A semiconductor-laser-device assembly includes a mode-locked semiconductor-laser-element assembly including a mode-locked semiconductor laser element, and a dispersion compensation optical system, on which laser light emitted from the mode-locked semiconductor laser element is incident and from which the laser light is emitted; and a semiconductor optical amplifier having a layered structure body including a group III-V nitride-based semiconductor layer, the semiconductor optical amplifier configured to amplify the laser light emitted from the mode-locked semiconductor-laser-element assembly.

A tunable laser includes a semiconductor optical amplifier (SOA) having a reflective end coupled to a shared reflector and an output end, which is coupled to a demultiplexer through an input waveguide. The demultiplexer comprises a set of Mach-Zehnder (MZ) lattice filters, which function as symmetric de-interleaving wavelength splitters, that are cascaded to form a binary tree that connects an input port, which carries multiple wavelength bands, to N wavelength-specific output ports that are coupled to a set of N reflectors. A set of variable optical attenuators (VOAs) is coupled to outputs of the MZ lattice filters in the binary tree, and is controllable to selectively add loss to the outputs, so that only a single favored wavelength band, which is associated with a favored reflector in the set of N reflectors, lases at any given time. An output waveguide is optically coupled to the lasing cavity.

In a multiple-wavelength laser source, a multiple-mode laser outputs a set of wavelengths in a range of wavelengths onto an optical waveguide, where a spacing between adjacent wavelengths in the set of wavelengths is smaller than a width of channels in an optical link. Furthermore, a set of ring-resonator filters in the multiple-wavelength laser source, which are optically coupled to the optical waveguide, output corresponding subsets of the set of wavelengths for use in the optical link based on free spectral ranges and quality factors of the set of ring-resonator filters. These subsets may include one or more groups of wavelengths, with another spacing between adjacent groups of wavelengths that is larger than the width of the given channel in the optical link. In addition, the one or more groups of wavelengths may include one or more wavelengths, with the spacing between adjacent wavelengths in the given group of wavelengths.

Disclosed is a semiconductor laser device assembly including a semiconductor laser device; and a dispersion compensation optical system, where a laser light exited from the semiconductor laser device is incident and exits to control a group velocity dispersion value of the laser light exited from the semiconductor laser device per wavelength.

A light-emitting device includes: a first light-emitting element including a first light-emission surface through which first light is emitted along a first optical axis; a second light-emitting element disposed apart from the first light-emitting element in a first direction that is perpendicular to the first optical axis, the second light-emitting element including a second light-emission surface through which second light is emitted along a second optical axis that is inclined with respect to the first optical axis in a second direction opposite to the first direction; and a third light-emitting element disposed apart from the first light-emitting element in the second direction, wherein the third light-emitting element includes a third light-emission surface through which third light is emitted along a third optical axis that is inclined with respect to the first optical axis in the first direction.

A tunable transmission optical filter is optically coupled between a laser section and semiconductor optical amplifier (SOA) section of a tunable laser device. The optical filter may be tuned to provide a high transmission near the lasing peak while suppressing a significant portion of back-propagating amplified spontaneous emission (ASE) of the SOA section. Without the optical filter, the laser output spectrum may develop side lobes of higher intensity after the ASE is amplified and reflected in the forward direction by the laser gain and mirror sections. While lessening the side lobes, the optical filter simultaneously transmits the laser peak for amplification by the SOA section.

A non-reciprocal optical assembly for injection locking a laser to a resonator is described. The laser emits a light beam, and the resonator receives the light beam and returns a feedback light beam to the laser such that the feedback light beam causes injection locking. The non-reciprocal optical assembly is interposed between and optically coupled to the laser and the resonator. The non-reciprocal optical assembly includes a first port that receives the light beam from the laser, and a second port that outputs the light beam to the resonator and receives the feedback light beam from the resonator. The first port also outputs the feedback light beam to the laser. The light beam passes through the non-reciprocal optical assembly with a first power loss, and the feedback light beam passes through the non-reciprocal optical assembly with a second power loss (the first power loss differs from the second power loss).

A control circuit in this laser equipment drives a drive circuit of a photonic crystal laser element under a predetermined condition. It was found that a wavelength width of a laser beam to be output from the photonic crystal laser element is dependent on a standardized drive current k and a pulse width T, and had a predetermined relationship with these. By meeting this condition, a laser beam with a plurality of wavelengths can be controlled and output.

A quantum interference device (atomic oscillator) includes: an atom cell that encapsulates an alkali metal; a first light source portion that emits light including a resonance light pair, the resonance light pair being circularly polarized in the same direction and causing the alkali metal to resonate; a second light source portion that emits light including adjustment light, the adjustment light being circularly polarized in a direction opposite to the resonance light pair and causing the alkali metal to resonate; and a light receiving portion that receives the resonance light pair having passed through the atom cell, in which the adjustment light is FM-modulated.

Exemplary apparatus and method are provided. In particular, an electromagnetic radiation can be emitted with, e.g. a light source arrangement. For example, the light source arrangement can include a cavity and a filter, and a spectrum of the electromagnetic radiation can be controlled, e.g., with such cavity and filter, to have a mean frequency that changes (i) at an absolute rate that is greater than about 100 terahertz per millisecond, and (ii) over a range that is greater than about 10 terahertz. Additionally or alternatively, the light source arrangement can include a frequency shifting device which can shift the mean frequency of the electromagnetic radiation.