In one embodiment the semiconductor laser comprises a carrier and an edge-emitting laser diode which is mounted on the carrier and which comprises an active zone for generating a laser radiation and a facet with a radiation exit region. The semiconductor laser further comprises a protective cover, preferably a lens for collimation of the laser radiation. The protective cover is fastened to the facet and to a side surface of the carrier by means of an adhesive. A mean distance between a light entrance side of the protective cover and the facet is at most 60 μm. The semiconductor laser is configured to be operated in a normal atmosphere without additional gas-tight encapsulation.

In one embodiment the semiconductor laser comprises a carrier and an edge-emitting laser diode which is mounted on the carrier and which comprises an active zone for generating a laser radiation and a facet with a radiation exit region. The semiconductor laser further comprises a protective cover, preferably a lens for collimation of the laser radiation. The protective cover is fastened to the facet and to a side surface of the carrier by means of an adhesive. A mean distance between a light entrance side of the protective cover and the facet is at most 60 μm. The semiconductor laser is configured to be operated in a normal atmosphere without additional gas-tight encapsulation.

A semiconductor device includes a substrate, a first type semiconductor structure, semiconductor columnar bodies between the substrate and the first type semiconductor structure, a first electrode and a second electrode. The first type semiconductor structure includes a first surface, a second surface opposite the first surface and away from the substrate, a first extension and a second extension respectively extending outward beyond the semiconductor columnar bodies. The first electrode and the second electrode are on the second surface of the first type semiconductor structure.

A semiconductor device includes a substrate, a first type semiconductor structure, semiconductor columnar bodies between the substrate and the first type semiconductor structure, a first electrode and a second electrode. The first type semiconductor structure includes a first surface, a second surface opposite the first surface and away from the substrate, a first extension and a second extension respectively extending outward beyond the semiconductor columnar bodies. The first electrode and the second electrode are on the second surface of the first type semiconductor structure.

A laser module includes a gain chip, temperature sensors, a case, and a thermoelectric cooler (TEC). The gain chip emits a laser beam. One of the temperature sensors measures a first temperature of the gain chip and is encompassed by the gain chip. The other temperature sensor is adhered to the case and measures a second temperature. The TEC tunes the laser beam emitted by the gain chip to a desired wavelength by varying the first temperature of the gain chip through a set of third temperatures for various values of the second temperature. The set of third temperatures is selected from various values of the first temperature such that the laser beam emitted at the set of third temperatures is mode-hop free.

A laser module includes a gain chip, temperature sensors, a case, and a thermoelectric cooler (TEC). The gain chip emits a laser beam. One of the temperature sensors measures a first temperature of the gain chip and is encompassed by the gain chip. The other temperature sensor is adhered to the case and measures a second temperature. The TEC tunes the laser beam emitted by the gain chip to a desired wavelength by varying the first temperature of the gain chip through a set of third temperatures for various values of the second temperature. The set of third temperatures is selected from various values of the first temperature such that the laser beam emitted at the set of third temperatures is mode-hop free.

An optical system comprising an optoelectronic device having a facet and a coating on the facet. The facet is configured to be in optical communication with at least a first optical medium during a first time period and a second optical medium during a second time period. The first optical medium has a first refractive index and the second optical medium has a second refractive index different from the first refractive index. The coating is configured to provide a first reflectance during the first time period for optical signals in a predetermined wavelength range and to provide a second reflectance during the second time period for optical signals in the predetermined wavelength range wherein the second reflectance is equal to the first reflectance within a negligible margin for optical signals having at least one wavelength in the predetermined wavelength range.

Building blocks are provided for on-chip chemical sensors and other highly-compact photonic integrated circuits combining interband or quantum cascade lasers and detectors with passive waveguides and other components integrated on a III-V or silicon. A MWIR or LWIR laser source is evanescently coupled into a passive extended or resonant-cavity waveguide that provides evanescent coupling to a sample gas (or liquid) for spectroscopic chemical sensing. In the case of an ICL, the uppermost layer of this passive waveguide has a relatively high index of refraction that enables it to form the core of the waveguide, while the ambient air, consisting of the sample gas, functions as the top cladding layer. A fraction of the propagating light beam is absorbed by the sample gas if it contains a chemical species having a fingerprint absorption feature within the spectral linewidth of the laser emission.

In an embodiment a semiconductor laser diode includes a semiconductor layer sequence comprising an active layer having a main extension plane, the semiconductor layer sequence configured to generate light in an active region and radiate the light via a light-outcoupling surface, wherein the active region extends from a rear surface opposite the light-outcoupling surface to the light-outcoupling surface along a longitudinal direction in the main extension plane and a continuous contact structure directly disposed on a surface of the semiconductor layer sequence, wherein the contact structure comprises in at least a first contact region a first electrical contact material in direct contact with the surface region and in at least a second contact region a second electrical contact material in direct contact with the surface region, wherein the first and second contact regions adjoin one another.

An exemplary multi quantum well structure may include a silicon platform having a pit formed in the silicon platform, a chip positioned inside the pit, a first waveguide formed in the chip, and a second waveguide formed in the silicon platform. The pit may be defined at least in part by a sidewall and a base. The chip may include a first side and a first recess in the first side. The first side may be defined in part by a first cleaved or diced facet. The first recess may be defined in part by a first etched facet. The first waveguide may be configured to guide an optical beam to pass through the first etched facet. The second waveguide may be configured to guide the optical beam to pass through the sidewall. The second waveguide may be optically aligned with the first waveguide.