Abstract: A laser diode module with a built-in high-frequency modulation IC used to remove the reflected noise generated as the laser beam reads the signal to be played back and directly packaged within a metal cap. The high-frequency modulation IC creates an electrical connection through wire bonding with several connection legs and the laser diode module. The packaged laser diode module has four connection legs. Two of these connection legs act as a positive and a negative terminal for supplying power to the built-in high-frequency modulation IC. The other two connection legs are electrically connected to an external automatic power control (APC) circuit and act as the positive terminal of the laser diode and the photo diode, respectively. In this way, the inconvenience of externally attaching a high-frequency current producing circuit board can be avoided, the productivity can be enhanced and the radiation of electromagnetic interference (EMI) can be reduced.

Abstract: An optical transmission controller includes a semiconductor-laser, a semiconductor laser driver, a monitor photoreceptor, a waveform detector and a phase relation adjuster. The semiconductor laser driver allows the semiconductor laser to output an optical signal. The monitor photoreceptor monitors the optical signal output. The waveform detector detects a fall state of the optical signal output. The phase relation adjuster adjusts a phase relation between a fall timing of an input current and a variation timing of a relaxation oscillation of the optical signal output in accordance with a detection result of the waveform detector.

Abstract: The present invention relates to a method for revising a wavelength of the EML by controlling a working temperature based on arithmetic functional relations between the DC-Offset voltage and the wavelength and between the working temperature and the wavelength, and a computer-readable recording medium thereof. The method includes the steps of: re-setting initial values of a working temperature, a amplifying voltage and the DC-Offset voltage; determining a wavelength with respect to the re-set DC-Offset voltage based on a functional relation between the DC-Offset voltage and the wavelength of the EML; and determining the revising working temperature for the determined wavelength based on the functional relation between the working temperature and the wavelength of the EML, and re-setting the working temperature with the revising working temperature.

Abstract: There is provided a laser driving circuit having a small circuit scale which is capable of low voltage operation and in which unnecessary writing in an optical disc, or the like, is entirely prevented. To this end, the laser driving circuit includes a source-grounded amplifier to which the supply voltage of the first power supply is supplied as well as to a laser driving circuit block and to which the voltage of the second power supply of a control circuit block is input. A bias input terminal of a differential amplifier is pulled up according to an output of the source-grounded amplifier till the voltage of the second power supply rises, whereby an output of the laser driving circuit block is suppressed. With such a structure, unnecessary emission of a semiconductor laser, breakage of the semiconductor laser, etc., are prevented.

Abstract: A driver circuit for a semiconductor laser of the invention comprises: first bias current supply means for supplying, at least at a time of non-output of data, a first bias current to an LD; signal processing means for generating a pulse current control signal in which a burst data signal is delayed, and generating a second bias current control signal which rises more rapidly by a predetermined time than the rise of burst data included in the pulse current control signal; pulse current supply means for supplying to the LD a pulse current generated in accordance with the pulse current control signal; and second bias current supply means for supplying to the LD a second bias current generated in accordance with the second bias current control signal.

Abstract: A light emitting element driving circuit drives a surface-emitting element, and the light emitting element driving circuit is equipped with a bias current driving circuit that supplies a generally constant bias current to the surface-emitting element, a modulation current driving circuit that supplies to the surface-emitting element a modulation current superimposed on the bias current, and a temperature detection circuit that detects the temperature of the surface-emitting element, wherein the modulation current driving circuit decreases the current amount of the modulation current, when the temperature detected rises. The bias current driving circuit may preferably supply the bias current to the surface-emitting element through a coil, and the modulation current driving circuit may preferably supply the modulation current to the surface-emitting element through a capacitor.

Abstract: High frequency laser diode (LD) and electro-absorption modulator (EAM) integrated circuit drivers using a cascaded output switch architecture that increases the output current and voltage edge speed and reduces the peaking and ringing of the output waveform, thus improving the deterministic jitter performance. Also disclosed is a method and apparatus that provides a modulation current dependence of both turn-on and turn-off driving currents that lead to an optimal compromise between the edge speed and output overshoot for a wide range of modulation currents. A PTAT temperature dependence of both voltage swing and current level in the predriver assures a low variation of the overshoot and rise/fall time over a wide temperature range. Using the cascaded output switch architecture provides an easy way of on-chip summation of the modulation and bias currents. Biasing the cascode device with a supply and modulation current dependent base voltage provides an optimum headroom output switch.

Abstract: A driver circuit and a method drive an electronic component such as a laser diode with a variable electric current that is controlledly switched between at least two discrete current levels. The driver circuit includes circuit elements that damp ringing or initial transient oscillations that arise when switching the current between the current levels. The driver circuit includes a current mirror having a mirror amplification factor dependent on the frequency of the variable electric current. In order to counteract parasitic capacitances and/or inductances leading to the ringing, an inductance and/or a resistance are connected between the two series circuits making up the current mirror, a capacitance is connected parallel to a reference resistor of one of the series circuits, and/or a capacitance is connected across the voltage supply.

Abstract: A system and method of sensing temperature at an optical fiber tip, including the steps of positioning a slug of fluorescent material adjacent the optical fiber tip, providing an optical stimulus having a wavelength within a first predetermined range through at least one fiber optically linked to the optical fiber tip, wherein a desired optical fluorescent response having a wavelength within a second predetermined range from the fluorescent slug is generated, detecting a signal representative of the optical stimulus, detecting a signal representative of the optical fluorescent response, digitally processing the optical stimulus signal and the optical fluorescent response signal to determine a phase difference therebetween, and calculating a temperature for the optical fiber tip as a function of the phase difference.

Abstract: A laser driver circuit with signal transition enhancement is disclosed. The laser driver circuit comprises a pair of laser driver input terminals, a current modulator circuit, a transition boost circuit, and a nonlinear integrator circuit. The pair of laser driver input terminals are configured to receive a pair of differential input signals. The current modulator circuit generates a pair of current modulator output signals in accordance with the pair of differential input signals. The transition boost circuit generates a pair of transition boost signals for enhancing signal transitions of the pair of current modulator output signals. The nonlinear integrator circuit integrates the pair of transition boost signals to generate a pair of differential current output signals.

Abstract: A light generating apparatus includes: a submount; a semiconductor laser chip mounted on the submount; a substrate which is mounted on the submount and includes an optical waveguide; and a substance having a predetermined thickness which is disposed between the semiconductor laser chip and the substrate. In an oscillation wavelength stabilizing apparatus for a light source, the light source is a semiconductor laser which includes: an active region for providing gain; and a distributed Bragg reflection (DBR) region for controlling an oscillation wavelength.

Abstract: The present invention provides a temperature control circuit for a semiconductor light-emitting device, in which scale of the circuit is not enlarged and noise due to the current switching is not generated. In the temperature control circuit of the present invention, although the DC voltage VATC supplied to the Peltier device is generated by the DC-to-DC converting from the external power VCC, the DC voltage VATC is feedback controlled so as to coincide with a target value of the DC voltage that is set based on an error signal generated by detecting a voltage drop of the Peltier device and comparing this drop voltage with a reference voltage. A control signal for setting the temperature of the laser diode to the target temperature through heating up or cooling down the Peltier device by flowing a current corresponding to an error between the target temperature and a practical temperature detected by the thermistor in the Peltier device from the thermoelectric controller current driver.

Abstract: A laser beam irradiation device according to the present invention is so constructed that it may increase or decrease the excitation electric current flowing through its semiconductor laser diode to enable a user to selectively practice both non-thermal and photo-thermal laser treatments. CPU 41 is responsive to switching-on and -off of an output-power switching unit S2 for sending a reference signal to an amplifier 472 via an I/O port 44 and a D/A converter 471, so that the amplifier 472 may provide at its output terminals a reference voltage, with respect to which a control reference voltage for a desired laser output can be determined. Semiconductor laser diode 35 radiates the laser beam from its opposite sides, and a photo-diode 473 receives one of the opposite laser beams to provide a light-accepting voltage at its output terminals. The so acquired light-accepting voltage is directed to an amplifier 474 for amplification, thereby obtaining the monitor voltage.

Abstract: A laser diode driving circuit includes two chip capacitors disposed in the vicinity of one side portion of an IC along which a high voltage power supply terminal, a low voltage power supply terminal and a driving signal output terminal are disposed. One end portion of each of the chip capacitors is connected to the high voltage power supply terminal and the other end portion of each of the chip capacitors is connected to the low voltage power supply terminal. The chip capacitors are adapted for serving to reduce a ripple component superposed on a power supply voltage when a switching element is operated. The chip capacitors are disposed so that the distance between itself and the high voltage power supply terminal, the low voltage power supply terminal and the driving signal output terminal is equal to or shorter than 10 mm.

Abstract: An apparatus and method are provided for setting the AC and DC bias levels of a laser diode in an optoelectronic transceiver so as to control the device's extinction ratio. An optical output of the transceiver is looped back to an optical input of the transceiver. The method includes setting a DC bias level for the laser diode, setting an AC bias level for the laser diode to each of a predefined sequence of AC bias level settings, and receiving from the transceiver a sequence of optical output power measurements, the sequence of optical output power measurements including an average optical output power measurement corresponding to each of the AC bias level settings in the predefined sequence. From the received sequence of optical output power measurements preferred AC and DC bias level settings are determined and stored in the transceiver so as to control the AC and DC bias levels of the laser diode.

Abstract: A phase modulation circuit for outputting a modulated signal of an input signal which has been modulated to a desired phase. The circuit includes a light emitting element for emitting light according to an input signal and outputting a modulated signal, a bias current source for supplying in advance to a light emitting element a bias current smaller than the light emitting threshold current of the light emitting element, a bias current control unit for controlling the bias current according to a desired phase for supplying to the light emitting element a modulation current for causing the light emitting element to emit light according to the input signal, and a modulation current control unit for controlling the modulation current according to the phase shift resolution in the phase modulation circuit. The modulation current control unit controls modulation current further according to the phase range in the phase modulation circuit.

Abstract: Methods and systems and apparatuses for reducing power consumption, in an environment including a laser driver that drives a laser diode, are provided. The voltage drop across a laser diode, driven by a laser driver, is monitored. This enables a supply voltage, used to power the laser driver, to be appropriately adjusted, based at least in part on the monitored voltage drop. For example, the supply voltage is increased when the monitored voltage drop across the laser diode increases, and decreased when the monitored voltage drop across the laser diode decreases.

Abstract: The laser light generator control circuit comprises a load section, a control section, a bias current circuit section, and a modulation current circuit section. The load section generates a monitor voltage V1 that corresponds to the optical current corresponding to the amount of light received by a monitor light receiving element for receiving light from the laser light generator. The control section selects a combination (Db, Dm) in accordance with the result of comparing a value corresponding to the monitor voltage V1, and a reference value, from a group of combinations (Db, Dm)n that comprises a plurality of combinations (Db, Dm) of a value Db that corresponds to the bias current and a value Dm that corresponds to the modulation current, these combinations being specified so that the light emission power and the extinction ratio are constant, and generates a first control signal V2 and a second control signal V3 on the basis of the selected combination (Db, Dm).

Abstract: Disclosed herein is a laser driving method including the step of adjusting an initial value of driving current for driving a laser when an operation mode is changed on a basis of a difference in magnitude between a first bias current including information on threshold current of the laser in a first operation mode and a second bias current including information on the threshold current in a second operation mode.

Abstract: A driving method of a semiconductor laser having an active layer region, a phase adjustment region and a distributed Bragg reflector region includes the steps of: calculating an average value of multipulse modulation currents modulated between a peak current and a bottom current input to said active layer region; calculating a difference between the average value of the multipulse modulation currents and a bias current input to the active layer region; and applying a first compensation current to the phase adjustment region when the multipulse modulation current is input to the active layer region, and applying a second compensation current corresponding to the difference to the phase adjustment region when the bias current is input to the active layer region.

Abstract: The invention provides a wavelength multiplexing transmission apparatus includes a plurality of optical signal outputting sections for outputting optical signals having different wavelengths from each other, and a wavelength multiplexing section for wavelength multiplexing the optical signals outputted from the optical signal outputting sections and sending out a resulting optical signal. Each of the optical signal outputting sections includes a transmission light source driven by an electric signal for outputting an optical signal of a predetermined wavelength, and a wavelength filter capable of passing therethrough and sending out only an optical signal of the predetermined wavelength to be outputted from the transmission light source to prevent a wavelength drift of the optical signal outputted from the transmission light source.

Abstract: A laser diode (LD) driver and method of compensating for a bias driving potential of an LD driver according to a change in a power level of a laser signal from an LD in a recording mode include storing the bias driving potential, detecting a change in a bias power level in the laser signal, and compensating the bias driving potential according to the detected change in the bias power level.

Abstract: In a directly modulated optical module, the input current to drive the semiconductor laser is controlled so as to make a rate of change in fall time smaller than a rate of change in rise time (inclination) in order to improve the eye opening of an eye pattern and extend the transmission distance. In addition, the input current is overshot at least during the period of transient state following the rising edge.

Abstract: A simply structured apparatus according to the present invention corrects an overdrive power level. A main controller allows an overdrive power generator to set an overdrive power current to zero, allows a base power controller to control a base power current with the target value of a base power monitor level set to a desired overdrive power level. When the base power monitor level has reached the target value, the main controller allows said overdrive power generator to increase the overdrive power current until a base power control signal monitored by a base power control signal monitor reaches a value corresponding to a desired base power level.

Abstract: Methods and system are provided for automatic power control of a laser diode, e.g., in a laser driver. In accordance with an embodiment of the present invention, a power controller includes a detector circuit adapted to detect the output of the laser diode and to produce a measured output therefrom. A comparator compares a desired output to the measured output, and produces an error signal therefrom. The error signal is provided to an integrator circuit that produces an integrated error signal. At least one digital-to-analog converter (DAC) uses the integrated error signal to produce a current drive signal that drives the laser diode.

Abstract: The present invention aims at providing a drive circuit and a drive method for a semiconductor laser module including an electro-absorption type optical modulator, capable of obtaining a stable optical output without controlling a module temperature to be constant. To this end, the drive circuit of the present invention detects a temperature in the semiconductor laser module comprising a semiconductor laser and an EA modulator, and based on the detected temperature, controls a drive current supplied to the semiconductor laser and a bias voltage and a modulated electric signal applied to the EA modulator, so that average power, an extinction ratio and an optical cross point of an optical signal output from the semiconductor laser module are held to be constant.

Abstract: A laser diode driving device of the present invention can appropriately shorten the rising time and the falling time of a laser diode drive current in a range from a small current region to a large current region. In synchronization with the addition of an original input current from an input constant current source to the laser diode drive current amplifier, a differentiated current is added to the input current through a differentiation circuit and a pull-in type V-I conversion circuit, whereby the rising of a laser diode drive current is made abrupt. Furthermore, by increasing a gate potential of an input PchMOS transistor constituting the laser diode drive current amplifier by a differentiation circuit and a push-out type V-I conversion circuit in synchronization with the disconnection of an input current, the falling of a laser diode drive current is made abrupt.

Abstract: The present invention provides an optical transmission module having a laser diode that generates laser beams and a differential type current switch provided with a first switch and a second switch in order to supply a modulating current to the laser diode. A terminal of the laser diode and the first switch are connected in series through a first transmission line and a first capacitor, the other terminal of the laser diode and the second switch are connected in series through a second transmission line and a second capacitor. The current driven by the second switch is terminated by a resistor connected to the first switch and the current driven by the first switch is terminated by a resistor connected to the second switch. Thus, the laser diode is modulated bidirectionally.

Abstract: Driver circuits of the present invention provide current to drive laser diodes. The output current of the driver circuit includes a data signal and a low frequency tone signal. The low frequency tone signal is within the bandwidth of a power control feedback loop. The tone signal introduces low frequency noise into the output signal of the driver circuit. The low frequency noise causes jitter at the zero crossing points of the driver circuit output signal. A laser driver circuit of the present invention provides a compensation current to a laser diode. The compensation current is out of phase with the tone signal. The compensation current eliminates the low frequency noise in the output signal of the laser driver circuit.

Abstract: A laser beam is obtained from a semiconductor laser by a stable emission light amount. A first semiconductor laser is thermally coupled with a second semiconductor laser and driven by a feedback circuit constructed by a photodetector, an I-V converter, and a current generator so as to stabilize the emission light amount. A current I0? having a correlation with a drive current I0 of the 1st laser is outputted from a current mirror circuit. A modulation signal is supplied to a current pull-in type current driving circuit via a multiplier and a linearity compensating circuit and a current I2 according to the modulation signal is extracted from a collector of a transistor. The 2nd laser is driven by a current I1 (I0??I2) and a laser beam modulated by the modulation signal is generated. Since the signal modulation by the 2nd laser is performed without influencing on I0 and the 2nd laser is driven by I0?, the emission light amount is stabilized.

Abstract: A laser device includes a laser diode, and a controller that superimposes a low-frequency signal on a modulating signal applied to the laser diode. The low-frequency signal has an amplitude that correlates with an amplitude of the modulating signal.

Abstract: Disclosed is a system and circuit for a multi-channel optoelectronic device driver. The system and circuit include a differential buffer amplifier, an output driver amplifier, a dedicated voltage regulator, a load compensation circuit, a wave shaping circuit and a laser fault detection circuit. In a multi-channel configuration, each channel has a dedicated voltage regulator such that each channel provides a channel-specific drive signal.

Abstract: The invention provides a semiconductor laser module which can suppress overcurrent flowing into a thermo-module, wherein the thermo-module (5) carries out a heating action when a reverse current flows from lead pin (16f) through lead pin (16a), and contrarily carries out a cooling action when a current flows from the lead pin (16a) through the lead pin (16f). An overcurrent limiting means (20) is provided, which can suppress overcurrent flowing into the thermo-module (5) in its heating direction. The overcurrent limiting circuit (20) is provided with a bypass line (21), a resistor (22), and a diode (23). When a current flows in the heating direction, the diode (23) is turned on, whereby the current is shunted to the thermo-module (5) and bypass line (21) for flow, and accordingly, the overcurrent flowing into the thermo-module (5) can be effectively suppressed.

Abstract: Method and system provide a variable delay between the external trigger pulse for a laser system and the light pulse such that the total delay is controlled. The method and system utilize a digital time measuring circuit which measure a time interval which corresponds to a time between the generation of the trigger pulse and generation or a laser light pulse. Based on the measurement by the digital time measuring circuit a processor controls a delay circuit which thereby controls the time between the trigger pulse and the generation of the laser light pulse.

Abstract: A method for characterizing tunable semiconductor laser diodes in which the laser is stimulated in a way that discloses the optical properties and tuning current dependency of the individual sections of the laser, separately for each section, and independently of the other sections. A section of the laser is current modulated in order to excite a continuum of modes related to the spectral response of other sections. This process is observed by viewing the overall spectral response at an integration time significantly longer than the modulation time. The spectral positions of the modes and their dependence on the tuning current, are used to determine the tuning characteristic of that particular section. This method substantially reduces the time required for characterization of such lasers in comparison with prior art methods.

Abstract: The LED brightness control system for a wide range of luminance control includes a brightness control module that provides a pulse width modulation (PWM) control signal and a peak current control signal. A pulse width modulation (PWM) converter circuit receives the PWM control signal and converts it to a PWM signal. A multiplier receives the PWM signal and the peak current control signal from the brightness control module and multiplies the same to provide a light emitting diode (LED) current control signal with a variable “on” time as well as variable “on” level. A voltage-controlled current source utilizes the LED current control signal and an LED current feedback signal for providing an LED current. An LED illuminator array receives the LED current. A current sensing element connected to the LED illuminator array for providing an LED current feedback signal representing LED peak current. The voltage-controlled current source controls a drive voltage to the LED illuminator array at a commanded level.

Abstract: The present invention provides a circuit capable of driving a diode with multiple amounts of current with a low supply voltage without the requirement of alternating current coupling. The circuit provides for headroom voltage for the current sources allowing them to operate correctly without the requirement of external components such as inductors to provide coupling. The circuit may provide one of at least two different amounts of current depending upon the voltage of at least two inputs suitable for driving a vertical cavity surface emitting laser diode.

Abstract: An optical output control circuit has a semiconductor laser for supplying a modulating electric current and a bias electric current thereto, a modulating electric current supplying device for supplying the modulating electric current on the basis of an inputted modulating signal, and a bias electric current supplying device for supplying the bias electric current. A first temperature correcting device for increasing the modulating electric current with a rise in ambient temperature is arranged in the modulating electric current supplying device, and a second temperature correcting circuit for increasing the bias electric current with the rise in ambient temperature is arranged in the bias electric current supplying device.

Abstract: A semiconductor laser driving circuit comprises a driving IC and a substrate on which the IC is mounted. The IC incorporates: a switching element for generating a driving signal; a high-potential power terminal and a low-potential power terminal for feeding supply voltage to the switching element; and a driving signal output terminal for outputting the driving signal generated at the switching element to an external device. These three terminals are disposed side by side at one of sides of a main body of the IC. The substrate incorporates three conductors to be connected to the three terminals. Two chip capacitors are disposed beside the one of the sides of the IC at which the three terminals are disposed. An end of each of the capacitors is connected to the high-potential power terminal while the other end is connected to the low-potential power terminal.

Abstract: In a semiconductor laser driving device using a voltage drive system, a drive current of a semiconductor laser is controlled by a drive current control circuit so that a light intensity of light beam emitted from the semiconductor laser is equal to a predetermined light intensity. In a drive voltage control circuit, the drive voltage applied to the semiconductor laser at the time of switching off the semiconductor laser LD is set on the basis of the detected voltage (terminal voltage).

Abstract: An optical transmitter and/or a constituent electro-optic transducer driver that performs active matching. The transducer driver performs active matching using a voltage step down through one base-emitter bipolar transistor, followed by a step up approach through the base-emitter of another bipolar transistor, thereby allowing for lower supply voltages. Furthermore, the voltage drop across the source resistor is minimal by using an operation amplifier in a feedback configuration, thereby further encouraging operability with low supply voltages. The electro-optic transducer driver is also beneficial in that it has high AC-coupling efficiency of the modulation current to the electro-optic transducer, may operate at high speeds with reduced jitter.

Abstract: A controller for use with sampled grating distributed Bragg reflector (SGDBR) lasers is presented. An exemplary controller includes a table of settings representing a control surface, each setting corresponding to a separate operating point of the SGDBR laser, a first mirror current controller and a second mirror current controller. The first mirror controller and the second mirror current controller respectively control a first mirror current and a second mirror current about an estimated extremum point of the control surface to substantially maintain alignment between each of a first mirror and a second mirror, and an associated cavity mode. The first mirror current and the second mirror current can be locked at a substantially fixed distance from the extremum of the control surface.

Abstract: A method of maintaining desirable optical performance of an optoelectronic apparatus at extreme temperatures is disclosed. At a first temperature, a first bias current at which the laser generates optical signals at a first level is determined. At a second temperature outside of a predefined range of the first temperature, a second bias current at which the laser generates optical signals at a second level is determined. If the second temperature is greater than the higher end-point temperature of the predefined range, the second predefined level is defined to be less than the first predefined level. If the second temperature is less than the lower end-point temperature of the predefined range, the second predefined range is defined to be greater than the first predefined level.

Abstract: The present invention provides an optical network unit having a control means. The control means uses programmable logic to cause the optical network unit to function within established protocols.

Abstract: An optical transmitter is provided that includes a laser subassembly generating an optical signal having a plurality of operating characteristics. A controller, which drives the laser subassembly by applying at least one control parameter thereto, includes a predetermined, empirically derived database relating the plurality of operating characteristics of the laser subassembly to the control parameters. The controller adjusts at least one control parameter based at least in part on data extracted from the database so that the operating characteristic is substantially optimized.

Abstract: A control system architecture that allows a semiconductor laser to be stabilized with respect to critical parameters, such as output power and/or emission wavelength, with a reduced cost with respect to the components required to implement control, while simultaneously maintaining or increasing precision of the control function. This is achieved using sophisticated integrated circuitry contained within the laser package to measure data related to multiple laser operation parameters and to transmit these parameters to a control circuit. In particular, precision thermal measurements may be used to eliminate the need for optical detectors in the laser package. The invention described herein has significant utility for different types of semiconductor lasers, including both edge emitting and VCSEL-type semiconductor lasers.

Abstract: A method for controlling a laser includes determining an average component of a laser drive current and adjusting a modulation component of the drive current based on the average component and a threshold current signal at the present temperature. Determining the average component includes adjusting the drive current until an output power of the laser is approximately equal to a reference signal that varies according to temperature. The method further includes calibrating the threshold current signal, which includes adjusting the drive current until the laser output power is approximately equal to a second reference signal, and storing the drive current signal as the threshold current signal at the present temperature. The method further includes recalibrating the threshold current signal, which includes storing a difference between a new value and a stored value of the threshold current signal as an offset for other stored values of the threshold current signal.

Abstract: A semiconductor laser driving circuit drives a plurality of semiconductor laser devices having different objective operating voltages, and has a power source for generating power voltages for the semiconductor laser devices, a power voltage changeover means for changeover from one of the power voltages to another, a current amplification section for supplying a driving current to the semiconductor laser device with the power voltage so that the semiconductor laser device comes to have its respective objective operating voltage.

Abstract: A laser driver circuit includes a biasing current source, a threshold current source, and a modulation current source, wherein the threshold current source produces a threshold current in response to an input signal with an interval exceeding an interval of a modulation current such that said interval of the threshold current includes the interval of said modulation current. The laser driver circuit drives the laser diode by a sum of a continuous bias current, the threshold current and the modulation current.

Abstract: It is an object of the present invention to provide a driving circuit which can drive a light emitting element in spite of a reduced power supply voltage and which is thus suitable for size reduction. The present invention provides a driving circuit which supplies a bias current to a light emitting element and which carries out modulation on the basis of voltage driving, the driving circuit comprising a boosting circuit that increases a power supply voltage Vcc, a resistance element connected between an output of the boosting circuit and an anode terminal of the light emitting element, and a capacitive element connected to the anode terminal of the light emitting element to supply a modulation signal to the light emitting element for voltage driving.