It is provided a method for fabricating an electroabsorption modulated laser comprising generating a single mode laser section and an electroabsorption modulator section, comprising fabricating at least one n-doped layer of the laser section and at least one n-doped layer of the modulator section; generating an isolating section for electrically isolating at least the n-doped layer of the laser section and the n-doped layer of the modulator section from one another. Generating the isolating section comprises epitaxially growing at least one isolating layer and structuring the isolating layer before the generation of the n-doped layer of the laser section and the n-doped layer of the modulator section.

A method of controlling a wavelength tunable laser device including a substrate and a plurality of semiconductor elements. A plurality of first optical waveguides are provided in the substrate. The plurality of semiconductor elements are formed of a III-V group compound semiconductor, have optical gains, and are optically coupled to the plurality of first optical waveguides of the substrate. Wavelengths with which gains of the plurality of semiconductor elements reach peaks differ from one another. The method includes, selecting a first optical waveguide configured to transmit light from among the plurality of first optical waveguides, and causing light to be emitted from a first semiconductor element that is a semiconductor element optically coupled to the selected first optical waveguide among the plurality of semiconductor elements.

An analyzer includes a quantum cascade laser that converts a cyclic driving signal to laser light; an optical receiver that receives the laser light having passed through a sample and outputs a detected signal depending on intensity of the laser light; and a data calculation portion that outputs information representing absorption characteristics of the sample. The data calculation portion includes a delaying unit that produces a time-delayed waveform by applying a time delay to a reference driving signal; an adding unit that produces a symmetrical waveform by adding the time-delayed waveform and the detected signal; a time inversion unit that produces a time-inverted waveform by time-inverting the symmetrical waveform; and a subtracting unit that produces a waveform difference between the time-inverted waveform and the symmetrical waveform. The data calculation portion repeatedly calculates the waveform difference by changing the time delay until the waveform difference is minimized.

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.

There is disclosed a DBR laser and a method of use. The DBR laser comprises a phase section in a cavity of the DBR laser and configured to adjust an optical path length of the cavity. A DBR section comprises a frequency tuning system configured 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; and to cause the frequency tuning system to adjust the Bragg frequency of the DBR section in order to reduce said deviation, or cause the phase section to adjust the optical path length of the cavity in order to reduce said deviation.

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 semiconductor laser source wherein a waveguide in which a filter is produced is made of a material that is less sensitive to temperature. The laser source also includes a tuning device able to shift the possible resonant wavelengths .sub.Rj of a Fabry-Prot optical cavity in response to an electrical controlling signal, a sensor able to measure a physical quantity representative of the difference between a central wavelength .sub.Cf of the filter and one of the possible wavelengths .sub.Rj, and an electronic circuit able to generate, depending on the physical quantity measured by the sensor, the electrical signal controlling the tuning device in order to keep one wavelength .sub.Rj at the center of each passband of the filter that selects an emission wavelength .sub.Li of the laser source.

An optical source is presented comprising a laser and an optical filter in optical communication with the laser. The laser comprises an optical gain section; and an optical phase control section. The filter is configured to receive light output from the laser and filter the said received light. The source is configured to input the filtered light back into the laser.

An external resonance type laser module includes a quantum cascade laser, a MEMS diffraction grating configured to include a diffraction/reflection portion configured to diffract and reflect light emitted from the quantum cascade laser and return a part of the light to the quantum cascade laser by swinging the diffraction/reflection portion, and a controller configured to control driving of the quantum cascade laser. The controller is configured to pulse-drive the quantum cascade laser such that pulsed light of a second frequency higher than a first frequency at which the diffraction/reflection portion swings is emitted from the quantum cascade laser and a phase of the pulsed light changes each time the diffraction/reflection portion reciprocates m times (m: an integer of 1 or more).