A laser diode is provided, including at least a defect blocking layer deposited between the GaAs substrate and the active layer, so that the crystal defects of the GaAs substrate can be blocked or reduced from propagation to the active layer when the epitaxial layer is formed on the GaAs substrate. As such, the crystal quality of the active layer can be improved, thereby improving the reliability and optical property of the laser diode.

A method of producing an ultraviolet laser diode with a low oscillation threshold current density includes stacking a first cladding layer, a light-emitting layer, and a second cladding layer on a substrate in this order to form a nitride semiconductor laminate (step S101), etching at least a portion of the nitride semiconductor laminate to form a mesa structure and setting the ratio between the length of the resonator end faces and the length of the side surfaces of the mesa structure in plan view between 1:5 and 1:500 (step S102), disposing first conductive material on a portion of a first area and applying heat treatment of 400° C. or higher to form a first electrode (step S103), and disposing a second conductive material in an area on the second cladding layer, at a distance of 5 um or more from the side surfaces, to form a second electrode (step S104).

The present invention provides a widely tunable, single mode emission semiconductor laser which comprises a semiconductor substrate, a first linear ridge waveguide which forms a first coupled cavity, and a second linear ridge waveguide which forms a second coupled cavity, with the first coupled cavity being separated from the second coupled cavity by a gap. The first and second coupled cavities comprise p-contacts and n-contacts for allowing laser currents I.sub.1, I.sub.2 to be injected into the first and second coupled cavities, respectively. The first and second coupled cavities comprise first and second heating resistors, respectively, for heating the first and second coupled cavities when heating currents H.sub.1, H.sub.2 are applied to the first and second heating resistors, respectively. A heating resistor is provided for heating the semiconductor substrate of the semiconductor laser so as to regulate the base temperature T of the chip (i.e., the semiconductor substrate).

A surface-emitting semiconductor laser includes: a substrate; a first electrode provided in contact with the substrate; a first light reflection layer provided over the substrate; a second light reflection layer provided over the substrate, with the first light reflection layer being interposed between the second light reflection layer and the substrate; an active layer provided between the second light reflection layer and the first light reflection layer; a current confining layer that is provided between the active layer and the second light reflection layer and includes a current injection region; a second electrode provided over the substrate, with the second light reflection layer being interposed between the second electrode and the substrate, at least a portion of the second electrode being provided at a position overlapping the current injection region; and a contact layer that is provided between the second electrode and the second light reflection layer and includes a contact region that is in contact with the second electrode, in which the contact region has a smaller area than an area of the current injection region.

Provided is a technique for manufacturing a nitride semiconductor substrate with which it is possible to manufacture a nitride semiconductor substrate having sufficiently reduced dislocation density with a large area even if manufactured on an inexpensive substrate made of sapphire, etc. A nitride semiconductor substrate in which a nitride semiconductor layer formed on a substrate is formed by laminating an undoped nitride layer and a rare earth element-added nitride layer to which a rare earth element is added as a doping material, and the dislocation density is of the order of 106 cm−2 or less. A method for manufacturing a nitride semiconductor substrate in which a step for growing GaN, InN, AlN, or a mixed crystal of two or more thereof on a substrate to form an undoped nitride layer, and a step for forming a rare earth element-added nitride layer to which a rare earth element is added so as to be substituted for Ga, In, or Al are performed via a series of formation steps using an organic metal vapor epitaxial technique at a temperature of 900 to 1200° C. without extraction from a reaction vessel.

An electronic element mounting substrate includes a first substrate including a first main surface and a mounting portion in a rectangular shape for mounting an electronic element, positioned on the first main surface and one end portion of the mounting portion in a longitudinal direction being positioned at an outer edge portion of the first main surface and a second substrate positioned on a second main surface opposite to the first main surface, formed of a carbon material, and including a third main surface facing the second main surface and a fourth main surface opposite to the third main surface. A thermal conduction of the mounting portion in a direction perpendicular to in a longitudinal direction is greater than a thermal conduction of the mounting portion in the longitudinal direction, in the third main surface or the fourth main surface, in plan view.

In an embodiment, a device includes: a first reflective structure including first doped layers of a semiconductive material, alternating ones of the first doped layers being doped with a p-type dopant; a second reflective structure including second doped layers of the semiconductive material, alternating ones of the second doped layers being doped with a n-type dopant; an emitting semiconductor region disposed between the first reflective structure and the second reflective structure; a contact pad on the second reflective structure, a work function of the contact pad being less than a work function of the second reflective structure; a bonding layer on the contact pad, a work function of the bonding layer being greater than the work function of the second reflective structure; and a conductive connector on the bonding layer.

The present disclosure falls into the field of optoelectronics, particularly, includes the design, epitaxial growth, fabrication, and characterization of Laser Diodes (LDs) operating in the ultraviolet (UV) to infrared (IR) spectral regime on patterned substrates (PSs) made with (formed on) low cost, large size Si, or GaN on sapphire, GaN, and other wafers. We disclose three types of PSs, which can be universal substrates, allowing any materials (III-Vs, II-VIs, etc.) grown on top of it with low defect and/or dislocation density.

In a semiconductor laser device that includes: a semiconductor laser element that outputs light from an output portion; and a metal stem that holds the semiconductor laser element, the metal stem includes a base that has a reference surface on an upper surface and a protrusion portion that protrudes upward from the reference surface, and the protrusion portion is provided with an installation surface on which the semiconductor laser element is installed and a side surface which is disposed on an identical plane with a part of an outer circumferential surface of the base.

The temperature sensitivity of a reflective electro-absorption modulator can be reduced through the use, e.g., in the optical cavity thereof, of optical materials having positive and negative thermo-optic coefficients (TOCs). In some embodiments, a multiple-quantum-well structure of the modulator comprises positive-TOC materials, and a Bragg reflector bounding the optical cavity comprises one or more negative-TOC materials. In some embodiments, the thicknesses of the layers of positive- and negative-TOC materials are selected such that the average refractive index along the optical path through the modulator is approximately temperature independent. In some embodiments, the optical length of the optical cavity is an integer multiple of a nominal operating wavelength.