A narrow-linewidth tunable external cavity laser includes, sequentially arranged along an optical path, a laser gain chip, a collimating lens, a bandpass filter, a tunable filter, and an output cavity surface. The laser gain chip includes a first end surface and a second end surface positioned along the optical path. The first end surface is further away from the collimating lens and is coated with a highly reflective film to form an external cavity with the output cavity surface.

There is provided a device to generate an output light. The device comprises a substrate, a quantum well structure (QWS) disposed on the substrate, and a waveguide disposed on the substrate and in contact with the QWS. The QWS has a first layer, a second layer, and a third layer. The second layer is disposed and quantum-confined between the first layer and the third layer. In addition, the second layer is to emit an input light when electrically biased. The input light has an optical field extending outside the QWS and into the waveguide, to optically couple the waveguide with the QWS. The waveguide is to provide an optical resonance cavity for the input light. Moreover, the waveguide has an optical outlet to transmit at least some of the input light out of the waveguide to generate the output light.

An on-chip laser includes a gain portion, a mirror in communication with the gain portion, a waveguide in communication with the gain portion, and a resonator optically coupled to the waveguide at an optical coupling. The resonator has a circular shape. The waveguide and the resonator are separate from the gain portion.

Embodiments of the disclosure are directed to a lateral current injection electro-optical device. The device comprises an active region with a stack of III-V semiconductor gain materials stacked along a stacking direction z. The active region may be formed as a slab having several lateral surface portions, each extending parallel to the stacking direction z. The device further comprises two paired elements, which include: a pair of doped layers of III-V semiconductor materials (an n-doped layer and a p-doped layer); and a pair of lateral waveguide cores. The two paired elements may be laterally arranged, two-by-two, on opposite sides of the slab. The elements distinctly adjoin respective ones of the lateral surface portions of the slab, so as for these elements to be separated from each other by the slab. The disclosure may be further directed to related silicon photonics devices and fabrication methods.

An optical apparatus comprises a semiconductor substrate and a slab-coupled optical waveguide (SCOW) emitter disposed on the semiconductor substrate. The SCOW emitter comprises an optical waveguide comprising: a first region doped with a first conductivity type; a second region doped with a different, second conductivity type; and an optically active region disposed between the first region and the second region. The optically active region comprises a plurality of quantum dots.

A monolithic integrated semiconductor random laser composed of a gain region and random feedback region, comprising: a substrate, a lower confinement layer on the substrate, an active layer on the lower confinement layer, an upper confinement layer on the active layer, a strip-shaped waveguide layer longitudinally made in middle of the upper confinement layer, a P.sup.+ electrode layer divided into two segments by an isolation groove and made on the waveguide layer, and an N.sup.+ electrode layer on a back face of the lower confinement layer. The two segments of the P.sup.+ electrode layer correspond respectively to the gain region and the random feedback region. The random feedback region uses a doped waveguide to randomly feed back light emitted and amplified by the gain region. As a result, random laser is emitted. Frequency and intensity of laser emitted by semiconductor laser are random, and a monolithic integration structure is used, making semiconductor laser be light, small, stable in performance, and strong in integration.

Higher power tunable lasers are feasible using photonics integrated circuit based external cavity laser configurations by using multiple RSOAs inside a single cavity to provide multiple on-chip coherent optical output at the same wavelength. The total collective output power in various output branches potentially adds up being higher than what commercial lasers can provide. Using multiple RSOA increases and distributes the number of gain materials, which keeps them in a linear regime and avoids available gain saturation, which thereby removes gain saturation limitation in optical amplifications.

A semiconductor laser source including a Mach-Zehnder interferometer including first and second arms. Each of these arms being divided into a plurality of consecutive sections. The first and second arms each include a gain-generating section forming first and second gain-generating waveguides, respectively. The laser source includes power sources able to deliver currents through the gain-generating waveguides such that the following condition is met:

[00001]$\underset{n=1}{\overset{N_2}{.Math.}}.Math.L_{2,n}.Math.{\mathrm{neff}}_{2,n}-\underset{n=1}{\overset{N_1}{.Math.}}.Math.L_{1,n}.Math.{\mathrm{neff}}_{1,n}=k_f.Math.{}_{\mathrm{Si}}$

where: k.sub.f is a preset integer number higher than or equal to 1, N.sub.1 and N.sub.2 are the numbers of sections in the first and second arms, respectively, L.sub.1,n and L.sub.2,n are the lengths of the nth sections of the first and second arms, respectively, neff.sub.1,n and neff.sub.2,n are the effective indices of the nth sections of the first and second arms, respectively.

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.

The embodiments herein describe a single-frequency laser source (e.g., a distributed feedback (DFB) laser or distributed Bragg reflector (DBR) laser) that includes a feedback grating or mirror that extends along a waveguide. The grating may be disposed over a portion of the waveguide in an optical gain region in the laser source. Instead of the waveguide or cavity being linear, the laser includes a U-turn region so that two ends of the waveguide terminate at the same facet. That facet is coated with an anti-reflective (AR) coating.