A light source device that includes a first resistor that is connected to a given potential, a light emitting element that is connected in series to the first resistor, a second resistor that is connected to the given potential, and a first current source that is connected in series to the second resistor and that is configured to supply a freely-selected current within a given range are included. A first voltage is taken out from a first connection part where the first resistor and the light emitting element are connected to each other and a second voltage is taken out from a second connection part where the second resistor and the first current source are connected to each other.

One or more embodiments are directed to laser circuits, methods and devices that include a current sensing circuit for sensing a lasing current provided to a laser diode or device. One embodiment is directed to a circuit that includes a laser device, a switching device, a current sensing circuit and a current comparator. The switching device has a first conduction terminal coupled to the laser device and a second conduction terminal coupled to a supply voltage. The switching device is configured to operatively supply a lasing current to the laser device. The current sensing circuit is coupled to the switching device and is configured to generate a sense current representative of the lasing current. The current comparator is configured to receive the sense current from the current sensing circuit, to receive a reference current, and to compare the sense current with the reference current. If the sense current exceeds the reference current, the current comparator is configured to output an overcurrent detection signal.

Resonant recharge for synchronous pulsed laser operation. At least one example embodiment is a method of activating a laser diode, the method including: creating an oscillating voltage at a node between an inductor and a first capacitor, the oscillating voltage having a positive half-cycle and a negative half-cycle; charging a firing capacitor during a positive half-cycle of the oscillating voltage, the charging from the node and through a diode; and driving, during a negative half-cycle of the oscillating voltage, a pulse of current from the firing capacitance through a laser diode.

A pulsed laser diode driver includes an inductor having a first terminal configured to receive a source voltage. A source capacitor has a first terminal connected to the first terminal of the inductor to provide the source voltage. A bypass switch has a drain node connected to a second terminal of the inductor and to a first terminal of a bypass capacitor. A laser diode has an anode connected to the second terminal of the inductor and to the drain node of the bypass switch. A laser diode switch has a drain node connected to a cathode of the laser diode. The laser diode switch and the bypass switch control a current flow through the inductor to produce a high-current pulse through the laser diode, the high-current pulse corresponding to a peak current of a resonant waveform developed at the anode of the laser diode.

A method of operating a laser includes generating a first signal having a first frequency, and generating a second signal having a second frequency. The first frequency varies in accord with an amplitude of a drive current provided to a laser. The method further includes incrementing or decrementing a count responsive to a relationship between the first frequency and the second frequency; determining the count satisfies a threshold count; and modifying operation of the laser when the count satisfies the threshold count.

By eliminating the need to use a high-precision clock in pulse width detection for pulse width adjustment in a case where light-emitting elements as vertical-cavity surface-emitting lasers are pulse-driven, circuit configuration is simplified and cost is reduced. A laser drive apparatus according to the present technology includes a drive circuit unit that drives light-emitting elements as vertical-cavity surface-emitting lasers to emit light on the basis of a pulse signal, a pulse width detection unit that detects the pulse width of the pulse signal on the basis of the potential of a capacitor when the capacitor is charged on the basis of the pulse signal, and a control unit that performs control so that the pulse width is adjusted on the basis of a detection result of the pulse width.

A laser diode driving method that reliably maintains average optical power and extinction ratio is disclosed. The present invention for laser driving uses a preloaded laser diode characteristic curve/table and/or mathematical equations to create a programmable bias and modulation current range. This ensures stable closed-loop operation and prevents system failure if the feedback signal is impaired by confining the operation of the laser diode to a normal operating range.

A machine learning apparatus includes: a state amount observation unit that observes a state amount of a laser apparatus including output data from an optical output detection unit, an optical output characteristic recording unit that records history of a driving current and optical output characteristics, and a driving condition/state amount recording unit that records history of a LD unit driving condition data and the state amount; an operation result acquisition unit that acquires a prediction result of characteristics and measurement result of optical output characteristics of the LD unit; a learning unit that learns the LD unit driving condition data with the state amount and the results of the LD unit driving condition data; and a decision-making unit that decides, from a learning result, the LD unit driving condition data.

An electronic device may have control circuitry and input-output components. The input-output components may include audio components, sensors, and other devices. A proximity sensor may supply the control circuitry with proximity sensor data. The control circuitry may adjust the audio components or take other suitable action in response to proximity sensor readings from the proximity sensor. The proximity sensor may have a light source such as an infrared laser diode and a light detector that measures a reflected portion of infrared light pulses emitted by the infrared laser diode. The control circuitry may include circuitry for safely producing pulses of emitted light with the light source. This circuitry may include a signal generator that produces ramped pulses, a differentiator that differentiates the ramped pulses to produce differentiated pulses, and an output driver that produces current pulses for the light source based on the differentiated pulses.

A method and a device is provided driving an optical laser diode (710, 711) during operation in an optical communication network, by determining a laser transfer function (741, 742) during operation of the laser diode (710, 711) and providing a control signal (750, 749) for driving the laser diode (710, 711) according to the laser transfer function (741, 742). Further, a method for driving a first and a second optical laser diode during operation in an optical communication network is provided. Furthermore, an optical amplifier and a communication system is suggested.