A photonic integrated circuit including a semiconductor substrate having integrate a semiconductor light source configured to emit coherent light of at least the first wavelength and the second wavelength, the semiconductor light source having a first factor; a waveguide structure optically coupled to the semiconductor light source, the waveguide structure having a second Q factor that is higher than the first Q factor, the waveguide structure configured to form an optical cavity for at least the light of the first wavelength and the second wavelength; an optical output structure configured to optically couple the waveguide structure with a plurality of optical channels to transmit light of the first wavelength and the second wavelength from the waveguide structure to the plurality of optical channels.

A system includes an array of light-collecting elements, each light-collecting element of the array of light-collecting elements configured to output a collected light signal to an optical fiber of a number of optical fibers, an optical fiber combiner coupled to the array of light-collecting elements by the number of optical fibers, the optical fiber combiner configured to receive the collected light signals from the array of light-collecting elements through the number of optical fibers and to combine the collected light signals to form one or more combined collected light signals, and an optical detector configured to receive the one or more combined collected light signals from the optical fiber combiner and convert the one or more combined light signals into one or more electrical signals.

Configurations for an optical device used for light splitting and wavelength locking are disclosed. The optical device may be a two by three coupler with a first waveguide coupled to a second waveguide, and a third waveguide coupled to the second waveguide. The first and third waveguides may receive input light and optically couple light to the second waveguide. The output signals of the first, second, and third waveguides may have a constant phase difference from one another over a broadband wavelength range, which may allow for phase unwrapping. By phase unwrapping the output signals over an FSR and performing further phase unwrapping over the broadband wavelength range, a continuous signal may be produced and used to sequentially lock each wavelength of light emitted by light sources over the broadband wavelength range.

An optical quantum circuit comprising a substrate; a first plurality of waveguides formed on a first layer of the substrate and a second plurality of waveguides formed on a second layer of the substrate wherein at least some of the waveguides in the first plurality of waveguides are configured formed to interface, in a pairwise fashion, such that in a at least first some interaction stages each of a at least first some of the first plurality of waveguides interface with a neighbouring waveguide in the first plurality of waveguides; and in a at least second some of the interaction stages each of a at least second some of the first plurality of waveguides interface with an adjacent waveguide of the second plurality of waveguides.

A semiconductor optical integrated element according to the present disclosure includes: a first optical amplifier which amplifies a signal beam inputted from a first end surface; a first passive optical waveguide which guides the amplified signal beam toward a direction different from a direction of the optical waveguide; an optical splitter which splits the guided signal beam into a plurality of signal beams; a phase modulator which is connected to the first passive optical waveguide and performs phase modulation on the plurality of signal beams; a second passive optical waveguide which guides each phase-modulated signal beam toward the direction of the optical waveguide; an optical multiplexer which multiplexes the plurality of phase-modulated signal beams into one signal beam; and a second optical amplifier which amplifies the signal beam guided by the second passive optical waveguide, and whose saturated beam output is smaller than that of the first optical amplifier.