Abstract: A laser beam irradiation apparatus includes an oscillation unit, an acousto-optic deflection unit for deflecting a laser beam oscillated by the oscillation unit, a condenser for condensing the deflected laser beam, and a control unit. The control unit determines an actual output power of the laser beam based on a light reception signal received from laser beam output detection means in response to a control signal for controlling a deflection angle adjustment unit of the deflection unit. Then, the control unit arithmetically operates the ratio of an actual output power corresponding to the control signal with reference to the lowest value of the actual output power. Further, the control unit arithmetically operates a correction value corresponding to the ratio of the actual output power to produce a control map and controls the output adjustment unit based on the control map.

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: 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 a laser power control apparatus for controlling a laser power of a combination drive, first laser light Lc applied onto a first optical disk and second laser light Ld applied onto a second optical disk is collected by one photodetector 8.

Abstract: The invention provides a driver for a semiconductor light emitting device, in particular a vertical cavity surface emitting laser (VCSEL) which includes a delay buffer for generating an output signal as a delayed version of an input signal; a pulse generation stage coupled in parallel with the delay buffer and adapted to produce selectively positive and negative output pulses starting concurrently with respective positive and negative edges of the output signal of the buffer; and a summer for summing the output signal and the pulses.

Abstract: A laser beam irradiation apparatus includes an oscillation unit, an acousto-optic deflection unit for deflecting a laser beam oscillated by the oscillation unit, a condenser for condensing the deflected laser beam, and a control unit. The control unit determines an actual output power of the laser beam based on a light reception signal received from laser beam output detection means in response to a control signal for controlling a deflection angle adjustment unit of the deflection unit. Then, the control unit arithmetically operates the ratio of an actual output power corresponding to the control signal with reference to the lowest value of the actual output power. Further, the control unit arithmetically operates a correction value corresponding to the ratio of the actual output power to produce a control map and controls the output adjustment unit based on the control map.

Abstract: A laser apparatus including a laser oscillating section, electric power source, a laser-power measuring section and a power-source controlling section. The power-source controlling section includes a power-supply instructing section instructing the power source to perform an electric-power supplying operation for the laser oscillating section in response to a laser-oscillation command value; and a function calculating section determining, based on different laser-oscillation command values given to the power-supply instructing section and different laser-power measured values obtained by the laser-power measuring section, a function approximatively representing a correlation of the laser-power measured values relative to the laser-oscillation command values.

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: This invention provides an automatic power control (APC) circuit for keeping an extinction ratio constant even when the efficiency of a laser diode (LD) deteriorates. The APC circuit according to this invention stores first control data for deciding the relationship between a bias current Ib and a modulation current Im so that the extinction ratio under a certain target power is a predetermined value. A central processing unit (CPU) decides the bias current Ib and modulation current Im on the basis of a current optical output power and the first control data and supplies them to an LD driver. The APC circuit also stores second control data for deciding the correction value for the optical output power corresponding to the temperature of the LD. The CPU acquires the current temperature before deciding the bias current Ib, decides a correction value corresponding to the current temperature according to the second control data, and corrects the target power.

Abstract: A driving circuit comprises: a constant-current source which supplies a current to a photodiode so as to forward-bias the photodiode; detecting means for detecting the forward voltage of the photodiode; determining means for determining whether or not the forward voltage detected by the detecting means is smaller than a predetermined reference voltage; and control means for controlling the supply of current from a current source to a laser diode, wherein when the determining means determines that the forward voltage is smaller than the predetermined reference voltage, the control means controls the current source so as to stop the supply of current to the laser diode.

Abstract: A femtosecond laser with stabilized output, and a method for stabilizing the output of a femtosecond laser. The femtosecond laser comprises a regenerative amplifier, a photodetector, a control portion and a variable attenuator, wherein the variable attenuator is provided so as to be capable of controlling an output beam of the regenerative amplifier, the photodetector is provided between the regenerative amplifier and the variable attenuator, the photodetector detects an output beam of the regenerative amplifier and transmits the results of the detection to a power controller, and the power controller controls the variable attenuator depending on the a difference between a predetermined target value and the results.

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: An optical communication system suitable for full duplex optical communication between a first and a second optical transceiver units. connected with each other by a single-core optical fiber. The first and second transceiver units may have different types of light emitting elements emitting light having different loss rates in the single-core optical fiber. The system enables stable full duplex communication without setting up large scale or costly transmission units by relatively reducing the optical crosstalk involved. The first optical transceiver unit provides transmission light to be coupled with the single-core optical fiber with the intensity in the range of TAmin–TAmax. The amount of light emitted from the light emitting element of the optical transceiver unit to be coupled with the single-core optical fiber is in the range TBmin–TBmax, which amount may be adjusted by a light emission adjusting unit provided in the optical transceiver unit.

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: A laser oscillator capable of executing a high-speed feedback control by reducing the control load of a main processor in the feedback control of the laser output. The laser is excited by an excitation source activated by one or more power supplies. The laser radiation is detected by a power sensor or a photodiode. A detected signal is A/D converted and fed to a sub processor or a high-speed DSP. The sub processor compares the current laser output value to a desired control value and calculates a deviation value in a predetermined period. The sub processor outputs a feedback signal to each of the power supplies according to a command from the main processor. Each power supply adjusts the supplied current to control the laser output. The main processor monitors conditions of the power supplies and controls a coolant circulation device. A factor regarding a load on a sequential control process, which may delay the feedback control, is eliminated and an analog circuit is unnecessary.

Abstract: A method of determining the time for executing optimal power calibration in an optical drive. First, relationships between values of a driving signal and ambient temperatures of the optical drive are recorded in look up table in a memory. According to the look up table, mappings from the values of a driving signal output by a compensator to the ambient temperature of the optical drive can be obtained. When the ambient temperature of the optical drive is higher than a predetermined temperature, an optimal power calibration is executed.

Abstract: The present invention provides a laser machining apparatus in a simple structure which can properly carry out laser machining by irradiating a laser beam easily at a predetermined energy density to a machining-target site in a predetermined range, and in addition, which can be downsized and can be kept with easy maintenance and has enhanced durability. The apparatus includes: a semiconductor stack 1 comprising a plurality of semiconductor laser elements; and a controller for controlling emission of the laser beam emitted from each of the semiconductor laser elements. The semiconductor stack 1 is divided into a plurality of blocks B11, B12, B13, B14 in correspondence with the machining-target site of a work piece. The controller controls the irradiation of the laser beam from each of the blocks B11, B12, B13, B14 to be changeable in terms of time.

Abstract: A laser transmitter bias circuit for a laser diode transmitter, for use in a optical transmission system, e.g. in commercial CATV systems. The laser transmitter bias circuit reduces power consumption and heat dissipation by eliminating the conventional need for a distinct constant DC current supply for biasing the laser diode. Radio frequency (RF) circuitry, e.g., a radio frequency amplifier (e.g., a Hybrid Amplifier), connected in series to the laser diode supplies both a DC bias-current (IB) and an RF drive-current (IP) through the laser diode. The DC bias current through the laser diode in turn powers (and/or biases) the radio frequency amplifier and, optionally, other radio frequency circuitry. An optional diode-bypass current (IBP) path may be connected in parallel with the laser diode, and in series with the radio frequency amplifier to control bias current.

Abstract: This disclosure discusses techniques for obtaining wavelength selected simultaneously super pulsed Q-switched and cavity dumped laser pulses utilizing high optical damage threshold electro-optic modulators, maintaining a zero DC voltage bias on the CdTe electro-optic modulator (EOM) so as to minimize polarization variations depending on the location of the laser beam propagating through the CdSe EOM crystal, as well as the addition of one or more laser amplifiers in a compact package and the use of simultaneous gain switched, Q-switched and cavity dumped operation of CO2 lasers for generating shorter pulses and higher peak power for the hole drilling, engraving and perforation applications.

Abstract: Field Effect Transistors (FETs) are used to regulate current in a light emitting diode (LED). FETs are fundamentally voltage driven devices, where output current is governed by junction voltage. Since junction voltage can be controlled with little or no support circuitry, FETs present a solution to current regulation where cost, complexity, and perhaps even size are important.

Abstract: There is provided a laser diode drive signal processor for driving a laser diode to be used to emit a laser beam for accessing an optical information recording medium with the laser beam. The processor has an alternating current side driving current supply circuit for supplying a first driving current according to a signal level of an alternating current component; a photo diode coupled to the laser diode for detecting a light amount of the laser beam; error signal generating circuit for generating an error signal based on the detected light amount of the laser beam and a reference signal; direct current side driving current supply circuit for supplying a second driving current according to a signal level of the error signal; and adding circuit for adding the first driving current from the alternating current side driving current supply circuit and the second driving current from the direct current side driving current supply circuit to generate a third driving current.

Abstract: Power density profile of a laser beam is characterized by scanning a thin thread across the beam and registering the intensity of radiation scattered from the thread. The diameter of the beam along the scan direction is determined by measuring the width of the signal received from the scattered power for the given speed of the thread across the beam.

Abstract: A circuit method for recognizing an interruption in a light waveguide link, wherein the amplified spontaneous emission output by an intensifying fiber is monitored for recognizing an interruption along a light waveguide link having an intensifying fiber and, given failure of the amplified spontaneous emission to arrive, the transmission unit supplying the light signals into the light waveguide link is shut off.

Abstract: A laser diode light emission sensing circuit comprises a photodiode 3 which senses a lightwave signal of a laser diode to convert it into a current signal, an I/V converting circuit 4 which converts the current signal from the photodiode 3 into a voltage signal, a comparator 6 which compares the voltage signal from the I/V converting circuit 4 with a reference voltage of a reference voltage source 5 to output a prescribed signal when the voltage signal from the I/V converting circuit 4 exceeds the reference voltage from the reference voltage source 5, the reference voltage source 5 which outputs the reference voltage to comparator 6, an inverter 9 which inverts an output of a CELL signal, and DFF circuit 7 which utilizes the output of the comparator 6 as a clock input, while utilizes an output of the inverter 9 as a reset input, and maintains always the data input at a high level, whereby a luminous state of the laser diode can be maintained digitally.

Abstract: A charging and discharging circuit for a pulse laser which enables the pulse laser to increase an oscillation frequency.

Abstract: An emission timing control apparatus for a pulsed laser including a magnetic pulse compression circuit having a switching section for carrying out a switching operation to connect and disconnect a charging power source to and from the magnetic pulse compression circuit. The pulsed laser executes pulsed laser oscillation at a prescribed repetition frequency by turning on the switching section with a pulse oscillation synchronizing signal having the prescribed repetition frequency received from a semiconductor exposure apparatus, in which the emission timing control apparatus includes a reference delay time setting section for setting a prescribed reference delay time, and delay section for delaying a pulse oscillation synchronizing signal received from the semiconductor exposure apparatus by the time difference &tgr; calculated in the delay time calculating section and outputting to the switching section.

Abstract: A simmer circuit 18 comprises a power supply unit 54 for the supply of a simmer current Is to an excitation lamp 22 and a control unit 56 for the control of the current value of the simmer current Is. In the control unit 56, a current detection signal Vs from a current sensor, e.g., a Hall CT 70 attached to the power supply unit 54 is fed via a buffer amplifier 72 for impedance conversion to a non-inversion input terminal of an operational amplifier 82 for signal amplification. The amplification factor &mgr; of the operational amplifier 82 differs depending on which one is selected from three switches 84, 86 and 88. A CPU 38 selects the switch 84 when switching the simmer current Is to 0.3 A for “low speed zone”, selects the switch 86 when switching to 2 A for “medium speed zone” and switches 88 when switching to 5 A for “high speed zone”.

Abstract: A burst mode optical transmitter circuit comprises a semiconductor laser, a photodiode for monitoring the light output from the semiconductor laser, a current-voltage converting circuit for converting the current detected by the photodiode into a voltage, an APC amplifier, a holding circuit for holding, as a current control signal, the output signal from the APC amplifier, a driving circuit for supplying a driving current to the semiconductor laser according the current control signal from the holding circuit and the the data input in the burst mode, and a data interruption detecting circuit for detecting an interrupt period of the data input to the driving circuit to reset the holding circuit, in which the current control signal held in the hold circuit is reset by the reset signal, whereby a stable burst optical transmission can be performed stably with a simple construction.

Abstract: An optical scanning device is provided with a light source that emits a light beam, a driver that controls output power and modulation of the light beam emitted by the light source, a controller that transmits, to the driver, power control data and modulation data respectively used for controlling the output power and modulation of the light beam. The optical scanning device is further provided with a single data bus that connects the driver and the controller. The power control data and the modulation data being transmitted through the single data bus at different timing.