Various implementations of the invention compensate for “phase wandering” in tunable laser sources. Phase wandering may negatively impact a performance of a lidar system that employ such laser sources, typically by reducing a coherence length/range of the lidar system, an effective bandwidth of the lidar system, a sensitivity of the lidar system, etc. Some implementations of the invention compensate for phase wandering near the laser source and before the output of the laser is directed toward a target. Some implementations of the invention compensate for phase wandering in the target signal (i.e., the output of the laser that is incident on and reflected back from the target). Some implementations of the invention compensate for phase wandering at the laser source and in the target signal.

Configurations for a diffraction grating design that mitigates thermal wavelength shifts and corresponding methods thereof are disclosed. The wavelength stability monitoring system may include a planar waveguide that receives input light directed toward a diffraction grating. The diffraction grating may reflect the light back through the planar waveguide and to one or more detectors. The planar waveguide may include multiple materials, such as a first material and a second athermal material that is adjacent to the first material. The athermal material may mitigate thermal wavelength shifts of the light. The design of the athermal material may include targeting a ratio of the input and output path lengths across sets of input and output angles of light that pass through the first material and the second athermal material. In some examples, the output waveguides may be positioned to receive leakage modes of light.

The present invention relates to a system and method for reconstruction of temporal wavefront changes for use in an optical system comprising: measuring the distribution function of the light intensity, e.g. the two-dimensional distribution function of the light intensity, in at least two different images taken at different times, wherein said images are taken in at least one optical plane, e.g. the same optical plane, of the optical system.

The present invention relates to a system and method for reconstruction of temporal wavefront changes for use in an optical system comprising: measuring the distribution function of the light intensity, e.g. the two-dimensional distribution function of the light intensity, in at least two different images taken at different times, wherein said images are taken in at least one optical plane, e.g. the same optical plane, of the optical system.

A distance measurement device including a pixel array and a cover layer is provided. The cover layer is covered on the pixel array. The cover layer includes a first cover pattern covering on a first area of a plurality of first pixels and a second cover pattern covering on a second area of a plurality of second pixels. The first area and the second area are rectangles of mirror symmetry along a first direction.

A distance measurement device including a pixel array and a cover layer is provided. The cover layer is covered on the pixel array. The cover layer includes a first cover pattern covering on a first area of a plurality of first pixels and a second cover pattern covering on a second area of a plurality of second pixels. The first area and the second area are rectangles of mirror symmetry along a first direction.

An optical modulator uses an optoelectronic phase comparator configured to provide, in the form of an electrical signal, a measure of a phase difference between two optical waves. The phase comparator includes an optical directional coupler having two coupled channels respectively defining two optical inputs for receiving the two optical waves to be compared. Two photodiodes are configured to respectively receive the optical output powers of the two channels of the directional coupler. An electrical circuit is configured to supply, as a measure of the optical phase shift, an electrical signal proportional to the difference between the electrical signals produced by the two photodiodes.

An optical modulator uses an optoelectronic phase comparator configured to provide, in the form of an electrical signal, a measure of a phase difference between two optical waves. The phase comparator includes an optical directional coupler having two coupled channels respectively defining two optical inputs for receiving the two optical waves to be compared. Two photodiodes are configured to respectively receive the optical output powers of the two channels of the directional coupler. An electrical circuit is configured to supply, as a measure of the optical phase shift, an electrical signal proportional to the difference between the electrical signals produced by the two photodiodes.

The invention concerns a method for characterizing mode group properties of multimodal light traveling through an optical component, comprising: launching a reference pulse of light with a wavelength λ.sub.t from a light source into said optical component, collecting light signal output by said optical component into a Mode Group Separating optical fiber; detecting light signal output by said Mode Group Separating optical fiber. The Mode Group Separating optical fiber is a multimode fiber with an α-profile graded index core with an α-value chosen such that said fiber satisfies the following criterion at the wavelength λ.sub.t: $\frac{.Math.\mathrm{\Delta \tau }.Math..L}{\Delta T_{\mathrm{REF}}}>4$
where: Δτ is a time delay difference between consecutive mode groups; L is a length of said fiber; ΔT.sub.REF is a Full Width at Quarter Maximum of said reference pulse.

The invention concerns a method for characterizing mode group properties of multimodal light traveling through an optical component, comprising: launching a reference pulse of light with a wavelength λ.sub.t from a light source into said optical component, collecting light signal output by said optical component into a Mode Group Separating optical fiber; detecting light signal output by said Mode Group Separating optical fiber. The Mode Group Separating optical fiber is a multimode fiber with an α-profile graded index core with an α-value chosen such that said fiber satisfies the following criterion at the wavelength λ.sub.t: $\frac{.Math.\mathrm{\Delta \tau }.Math..L}{\Delta T_{\mathrm{REF}}}>4$
where: Δτ is a time delay difference between consecutive mode groups; L is a length of said fiber; ΔT.sub.REF is a Full Width at Quarter Maximum of said reference pulse.