A head-mounted device may have a head-mounted housing and optical components supported by the head-mounted housing. The optical components may include cameras, movable optical modules, and other components. Each optical module may include a display that displays an image and a lens that provides the image to a corresponding eye box. Optical self-mixing sensors may be included in the optical modules and other portions of the head-mounted device to measure changes in optical component position. In response to detecting a change in optical component position, actuators in the device may be adjusted to move the optical components or other action may be taken to compensate for the change.

A system and method for generating, enhancing, and detecting the amplitude and phase modulation of a laser under a condition of self-mixing is provided. The system may comprise a laser and a detector to extract the characteristic self-mix signal, which is then interpreted using algorithms implemented in hardware or software. In the case of the laser being a Vertical Cavity Surface Emitting laser (VCSEL), the output signal can be detected by monitoring the surface light emission by means of a beam splitter, or in some embodiments as emission from the bottom surface of the laser. In some embodiments, the system may further comprise a wavelength filter such as an etalon in the signal path.

A portable electronic device is operable in a particulate matter concentration mode where the portable electronic device uses a self-mixing interferometry sensor to emit a beam of coherent light from an optical resonant cavity, receive a reflection or backscatter of the beam into the optical resonant cavity, produce a self-mixing signal resulting from a reflection or backscatter of the beam of coherent light, and determine a particle velocity and/or particulate matter concentration using the self-mixing signal. The portable electronic device is also operable in an absolute distance mode where the portable electronic device determines whether or not an absolute distance determined using the self-mixing signal is outside or within a particulate sensing volume associated with the beam of coherent light. If not, the portable electronic device may determine a contamination and/or obstruction is present that may result in inaccurate particle velocity and/or particulate matter concentration determination.

Disclosed herein are electronic devices having touch input surfaces. A user's touch input or press on the touch input surface is detected using a set of lasers, such as vertical-cavity surface-emitting lasers (VCSELs) that emit beams of light toward the touch input surface. The user's touch causes changes in the self-mixing interference within the VCSEL of the emitted light with reflected light, such as from the touch input surface. Deflection and movement (e.g., drag motion) of the user's touch is determined from detected changes in the VCSELs' operation due to the self-mixing interference.

An eye-tracking device includes an optical device that includes a light source with an optical cavity and a light sensor. The light source is positioned to output coherent light toward an eye of a user and receive at least a portion of the coherent light back from the eye of the user as feedback light. The feedback light enters the optical cavity and causes modulation of an intensity of the coherent light. The light sensor is optically coupled with the light source for detecting the modulated intensity of the coherent light and generating one or more signals based on the detected intensity of the coherent light. The eye-tracking device also includes one or more processors that are coupled to the optical device for determining, from the one or more signals, movement information of the eye. A method of detecting movement of an eye using the eye-tracking device is also disclosed.

A device includes an electronic display, a cover through which the electronic display projects an image, and an array of SMI sensors. The array of SMI sensors is positioned on a same side of the cover as the electronic display. Each SMI sensor is configured to emit electromagnetic radiation toward a respective portion of: an interior surface of the cover, or a surface of a component of the device attached to the cover; and generate a respective SMI output including information indicative of vibration of the respective portion of the cover or the component. The device also includes circuitry configured to characterize a vibratory waveform impinging on the device. The vibratory waveform is characterized using at least two of the SMI outputs.

Disclosed herein are electronic devices having touch input surfaces. A user's touch input or press on the touch input surface is detected using a set of lasers, such as vertical-cavity surface-emitting lasers (VCSELs) that emit beams of light toward the touch input surface. The user's touch causes changes in the self-mixing interference within the VCSEL of the emitted light with reflected light, such as from the touch input surface. Deflection and movement (e.g., drag motion) of the user's touch is determined from detected changes in the VCSELs' operation due to the self-mixing interference.

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 eyebox region is illuminated with first coherent light and second coherent light having a different wavelength than the first coherent light. A first self-mixed interferometer (SMI) signal is generated in response to first feedback light received back from the eyebox region. A second SMI signal is generated in response to second feedback light received back from the eyebox region. Eye data is generated in response to at least the first SMI signal and the second SMI signal.

Disclosed herein are wearable devices, their configurations, and methods of operation that use self-mixing interferometry signals of a self-mixing interferometry sensor to recognize user inputs. The user inputs may include voiced commands or silent gesture commands. The devices may be wearable on the user's head, with the self-mixing interferometry sensor configured to direct a beam of light toward a location on the user's head. Skin deformations or vibrations at the location may be caused by the user's speech or the user's silent gestures and recognized using the self-mixing interferometry signal. The self-mixing interferometry signals may be used for bioauthentication and/or audio conditioning of received sound or voice inputs to a microphone.