Abstract: A laser diode driver for driving laser light sources of a N-wavelength optical pickup capable of recording on and playing N types of optical discs by using N laser beams having different wavelengths, the N-wavelength optical pickup including first to N-th laser diodes for emitting first to N-th laser beams as the laser light sources and one front monitor for monitoring intensity of the first to N-th laser beams, the laser diode driver comprising a current/voltage conversion amplifier for converting a monitor current monitored by the front monitor into a monitor voltage and outputting the monitor voltage as a monitor output signal, wherein N is an integer which is two or more.

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: In the present invention, the extremely complicated setting and control and an extremely expensive optical component (wavelength locker) are not required, and optical output wavelength and optical output power can simply be set and controlled at a moderate price. At least one value for determining a dependence of the optical output wavelength on drive current and device temperature and at least one value for determining a dependence of the optical output power on drive current and device temperature in a light emitting device constituting first means 1 for emitting light are stored in fourth means 4.

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: Semiconductor lasers are driven such that high output laser beams are stably obtained without a long start up time. The light outputs of a plurality of semiconductor lasers are detected by photodetectors. The semiconductor lasers are driven by automatic power control based on comparison results between the output of the photodetectors and a set value corresponding to a target light output for the semiconductor lasers. A correction pattern that corrects the set value and/or the output of the photodetectors such that the actual light output becomes uniform is generated in advance. The set value and/or the output are varied according to the correction pattern for a predetermined period of time from initiation of drive. A single correction pattern is employed in common with respect to the plurality of semiconductor lasers.

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: 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 laser projection device suitable for displaying full color images is disclosed. The LPD includes a variety of techniques for modulating laser beams produced by one or more lasers with image data to controllably produce the image using a modified raster scan.

Abstract: The present invention generally relates to dynamic thermal management of a device. In one aspect, a method for thermally controlling a device is provided. The method includes setting a value of a set point in a thermoelectric cooler, wherein the set point corresponds to a first operating state. The method also includes monitoring a condition of the device to determine if the device is in the first operating state or a second operating state. Additionally, the method includes dynamically altering the value of the set point according to an algorithm upon determination that the device is in the second operating state. In another aspect, a method for dynamically controlling a device having a thermoelectric cooler is provided. In yet a further aspect, a system for dynamic thermal management of a device is provided.

Abstract: The quality of pulses output from laser systems such as super-pulsed CO2 slab lasers can be improved using half-wavelength electro-optic modulators (EOMs), in combination with thin film polarizers (TFPs). A voltage applied across a CdTe crystal of the EOM rotates the polarization of a pulse passing through the EOM by 90°. The polarization determines whether the pulse passes through, or is redirected by, the TFP. The voltage applied to the crystal can be pulsed to prevent a drop in charge, which could allow radiation to leak to the application. A totem pole switch used to apply voltage to the EOM can receive a pulsed voltage for improved performance. Directing by the EOM allows pulses to be clipped at the front/back end(s), split into portions, and/or directed to separate scanners. Directing pulses or pulse portions to different scanners can increase the output of systems such as hole drilling systems.

Abstract: Protection methods and protection systems for semiconductor devices with diode junctions.

Abstract: One embodiment of a laser driver for high speed interconnections includes a buffered level shifter to shift the input voltage level to an appropriate level. In some embodiments the buffered level shifter may be tuned to provide a desired level shift with impedance matched to the driving load. Another embodiment converts a digital signal to a current train of a bias mode to represent logical zero and of a modulation mode to represent logical one, wherein one or both of the bias mode and modulation mode may be adjusted, for example by a programmable control circuit or by an adaptive control circuit. Some embodiments also provide circuitry for reducing overshoot of the output signal.

Abstract: A circuit for driving a semiconductor laser, in particular a vertical cavity surface-emitting laser that comprises a differential amplifier for driving the semiconductor laser directly. The semiconductor laser is differentially driven by means of the differential amplifier, a first output of the differential amplifier being direct-current-coupled to a first terminal of the semiconductor laser and a second output of the differential amplifier being alternating-current-coupled to a second terminal of the semiconductor laser.

Abstract: The present invention is to present a sample analyzer capable of automatically stabilizing the laser diode in multi-mode oscillation. A sample analyzer 1 comprises: a laser diode (LD) 501d for irradiating a sample with laser light; a photodiode (PD) 501e for detecting amount of light emitted from the LD 501d; a APC circuit 501b for outputting a direct current to be supplied to the LD 501d such that the amount of light emitted from the LD 501d is maintained at a predetermined amount, based on the amount of light detected by the PD 501e; a high frequency oscillation circuit 501f for superimposing a high frequency component on the direct current outputted from the APC circuit 501b; and a high frequency automatic adjustment circuit 501c for controlling amplitude of the high frequency component outputted from the high frequency oscillation circuit 501f according to magnitude of the direct current outputted from the APC circuit 501b such that the LD 501d oscillates in a multi-mode.

Abstract: An optical disk apparatus uses a laser driver which can measure the frequency of the high-frequency superimposed current of the semiconductor laser simply and accurately. The apparatus includes a semiconductor laser which emits a laser beam onto the optical disk, a laser driver which drives the semiconductor laser with a current, with the high-frequency current being superimposed thereon, and measures the frequency of the high-frequency current, and a main controller which controls the frequency of the high-frequency current produced by the laser driver by using the frequency measured by the laser driver.

Abstract: In one example configuration, an optical package includes a substrate that supports a laser. The laser is configured for electrical communication with circuitry disposed on the substrate, and the laser is arranged to emit an optical signal along a first path. The optical package also includes a beam steering device supported by the substrate and arranged so as to receive the optical signal from the laser along the first path. The beam steering device is configured such that the optical signal is output from the beam steering device along a second path. A group of electronic leads is provided that electronically communicates with the circuitry on the substrate. In this example, the group includes a set of modulation leads in electrical communication with the laser, and a set of bias leads in electrical communication with the laser. The set of bias leads is electrically isolated from the set of modulation leads.

Abstract: A control circuit for a laser diode is disclosed, in which the driving current may be suppressed even when the monitor PD breaks down to make the APC feedback control inoperable. The control circuit comprises an LD driver to supply the driving current to the LD, a monitor PD to detect a portion of output light from the LD, and the APC controller to adjust the driving current. The current limiter, when the driving current reaches or exceeds the threshold, controls the driving current Id so as to keep the current in a preset value or a value just before the extraordinary increase of the driving current occurs.

Abstract: A control method for a laser diode is conducted such that optical output and OMA (optical modulation amplitude) or extinction ratio of the laser diode are controlled while modulating the optical output of the laser diode by applying a bias current and a modulation current to the laser diode. The method has: a first step of measuring the optical output of the laser diode; a second step of measuring a slope efficiency or a corresponding value of the slope efficiency while conducting APC (automatic power control) to adjust the bias current such that the optical output coincides with a predetermined value; and a third step of adjusting the modulation current by AAC (automatic amplitude control) according to the slope efficiency or the corresponding value of the slope efficiency such that the OMA or extinction ratio coincides with a predetermined value.

Abstract: The present invention relates generally to semiconductor lasers and laser scanning systems and, more particularly, to schemes for controlling wavelength in semiconductor lasers. According to one embodiment of the present invention, a method of minimizing laser wavelength variations in a semiconductor laser is provided. According to the method, one or more of the laser drive currents is configured to comprise a drive portion and a wavelength recovery portion. The wavelength recovery portion of the drive current comprises a recovery amplitude IR that is distinct from the drive amplitude ID and a recovery duration tR that is less than the drive duration tD. The recovery amplitude IR and duration tR are sufficient to recover carrier density distribution distorted by gain compression effects prior to recovery. Additional embodiments are disclosed and claimed.

Abstract: An LED drive circuit, wherein a circuit that drives light-emitting diode with a common connected cathode has a resistor connected to the anode of the light-emitting diode, an NPN-type transistor connected to the second terminal of the resistor that approximately determines the control current for the emission of light in cooperation with the resistor, an NPN-type transistor positioned in parallel with the resistor and connected to the anode of the light-emitting diode, and a current supply, a level shifter, and a switch for selectively changing the voltage between the base-emitter of the second transistor, which are placed between the base of transistor and resistor.

Abstract: A laser control apparatus and control method thereof includes multiple laser elements, a photodetector for monitoring optical outputs of the laser elements, a modulation. circuit for modulating with respect to each laser element based on data, a first drive source for applying a bias current to each laser element, a second drive source for generating a modulation current in the modulation circuit, and a controller for controlling the first drive source and the second drive source to couple an amount of a variation of a drive current as a test current to the bias current and the modulation current and for controlling the bias current according to an amount of variation of the optical output which occurs by coupling of the test current and an amount of the bias current.

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: The present invention provides an optical transmitter that enables to distinguish failure modes of the auto-power control (APC) of the laser diode (LD). The transmitter provides the APC circuit comprised of the driver for supplying the driving current, the LD, the PD for monitoring a portion of the output light from the LD, and the control unit for setting the driving current. The control unit monitors, at regular intervals, the bias current to the LD and the time differential of the bias current. The control unit only stops the APC circuit when both the bias current and the time differential of the bias current exceed respective references.

Abstract: A method for compensating for changes in output power or wavelength of an optical source with temperature. Many optical sources have power and/or wavelength variations with temperature which can be compensated by open- or closed-loop methods if a method of accurately measuring the optical source temperature is available. The voltage across a semiconductor junction varies with temperature. Measuring the optical source power or wavelength variation with temperature and tracking the voltage across the semiconductor junction provides a means for compensating an instrument for temperature induced optical output power or wavelength variations. An important field of application is optical density or turbidity measurements in cellular media.

Abstract: An automatic power control system provides a control signal that regulates the output power of at least one laser diode. Coarse adjustment of the control signal is provided by a first means, preferably a digital variable resistor, while fine adjustment and compensation is provided by a second means, preferably by a digital-to-analog converter that receives an input signal proportional to a sensed control system parameter. The control system includes an operational amplifier having a first input coupled to sense output power, and a second input coupled to a DAC to provide finer resolution control. Memory can store system parameter or system parameter variations that can be coupled to the DAC and/or variable resistor to enhance system stability over ambient variations.

Abstract: Particular embodiments of the present invention relate generally to semiconductor lasers and laser scanning systems and, more particularly, to schemes for controlling semiconductor lasers. According to one embodiment of the present invention, a laser is configured for optical emission of encoded data. At least one parameter of the optical emission is a function of a drive current IGAIN injected into the gain section of the semiconductor laser and one or more additional drive currents I/VPHASE, I/VDBR. Mode selection in the semiconductor laser is altered by perturbing at least one of the additional drive currents I/VPHASE, I/VDBR with a perturbation signal I/VPTRB to alter mode selection in the semiconductor laser such that a plurality of different emission modes are selected in the semiconductor laser over a target emission period.

Abstract: The present invention provides an optical amplifying apparatus having: a CPU 11 for processing various signals; a plurality of circuits 17, 18 for controlling respective devices 4, 9 required for optical amplification; a first storing unit 14 for storing a program supplied from a user a gate array 12 for storing various parameters for controlling the devices 4, 9, the gate array being updated based on the program which is stored in the first storing unit 14 and sent via the CPU 11; a latch unit 13, provided between the gate array 12 and the circuits 17, 18, for interrupting a signal path from the gate array 12 to the circuits 17, 18 after receiving a starting signal of an update from the CPU 11 until the update being finished and for controlling the circuits 17, 18 based on the parameters stored in the gate array 12 before the signal path is interrupted; and a second storing unit 16 for, at least during the update, storing the various parameters which are stored in the gate array 12 before the update.

Abstract: A laser driver comprises a PNP transistor current source, an inductor coupled to the PNP transistor current source, a switch coupled to the inductor, and a current sink coupled to the switch. The PNP transistor current source supplies a first current to a laser if the switch is closed and a second current to the laser if the switch is open. The PNP transistor current source, inductor, switch, and current sink are on a single semiconductor chip.

Abstract: An image data processing section subjects input image data to image processing, and outputs first to fourth image data. First to fourth pulse width modulation circuits are PWM circuits in each of which a plurality of reference positions are set in one pixel, and output pulses corresponding to the first to fourth image data. A synthesis circuit synthesizes the pulses output from the first to fourth pulse width modulation circuits, and a laser emits a light beam in accordance with the synthesized pulse.

Abstract: A method for determining a condition of the laser system includes determining a change in a laser current from an initial value. A method for measuring a laser current includes determining a difference between the values of a power supply current, which is the value of the laser current. A method for measuring a transmitted power includes generating a first control signal that sets a magnitude of a bias current supplied to a laser, generating a second control signal that sets a of a modulation current supplied to the laser, and determining a difference between values of a high and a low transmitted powers. A method for measuring a received optical power includes determining a received OMA corresponding to the power signal, which is the transmitted OMA minus a known loss through a calibration fiber that couples the laser transmitter to the laser receiver.

Abstract: This disclosure concerns systems, methods and devices for temperature-based control of laser performance. One example of a method is performed in connection with a laser of an optoelectronic transceiver. In particular, the laser is operated over a range of temperatures and the optical output of the laser is monitored. During operation of the laser, the bias current and current swing supplied to the laser are adjusted to the extent necessary to maintain a substantially constant optical output from the laser over the range of temperatures.

Abstract: A semiconductor laser comprises two optical ring resonators, each comprising an optical waveguide electrically pumped to provide optical gain. The two ring resonators have different round-trip optical path lengths, and are coupled to each other through a half-wave optical coupler. The half-wave optical coupler has a predetermined cross-coupling coefficient and a 180-degree cross-coupling phase. The cross-coupling coefficient is substantially less than the self-coupling coefficients in order to achieve an optimal single-mode selectivity of the laser. The first ring resonator has an optical path length such that its resonant wavelengths correspond to a set of discrete operating channels. The second ring resonator has a slightly different length so that only one resonant wavelength coincides with one of the resonant wavelengths of the first ring resonator over the operating spectral window. The lasing action occurs at the common resonant wavelength.

Abstract: Threshold current may be determined and one or more bias sources may be programmed in a laser drive circuit. For example, a laser diode emits light along first and second optical paths. A polarizer is positioned in the first optical path between the laser diode and a first detector, which outputs a first detector signal corresponding to the measured optical power of polarized light. A second detector monitors light along the second optical path and provides a second detector signal. A bias compensation circuit receives the first and second detector signals and provides a bias current control signal, which is utilized to program a bias current source supplied to the laser diode. Additionally, multiple polarizer devices may be utilized e.g., a first polarizer in a first optical path aligned with the laser beam and a second polarizer in a second optical path aligned substantially orthogonal to the polarization of the laser beam.

Abstract: A semiconductor laser wavelength control device capable of controlling the optical wavelength constant even if the optical output intensity of the semiconductor laser varies and permitting a reduction in overall size is to be provided. It is provided with control means which controls the optical wavelength of a laser diode 1 to a prescribed wavelength by driving a temperature control unit to control the temperature of the laser diode 1.

Abstract: An optical amplifier including: a photonic gain clement; and, a transistor electromagnetically coupled to the gain element to inject current into the gain element responsively to the internal optical intensity of the gain element. The coupling of the transistor and the photonic gain element is such that as the optical intensity within the photonic gain element increases, the current injected by the transistor increases, thereby preventing filamentation in the photonic gain element.

Abstract: An image data processing section subjects input image data to image processing, and outputs first to fourth image data. First to fourth pulse width modulation circuits are PWM circuits in each of which a plurality of reference positions are set in one pixel, and output pulses corresponding to the first to fourth image data. A synthesis circuit synthesizes the pulses output from the first to fourth pulse width modulation circuits, and a laser emits a light beam in accordance with the synthesized pulse.

Abstract: Optoelectronic devices and methods are used to maintain a CWDM transmitter operating within design parameters over an extended ambient temperature range. In order to avoid excessive wavelength drift with temperature shifts, lasers in the CWDM transmitters are heated or cooled to a selected temperature, for example by using a thermoelectric cooler. By heating and cooling the lasers, any wavelength drift that an ambient temperature variation might inflict on the laser is minimized to the range hotter or colder than the selected temperature. As the temperature range of the laser increases above the selected temperature, the AC swing driving the laser is increased to maintain a sufficient extinction ratio for acceptable transmitter performance.

Abstract: An infrared transmitter circuit causes an output current to flow to a light emission diode via a current mirror circuit constituted of three transistors by using a current supplied from a power source circuit, so that the light emission diode emits light. When a voltage V1 varied by charging a capacitor with a current flowing from the power source circuit exceeds a reference voltage (voltage V2), an output of a comparator resets a D flip-flop, so that an output of the D flip-flop varies to “0”. Thus, an output of a NAND gate to which that output and a transmission signal are inputted causes a transistor (N-channel FET) to turn ON so as to stop operation of the current mirror circuit, and causes a transistor (P-channel FET) to turn OFF so as to cut a connection between the power source circuit and a power source line. Thus, it is possible to reduce power consumption in operation of a protection circuit which stops supplying the output current to the light emission diode.

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: A laser power control apparatus for controlling the output power of a semiconductor laser used to record and reproduce data in and from a recording medium is provided. The laser power control apparatus includes a controller configured to vary the peak output power level of the semiconductor laser in a stepwise manner, calculate a differential efficiency at each of the varied peak output power levels, and determine a laser driving current based on a relation between the differential efficiency and the peak output power level. In addition, a laser driving unit is configured to drive the semiconductor laser using the laser driving current determined by the controller.

Abstract: A driver circuit is provided, which includes a differential amplifier whose output signal controls the driving input signal, a reference signal generator that supplies a reference input of the differential amplifier, an external feedback that applies a signal, which is dependent on the output signal, to a feedback input of the differential amplifier, an adapter circuit, and an internal feedback activated in a compensation mode as an alternative to the external feedback, which internal feedback provides a signal to both the feedback input and the adapter circuit even for input signals that do not exceed the first threshold. The adaptor circuit generates and stores a compensation signal that compensates an offset signal acting alone at the reference input when the reference signal generator is switched off, and feeds the stored compensation signal, together with a reference signal, to the reference input or feedback input when the external feedback is activated.

Abstract: A multi semiconductor source tunable spectroscopy system has two or more semiconductor sources for generating tunable optical signals that are tunable over different spectral bands. The system enables the combination of these tunable signals to form an output signal that is tunable over a combined band including these individual spectral bands of the separate semiconductor sources. The system further compensates for spectral roll-off associated with the semiconductor sources. Specifically, near the limits of the semiconductor sources' spectral bands, the power in the tunable signal tends to degrade or decrease. The system compensates for this roll-off using drive current control, attenuators, or electronic compensation.

Abstract: Systems and methods are provided for configuring an optoelectronic device so as to control various operating conditions at various temperatures. The method includes operating the optoelectronic device at a first temperature, adjusting a first control parameter of the optoelectronic device to satisfy a first operating requirement and recording an associated first value of the first control parameter. Further, the method includes operating the optoelectronic device at a second temperature, adjusting the first control parameter of the optoelectronic device to satisfy the first operating requirement, and recording an associated second value of the first control parameter. From the first and second recorded values of the first control parameter, a sequence of values for the first control parameter for a corresponding sequence of temperatures in a predefined range of temperatures is determined and stored in a programmable device within the device.

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: A method for driving a light emitting device includes providing a first current source coupled to an input terminal of the light emitting device, and providing a second current source coupled to an output terminal of the light emitting device.

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: An integrated circuit is provided for driving a light source. The light source outputs light. A light receiver receives part of the light output from the light source. In response to a detection current from the light receiver, an automatic power controller adjusts an operating current of the light source. A power converter efficiently supplies power from a power supply to the light source. A modulation signal input unit inputs a modulation signal for modulation of light output power. This circuit structure performs a control operation for constantly maintaining the intensity of light even in a variation in an ambient temperature or deterioration in the light source and also reduces power consumption in the integrated circuit for driving the light source.

Abstract: Embodiments of the present invention provide a system for increasing an operational life of a VCSEL. The system can include control circuitry for reducing an amount of bias current at high temperatures and increasing a power of the laser at low temperatures. This control circuitry can further include at least one of a temperature sensor, a Field Programmable Gate Array, a read only memory module, and an electrically erasable programmable read only memory module (EEPROM). In alternate embodiments, the control circuitry can further include a lookup table that sets the bias current depending on a temperature of the laser. The laser can be part of an optoelectronic transceiver module which can include, by way of example and not limitation, SFP, XFP, X2, XAUI, XENPAK, XPAK, GBIC, 8G, 16G, and other optoelectronic modules.

Abstract: The present invention is intended to prevent a light-emitting diode from emitting light continuously in the case when the level at an input terminal is fixed high because of software or the like and to avoid various problems, such as battery exhaustion and breakdown of the light-emitting diode, in PDAs, cellular phones, etc. For these purposes, a high-pass filter 21 for passing the high-frequency components of an optical transmission input signal having a pulse waveform and a binary circuit 22 for binarizing the output signal of the high-pass filter 21 so as to be returned to a pulse waveform are provided in the preceding stage of a light-emitting device driving circuit 23 for driving a light-emitting diode 8 for optical transmission.