A lead pin (2a,2b) penetrates a metal stem (1). A support block (3) is mounted on the metal stem (1). A dielectric substrate (4) is mounted on a side surface of the support block (3). A signal line (5a,5b) is formed on the dielectric substrate (4). One end of the signal line (5a,5b) is connected to the lead pin (2a,2b). A semiconductor optical modulation device (6) is mounted on the dielectric substrate (4). A conductive wire (8a,8b) connects the other end of the signal line (5a,5b) and the semiconductor optical modulation device (6). The semiconductor optical modulation device (6) includes a plurality of optical modulators (6b,6c) separated from each other.

A lead pin (2a,2b) penetrates a metal stem (1). A support block (3) is mounted on the metal stem (1). A dielectric substrate (4) is mounted on a side surface of the support block (3). A signal line (5a,5b) is formed on the dielectric substrate (4). One end of the signal line (5a,5b) is connected to the lead pin (2a,2b). A semiconductor optical modulation device (6) is mounted on the dielectric substrate (4). A conductive wire (8a,8b) connects the other end of the signal line (5a,5b) and the semiconductor optical modulation device (6). The semiconductor optical modulation device (6) includes a plurality of optical modulators (6b,6c) separated from each other.

Provided are a lens, a stem, an LD chip to emit laser light with a beam center directed along a mounting surface of the stem, and a PD chip having a reflective surface formed with a dielectric multilayer film on its surface, reflecting the laser light emitted from the LD chip toward the lens, and measuring an amount of the laser light, wherein the LD chip is provided with a waveguide portion having a tip portion that is formed on a side of a front end face and has a width of 0.5 to 0.7 μm, and having a tapered portion that is connected to the tip portion and becomes narrower toward the tip portion at a gradient of 0.018 to 0.033.

Provided are a lens, a stem, an LD chip to emit laser light with a beam center directed along a mounting surface of the stem, and a PD chip having a reflective surface formed with a dielectric multilayer film on its surface, reflecting the laser light emitted from the LD chip toward the lens, and measuring an amount of the laser light, wherein the LD chip is provided with a waveguide portion having a tip portion that is formed on a side of a front end face and has a width of 0.5 to 0.7 μm, and having a tapered portion that is connected to the tip portion and becomes narrower toward the tip portion at a gradient of 0.018 to 0.033.

A header for a semiconductor package, includes an eyelet having a through hole penetrating the eyelet from an upper surface to a lower surface of the eyelet, a first lead inserted inside the through hole, and an insulating substrate disposed on the upper surface of the eyelet, and provided with a first through hole at a position overlapping one end of the first lead in a plan view. The insulating substrate has a thermal conductivity lower than a thermal conductivity of the first lead. A first conductive layer is formed on an inner wall defining the first through hole, and the first conductive layer extends to an upper surface of the insulating substrate. The one end of the first lead is electrically connected to the first conductive layer, and a space is provided above the one end of the first lead inside the first through hole.

Provided is a thermoelectric cooler built-in stem, including a first stem member on a top face of which a temperature controlled target device such as an optical module or the like is mounted, a second stem member which opposes to the first stem member each other, and a thermoelectric cooler being sandwiched between the first stem member and the second stem member, for controlling the temperature controlled target device, whereby a space between the first stem member and the second stem member is filled by an insulating resin whose thermal conductivity is low.

Provided is a thermoelectric cooler built-in stem, including a first stem member on a top face of which a temperature controlled target device such as an optical module or the like is mounted, a second stem member which opposes to the first stem member each other, and a thermoelectric cooler being sandwiched between the first stem member and the second stem member, for controlling the temperature controlled target device, whereby a space between the first stem member and the second stem member is filled by an insulating resin whose thermal conductivity is low.

Heatsinking in laser devices may be improved via a device, including: a header disk having a first face with a circumference; a header post that is thermally conductive, and having: a second face connected to the first face coterminously with the circumference; a third face opposite to the second face; and a fourth face perpendicular to the second face and the third face; a lens holder, having a fifth face connected to the third face; and an optical subassembly connected to the fourth face and optically aligned with the lens holder. The device may also be understood to comprise: a header disk having a circumference; a header post that is thermally conductive, the header post having: an arc coterminous to a portion of the circumference; a mounting face, perpendicular to a plane in which the arc and the circumference are defined; and a bonding face perpendicular to the mounting face.

Packaged light emitter module can provide improved safety features to facilitate sensing the presence of moisture or a mechanical defect such as a crack in a transmissive cover (22) that may result in a safety hazard caused by the emitted light (24) if the defect or other situation is not addressed in a timely manner. Different electrically conductive structures, such as different electrically conductive traces (20, 22), allow monitoring and detection of mechanical defects to be decoupled from monitoring and detection of problems arising from the presence of moisture. The decoupling can allow the respective configuration for each of the electrically conductive structures to be optimized for detection of particular situations that may lead to a safety hazard.

A semiconductor laser device includes a semiconductor laser element, a base material supporting the semiconductor laser element, and a wiring portion formed on the base material and constituting a conduction path to the semiconductor laser element. The base material includes a mounting face oriented to one side in a thickness direction of the base material and having the semiconductor laser element mounted thereon, while also including an emission part located on one side with respect to the semiconductor laser element in a first direction perpendicular to the thickness direction. Light from the semiconductor laser element is emitted through the emission part to the outside.