A driver circuit may include an optical emitter, a capacitive element, and an inductive element. The driver circuit may include a first switch that, in a closed state, is to cause charging of the inductive element, and when transitioning from the closed state to an open state is to cause discharging of the inductive element to charge the capacitive element. The driver circuit may include a second switch that in a closed state is to cause discharging of the capacitive element to provide an electrical pulse to the optical emitter. The driver circuit may include a signal generator configured to generate a first signal for controlling the open state and the closed state of the first switch, and a pulse shortening element configured to shorten a pulse width of the first signal to generate a second signal for controlling the open state and the closed state of the second switch.

A driver circuit may include an optical emitter, a capacitive element, and an inductive element. The driver circuit may include a first switch that, in a closed state, is to cause charging of the inductive element, and when transitioning from the closed state to an open state is to cause discharging of the inductive element to charge the capacitive element. The driver circuit may include a second switch that in a closed state is to cause discharging of the capacitive element to provide an electrical pulse to the optical emitter. The driver circuit may include a signal generator configured to generate a first signal for controlling the open state and the closed state of the first switch, and a pulse shortening element configured to shorten a pulse width of the first signal to generate a second signal for controlling the open state and the closed state of the second switch.

A light-emitting device includes a semiconductor diode structure, a surface-lattice-mode (SLR) structure against the back of the diode structure, and a reflector against the back of the SLR structure. The diode structure includes first and second doped semiconductor layers and an active layer between them; the active layer emits output light at a nominal emission vacuum wavelength λ.sub.0 to propagate within the diode structure. The SLR structure includes an index-matched layer, a lower-index layer, and scattering elements, and is in near-field proximity to the active layer relative to λ.sub.0. At least a portion of the output light, propagating perpendicularly within the diode structure relative to a device exit surface, exits the diode structure as device output light. The scattering elements redirect output light propagating within the device, including in laterally propagating surface-lattice-resonance modes supported by the SLR structure, to propagate perpendicularly toward the device exit surface.

To provide a light-emitting apparatus capable of suitably controlling light emitted from a light-emitting element. A light-emitting apparatus according to the present disclosure includes: a substrate; a plurality of light-emitting elements which are provided on a side of a first surface of the substrate; and an optical element which is provided on a side of a second surface of the substrate and into which light emitted from the plurality of light-emitting elements is incident, wherein the optical element includes a liquid crystal layer which is configured to function as a lens.

Sensing Method and Sensor System A sensing method comprises using a vertical cavity surface emitting laser (VCSEL) to oscillate and emit a laser beam. A diaphragm is used to reflect a portion of the laser beam back into the VCSEL. This method can be referred as self mixing interferometry. A current or voltage at the VCSEL is monitored, and is used to sense movement of the diaphragm. This allows a property external to the VCSEL to be sensed without using a photo-detector.

In various examples, a head-mountable display (“HMD”) may include a light source to emit light across a target region of a wearer, a light sensor, and a circuitry operably coupled with the light source and the light sensor. The circuitry may operate the light source to periodically emit light across the light sensor. Based on a determination that a time interval since the circuitry last received a signal from the light sensor satisfies a threshold, the circuitry may trigger a remedial action to cause the light source to cease emission of light across the target region of the wearer.

III-Nitride layers having spatially controlled regions or domains of porosities therein with tunable optical, electrical, and thermal properties are described herein. Also disclosed are methods for preparing and using such III-nitride layers.

A light emitting device according to an embodiment of the present disclosure includes: a substrate; a first contact layer; a buffer layer in which at least any of a carrier concentration, a material composition, and a composition ratio is different from that of the first contact layer; and a semiconductor stacked body. The substrate has a first surface and a second surface that are opposed to each other. The first contact layer is stacked on the first surface of the substrate. The buffer layer is stacked on the first contact layer. The semiconductor stacked body is stacked above the first surface of the substrate with the first contact layer and the buffer layer interposed in between. The semiconductor stacked body has a light emitting region configured to emit laser light.

A MEMS tunable VCSEL includes a membrane device having a mirror and a distal-side electrostatic cavity for displacing the mirror to increase a size of an optical cavity. A VCSEL device includes an active region for amplifying light. Then, one or more proximal-side electrostatic cavities are defined between the VCSEL device and the membrane device and used to displace the mirror to decrease a size of an optical cavity.

A MEMS tunable VCSEL includes a membrane device having a mirror and a distal-side electrostatic cavity for displacing the mirror to increase a size of an optical cavity. A VCSEL device includes an active region for amplifying light. Then, one or more proximal-side electrostatic cavities are defined between the VCSEL device and the membrane device and used to displace the mirror to decrease a size of an optical cavity.