Abstract: A quantum cascade element includes a first substrate, a quantum cascade layer and a second substrate. The quantum cascade layer is provided at a front surface side of the first substrate. The quantum cascade layer includes a plurality of quantum well layers and a plurality of barrier layers alternately stacked in a direction perpendicular to the front surface of the first substrate. The second substrate is bonded to the first substrate with the quantum cascade layer interposed. The second substrate includes a photonic crystal contacting the quantum cascade layer. The photonic crystal includes a plurality of recesses at a side contacting the quantum cascade layer. The plurality of recesses faces an uppermost layer of the plurality of barrier layers.

Abstract: A quantum cascade laser includes light-emitting quantum well layers configured to emit infrared laser light by an intersubband transition; and injection quantum well layers configured to relax carrier energy. The light-emitting quantum well layers and the injection quantum well layers are stacked alternately. The injection quantum well layers relax the energy of carriers injected from the light-emitting quantum well layers, respectively. The light-emitting quantum well layers and the injection quantum well layers including barrier layers. At least one barrier layer includes first and second regions of a first ternary compound semiconductor, and a binary compound semiconductor thin film. The binary compound semiconductor thin film is provided between the first and second regions. The first ternary compound semiconductor includes Group III atoms and a Group V atom. The binary compound semiconductor thin film includes one Group III atom of the first ternary compound semiconductor and the Group V atom.

Abstract: According to one embodiment, a surface emitting quantum cascade laser includes: a first surface that emits laser light; a second surface opposite to the first surface; an active layer provided between the first surface and the second surface; a photonic crystal provided between the active layer and the first surface or between the active layer and the second surface, the photonic crystal having a predetermined periodicity; a first electrode located on the first surface outside a region where the laser light is emitted; a second electrode provided on the second surface, the photonic crystal being located between the first surface and the second electrode; and a third electrode provided on the second surface and separated from the second electrode, the active layer extending between the first surface and the second electrode and between the first surface and the third electrode.

Abstract: A marking device includes an ink jet printer (6) using an on-demand system. The printer (6) includes a body (18), a head (22), a slide table (24), a tray (26), an ink vessel (28), a solvent vessel (30), a pump (32) and a rest (34). The head (22) has a nozzle. The shortest distance between the tip of the nozzle and a golf ball (46) set into the tray (26) is equal to or greater than 0.2 mm. The ink vessel (28) is filled with an oil-based ink or an ultraviolet setting type ink. The ink is fed to the head (22) through a tube (48). The ink is discharged from the nozzle and is then moved to the surface of the golf ball (46). The solvent is supplied from the solvent vessel (30) toward the rest (34) through a tube (50) and the pump (32). When the printer (6) is stopped, the nozzle is immersed in the solvent of the rest (34).

Abstract: A marking device comprises an ink jet printer (6) using an on-demand system. The printer (6) includes a body (18), a head (22), a slide table (24), a tray (26), an ink vessel (28), a solvent vessel (30), a pump (32) and a rest (34). The head (22) has a nozzle. The shortest distance between the tip of the nozzle and a golf ball (46) set into the tray (26) is equal to or greater than 0.2 mm. The ink vessel (28) is filled with an oil-based ink or an ultraviolet setting type ink. The ink is fed to the head (22) through a tube (48). The ink is discharged from the nozzle and is then moved to the surface of the golf ball (46). The solvent is supplied from the solvent vessel (30) toward the rest (34) through a tube (50) and the pump (32). When the printer (6) is stopped, the nozzle is immersed in the solvent of the rest (34).