In accordance with one aspect of the present application there is provided a DBR, laser. The DBR laser comprises a phase section in a cavity of the DBR laser configured to adjust an optical path length of the cavity. The laser also comprises a DBR section comprising a frequency tuning system, the frequency tuning system comprising a resistance heater configured to apply heat to a grating of the DBR section in order to adjust a Bragg frequency of the DBR section. A detector is configured to detect laser light transmitted through the DBR section. A controller is configured: to cause the phase section to apply a dither to the optical path length of the cavity or cause the frequency tuning system to apply a dither to the Bragg frequency of the DBR section; to use the detector to monitor intensity of light transmitted from the laser cavity via the DBR section during application of the dither; to determine a deviation from longitudinal mode centre operation on the basis of the monitored intensity; to cause the phase section to adjust the optical path length of the cavity in order to reduce said deviation; to determine an output frequency of the DBR laser on the basis of a resistance of the resistance heater; and to control the output frequency of the DBR laser by controlling power to the resistance heater.

Narrow linewidth multi-wavelength (MW) light sources and related methods are disclosed. Such a light source includes gain chips coupled to a wavelength combiner and reflection chip that includes phase control sections (PCSs), a wavelength division multiplexer (WDM), and a micro-ring resonator (MRR) based reflector. The WDM combines light beams received from the gain chips, via the PCSs, into a combined light beam. The MRR based reflector receives the combined light beam and generates both a reflection MW light beam and a transmission MW light beam. The WDM receives the reflection MW light beam, separates it into different wavelengths, and provides each different wavelength of light via a respective one of the PCSs to a respective one of the gain chips to self seed an internal laser cavity thereof. The transmission MW light beam is, or is used to produce, the narrow linewidth MW light produced by the light source.

A tunable wavelength laser comprising a laser cavity formed by a broadband mirror and a comb mirror. The laser cavity comprising a gain region. The laser cavity is configured such that a non-integer number of cavity modes of the laser cavity are between two consecutive reflection peaks of the comb mirror.

A laser assembly comprising: a semiconductor laser with a fast gain medium, wherein the gain relaxation time of the gain medium is smaller than the round-trip time in a standing wave cavity; a DC source coupled to the standing wave cavity; and an AC injection device for injecting an electrical AC signal within a range and/or within an integer multiple of the range into the standing wave cavity, the range within 1% of the natural round-trip frequency in the standing wave cavity, comprising at least a first and second electric contact section extending along a first longitudinal side of the longitudinal extension of the standing wave cavity, the AC injection device coupled to the first and/or second electric contact section such that the complex amplitude of the electrical AC signal differs for the first and second longitudinal electric contact section.

An optical apparatus comprising at least two optoelectronic devices fabricated on the same substrate and in thermal communication with each other. A first optoelectronic device is configured to generate optical signals and provide them to an optical system via an optical output port. A second optoelectronic device is configured to provide heat compensation for the first optoelectronic device. An electrical circuitry provides first electrical signals to the first optoelectronic device and second electrical signals to the second optoelectronic device. The electrical circuitry is configured to adjust at least the second electrical signals to controllably adjust a temperature of the first optoelectronic device.

A narrow linewidth laser includes a passive ring resonant cavity, an FP resonant cavity, and a first gain region. The passive ring resonant cavity and the FP resonant cavity are combined to form an M-Z (Mach-Zehnder interference structure) compound external cavity structure, and the M-Z compound external cavity structure is at least used for providing wavelength selection and narrowing laser linewidth. The first gain region is provided on the outer side of the M-Z compound external cavity structure and is used for providing a gain for the whole laser. The narrow linewidth laser is simple in structure, high in side-mode suppression ratio, narrow in linewidth, and high in output power. By further integrating a PN junction region or MOS junction region, broadband and rapid tuning with low power consumption can also be achieved, and tuning management is simple.

A method (700) of biasing a tunable laser (310) during burst-on and burst-off states includes receiving a burst mode signal (514) indicative of the burst-on state or the burst-off state and when the burst mode signal is indicative of the burst-on state: delivering a first bias current (I.sub.GAIN) to an anode of a gain-section diode (590a) disposed on a shared substrate of the tunable laser; and delivering a second bias current (I.sub.PH) to an anode of phase-section diode (590b) disposed on the shared substrate. The second bias current is less than the first bias current. When the burst mode signal transitions to be indicative of the burst-off state, the method also includes delivering the first bias current to the anode of the gain-section diode; and delivering the second bias current to the anode of the phase-section diode wherein the first bias current is less than the second bias current.

A light source device includes: a plurality of laser light sources, each configured to emit a light beam; a plurality of collimating lenses, each configured to collimate the light beam emitted from a corresponding one of the laser light sources; a first transmission diffraction grating configured to diffract and combine, in an identical diffraction angle direction, the light beams transmitted through the collimating lenses and incident on a single region at different incident angles; a sensor configured to detect a positional deviation in diffracted light beams that are diffracted and combined by the first transmission diffraction grating; and a plurality of wavelength selecting elements, each disposed on an optical path between a respective one of the collimating lenses and the first transmission diffraction grating and configured to select a wavelength of a corresponding one of the light beams incident on the first transmission diffraction grating.

An optical waveguide structure includes a lower cladding layer positioned on a substrate; an optical guide layer positioned on the lower cladding layer; an upper cladding layer positioned on the optical guide layer; and a heater positioned on the upper cladding layer. The lower cladding layer, the optical guide layer, and the upper cladding layer constitute a mesa structure. The optical guide layer has a lower thermal conductivity than the upper cladding layer. An equation W.sub.wgW.sub.mesa3W.sub.wg is satisfied, wherein W.sub.mesa represents a mesa width of the mesa structure, and W.sub.wg represents a width of the optical guide layer. The optical guide layer occupies one-third or more of the mesa width in a width direction of the mesa structure.

A discrete wavelength tunable laser capable of switching between a plurality of lasing channels of different wavelengths, the tunable laser comprising: a semiconductor optical amplifier (SOA); a wavelength demultiplexer (Demux), having a Demux input which receives the output from the SOA, and a plurality of Demux outputs, each Demux output defining a different spatial path for a respective lasing channel; each of the respective lasing channels being within the bandwidth of the SOA; a reflector located within each spatial path for reflecting light of the respective lasing channel; and a lasing suppression mechanism located within each lasing channel; wherein one or more desired lasing channels are selected by application of the lasing suppression mechanism in each spatial path other than the one or more spatial paths corresponding to the one or more desired lasing channels.