Various sensors, including particulate matter sensors, are described. One particulate matter sensor includes a self-mixing interferometry sensor and a set of one or more optical elements. The set of one or more optical elements is positioned to receive an optical emission of the self-mixing interferometry sensor, split the optical emission into multiple beams, and direct each beam of the multiple beams in a different direction. The self-mixing interferometry sensor is configured to generate particle speed information for particles passing through respective measurement regions of the multiple beams.

Disclosed herein are self-mixing interferometry (SMI) sensors, such as may include vertical cavity surface emitting laser (VCSEL) diodes and resonance cavity photodetectors (RCPDs). Structures for the VCSEL diodes and RCPDs are disclosed. In some embodiments, a VCSEL diode and an RCPD are laterally adjacent and formed from a common set of semiconductor layers epitaxially formed on a common substrate. In some embodiments, a first and a second VCSEL diode are laterally adjacent and formed from a common set of semiconductor layers epitaxially formed on a common substrate, and an RCPD is formed on the second VCSEL diode. In some embodiments, a VCSEL diode may include two quantum well layers, with a tunnel junction layer between them. In some embodiments, an RCPD may be vertically integrated with a VCSEL diode.

An integrated photonic circulator is described, an application of which may be deployed on a chip-scale light-detection and ranging (LiDAR) device. The photonic circulator includes a micro-ring resonator waveguide, a heating element, first and second bus waveguides, a magneto-optic substrate, a magneto-optic element, a magnetic ring disposed on a photonic substrate, and a silicon substrate. The first and second bus waveguides are coupled to the micro-ring resonator waveguide, and the micro-ring resonator waveguide is affixed onto a first side of the photonic substrate. The magneto-optic element and the magneto-optic substrate are arranged on the micro-ring resonator waveguide, the magnetic ring is affixed to the magneto-optic substrate, the heating element is affixed to the photonic substrate, the photonic substrate is affixed to the silicon substrate, and the magnetic ring is concentric with the micro-ring resonator.

An architecture for a chip-scale optical phased array-based scanning frequency-modulated continuous wave (FMCW) Light-detection and ranging (LiDAR) device is described. The LiDAR device includes a laser, a transmit optical splitter, an optical circulator, photodetectors, and an optical phased array. The laser, the transmit optical splitter, the optical circulator, the photodetectors, and the optical phased array are arranged as a chip-scale package on a single semiconductor substrate. The laser generates a first light beam that is transmitted to the optical phased array aperture via the transmit optical splitter, the optical circulator, and the optical phased array. A fraction of the first light beam is transmitted to the photodetectors via the transmit optical splitter to serve as the optical local oscillator (LO), the aperture of the optical phased array captures a second light beam that is transmitted to the photodetectors via the optical phased array and the optical circulator.

An apparatus including a light detection and ranging (LiDAR) antenna of an optical phased array includes a silicon-on-insulator substrate including a silicon wire waveguide embedded within the substrate and a grating layer disposed over the substrate. The grating layer includes a silicon nitride layer coating the silicon-on-insulator substrate and including a plurality of etchings formed in a direction perpendicular to a longitudinal axis of the optical phased array and a silicon oxynitride layer coating the silicon nitride layer and filling the etchings. The etchings are relatively thin in the direction of the longitudinal axis of the optical phased array at a first end of the optical antenna and are relatively thick in the direction of the longitudinal axis at a second end. The etchings gradually increase in thickness between the first end of the optical phased array and the second end of the optical antenna.

An optical proximity sensor includes a first vertical cavity surface-emitting laser configured for self-mixing interferometry to determine distance to and/or velocity of an object. The optical proximity sensor also includes a second vertical cavity surface-emitting laser configured for self-mixing interferometry to determine whether any variation in a fixed distance has occurred. The optical proximity sensor leverages output from the second vertical cavity surface-emitting laser to calibrate output from the second vertical cavity surface-emitting laser to eliminate and/or mitigate environmental effects, such as temperature changes.

A circuit module of a LIDAR system includes a transmit optical coupler, a first optical mixer, a second optical mixer, and an optical switch. The transmit optical coupler emits a transmit beam in response to a first portion of an optical signal. The transmit beam reflects from an object back to the circuit module as a returning beam. The first optical mixer is disposed on a first optical path to receive the returning beam in response to the returning beam having a first displacement. The second optical mixer is disposed on a second optical path to receive the returning beam in response to the returning beam having a second displacement. The optical switch is coupled to provide a particular portion of the optical signal to the first optical mixer or the second optical mixer based on whether the returning beam has the first displacement or the second displacement.

A method and an apparatus for measuring the properties of a liquid that exploit the power modulation a laser light beam undergoes due to the retro-reflection of the laser light beam itself towards the laser cavity from which the laser is generated when this laser light is directed towards a transparent conduit through which the liquid for which the properties are to be measured flows, where this power modulation is detected by at least one photodiode arranged downstream of the transparent conduit.

A light detection and ranging (LIDAR) system includes a first receive optical coupler, a second receive optical coupler, a first optical mixer, a second optical mixer, and an optical switch. The first optical mixer is configured to receive a first receive signal from the first receive optical coupler. The second optical mixer is configured to receive a second receive signal from the second receive optical coupler. The optical switch is configured to switch an oscillator light signal between the first optical mixer and the second optical mixer.

The invention relates to a device and to a method for measuring an object that moves in a direction of movement along a movement axis, wherein the device has a first sensor arrangement having a first SMI sensor and a second SMI sensor, wherein the SMI sensors irradiate measurement light beams in opposite directions along a movement axis. A control and evaluation unit is configured to receive first and second measured signals, to determine a speed of the object along the movement axis from at least one of the measured signals, to detect a first characteristic change of the second measured signal, a first characteristic change of the first measured signal, and a second characteristic change of the first measured signal, and to determine an object length of the object along the movement axis.