Abstract: According to aspects of an embodiment of the disclosed subject matter, a line narrowed high average power high pulse repetition laser micro-photolithography light source bandwidth control method and apparatus are disclosed which may comprise a bandwidth metrology module measuring the bandwidth of a laser output flight pulse beam pulse produced by the light source and providing a bandwidth measurement; a bandwidth error signal generator receiving the bandwidth measurement and a bandwidth setpoint and providing a bandwidth error signal; an active bandwidth controller providing a fine bandwidth correction actuator signal and a coarse bandwidth correction actuator signal responsive to the bandwidth error. The fine bandwidth correction actuator and the coarse bandwidth correction actuator each may induce a respective modification of the light source behavior that reduces bandwidth error. The coarse and fine bandwidth correction actuators each may comprise a plurality of bandwidth correction actuators.

Abstract: A method and apparatus are disclosed for controlling bandwidth in a multi-portion laser system comprising a first line narrowed oscillator laser system portion providing a line narrowed seed pulse to an amplifier laser system portion, may comprise utilizing a timing difference curve defining a relationship between a first laser system operating parameter other than bandwidth and the timing difference and also a desired point on the curve defining a desired timing difference, wherein each unique operating point on the curve corresponds to a respective bandwidth value; determining an actual offset from the timing difference at the desired point on the curve to an actual operating point on the curve; determining an error between the actual offset and a desired offset corresponding to a desired bandwidth; modifying the firing differential timing to remove the error between the actual offset and the desired offset.

Abstract: Circuits and methods for damping out parasitic resonance within a packaged integrated circuit (IC) are provided. A conductive path including a resistor and a conductor is added in parallel with a conductive path that provides power to components within a die of the packaged IC. When implemented in a packaged laser driver integrated circuit (IC), a conductive path including a resistor and a conductor in placed in parallel with a conductive path that provides a laser driver output, of the packaged laser driver IC, to a laser diode. This abstract is not intended to be a complete description of the various embodiments of the present invention.

Abstract: A control system for a laser source driven by a direct current drive voltage includes a system control board, a laser driver, and a power stabilizing circuit. The system control board is configured to output a control signal based on input data. The laser driver is coupled to the laser source and to the system control board. The laser driver is configured to drive the laser source with the drive voltage to generate a laser beam modulated according to the control signal. The power stabilizing circuit is configured to regulate the drive voltage to a given constant level. The power stabilizing circuit includes a first circuit and a second circuit. The first circuit is configured to boost the drive voltage to a level exceeding the given constant level. The second circuit is configured to limit the boosted drive voltage to the given constant level.

Abstract: A laser projector including a green diode pumped microchip laser module projecting a green laser beam, an optical sensor receiving the laser beam, a power control circuit for the green diode pumped microchip laser module receiving a signal from the optical sensor relative to the power output of the laser beam, and control electronics receiving the signal from the optical sensor connected to the power control circuit modulating the power output of the green diode pumped microchip laser module to maintain a substantially constant power output from the green diode pumped microchip laser module.

Abstract: A method and apparatus are disclosed for controlling bandwidth in a multi-portion laser system comprising a first line narrowed oscillator laser system portion providing a line narrowed seed pulse to an amplifier laser system portion, may comprise utilizing a timing difference curve defining a relationship between a first laser system operating parameter other than bandwidth and the timing difference and also a desired point on the curve defining a desired timing difference, wherein each unique operating point on the curve corresponds to a respective bandwidth value; determining an actual offset from the timing difference at the desired point on the curve to an actual operating point on the curve; determining an error between the actual offset and a desired offset corresponding to a desired bandwidth; modifying the firing differential timing to remove the error between the actual offset and the desired offset.

Abstract: A method for a laser system to compensate a variability of a signal converter in the laser system includes generating a temperature signal corresponding to a temperature of a laser and adjusting a signal of the signal converter based on at least the temperature signal. A laser transceiver includes a memory, a controller, a bandwidth circuit, and a modulation driver. The controller generates at least one control signal set by a host in the memory. The bandwidth circuit is a programmable low-pass filter (LPF) receiving the control signal and at least one input terminal receiving at least one data signal. The programmable LPF filters the data signal based on the control signal. The modulation driver has at least one input terminal receiving the filtered data signal. The modulation driver provides a modulation current to a laser in response to the filtered data signal.

Abstract: The invention provides a driving circuit for driving a laser diode of a pickup head. In one embodiment, the driving circuit comprises an automatic power control (APC) module, a clamp value determination unit, and a clamp circuit. The automatic power control module generates at least one power control signal. The clamp value determination unit dynamically determines at least one clamp value corresponding to the power control signal when the pickup head accesses an optical storage medium. The clamp circuit clamps the power control signal according to the clamp value to obtain a clamped power control signal. A driving signal for driving the laser diode can then be generated according to at least the clamped power control signal.

Abstract: The temperature of a laser diode changes in response to video content across a line of a displayed image, and the radiance changes as a function of temperature. An adaptive model estimates the temperature of the laser diode based on prior drive current values. For each displayed pixel, diode drive current is determined from the estimated diode temperature and a desired radiance value. A feedback circuit periodically measures the actual temperature and updates the adaptive model.

Abstract: A system and method is provided which compensates for the effects of relaxation oscillations and turn-on delays of diode laser devices. In particular, there is provided a method and system for tuning the shape of the power profile of an output optical signal and its position with respect to a channel bit clock of an optical recording system.

Abstract: A semiconductor lighting device has an array of semiconductor light sources arranged in an x-y grid, a power input in electrical connection with the array and arranged to provide power to the light sources, a microcontroller in electrical connection with the array arranged to alter operation of the array as necessary, and a connector in electrical connection with the microcontroller, arranged to provide an interface to the microcontroller.

Abstract: A light source device includes a semiconductor laser, and a drive circuit supplying the semiconductor laser with a pulsed drive current, and in the semiconductor laser, a laser emitting element and a free wheel diode are formed on the same substrate, and a cathode of the free wheel diode is connected to a current input terminal of the laser emitting element, and an anode of the free wheel diode is connected to a current output terminal of the laser emitting element.

Abstract: The apparatus includes a diode laser and a current source interconnected with the diode laser. Two independent circuits in the current source are configured to limit current flowing through the diode laser. A first current limiter circuit configured to limit a current output from the current source to an anode of the diode laser, and an independent second current limiter circuit configured to limit a current return from a cathode of the diode laser to the current source so that laser output power does not exceed a specified maximum regardless of a single fault in either the first or second current limiter circuits.

Abstract: A lamp-pumped laser includes a pump light source for optically pumping a laser medium, such as a laser rod, a pump light sensor that detects the optical pumping power of the pump light source, and a control unit connected to receive an output signal from the pump light sensor and to increase the electric power of the pump light source on the basis of the detected optical pumping power and in correspondence with a predetermined rise characteristic of the optical pumping power.

Abstract: A laser array circuit decreases the size of a circuit pattern. A laser-diode (LD) driving switching element with a low on resistance is used in common with and switches conduction and non-conduction of a large current to each of a plurality of charge capacitors and charge switching elements that accumulate charge in the charge capacitors in respective drive circuits. An LD array and the LD driving switching element are closely located on a light-emitting board. By laying out the LD array and charge capacitors considering only the positional relationship therebetween, the size of a circuit pattern including LDs and the charge capacitors can be decreased.

Abstract: The present invention provides an auto-power control (APC) circuit and a method to stabilize the extinction ratio of an optical output from a laser diode (LD) in an optical transmitter. The APC circuit according to the invention includes two feedback loops for the modulation IM and the bias current IB each having variable loop gain. The extinction ratio of the optical output from the LD is kept constant by setting the ratio of the loop gains of respective APC circuits to be ER?1.

Abstract: VCSEL array with a structure in which vertical cavity surface emitting devices are arranged on a substrate. The VCSEL array includes first and second optical devices. The second optical device receives light that is directed parallel to the substrate and emitted from the first optical device and converts the light into an electric signal when a voltage applied to the second optical device is switched to a reverse bias. The second optical device emits light that is directed parallel to the substrate when a voltage applied to the second optical device is switched to a forward bias.

Abstract: A circuit for driving a semiconductor laser including a semiconductor integrated circuit, which controls the drive of the semiconductor laser, and is connected to one end of the semiconductor laser. Moreover, the driving circuit incorporates a first power source +Vcc that supplies by way of the semiconductor integrated circuit a drive voltage to one end of the semiconductor laser and a second power source ?Vcc, which is connected to the other end of the semiconductor laser and supplies a drive voltage to the other end. Furthermore, the drive circuit incorporates a voltage clamp circuit, connected to a connection terminal connecting the semiconductor laser and the semiconductor integrated circuit, for adjusting the electric potential of the connection terminal.

Abstract: A light source assembly includes multiple light emitters having output that are focused and mixed onto a optical fiber leading to an endoscope or other device. The emitters can be LEDs or solid state lasers that emit different colors. A driver circuit controls the relative output intensities of the light emitters so as to produce a desired light spectrum. A driver circuit includes a buck topology connected to a controller that provides current mode control. Pulse width modulation of the buck current is provided by a semiconductor switch across a solid state laser. A second order filter, formed by the an external inductor and the output capacitance of the buck topology, minimizes AC current ripple to the laser.

Abstract: A light source driving apparatus, which adjusts a bias current to be supplied so as to control intensity of a light source, comprises a power source which outputs a variable reference voltage; a light receiving unit which receives light output from the light source and converts the light into an electric signal; a bias supply unit which supplies a bias current, which is based on an intensity control signal according to the electric signal converted by the light receiving unit and the reference voltage output from the power source, to the light source; and a voltage control unit which acquires information about intensity characteristics with respect to the intensity control signal of the light source and controls the reference voltage according to the acquired information about the intensity characteristics.

Abstract: Apparatus and method for driving laser diodes with electrical power in pulsed operation. Pulsed power, for example using pulse-width modulation, is applied through an inductor in one or more parallel regulator circuits having little or no output capacitance to provide a high-efficiency laser-diode-driver power supply. Some embodiments that use two or more parallel regulator circuits in the laser-diode driver, drive each from a different phase of a clock signal. Some embodiments provide a first DC-to-DC converter has a relatively high-voltage input (e.g., about 275 volts, 0.75 amps) and an intermediate output of, e.g., 11 to 15 volts, 15 to 11 amps used to charge a storage capacitor, and a second DC-to-DC converter diode driver having one or more parallel circuits (each having, e.g., a PWM switching-mode controller and its respective switch, inductor, and diode) to turn on, regulate, and turn off a constant laser-diode current through one or more laser diodes.

Abstract: Laser modulation is controlled by using a measurement of the average output power level of the laser to adjust the amplitude of the modulation current as necessary to prevent the laser from being over- or under-modulated and to adjust the amplitude of the bias current as necessary to maintain the average output power level of the laser at a desired, reasonably constant level. The laser controller receives an electrical feedback signal from a laser output power monitoring device and uses this signal to obtain the measurement of the average output power level of the laser. Based on this measurement, a bias current control signal and a modulation current control signal are generated and output to the laser driver to cause the laser driver to set the amplitude of the bias current to achieve a desired average output power level and to set the amplitude of the modulation current to prevent over- and under-modulation.

Abstract: Disclosed is a laser driving technique capable of reducing power consumption in a laser driving circuit to achieve reduced heat generation in an optical pickup of a recording/reading equipment for an optical disc. A base-voltage control circuit is connected to a base of a grounded-base cascode transistor connected between a driver circuit and a laser diode (LD), and a LD-anode-voltage control circuit is connected to an anode of the laser diode. The base-voltage control circuit and the LD-anode-voltage control circuit are connected to a controller, and operable to variously change an anode voltage of the laser diode and a base voltage of the cascode transistor depending on a driving current for the laser diode.

Abstract: The present invention provides a laser diode driver (LD-driver) able to precisely control the driving current reducing the influence of the overshoot and undershoot of the monitored signal. The LD-driver includes a photodiode (PD), an I/V-converter (I/V-C), a comparator, an integrator, a processing unit, and a current source. The PD generates the photocurrent, the I/V-C converts the photocurrent to a voltage signal, the comparator compares the voltage signal coupled by the AC-mode with a threshold, and the integrator integrates the output of the comparator. The processing unit, based on the output of the integrator, controls the driving current. In the LD-driver, the output of the integrator only determines the control mode, namely, the increment or the decrement of the current, the magnitude of the change in the driving current and its speed are given by the present conditions.

Abstract: A differential driver configured to drive an optical source. The differential driver includes an anode transistor configured to connect to a diode anode. The differential driver further includes a cathode transistor configured to connect to a diode cathode. The differential driver additionally includes a tail current transistor. The tail current transistor controls the amount of modulation current through a diode. The tail current transistor includes provisions that control the current through the tail current transistor for controlling the amount of modulation current through the diode. The provisions are dependant on a temperature in or at which the diode operates.

Abstract: A semiconductor light source includes a light-emitting device 101 having a plurality of semiconductor layers made of nitride semiconductors, and a drive circuit 102 for driving the light-emitting device 101. The drive circuit 102 performs forward drive operation, in which a forward current is supplied to the light-emitting device to make the light-emitting device 101 emit light, and reverse drive operation, in which a reverse bias is applied to the light-emitting device. The magnitude of the reverse bias is limited by the value of a reverse current flowing through the light-emitting device.

Abstract: Modules and signal control circuits configured to at least partially compensate for or adjust for asymmetric rise/fall time. The circuit may include a first input node configured to receive a first data signal and a second input node configured to receive a second data signal that is complementary of the first data signal. The circuit may also include a first stage having a first node coupled to the first input node and a second node coupled to the second input node and a second stage having a first node coupled to a third node of the first stage and a second node coupled to a fourth node of the first stage. The second stage may be configured to drive a load such as a laser. The circuit may further include a third input node configured to receive a third data signal and a fourth input node configured to receive a fourth data signal that is the complementary of the third data signal.

Abstract: The laser drive circuit of the present invention includes a first drive circuit 105 receiving an input of a current from a variable current source 103 and a first pulse control signal 101 and outputting a first drive current in synchronism with the first pulse control signal 101; a pulse output circuit 107 outputting a pulse signal in response to a falling edge of the first pulse control signal 101; and a second drive circuit 106 receiving an input of a current from a variable current source 104 and a second pulse control signal 102, generating a second drive current in synchronism with the second pulse control signal 102, and outputting a decreased current value of the second drive current at least in synchronism with the pulse signal. According to this configuration, the falling time of the pulse can be shortened regardless of the relationship between the voltage of a laser connecting terminal and the power source voltage of a drive circuit or a ground voltage.

Abstract: A current control mechanism for use in low power consumption circuits with limited headroom includes a differential transistor pair from whose collectors a current output is taken. The current output is a function of a reference voltage provided at bases of a reference transistor pair having emitters that are coupled to the bases of the differential pair. The reference voltage is controlled by a pair of control transistors that control current through a load. A pair of tracking transistors can be provided to track supply voltage. A single-ended topology can also be implemented.

Abstract: A laser diode driver with means for adjusting the compliance voltage to allow a current source to accurately reproduce a current command while simultaneously minimizing the power dissipation of the current source. For a slowly-varying or DC current command, the compliance voltage is continuously adjusted to limit the power dissipation of the current source to below a predetermined minimum. For a pulsed current waveform, the compliance voltage is maximized during periods of zero or low current demand so that sufficient energy is stored to faithfully reproduce the leading edge of a pulsed current command, and reduced during the plateau portion of a pulsed current command to minimize the power dissipation of the current source.

Abstract: A laser control system contains an oscillator gas chamber and an amplifier gas chamber. A first voltage input is operatively connected to deliver electrical pulses to a first pair of electrodes within the oscillator gas chamber and a second pair of electrodes within the amplifier gas chamber. An output of the gas chambers is an energy dose calculated by a trapezoidal window. A control circuit connects to the first voltage input for modifying the first voltage input. A feedback control loop communicates an output of the gas chambers to the control circuit for modifying the first voltage input.

Abstract: A laser control system contains an oscillator gas chamber and an amplifier gas chamber. A first voltage input is operatively connected to deliver electrical pulses to a first pair of electrodes within the oscillator gas chamber and a second pair of electrodes within the amplifier gas chamber. An output of the gas chambers is an energy dose calculated by a trapezoidal window. A control circuit connects to the first voltage input for modifying the first voltage input. A feedback control loop communicates an output of the gas chambers to the control circuit for modifying the first voltage input.

Abstract: Laser diode driver architectures are disclosed. Some example current drivers are described, including a current channel to provide an output current. The current channel includes a current mirror with emitter degeneration, a startup transistor coupled to the current mirror to generate a DC bias on the current mirror, a beta helper circuit coupled to the current mirror and the startup transistor, to maintain the DC bias on the current mirror, and a cutoff transistor coupled to an emitter terminal of a current mirror transistor and to a reference voltage, to selectively couple the emitter terminal to the reference voltage to conduct the pre-determined output current. The example current drivers also include an output stage coupled to the output of the current mirror and to an output device, wherein the output stage provides a current gain in response to the cutoff transistor coupling the emitter terminal to the reference voltage.

Abstract: Laser power control arrangements interrupt power to a laser used in electro-optical readers upon detection of operating conditions not conforming to preestablished standards, and adjust power to the laser to enhance reader performance without violating prevalent safety standards. Dual monitors are used to independently monitor the output power of the laser.

Abstract: The apparatus includes a diode laser, a current source interconnected with the diode laser, and four limiting circuits. The first limiting circuit limits peak current flowing to an anode connection of the diode laser. The second limiting circuit limits peak current flowing from a cathode connection of the diode laser, wherein the first and second limiting circuits are independent from each other. The third limiting circuit limits average current flowing through the diode laser. Finally, the fourth limiting circuit limits average current flowing through the diode laser, wherein the third and fourth limiting circuits are independent from each other. Other embodiments and features are also disclosed.

Abstract: An output voltage of a cathode driving type semiconductor laser driving circuit is made minimum, power consumption of a driving circuit section is suppressed, and heat generation of an optical head or an optical disc device is reduced. In addition to the conventional constitution, the semiconductor laser driving circuit permits the output voltage of the semiconductor laser driving circuit to be at a prescribed level by measuring a cathode voltage (Vout) of a semiconductor laser (1) and controlling an anode voltage (Vld) so that the cathode voltage (Vout) is at the prescribed level, reduces power consumption of the driving circuit and suppresses temperature increase of the optical head or the optical disc device to be minimum.

Abstract: In an extreme ultra violet light source apparatus having a comparatively large output power for exposing, a solid target is supplied fast and continuously while heat dissipation for irradiation of a driver laser light is performed successfully. The extreme ultra violet light source apparatus includes: a chamber in which extreme ultra violet light is generated; a target material supplying unit which coats a wire with target material, a wire supplying unit which supplies the wire coated with the target material to a predetermined position within the chamber, a driver laser which applies a laser beam onto the wire coated with the target material to generate plasma; and a collector mirror which collects the extreme ultra violet light radiated from the plasma and outputting the extreme ultra violet light.

Abstract: A laser driving circuit configured to drive a semiconductor laser diode, which is less susceptible to noise interference and capable of achieving the control of laser light intensity with high accuracy. Respective circuit components in the laser driving circuit such as an amplifier circuit, a sample hold circuit, a voltage-to-current converter, and a switching circuit are all integrated into an integrated circuit. A capacitor included in the sample hold circuit is further provided as built-in in the integrated circuit, which is previously attached externally. In addition, by changing the resistance of a resistor which is externally connected between the bias current setting terminal of the amplifier circuit and the ground potential by way of a terminal of the integrated circuit, the current outputting capability of the amplifier circuit can be variably adjusted through the adjustment of the charging time of the capacitor.

Abstract: Various systems and methods are provided to achieve laser power control. In one embodiment, a system is provided that comprises a counter that holds a digital value. An digital-to-analog converter is employed to convert the digital value to an analog current. A data threshold current is generated by a laser driver based upon the analog current. The data threshold current is employed to represent a data value in a data signal employed to drive a laser diode. Also, circuitry is employed to adjust the digital value based upon a comparison between a target threshold current and a feedback current generated from a laser output of the laser diode.

Abstract: Semiconductor lasers are driven such that high output laser beams are stably obtained without a long start up time. A method for driving semiconductor lasers by automatic current control or automatic power control with a constant current source involves the steps of: generating a pattern of drive current values for the semiconductor lasers, which is defined according to the amount of time which has elapsed since initiating driving thereof, that enables obtainment of substantially the same light output as a target light output by the automatic current control or the automatic power control; and varying the drive current of the semiconductor lasers in stepwise increments according to the pattern for a predetermined period of time from initiation of drive thereof. A single pattern is used in common to drive the plurality of semiconductor lasers.

Abstract: A laser control system contains an oscillator gas chamber and an amplifier gas chamber. A first voltage input is operatively connected to deliver electrical pulses to a first pair of electrodes within the oscillator gas chamber and a second pair of electrodes within the amplifier gas chamber. An output of the gas chambers is an energy dose calculated by a trapezoidal window. A control circuit connects to the first voltage input for modifying the first voltage input. A feedback control loop communicates an output of the gas chambers to the control circuit for modifying the first voltage input.

Abstract: This invention makes it possible to meet a requirement of high-quality image printing and high-speed driving of a semiconductor laser driver in a laser beam printer or the like while suppressing radiant noise. A laser circuit substrate includes a first wiring pattern and second wiring pattern connected to a main wiring pattern, a first circuit which is connected to the first wiring pattern and has a semiconductor laser element and a driving circuit for driving the semiconductor laser element, a second circuit which is connected to the second wiring pattern and compensates noise generated by the first circuit, a first capacitor which is connected to a first point in the first wiring pattern, and a second capacitor which is connected to a second point in the second wiring pattern.

Abstract: A driver circuit is provided which comprises a series-connected unit having a light-emitting element and a current limiting inductor directly connected to the light-emitting element, a regenerative diode which is connected in parallel to the series-connected unit and which regenerates energy stored in the current limiting inductor, a transistor which controls a current flowing through the light-emitting element and the current limiting inductor, and a controller which controls an operation of the transistor, wherein the controller controls the transistor according to a voltage value of a power supply applied to the light-emitting element.

Abstract: The present invention provides a laser diode driving circuit able to reduce the degradation of the optical output from the laser diode even when the characteristic of the laser diode widely scatters. The circuit provides a filter circuit connected in parallel to the laser diode that compensates the frequency dependence of the laser diode. In the invention, the frequency characteristic of this filter circuit may be varied depending on the scattering in the frequency response of the laser diode, or on the temperature characteristic of the diode.

Abstract: A laser control system contains an oscillator gas chamber and an amplifier gas chamber. A first voltage input is operatively connected to deliver electrical pulses to a first pair of electrodes within the oscillator gas chamber and a second pair of electrodes within the amplifier gas chamber. An output of the gas chambers is an energy dose calculated by a trapezoidal window. A control circuit connects to the first voltage input for modifying the first voltage input. A feedback control loop communicates an output of the gas chambers to the control circuit for modifying the first voltage input.

Abstract: A laser control system contains an oscillator gas chamber and an amplifier gas chamber. A first voltage input is operatively connected to deliver electrical pulses to a first pair of electrodes within the oscillator gas chamber and a second pair of electrodes within the amplifier gas chamber. An output of the gas chambers is an energy dose calculated by a trapezoidal window. A control circuit connects to the first voltage input for modifying the first voltage input. A feedback control loop communicates an output of the gas chambers to the control circuit for modifying the first voltage input.

Abstract: A laser diode driving apparatus comprising an oscillator (11) for generating a high-frequency signal; an amplifier (12) for amplifying the high-frequency signal and outputting the amplified high-frequency signal; current mirror circuits (7, 8 and 9) for receiving the output current of the amplifier (12) and driving multiple laser diodes (1, 2 and 3), respectively; a DC current supply source (10) for supplying a DC current to the current mirror circuits, wherein the laser diode is driven using a current obtained by superimposing the high-frequency signal on the DC current, the laser diode driving apparatus further comprising a high-frequency signal superimposed amplitude setting circuit (14) for changing the amplitude of the amplifier so as to be suited for the selection of the current mirror circuit.

Abstract: A purpose of this invention is to suppress radiation noise while satisfying demands for higher speeds and higher image qualities of a semiconductor laser driving device in a laser beam printer or the like. A laser driving circuit includes a first wiring pattern and a second wiring pattern which are connected to a main wiring pattern, a first circuit which is connected to the first wiring pattern and has a semiconductor laser element (7) and a laser driving device for driving the semiconductor laser element, a second circuit which is connected to the second wiring pattern, has a compensation element and a compensation driving device, and compensates for noise in the first circuit, and a common mode choke coil which is connected to the first and second wiring patterns and selectively increases impedances to in-phase signal components in a signal flowing through the first wiring pattern and the first circuit and a signal flowing through the second wiring pattern and the second circuit.

Abstract: A semiconductor laser driving unit is disclosed that includes a first part generating a bias current; a second part generating a first current for causing the semiconductor laser to emit light, and outputting the first current to the semiconductor laser in accordance with an input control signal; a third part performing initialization to detect a light emission characteristic of the semiconductor laser, and causing the second part to generate a second current of a value obtained from the detected light emission characteristic; and a fourth part causing the second part to generate the first current in which a set offset current is added to the second current. The first part detects the amount of light emission of the semiconductor laser, and generates and outputs the bias current so that the amount of light emission produced by the sum of the bias current and the first current is a predetermined value.

Abstract: A semiconductor laser driving device includes a current supply unit supplying current to a semiconductor laser; a first control unit controlling the current supply unit to supply a first current which is half or less of a lasing threshold of the semiconductor laser; and a second control unit controlling the current supply unit to supply a second current which is larger than the lasing threshold after a first time is passed from an edge of a clock signal.