An edge-emitting semiconductor laser diode chip 15 with mutually opposed front and back end facet mirrors 22, 24. First and second ridges 26.sub.1, 26.sub.2 extend between the chip end facets 22, 24 to define first and second waveguides in an active region layer. Low and high slope efficiency laser diodes are thus formed that are independently drivable by respective electrode pairs 21.sub.1, 23.sub.1 and 21.sub.2, 23.sub.2. The single chip 15 thus incorporates two laser diodes sharing a common heterostructure, one with low slope efficiency optimized for low power operation with good power stability against temperature variations and random threshold current fluctuations in the close-to-threshold power regime, and the other with high slope efficiency optimized for high wall plug efficiency operation at higher output powers when the chip is operating far above threshold.

A semiconductor device includes: a mesa portion that has a semiconductor layered structure, and that extends in a predetermined direction; an extending portion that extends along the mesa portion and that is separated by trench grooves arranged respectively on both sides of the mesa portion; insulating portions that are made from an insulating material, and are arranged in the respective trench grooves; and a conductive portion that is arranged on an upper side of the mesa portion. Further, at least one of the insulating portions adheres intimately to the mesa portion, and forms a gap between the at least one of the insulating portions and the extending portion in at least a part of an extending direction of the mesa portion, and the conductive portion is arranged across at least one of the insulating portions and the mesa portion.

A two-kappa DBR laser includes an active section, a HR mirror, a first DBR section, and a second DBR section. The HR mirror is coupled to a rear of the active section. The first DBR section is coupled to a front of the active section, the first DBR section having a first DBR grating with a first kappa κ1. The second DBR section is coupled to a front of the first DBR section such that the first DBR section is positioned between the active section and the second DBR section. The second DBR section has a second DBR grating with a second kappa κ2 less than the first kappa κ1. The two-kappa DBR laser is configured to operate in a lasing mode and has a DBR reflection profile that includes a DBR reflection peak. The lasing mode is aligned to a long wavelength edge of the DBR reflection peak.

In one embodiment, a nanobeam cavity device includes an elongated waveguide having a central optical cavity, first and second lateral substrates that are positioned on opposed lateral sides of the waveguide, and carrier-injection beams that extend from the first and second lateral substrates to the central optical cavity of the elongated waveguide.

A monolithic laser device assembly 10A in the present disclosure includes a first gain portion 20 having a first end portion 20A and a second end portion 20B, a second gain portion 30 having a third end portion 30A and a fourth end portion 30B, one or multiple ring resonators 40, a semiconductor optical amplifier 50 for amplifying a laser light emitted from the first gain portion 20, and a pulse selector 60 disposed between the first gain portion 20 and the semiconductor optical amplifier 50, in which the ring resonator 40 is optically coupled with the first gain portion 20 and with the second gain portion 30, and laser oscillation is performed on either the first gain portion 20 or the second gain portion 30.

Disclosed are devices, methods, and systems for controlling output of a laser. An example device can comprise a first portion comprising a gain element and a second portion comprising a silicon material. The second portion can comprise a waveguide configured to receive light from the gain element, an optical resonator configured to at least partially reflect light back to the gain element via the waveguide, and a first tuning element configured to tune a resonant frequency of the optical resonator.

A tunable laser for a transceiver includes a silicon photonics substrate, first and second patterned regions each being defined in the substrate a step lower than a flat surface region of the substrate, first and second laser diode chips arranged in the first and second patterned regions, the patterned regions being configured to align the gain regions of the first and second laser diode chips with integrated couplers formed in the substrate adjacent to the first and second patterned regions to facilitate flip-bonding the first and second laser diode chips within the patterned regions, and a tuning filter coupled to the first laser diode chip and the second laser diode chip via the integrated couplers. The tuning filter is configured to receive laser light from each of the first and second laser diode chips and generate a laser output having a gain determined by each of the gain regions.

A tunable laser for a transceiver includes a silicon photonics substrate, first and second patterned regions each being defined in the substrate a step lower than a flat surface region of the substrate, first and second laser diode chips arranged in the first and second patterned regions, the patterned regions being configured to align the gain regions of the first and second laser diode chips with integrated couplers formed in the substrate adjacent to the first and second patterned regions to facilitate flip-bonding the first and second laser diode chips within the patterned regions, and a tuning filter coupled to the first laser diode chip and the second laser diode chip via the integrated couplers. The tuning filter is configured to receive laser light from each of the first and second laser diode chips and generate a laser output having a gain determined by each of the gain regions.

To realize a reservoir computing system with a small size and reduced learning cost, provided is a laser apparatus including a laser; a feedback waveguide that is operable to feed light output from the laser back to the laser; an optical splitter that is provided in a path of the feedback waveguide and is operable to output a portion of light propagated in the feedback waveguide to outside; and a first ring resonator that is operable to be optically connected to the feedback waveguide, as well as a reservoir computing system including this laser apparatus.

A semiconductor optical amplifier includes: a substrate; a light source unit that is formed on the substrate; and an optical amplification unit that includes a conductive region extending, from the light source unit, in a predetermined direction along a surface of the substrate, and a nonconductive region around the conductive region. The optical amplification unit amplifies propagation light that propagates, from the light source unit, in the predetermined direction as slow light, and emits the propagation light that is amplified in an emission direction that intersects with the surface. The maximum optical power of the propagation light is larger than the maximum optical power in a vertical oscillation mode.