A laser diode driver circuit is provided that has a loop including a laser diode, a drive capacitor for storing drive charge, and a switch element, a first inductor coupled in series with the laser diode, a parallel capacitor coupled in parallel with a series circuit composed of the laser diode and the first inductor, and a first diode coupled in parallel with the series circuit in opposite polarity to the laser diode.

The disclosed light source device includes a light emitting element including a first reflector, a second reflector, and a resonator spacer portion provided between the first reflector and the second reflector and including an active layer, and emits a first light as a laser beam and a second light as a spontaneous emission light, a light receiving element that determines an amount of the second light, and a determination unit that determines a timing at which the first light oscillates based on a decrease in the amount of the second light determined by the light receiving element.

A method and apparatus provide for determining a temperature at a junction of a laser diode when the laser diode is operated in a lasing state that facilitates heat-assisted magnetic recording, comparing the junction temperature and an injection current supplied during the lasing state to stored combinations of junction temperature and injection current, and determining a likelihood of mode hopping occurring for the laser diode during the lasing state based on the comparison to stored combinations of junction temperature and injection current.

A driver circuit includes a fly capacitor with a first end and a second end. The driver circuit includes a laser diode having an anode and a cathode. The driver circuit is configured to operate in first and second operating states. The anode is coupled to the first end of the fly capacitor. In the first operating state, the cathode is coupled to a first voltage supply node, the first end of the fly capacitor is coupled to a second voltage supply node, and the second end of the fly capacitor is coupled to a first reference terminal. In the second operating state, the cathode is coupled to a second reference terminal and decoupled from the first voltage supply node, the first end of the fly capacitor is decoupled from the second voltage supply node, and the second end of the fly capacitor is coupled to a third reference terminal.

A light emitting device includes a wiring board having a first wiring layer and a second wiring layer adjacent to the first wiring layer via an insulating layer, and a laser having a cathode electrode and an anode electrode, mounted on the wiring board, and driven through low-side driving. The first wiring layer includes a cathode wire connected to the cathode electrode, an anode wire connected to the anode electrode, and a first reference potential wire connected to a reference potential. The second wiring layer includes a second reference potential wire connected to the reference potential. An area of an overlap between the second reference potential wire and the anode wire is larger than an area of an overlap between the second reference potential wire and the first reference potential wire.

The present disclosure provides a narrow-pulse-width pulse laser, including a circuit substrate, a laser chip, one or more capacitors, and a field effect transistor. Each of the field effect transistor, the capacitor, and the laser chip is electrically connected to the circuit substrate. The capacitors are arranged between the field effect transistor and the laser chip along an extension direction of a gap between the field effect transistor and the laser chip. The circuit substrate may include a first conductor layer; a second conductor layer; and an insulating layer arranged between the first conductor layer and the second conductor layer, wherein the first conductor layer and the second conductor layer are electrically connected through a via hole in the insulating layer.

A light-emitting component includes a substrate, plural light-emitting elements that are disposed on the substrate and emit light in a direction intersecting with a surface of the substrate, and a gate electrode that is electrically connected to each of the plural light-emitting elements and that performs control so that the plural light-emitting elements are switched ON/OFF together. A distance between each of the plural light-emitting elements and the gate electrode is smaller than a largest distance between two light-emitting elements among the plural light-emitting elements.

A light-emitting component includes a substrate and plural light-emitting elements that are disposed on the substrate and emit light in a direction intersecting with a surface of the substrate and that are switched ON/OFF together. The plural light-emitting elements include a gate layer, the gate layer performing control so that the plural light-emitting elements are switched ON/OFF together, a film thickness of the gate layer being greater than a wavelength of light emitted from the plural light-emitting elements.

A light-emitting component includes a substrate, plural light-emitting elements that are disposed on the substrate and emit light in a direction intersecting with a surface of the substrate, and a gate electrode that is electrically connected to each of the plural light-emitting elements and performs control so that the plural light-emitting elements are switched ON/OFF together. Plural holes are disposed around each of the plural light-emitting elements.

A light emitting device includes: a resonant circuit that is provided with an electric accumulator accumulating electric charge and generates resonance; a light emitting element that emits light in a case where a current in the resonant circuit is supplied; and a first switching unit that is connected to a circuit between a power supply that supplies electric charge to the electric accumulator and the resonant circuit, and switches between a conduction state in which a circuit from the power supply to the resonant circuit is conductive and a non-conduction state in which the circuit is not conductive.