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.

A vertical cavity surface emitting laser (VCSEL) may include a substrate layer, epitaxial layers on the substrate layer, and angled reflectors configured to receive an optical beam emitted toward a bottom surface of the VCSEL and redirect the optical beam through an exit window in a top surface of the VCSEL. In some implementations, the angled reflectors may be formed in the substrate layer. Additionally, or alternatively, the VCSEL may include molded optics, where the molded optics include the angled reflectors. In some implementations, the exit window may include an integrated lens.

Integrated laser sources emitting multi-wavelengths of light with reduced thermal transients and crosstalk and methods for operating thereof are disclosed. The integrated laser sources can include one or more heaters and a temperature control system to maintain a total thermal load of the gain segment, the heater(s), or both of a given laser to be within a range based on a predetermined target value. The system can include electrical circuitry configured to distribute current to the gain segment, the heater(s), or both. The heater(s) can be located proximate to the gain segment, and the distribution of current can be based on the relative locations. In some examples, the central laser can be heated prior to being activated. In some examples, one or more of the plurality of lasers can operate in a subthreshold operation mode when the laser is not lasing to minimize thermal perturbations to proximate lasers.

A multi-emitter laser diode device includes a carrier chip singulated from a carrier wafer. The carrier chip has a length and a width, and the width defines a first pitch. The device also includes a plurality of epitaxial mesa dice regions transferred to the carrier chip from a substrate and attached to the carrier chip at a bond region. Each of the epitaxial mesa dice regions is arranged on the carrier chip in a substantially parallel configuration and positioned at a second pitch defining the distance between adjacent epitaxial mesa dice regions. Each of the plurality of epitaxial mesa dice regions includes epitaxial material, which includes an n-type cladding region, an active region having at least one active layer region, and a p-type cladding region. The device also includes one or more laser diode stripe regions, each of which has a pair of facets forming a cavity region.

Wavelength division multiplexing (WDM) has enabled telecommunication service providers to provide multiple independent multi-gigabit channels on one optical fiber. To meet demands for improved performance, increased integration, reduced footprint, reduced power consumption, increased flexibility, re-configurability, and lower cost monolithic optical circuit technologies and microelectromechanical systems (MEMS) have become increasingly important. However, further integration via microoptoelectromechanical systems (MOEMS) of monolithically integrated optical waveguides upon a MEMS provide further integration opportunities and functionality options. Such MOEMS may include MOEMS mirrors and optical waveguides capable of deflection under electronic control. In contrast to MEMS devices where the MEMS is simply used to switch between two positions the state of MOEMS becomes important in all transition positions. Improvements to the design and implementation of such MOEMS mirrors, deformable MOEMS waveguides, and optical waveguide technologies supporting MOEMS devices are presented where monolithically integrated optical waveguides are directly supported, moved and/or deformed by a MEMS.

A semiconductor optical device includes a substrate having an optical waveguide, a gain section formed of a compound semiconductor having an optical gain and bonded to an upper surface of the substrate, the gain section having a first mesa, and a first wiring line electrically connected to the gain section. The first mesa of the gain section is optically coupled to the optical waveguide. The substrate includes a first layer, a second layer, and a third layer. The first layer has a higher thermal conductivity than the second layer. The second layer is stacked on the first layer. The third layer is stacked on the second layer. A recess provided in the substrate extends through the third layer to the second layer in the thickness direction. The first wiring line extends from the first mesa of the gain section to the recess.

Provided is a semiconductor epitaxial wafer, including a substrate, a first epitaxial structure, a first ohmic contact layer and a second epitaxial stack structure. It is characterized in that the ohmic contact layer includes a compound with low nitrogen content, and the ohmic contact layer does not induce significant stress during the crystal growth process. Accordingly, the second epitaxial stack structure formed on the ohmic contact layer can have good epitaxial quality, thereby providing a high-quality semiconductor epitaxial wafer for fabricating a GaAs integrated circuit or a InP integrated circuit. At the same time, the ohmic contact properties of ohmic contact layers are not affected, and the reactants generated during each dry etching process are reduced.

In one embodiment, the substrate is configured for a semiconductor laser diode and comprises a plurality of substrate layers. The substrate layers include insulating layers and carrier layers, which are thicker. A plurality of electrical contact surfaces, which are configured for the semiconductor laser diode, a laser capacitor and a control chip, are located on an assembling side of a first, uppermost substrate layer, which is an insulating layer. Electrical conductor tracks, which electrically interconnect the contact surfaces, are located on the one hand between the first insulating layer and a second insulating layer, and on the other hand between the second insulating layer and a third substrate layer, which is preferably an insulating layer.

A semiconductor laser element includes: a semiconductor substrate; a semiconductor laminate; a first electrode in which a ridge portion of the semiconductor laminate is embedded; and a second electrode. A first region of a side surface of the first electrode is separated from a first end surface in such a manner to extend away from the first end surface as the first region extends away from the ridge portion to both sides. A shortest distance between a first side surface and the first region is smaller than each of a shortest distance between a third side surface and a third region and a shortest distance between a fourth side surface and a fourth region. The first region does not include a corner in a range satisfying D.sub.1 ≤ S.sub.1 and D.sub.1 ≤ S.sub.2.

A gallium- and nitrogen-containing laser device including an etched facet with surface treatment to improve an optical beam is disclosed.