A tunable laser system includes a tunable laser to be scanned over a range of frequencies and an interferometer having a plurality of interferometer outputs. At least two interferometer outputs of the plurality of interferometer outputs have a phase difference. A wavelength reference has a spectral feature within the range of frequencies, and the spectral feature does not change in an expected operating environment of the tunable laser. Processing circuitry uses the spectral feature and the plurality of interferometer outputs to produce an absolute measurement of a wavelength of the tunable laser and controls the tunable laser based on a comparison of the absolute measurement of the wavelength of the tunable laser with a setpoint wavelength.

In some implementations, an optical assembly comprises an optical cavity; one or more detectors; and an optical component having an input face and an output face configured to receive an input beam to the input face and to produce one or more primary output beams, and a plurality of secondary output beams from the output face, the secondary output beams resulting from multiple internal reflections within the optical component. At least one of the input face is not perpendicular to the input beam or the output face is not perpendicular to the one or more primary output beams. Each primary output beam is transmitted through the optical cavity perpendicular to at least one surface of the optical cavity, and directed to a respective one of the one or more detectors. Each detector is arranged to exclude at least a portion of each secondary output beam.

The invention provides a wavelength tracking system comprising a wavelength tracking unit and an interferometer system. The wavelength tracking unit has reflection surfaces at stabile positions providing a first reflection path with a first path length and a second reflection path with a second path length. The first path length is substantially larger than the second path length. The interferometer system comprises: a beam splitter to split a light beam in a first measurement beam and a second measurement beam; at least one optic element to guide the first measurement beam, at least partially, along the first reflection path and the second measurement beam, at least partially, along the second reflection path; a first light sensor arranged at an end of the first reflection path to receive the first measurement beam and to provide a first sensor signal on the basis of the first measurement beam; a second light sensor arranged at an end of the second reflection path to receive the second measurement beam and to provide a second sensor signal on the basis of the second measurement beam; and a processing unit to determine a wavelength or change in wavelength on the basis of the first sensor signal and the second sensor signal.

The invention provides a wavelength tracking system comprising a wavelength tracking unit and an interferometer system. The wavelength tracking unit has reflection surfaces at stabile positions providing a first reflection path with a first path length and a second reflection path with a second path length. The first path length is substantially larger than the second path length. The interferometer system comprises: a beam splitter to split a light beam in a first measurement beam and a second measurement beam; at least one optic element to guide the first measurement beam, at least partially, along the first reflection path and the second measurement beam, at least partially, along the second reflection path; a first light sensor arranged at an end of the first reflection path to receive the first measurement beam and to provide a first sensor signal on the basis of the first measurement beam; a second light sensor arranged at an end of the second reflection path to receive the second measurement beam and to provide a second sensor signal on the basis of the second measurement beam; and a processing unit to determine a wavelength or change in wavelength on the basis of the first sensor signal and the second sensor signal.

An optical assembly includes an optical cavity; an output detector; a reference detector; and a plate beam splitter, wherein the plate beam splitter has a first face and a second face, and is configured to form, from an input beam: a first output beam, that passes through the optical cavity and impinges the output detector, a first reference beam that impinges on the reference detector, a second output beam parallel to the first output beam, and a second reference beam parallel to the first reference beam; one of the first output beam or the first reference beam is a reflection of the input beam in the first face of the plate beam splitter; the output detector is configured to exclude at least a portion of the second output beam; and the reference detector is configured to exclude at least a portion of the second reference beam.

A phase modulation structure includes a recording surface including phase angle recording regions in a plurality of calculated element regions corresponding to reconstruction points of an image on a one-to-one basis, each phase angle recording region being formed of a plurality of unit blocks in each of which a phase angle is recorded, the phase angle being calculated based on a phase that is a sum of a plurality of phases of light from the corresponding reconstruction points; and a representative area that is one of divisions of the calculated element region, the representative area being obtained by radially dividing the calculated element region centered on a point on the calculated element region, the point being obtained by extending a normal line from the corresponding reconstruction point to the calculated element region on the recording surface.

Described are various configurations of integrated wavelength lockers including asymmetric Mach-Zehnder interferometers (AMZIs) and associated detectors. Various embodiments provide improved wavelength-locking accuracy by using an active tuning element in the AMZI to achieve an operational position with high locking sensitivity, a coherent receiver to reduce the frequency-dependence of the locking sensitivity, and/or a temperature sensor and/or strain gauge to computationally correct for the effect of temperature or strain changes.

An interferometer for use in remote sensing systems includes a beam splitter that separates an input wave into a reflected wave, which travels along a first optical path within an upper interferometer arm, and a transmitted wave, which travels along a second optical path within a lower interferometer arm. The reflected and transmitted waves are subsequently recombined by the beam splitter for imaging onto a sensor. A highly dispersive element is incorporated into at least one of the pair of interferometer arms. Due to anomalous dispersion, a frequency shift in a wave transmitted through a dispersive element changes the optical path length within its corresponding arm. As a result, the recombined wave produces an interference pattern with a measurable phase change that can be utilized to calculate the original frequency shift in the input wave with great precision and potential sub-Hertz sensitivity.

In some implementations, an optical assembly comprises an optical cavity; one or more detectors; and an optical component having an input face and an output face configured to receive an input beam to the input face and to produce one or more primary output beams, and a plurality of secondary output beams from the output face, the secondary output beams resulting from multiple internal reflections within the optical component. At least one of the input face is not perpendicular to the input beam or the output face is not perpendicular to the one or more primary output beams. Each primary output beam is transmitted through the optical cavity perpendicular to at least one surface of the optical cavity, and directed to a respective one of the one or more detectors. Each detector is arranged to exclude at least a portion of each secondary output beam.

According to the present disclosure, there is provided a device (2) and a method for measuring a wavelength for a laser device. The device (2) for measuring a wavelength for a laser device includes: a first optical path assembly and a second optical path assembly. The first optical path assembly and the second optical path assembly constitute a laser wavelength measurement optical path. The second optical path assembly includes: an FP etalon assembly (11) and an optical classifier (13). The homogenized laser beam passes through the FP etalon assembly (11) to generate an interference fringe. The optical classifier (13) is arranged after the FP etalon assembly (11) in the laser wavelength measurement optical path, and configured to deflect the laser beam passing through the FP etalon assembly (11). The FP etalon assembly (11) allows two FP etalons (FP1, FP2) to share the same optical path for an interference imaging, and therefore a compact structure having a small volume, a simple design, and a high stability are achieved. In cooperation with the optical classifier (13), a precise measurement for a laser wavelength may be achieved, and at the same time a wavelength measurement range is large. It is suitable for an online measurement for a laser wavelength and a corresponding closed-loop control feedback.