The invention relates to a method for generating a laser pulse, wherein during the method a first semi-conductor laser in the form of a broadband laser diode is used to generate a pump laser pulse, the pump laser pulse is used to pump a second semi-conductor laser, the laser pulse being shorter than the pump laser pulse and the second semi-conductor laser comprising at least 20 quantum wells arranged above one another in the emission direction of the laser pulse.

A semiconductor optical device (40, 50, 60) comprises a first region 42 comprising an active region configured such that electrons and holes recombine in the active region to produce photons when a voltage is applied to the device. The device comprises at least one second region (43, 44, 53, 54, 62, 63) comprising a quantum well structure which is configured to trap electrons only, to trap holes only, or to trap different amounts of electrons and holes. The second region is arranged at a distance from the first region which is sufficiently close to the first region such that a charge imbalance develops in the first region when a voltage is applied to the device, thereby to reduce Auger recombination in the first region.

In an embodiment, a laser includes a gain section. The gain section includes an active region, an upper separate confinement heterostructure (SCH), and a lower SCH. The upper SCH is above the active region and has a thickness of at least 60 nanometers (nm). The lower SCH is below the active region and has a thickness of at least 60 nm.

A quantum cascade laser includes a semiconductor substrate and an active layer having a cascade structure, in which unit layered bodies, each composed of a quantum well light emitting layer and an injection layer, are stacked, wherein the unit layered body has a subband level structure having an upper laser level, a lower laser level, and a relaxation miniband composed of at least two energy levels with an energy spacing smaller than the energy difference (E.sub.UL) between the upper laser level and the lower laser level, the energy width of the relaxation miniband is smaller than the energy (E.sub.LO−E.sub.UL) obtained by subtracting the energy difference (E.sub.UL) from the energy (E.sub.LO) of longitudinal optical phonons, and electrons subjected to the intersubband transition are relaxed in the relaxation miniband and are injected into a quantum well light emitting layer in a subsequent unit layered body.

The invention relates to a semiconductor device, e.g. for the emission or absorption of light, preferably in the deep ultraviolet (DUV) range. The device, e.g. a resonant cavity light emitting diode (RCLED) or a laser diode, is formed from: a substrate layer (302), preferably comprising a distributed Bragg reflector (DBR); a graphitic layer (304); and at least one semiconductor structure (310), preferably a wire or a pyramid, grown on the graphitic layer, with or without the use of a mask layer (306). The semiconductor structure is constructed from at least one III-V semiconductor n-type doped region (316) and a hexagonal boron-nitride (hBN) region (312), preferably being p-type doped hBN.

A gain medium for semiconductor optical amplifier in high-power operation includes a substrate with n-type doping; a lower clad layer formed overlying the substrate; a lower optical confinement stack overlying the lower clad layer; an active layer comprising a multi-quantum-well heterostructure with multiple well layers characterized by about 0.8% to 1.2% compressive strain respectively separated by multiple barrier layers characterized by about −0.1% to −0.5% tensile strain. The active layer overlays the lower optical confinement stack. The gain medium further includes an upper optical confinement stack overlying the active layer, the upper optical confinement stack being set thinner than the lower optical confinement stack; an upper clad layer overlying the upper optical confinement stack; and a p-type contact layer overlying the upper clad layer.

The invention relates to an AlInGaN alloy based superluminescent diode, comprising a gallium nitride bulk substrate, a lower cladding layer with n-type electrical conductivity. Further it includes a lower light-guiding layer with n-type electrical conductivity, a light emitting layer, an electron blocking layer with p-type electrical conductivity, an upper light-guiding layer, an upper cladding layer with p-type electrical conductivity, and a subcontact layer with p-type electrical conductivity. The gallium nitride bulk substrate has a spatially varying surface misorientation in the relation to the crystallographic plane M in range of 0° to 10°.

The invention relates to an AlInGaN alloy based superluminescent diode, comprising a gallium nitride bulk substrate, a lower cladding layer with n-type electrical conductivity. Further it includes a lower light-guiding layer with n-type electrical conductivity, a light emitting layer, an electron blocking layer with p-type electrical conductivity, an upper light-guiding layer, an upper cladding layer with p-type electrical conductivity, and a subcontact layer with p-type electrical conductivity. The gallium nitride bulk substrate has a spatially varying surface misorientation in the relation to the crystallographic plane M in range of 0 to 10.

To increase the maximum operating temperature of quantum cascade lasers of a terahertz region, a quantum cascade laser element 1000 according to the present invention has a semiconductor superlattice structure sandwiched between a pair of electrodes, the semiconductor superlattice structure has an active region 100 that emits electromagnetic waves of a frequency in a THz region under an external voltage applied through the pair of electrodes for operation, and the active region 100 has plural unit structures 10U, each of which is repeatedly layered over one another. Each of the unit structures 10U has a double quantum well structure formed of a first well layer 10W1 and a second well layer 10W2 separated from each other by a barrier layer, the first well layer 10W1 and the second well layer 10W2 have compositions different from each other, and when the external voltage is not being applied, potential energy for electrons in the second well layer 10W2 is lower than that in the first well layer 10W1.

To increase the maximum operating temperature of quantum cascade lasers of a terahertz region, a quantum cascade laser element 1000 according to the present invention has a semiconductor superlattice structure sandwiched between a pair of electrodes, the semiconductor superlattice structure has an active region 100 that emits electromagnetic waves of a frequency in a THz region under an external voltage applied through the pair of electrodes for operation, and the active region 100 has plural unit structures 10U, each of which is repeatedly layered over one another. Each of the unit structures 10U has a double quantum well structure formed of a first well layer 10W1 and a second well layer 10W2 separated from each other by a barrier layer, the first well layer 10W1 and the second well layer 10W2 have compositions different from each other, and when the external voltage is not being applied, potential energy for electrons in the second well layer 10W2 is lower than that in the first well layer 10W1.