angles, a THz wave in which interference occurs between a component reflected at an interface between the incidence member and the sample and a component reflected at an interface between the sample and the reflection member, of each portion of the sample unit, and outputs a signal.

Abstract: A light oscillation part including an active layer for generating light by current injection, a tuning layer with an intermediate layer formed between the active layer and the tuning layer, for varying an oscillation wavelength by current injection and a diffraction grating formed near the active layer and the tuning layer, and a light amplification part including an active layer for amplifying light by current injection are formed on a semiconductor substrate. Light oscillation elements having wide wavelength variation ranges and the light amplification are integrated on a semiconductor substrate, whereby wide wavelength variation ranges can be obtained and the output light can be much increased.

Abstract: A tuning layer is disposed spaced by some distance apart from an active layer in a thickness direction, the tuning layer having a transition wavelength shorter than a wavelength of light radiated from the active layer. A diffraction grating layer is disposed between the active layer and tuning layer, a refractive index of the diffraction grating layer being periodically changed along an optical resonator direction. A first electrode supplies the active layer with current. A second electrode supplies the tuning layer with current independently from the current to be supplied to the active layer. A TTG-DFB laser is provided which can maintain a proper coupling coefficient and has characteristics suitable for application to communication light sources.

Abstract: A gain-coupled DFB laser diode includes a multiple quantum well active layer and a pair of cladding layers sandwiching the multiple quantum well active layer vertically, wherein the multiple quantum well active layer includes a plurality of gain regions aligned in a direction of propagation of a laser beam and repeated periodically, each of the gain regions having a multiple quantum well structure, and a buried layer fills a gap between a pair of adjacent gain regions, wherein the buried layer includes a plurality of high-refractive index layers and a plurality of low-refractive index layers, each of the high-refractive index layers is formed of a first semiconductor material having a first bandgap, while each of the low-refractive index layers is formed of a second semiconductor material having a second, larger bandgap.

Abstract: A semiconductor device has a structure in which a GaAs substrate and an InP substrate, different in lattice constant, are bonded to each other. An amorphous layer made of constituent atoms of the GaAs and InP substrates is formed at the interface between the GaAs and InP substrates. Forming the amorphous layer makes it possible to prevent a reduction of light-emitting efficiency caused by a thermal stress at the interface, even when a light-emitting layer by laser oscillation is formed near the interface. Besides, a linear current-voltage characteristic can be obtained at the interface.

Abstract: A tuning layer is disposed spaced by some distance apart from an active layer in a thickness direction, the tuning layer having a transition wavelength shorter than a wavelength of light radiated from the active layer. A diffraction grating layer is disposed between the active layer and tuning layer, a refractive index of the diffraction grating layer being periodically changed along an optical resonator direction. A first electrode supplies the active layer with current. A second electrode supplies the tuning layer with current independently from the current to be supplied to the active layer. A TTG-DFB laser is provided which can maintain a proper coupling coefficient and has characteristics suitable for application to communication light sources.

Abstract: An light oscillation part including an active layer 20 for generating light by current injection, a tuning layer 24 with an intermediate layer 22 formed between the active layer 20 and the tuning layer 24, for varying an oscillation wavelength by current injection and a diffraction grating 28 formed near the active layer 20 and the tuning layer 24, and a light amplification part including an active layer 20 for amplifying light by current injection are formed on a semiconductor substrate. Light oscillation elements having wide wavelength variation ranges and the light amplification are integrated on a semiconductor substrate, whereby wide wavelength variation ranges can be obtained and the output light can be much increased.

Abstract: A laser diode comprises a first cladding layer having a first conductivity, a second cladding layer having a second conductivity, an active layer located between the first cladding layer and the second cladding layer and extending from one end surface to the other end surface, a first electrode configured to inject a carrier with a first polarity into the active layer via the first cladding layer, and a second electrode configured to inject a carrier with a second polarity into the active layer via the second cladding layer. The active layer comprises a first active region and a second active region, which are arranged alternately and periodically from one end surface to the other end surface in the direction of light propagation, and the first active region and the second active region define type-II hetero junction between them.

Abstract: A laser diode comprises a first cladding layer having a first conductivity, a second cladding layer having a second conductivity, an active layer located between the first cladding layer and the second cladding layer and extending from one end surface to the other end surface, a first electrode configured to inject a carrier with a first polarity into the active layer via the first cladding layer, and a second electrode configured to inject a carrier with a second polarity into the active layer via the second cladding layer. The active layer comprises a first active region and a second active region, which are arranged alternately and periodically from one end surface to the other end surface in the direction of light propagation, and the first active region and the second active region define type-II hetero junction between them.

Abstract: A gain-coupled DFB laser diode includes a multiple quantum well active layer and a pair of cladding layers sandwiching the multiple quantum well active layer vertically, wherein the multiple quantum well active layer includes a plurality of gain regions aligned in a direction of propagation of a laser beam and repeated periodically, each of the gain regions having a multiple quantum well structure, and a buried layer fills a gap between a pair of adjacent gain regions, wherein the buried layer includes a plurality of high-refractive index layers and a plurality of low-refractive index layers, each of the high-refractive index layers is formed of a first semiconductor material having a first bandgap, while each of the low-refractive index layers is formed of a second semiconductor material having a second, larger bandgap.

Abstract: A semiconductor device has a structure in which a GaAs substrate and an InP substrate, different in lattice constant, are bonded to each other. An amorphous layer made of constituent atoms of the GaAs and InP substrates is formed at the interface between the GaAs and InP substrates. Forming the amorphous layer makes it possible to prevent a reduction of light-emitting efficiency caused by a thermal stress at the interface, even when a light-emitting layer by laser oscillation is formed near the interface. Besides, a linear current-voltage characteristic can be obtained at the interface.