Abstract: An apparatus comprising: a processor for determining if a laser is operating in a single-mode state and for determining the degree to which one of one or more tunable parameters for the laser must be adjusted so that laser operates in a single-mode state if not operating in a single-mode state, wherein the one or more tunable parameters include the following parameters: the laser current and the wavelength of the output light. The apparatus may include a laser and/or a holographic storage medium. Also provided is a method for determining if a laser is operating in a single-mode state and for determining the degree to which one of one or more tunable parameters for the laser must be adjusted so that laser operates in a single-mode state if not operating in a single-mode state.

Abstract: Various circuits and methods are provided for driving a laser. A laser driver circuit is configured to generate a modulated current through a laser. Also, a peak current source is employed to generate a peak current that is differentially applied to the laser to enhance a transition rate of the laser.

Abstract: Various laser drivers and methods are provided. In one embodiment, a laser driver is provided that comprises a laser driver circuit having a common anode portion and a common cathode portion. The common anode portion and the common cathode portion are each configured to drive a laser. Also, the laser driver includes a control input to alternatively enable one of the common anode portion and the common cathode portion to drive the laser.

Abstract: This invention relates to a method and system to detect hysteresis/unstable regions of multi-section lasers. The method comprises the steps of obtaining a first set of measurement values for the output of the laser diode by increasing a first current through a range of values in a positive direction, increasing a second control current by a step, obtaining a second set of measurement values for the output of the laser diode by decreasing the first control current through a range of values in a negative direction, and increasing a second control current by a step. The process is repeated until a sufficient range of the second control currents has been used to provide resultant data which can then be processed in order to identify regions of hysteresis of the laser diode.

Abstract: A light source device includes: a plurality of laser light sources that emit laser light; and a light source driving section that drives at least one of the laser light sources by a first driving value that is a value less than a threshold level of at least one of the laser light sources, or by a second driving value that is a value greater than a threshold level of at least one of the laser light sources, and that varies at least one of the number of laser light sources that are driven by the first driving value and the number of laser light sources that are driven by the second driving value in the laser light sources, thereby controlling the total output of laser light emitted from the laser light sources.

Abstract: Objects are achieved by an optical semiconductor device comprising: a structure 61 including a substrate 50, a diffraction grating 52a, an active layer 54 and a refractive index control layer 60; and an laser element 100 including an electrode 92a for the active layer, an electrode 92b for the refractive index control layer and an electrode 92c for switching, wherein a pre-bias current is previously supplied from the electrode 92a for the active layer to the active layer 54 in a state where a switching current is not supplied from the electrode 92c for switching to the active layer 54, and then while a current Idrive for activation is supplied from the electrode 92a for the active layer to the active layer 54, the laser element 100 is turned on by supplying the switching current Isw from the electrode 92c for switching to a part of the active layer 54, as well as turning off the laser element 100 by halting the supply of the switching current Isw.

Abstract: A semiconductor laser driving apparatus controls a semiconductor laser to output a prescribed intensity of laser light. The semiconductor laser driving apparatus includes at least two semiconductor laser driving circuits each outputting a prescribed amount of current to the semiconductor laser when operated, and a control circuit selectively transmitting a control signal and controlling one or more semiconductor laser driving circuits to operate in accordance with a prescribed intensity of laser light to be irradiated from the semiconductor laser.

Abstract: A drive signal for driving a semiconductor laser is generated on the basis of an image signal inputted in synchronism with a pixel clock. A bias signal to the semiconductor laser is generated at a timing earlier than the drive signal by a predetermined time. The bias signal is disabled in synchronism with the leading edge of the drive signal.

Abstract: The invention provides a method of reducing a time-averaged coherence of laser radiation for current-tunable lasers, and a laser apparatus realizing the method, by modulating the laser drive current using a modulation function optimized for obtaining a pre-determined time-averaged spectral profile of the laser radiation. In a preferred embodiment, the pre-determined time-averaged spectral profile has a substantially Gaussian shape. The method is described in reference to laser diodes.

Abstract: An optical transceiver module having digital control of laser current peaking is disclosed. The optical transceiver module comprises a controller and integrated post-amplifier/laser driver, which are included on a printed circuit board disposed in the module. Transmitting and receiving optical sub-assemblies are also disposed in the module. A digital signal interface interconnects the controller with the integrated post-amplifier/laser driver. Digital control signals produced by the controller are transmitted via the digital signal interface to the integrated post-amplifier/laser driver, where they are converted to analog control signals. The analog control signals are forwarded to control components responsible for governing the electrical current supplied to the laser of the transmitting optical sub-assembly. The laser current is intermittently peaked by the control signal in order to hasten the transition from light to no-light emission, thereby improving laser response and performance.

Abstract: A system is provided that electrically isolates a diode laser when the health of the diode laser deteriorates past a preset value. In addition to the diode laser and its power supply, the system includes a monitoring system that monitors the voltage across the diode laser and/or the voltage across a series resistor and/or the operating temperature of the diode laser and/or one or more characteristics of the output beam of the diode laser and/or the temperature of the diode laser coolant and/or the flow rate of the diode laser coolant. The system also includes a power supply controller and associated control circuit that is activated upon receipt of a trigger signal from the monitoring system.

Abstract: A method is provided for determining a laser threshold of a laser diode, which is operated by a drive circuit as a function of a first signal in a first feedback and a second signal in a second feedback, the first feedback being supplied via an optical coupling of an optical output signal of the laser diode.

Abstract: A circuit arrangement for generating light pulses includes an electro-optical converter; a switching element; and a charge store. The electro-optical converter is connected to the charge store via the switching element. The closing of the switching element triggers a discharging process in the charge store and, in the process, generates an electrical pulse that is converted to a light pulse in the electro-optical converter. First and second impedance matching circuits are arranged, respectively, between the charge store and the switching element and between the switching element and the electro-optical converter.

Abstract: A semiconductor laser light emitting circuit includes a semiconductor laser diode emitting a laser light by modulating a current supplied thereto, a light intensity detection circuit that detects the laser light and generates a voltage, and a voltage-current conversion circuit converting a voltage into a current supplied to the laser diode. A S/H capacitance is provided to store electric charge and output a voltage to the voltage/current conversion circuit. A first operational amplifier is provided to output a first current charging the S/H capacitance. A rapidly charging circuit is provided to charge the S/H capacitance with a second current. The rapidly charging circuit terminates charging when the voltage is equal to or more than a second reference voltage.

Abstract: High-speed measurements of the output power level of a laser are obtained by using a high-speed laser output power monitoring device that is capable of producing an electrical feedback signal having an amplitude that varies as the output power level of the laser varies. A high-speed amplitude detector receives the electrical feedback signal and detects the amplitude of the feedback signal and produces an optical modulation amplitude (OMA) detection signal. The OMA detection signal is received in a high-speed amplitude measurement device that measures the OMA and produces an OMA measurement value. The OMA measurement value is then processed by the laser controller to obtain a modulation current control signal, which is then output to the laser driver to cause the laser driver to adjust the laser modulation current to obtain a desired or optimum laser output power level.

Abstract: A laser driver comprises a plurality of current sources, including at least one bias current source and at least two drive current sources. To control the laser driver, a set of operating states is defined where each operating state corresponds to a desired laser output power level and a ratio is defined that establishes a relationship between a first desired laser output and a second desired laser output. A calibration operation samples laser output power of the laser source for less than all of the operating states, computes adjustments to the current levels of the current sources based at least in part upon the ratio such that sampled laser power levels converge towards their corresponding desired laser output level. The current sources are adjusted to their corresponding computed current levels.

Abstract: A semiconductor laser driving circuit has a circuit protection function at low temperature and includes a voltage current converter that converts an input voltage Vin, which is determined according to a desired light brightness of the semiconductor laser to be driven, into a current. A current limiter limits an output current of the voltage current converter to a specified current value or less. An output amplifier amplifies the output current of the voltage current converter and supplies the amplified current as a drive current to the semiconductor laser. A temperature detection circuit detects a low temperature state and, in the low temperature state, decreases the specified current value of the current limiter.

Abstract: The present invention is directed to an optical disc recorder laser power control apparatus utilizing two different current sources to solve the problem caused by the contradiction between control resolution and control range. The first current source and the second current source are connected in parallel to a single control output pin. The first current source and the second current source may work independently from each other. The laser driver controls emission power of one of the laser diodes with a driving current supplied from the single control output pin coupled to both the first current source and the second current source. Advantageously, the fine laser power control pitch from the first current source contributes to fine control resolution, while the coarse laser power control from the second current source provides a wide control range for various kinds of laser diodes.

Abstract: A method for calibrating the calculation of a laser power measurement with respect to specified operational and/or environmental parameters in an optoelectronic device, such as an optical transceiver module having a laser diode, is disclosed. In particular, the method includes sensing analog data that relates to light emission from the laser diode using a monitor photodiode disposed in the optical transceiver module. Additional sensors are then used to sense analog data that relates to the temperature and voltage of the monitor photodiode. The analog data is converted into digital data, then a formulaic relationship that relates the light emission data to the temperature and voltage data is used to calculate the laser power of the laser diode. Calibration by this method accounts for unintended effects caused by temperature and voltage fluctuations in the optical transceiver module.

Abstract: A driver for a vertical-cavity surface emitting laser (VCSEL) is provided that includes a bias current source, a modulation current source, and an output tracking circuit. The bias current source is operable to generate a bias current and an output voltage for the VCSEL and to generate a replica output voltage. The modulation current source is coupled to the bias current source by at least one switch and is operable to generate a modulation current for the VCSEL when the switch is closed. The output tracking circuit is coupled to the bias current source. The output tracking circuit is operable to generate a feedback signal for the bias current source based on the output voltage and the replica output voltage. The bias current source is also operable to generate the output voltage and the replica output voltage based on the feedback signal.

Abstract: Laser power control arrangements interrupt power to a laser used in electro-optical readers upon detection of an over-power condition not conforming to preestablished regulatory standards. In one embodiment, during an operational mode, a difference between laser drive currents at two operating points is compared to a difference between laser drive currents at the same two operating points during a calibration mode. The over-power condition is recognized when the difference during the operational mode exceeds the difference during the calibration mode by a predetermined amount. In another embodiment, the laser is only energized to emit the beam at a reduced power level well below regulatory standards for staring at even if a motor drive failed.

Abstract: Embodiments of the present invention are directed to current driver circuits and methods for driving a load. The current driver circuit includes a first transistor (Q1) and a second transistor (Q2) each having a gate, a drain and a source. The drain of the second transistor (Q2) forms the output of the current driver circuit. The first and second transistors (Q1) and (Q2) function as a current mirror when the gates of the first and second transistors (Q1) and (Q2) are selectively connected together. The current driver circuit also includes a current source, a load mimic circuit, and a control loop (e.g., including an op-amp), which are configured to cause the voltage at the drain of the first transistor (Q1) to substantially equal the voltage at the output of the current driver circuit.

Abstract: A driver circuit including an amplifier, which generates a control signal from a reference signal; a driver current mirror; and a control current switch located between the amplifier and the driver current mirror which selectably isolates the driver current mirror from the amplifier or connects the driver current mirror to the amplifier, wherein the driver current mirror, when in a state connected to the amplifier, amplifies the control signal into a driver signal. A compensating circuit is provided that generates a correction signal, as a function of an error current of the driver current mirror and provides the correction signal to an input of the amplifier, wherein a feedback signal input of the amplifier is fed through a feedback path from a feedback signal coupled out of a control branch of the driver current mirror, and the compensating circuit additively provides the correction signal at an input of the amplifier.

Abstract: A laser diode driving circuit capable of providing a suitable output current to a laser diode is disclosed. The laser diode driving circuit includes a current supply, a first pseudo laser diode, a second pseudo laser diode, and an output current mirror circuit. An input current provided by the current supply is output through the output current mirror circuit to the laser diode. By making the characteristic of each of the first and second pseudo laser diodes substantially equal to the characteristic of the laser diode, the non-linearity between the input current and the output current is compensated.

Abstract: The invention relates to a method for initializing a control of a supply voltage of a light source, such as a laser diode, the light source being arranged in a first circuit configuration having an associated first reference voltage level or the light source being arranged in an alternative second circuit configuration having an associated alternative second reference voltage level, the method comprising the steps of gradually changing the supply voltage into the direction of the first reference voltage, measuring a light emission of the light source while gradually changing the supply voltage, if no light emission is measured: starting the control of the supply voltage of the light source after the first reference voltage has been reached and if a light emission is measured gradually changing the supply voltage into the direction of the second reference voltage and starting the control of the supply voltage of the light source after the second reference voltage has been reached.

Abstract: The present invention provides an optical transmitter comprising one control unit and a plurality of optical sources. Control signals are multiplexed and de-multiplexed as appropriate to enable control of all optical sources by the control unit.

Abstract: An inexpensive laser drive device which is capable of driving a laser for emission of an appropriate amount of light. Electric currents supplied from a supply current control device formed in an integrated circuit to a plurality of predetermined ports of the integrated circuit are turned on and off by switching devices in response to a signal from a signal output device of the supply current control device, and the on currents are supplied, as a driving current, from the supply current control device to a laser beam-emitting device through corresponding ones of the predetermined ports and resistors externally attached to these ports. A generator device formed in the integrated circuit generates a pulse signal for turning on and off a laser beam based on image data.

Abstract: A DBR semiconductor laser is controlled in an image projecting apparatus, which includes the DBR laser having a phase and DBR region, a light wavelength converting device for converting fundamental-wave light emitted from the DBR laser into second harmonic wave light, an optical deflector for scanning the second harmonic wave in a one or two-dimensional manner, and a modulating portion for modulating the DBR laser. Coefficient calculating and wavelength adjusting steps are performed within a non-drawing time. The coefficient calculating step calculates at least one coefficient in a relationship between a DBR current to be injected into the DBR region and a phase current to be injected into the phase region for continuously shifting the wavelength of the fundamental-wave light. The wavelength adjusting step changes DBR current injected into the DBR region and phase current injected into the phase region based on the relationship.

Abstract: A laser output power command determination value from a controller (17) is input to an upper limit current determination unit (32), and an upper limit current value to be decided based on the laser output power command determination value is determined. Then, a second comparator (30) compares a command current value determined from the laser output power command determination value and a laser output power command determination value measured with a power monitor (13), with an upper limit current value determined with a upper limit current determination unit (32). The second comparator (30) determines a command current value when the upper limit current value is greater than the command current value and the upper limit current value when the command current value is greater than the upper limit current value, as a reference current value, by which reference current value a current to be supplied to pumping means is configured to be controlled.

Abstract: A laser drive circuit may be used to induce high limit clipping corresponding to natural low limit clipping in a laser, such as a laser diode, to reduce even order distortion such as composite second order (CSO) distortion. A drive current input may be provided to the active region of the laser to produce a modulated optical output in response to the drive current input. The laser drive circuit may include a current clamp at the drive current input, which clamps the drive current to provide the high limit clipping. The current clamp may receive an input current including current from a RF signal provided by a RF source together with a bias current provided by a bias current source.

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: The present invention relates to the field of pulsed laser oscillators. It relates to a pulsed laser oscillator (15) for emitting a laser pulse, including a laser cavity (15), said laser cavity including a laser medium (4) able to be pumped by pump radiation emitted by at least one pump radiation source (5) and to emit laser radiation, said laser cavity (15) including seal means (7) able to seal said cavity for a period of sealing, characterized in that said seal means (7) are electro-optical seal means, and in that said seal means are able to be powered by a supply voltage, so that the duration of the pulse emitted is modified when the value of the supply voltage is modified.

Abstract: An accelerator circuit is incorporated in a laser diode system for accelerating the turn-on operation of the laser diode independent of the control loop bandwidth of the laser diode system. The accelerator circuit provides a boost current to a compensation capacitor upon laser turn-on which compensation capacitor operates to establish the control loop bandwidth of the laser diode system. The boost current enables the control loop to increase the bias current to the laser diode quickly. When the laser diode reaches the desired operating point, the boost current is terminated and the control loop of the laser diode system resumes normal control of the bias current. In one embodiment, the accelerator circuit includes a timer circuit controlling a current source to implement open loop turn-on control. In another embodiment, the accelerator circuit includes a comparator circuit working in conjunction with an one-shot logic circuit for providing close loop control.

Abstract: An optical disk device includes: a light emitting element which applies light to an optical disk; a light detection unit which receives the light emitted from the light emitting element and outputs an intensity signal corresponding to an intensity of the light emitting element; a difference detection unit which generates a control signal based on a difference between the intensity signal and a reference intensity signal; a first current supply unit which supplies a first current based on the control signal; a second current supply unit which supplies a second current; a current adding unit which adds the first and second currents to generate a third current and supplies the third current to the light emitting element; an optical pickup on which the first current supply unit and the adding unit are placed; and a circuit board on which the second current supply unit is placed.

Abstract: The invention discloses an optical transmission module with digital adjustment and method thereof. The module includes a laser (21), a laser driver (22), an automatic power adjustment circuit (23), an automatic temperature adjustment circuit (24), a digital adjustment circuit (25) and a memory (26). The digital adjustment circuit, consisted of a digital-to-analog converter or a digital adjustment potentiometer, receives a digital adjustment signal and outputs, respectively, a extinction ratio adjustment signal and a cross point adjustment signal to the laser driver, an optical power adjustment signal to the automatic power adjustment circuit and an optical wavelength adjustment signal to the automatic temperature adjustment circuit. The memory stores data, using for on-line adjustment of the optical transmission module, at least including parameters of said optical transmission module and said laser emitting optical power parameters, to be reported upward.

Abstract: An integrated circuit for providing burn-in current to a laser diode. The integrated circuit includes a laser driver having an output for connection to the laser diode. Burn-in circuitry is formed on the integrated circuit and generates a burn-in current. A switch is formed on the integrated circuit and couples the burn-in current to the laser diode in response to an enable signal.

Abstract: To achieve both a fast risetime and a desired flat top current pulse, or to be able to independently specify a risetime and pulse width (energy), a supplemental or “fast” voltage discharge stage (or multiple supplemental or “fast” voltage discharge stages) having a faster and shorter voltage discharge characteristic and a higher starting voltage relative to the main or “slow” voltage discharge stage is used in parallel with the slow voltage discharge stage. The energy storage element of the slow voltage discharge stage has sufficient energy storage at an appropriate voltage level for maintaining the desired flat top current throughout the pulse duration, while the energy storage element of the fast voltage discharge stage has less energy storage capability but a higher starting voltage for achieving the desired fast current pulse risetime.

Abstract: A light emitting diode driving device for driving an LED includes (i) a driving pulse current generating circuit for generating a driving current for the LED in accordance with a driving pulse signal supplied from outside and (ii) a differentiating circuit for generating a peaking current obtained by differentiating the driving pulse signal. A current that is equal to the sum of the driving current and the peaking current flows to the LED. The light emitting diode driving device further includes a peaking control circuit for controlling the magnitude of the peaking current generated from the differentiating circuit.

Abstract: Beth of highly stable light having the same optical performance and fast-modulated light are emitted simply and inexpensively.

Abstract: An optical power control apparatus includes a changing unit which changes, a plurality of number of times, the value of a current flowing to an optical beam output apparatus, and an obtaining unit which obtains, in correspondence with each current value, a peripheral optical power representing an optical power at the peripheral part of the spot of the optical beam output from the optical beam output apparatus. The optical power control apparatus also includes a correction unit which corrects the peripheral optical power so that the peripheral optical power and a central optical power representing an optical power at the central part of the spot have an approximately linear relationship in correspondence with each current value. The optical power control apparatus also includes a control unit which controls the optical power of the optical beam output from the optical beam output apparatus in accordance with the corrected peripheral optical power.

Abstract: An accelerator circuit is incorporated in a laser diode system for accelerating the turn-on operation of the laser diode independent of the control loop bandwidth of the laser diode system. The accelerator circuit provides a boost current to a compensation capacitor upon laser turn-on which compensation capacitor operates to establish the control loop bandwidth of the laser diode system. The boost current enables the control loop to increase the bias current to the laser diode quickly. When the laser diode reaches the desired operating point, the boost current is terminated and the control loop of the laser diode system resumes normal control of the bias current. In one embodiment, the accelerator circuit includes a timer circuit controlling a current source to implement open loop turn-on control. In another embodiment, the accelerator circuit includes a comparator circuit working in conjunction with an one-shot logic circuit for providing close loop control.

Abstract: In case of driving each of light emitting parts of a surface emitting laser, each of light emitting parts is made to be in forward-bias state and switches appropriately change bias voltage, which is lower than laser oscillation threshold voltage, and drive voltages, which are not less than the laser oscillation threshold voltage to directly apply the changed voltage to each of drive ends of the light emitting parts. Whereby, each of light emitting parts is driven.

Abstract: A laser power control circuit that is constituted by CMOS transistors reduces variations in a laser power that is emitted from a semiconductor laser, which are caused by a mismatch of the transistors. An offset amount of a differential amplifier is digitally calculated using an A/D converter that is located on the same chip, and a voltage value of a variable voltage source is controlled for applying a voltage in a direction opposite to the offset voltage of the differential amplifier to correct the offset voltage of the laser power control circuit, thereby reducing the variations in the laser power emitted from the semiconductor laser.

Abstract: A laser light source comprises a semiconductor laser adapted for pulsed operation, a partially transmitting wavelength selective light reflector. The semiconductor laser comprises a front facet and a back facet. The front facet and the back facet define an internal laser cavity. The internal laser cavity comprises a laser active medium. The partially transmitting wavelength selective light reflector has a peak reflectivity within a gain bandwidth of said laser active medium. The wavelength selective light reflector and the back facet define an external laser cavity. A roundtrip time of light in the external laser cavity is about 20 nanoseconds or less. A full width half maximum bandwidth of the wavelength selective light reflector is adapted to accommodate at least 12 longitudinal modes of the internal laser cavity and at least 250 longitudinal modes of the external laser cavity.

Abstract: An operating current modifying device is provided for a power generating element. The power generating element generates an output power when the operating current is larger than a threshold current in the power generating element. A functional relationship exists between the threshold current and the temperature of the electrical device. The operating current modifying device may include a threshold current modifying module, a power modifying module, a current compensating module, and a power control module.

Abstract: A method, system, and electrical circuit for determining a magnitude of a modulation current provided to a laser device based upon an approximated slope efficiency, wherein the approximated slope efficiency is based upon at least one discrete incremental change in a bias current to the laser device and at least one change in output power from the laser device.

Abstract: An apparatus and method to safely control the power output of a laser source. A power monitor is optically coupled to monitor a power output of laser source generating an optical signal. The power monitor is coupled to generate power feedback data indicative of the power output. A processor is coupled to control the power output of the laser source in real-time in response to the power feedback data from the power monitor.

Abstract: A method for optimizing a dc operating drive current of a laser diode is presented. Lasers of a particular type are characterized in terms of the dependency of certain parameters on temperature and of the minimum bias current required for adequate laser speed. The minimum bias current is determined using the operating bias current minus the threshold current all normalized by the threshold current. For individual laser diodes, the threshold current and slope efficiency are obtained at various temperatures to allow calculation at operating temperatures of interest. The minimum laser bias current for speed can then be determined over the operating temperature range. This may be done by setting the optical power to the highest value calculated using this minimum acceptable bias criterion over the operating temperature range. The ac and dc laser driver current sourcing requirements may be computed to ensure laser and module compatibility.

Abstract: The present invention relates to an optical power and extinction ratio controlling device and method. An optical signal output from a light source is detected and optical power and extinction ratio of the light source are controlled. In detail, a feedback signal is provided to the light source to automatically control the bias current based on a DC signal output by a photodetector detecting the optical signal. Therefore, the optical output of the light source is maintained. Also, an optical signal output by the photodetector is converted into a predetermined times DC signal, and a feedback signal is provided to the light source to automatically control the modulation current based on the DC signal. Therefore, the extinction ratio of the light source is maintained. As a result, the extinction ratio is automatically maintained to satisfy the change of condition and the characteristic of light source, thereby maintaining quality optical outputs.

Abstract: A laser driver IC has an RS flip-flop for latching a signal that indicates an event of fault detection, to output it as an internal fault signal, and a fault signal processing section for generating a disable signal for inactivating the driving function of the laser driver IC in response to output of the RS flip-flop. One of outputs of the fault signal processing section is connected to a fault signal output terminal linked to outside the laser driver IC.