A first burying layer burying a side of a first ridge structure is formed by selective growth using a first selective growth mask and a third selective growth mask. The first burying layer is formed by regrowth from a surface of a second semiconductor layer on a side of the first ridge structure. At the same time, by selective growth using a second selective growth mask and a fourth selective growth mask, a second burying layer burying a side of a second ridge structure is formed. The second burying layer is formed by regrowth from a surface of a fourth semiconductor layer on a side of the second ridge structure.

An embodiment semiconductor optical device includes an optical waveguide including a core, and an active layer extending in the waveguide direction of the optical waveguide for a predetermined distance and arranged in a state in which the active layer can be optically coupled to the core. The core and the active layer are arranged in contact with each other. The core is formed of a material with a refractive index of about 1.5 to 2.2, such as SiN, for example. In addition, the core is formed to a thickness at which a higher-order mode appears. The higher-order mode is an E.sub.12 mode, for example.

Embodiments herein relate to an apparatus for use in a hybrid laser. The apparatus may include a silicon substrate and a waveguide to facilitate transmission of an optical signal in a first direction that is orthogonal to a surface of the silicon substrate. The apparatus may further include a metal shunt that is less than or equal to 10 micrometers from the waveguide in a second direction that is orthogonal to the surface of the silicon substrate and orthogonal to the first direction. Other embodiments may be described and/or claimed.

Examples disclosed herein relate to quantum-dot (QD) photonics. In accordance with some of the examples disclosed herein, a QD semiconductor optical amplifier (SOA) may include a silicon substrate and a QD layer above the silicon substrate. The QD layer may include an active gain region to amplify a lasing mode received from an optical signal generator. The QD layer may have a gain recovery time such that the active gain region amplifies the received lasing mode without pattern effects. A waveguide may be included in an upper silicon layer of the silicon substrate. The waveguide may include a mode converter to facilitate optical coupling of the received lasing mode between the QD layer and the waveguide.

A spectroscopic laser sensor based on hybrid III-V/IV system-on-a-chip technology. The laser sensor is configured to either (i) be used with a fiber-optic probe connected to an intravenous/intra-arterial optical catheter for direct invasive blood analyte concentration level measurement or (ii) be used to measure blood analyte concentration level non-invasively through an optical interface attached, e.g., to the skin or fingernail bed of a human. The sensor includes a III-V gain-chip, e.g., an AlGaInAsSb/GaSb based gain-chip, and a photonic integrated circuit, with laser wavelength filtering, laser wavelength tuning, laser wavelength monitoring, laser signal monitoring and signal output sections realized on a chip by combining IV-based semiconductor substrates and flip-chip AlGa1-nAsSb/GaSb based photodetectors and embedded electronics for signal processing. Embodiments of the invention may be applied for real-time monitoring of critical blood analyte concentration levels such as lactates, urea, glucose, ammonia, albumin, etc.

In an optical device, a first semiconductor layer and a second semiconductor layer are formed to be thinner than a core, an active layer has a shape with an end in a waveguide direction tapers toward a tip end, the first semiconductor layer having a trapezoidal shape with a width thereof decreases toward a side of a third semiconductor layer from a side of the core in a plan view and a width thereof decreases as one end in the waveguide direction recedes from a central portion of the active region, and the second semiconductor layer having a trapezoidal shape with a width thereof decreases toward a side of a fourth semiconductor layer from the side of the core in a plan view and a width thereof decreases as one end in the waveguide direction recedes from the central portion of the active region.

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.

Temperature measurements of photonic circuit components may be performed optically, exploiting a temperature-dependent spectral property of the photonic device to be monitored itself, or of a separate optical temperature sensor placed in its vicinity. By facilitating measurements of the temperature of the individual photonic devices rather than merely the photonic circuit at large, such optical temperature measurements can provide more accurate temperature information and help improve thermal design.

A MEMS tunable VCSEL includes a membrane device having a mirror and a distal-side electrostatic cavity for displacing the mirror to increase a size of an optical cavity. A VCSEL device includes an active region for amplifying light. Then, one or more proximal-side electrostatic cavities are defined between the VCSEL device and the membrane device and used to displace the mirror to decrease a size of an optical cavity.

A symmetric distributed feedback (DFB) laser that is integrated in a silicon based photonic integrated circuit can output light from both sides of the symmetric DFB laser onto waveguides. The light in the waveguides can be phase adjusted and combined using an optical coupler. The symmetric DFB laser can generate light and symmetrically output light onto different lanes of a multi-lane transmitter.