Abstract: Systems and methods for stabilizing a CO2 laser are disclosed. The system includes a detector unit for measuring the power in a select portion of the output beam. The detector unit generates an electrical signal corresponding to the measured power. The modulation frequency of the signal used to modulate the relatively high-frequency radio-frequency (RF) pump signal is filtered from the electrical signal. The filtered electrical signal is then-compared to a desired value for the output power in the output beam. Based on the comparison, a modulation control signal for modulating the RF pump signal is formed. The modulation control signal has a varying duty cycle that varies the amount of laser pump power to reduce or eliminate the measured variations in the output beam power. The result is an output beam power that remains stable over time.

Abstract: A method includes a scheme for trimming and compensation for a laser emitter in a fiber optic link. Data models of laser performance are provided and used to determine a base power level. It is then confirmed that the base power level is satisfactory. If necessary, adjustments are made to a set of user specified performance parameters until a satisfactory base power level is obtained. Then a table or relation of temperatures and associated current and target average optical power values is generated such that they can be used to regulate laser emitter performance over a range of temperature. Additionally, fiber optic links capable of trimming and compensation are also disclosed.

Abstract: An optical apparatus includes a light source for emitting laser light perpendicularly to a surface of a semiconductor substrate; a positioning member for positioning the light source; an aperture stop defining an opening for limiting transmission of laser light emitted from the light source; a light detection member, provided on or close to the positioning member, for detecting an intensity of laser light; a reflection member, provided on the aperture stop, for reflecting the laser light from the light source toward the light detection member; and an adjusting means for adjusting an intensity of laser light emitted from the light source on the basis of a detection result of the light detection member.

Abstract: The object of the present invention is to provide an optical module for the WDM communication system, in which the oscillation wavelength is on the grid of the WDM regulation, moreover the optical output power and the oscillation wavelength can be controlled independently. The present module comprises a semiconductor light-emitting device, a wedge shaped etalon device and two light-receiving devices. The etalon device contains a first portion, on which the anti-reflection films are coated, and a second portion. One of the receiving devices detects light transmitted through the first portion of the etalon device, while the other device detects light through the second portion. Signal from the former device controls the output power of the light-emitting device, while the signal from the latter receiving device controls the oscillation wavelength of the laser.

Abstract: The present invention provides a compact analog directly modulated laser configuration that is suitable for use in the field that uses electrical feedback to compensate for non-linearity in real time, such that no matter how the LI curve changes, the electrical feedback compensates for non-linearity by amplifying a portion of the output analog optical signal and combining it with the input analog electrical signal using the standard control method of negative feedback. When the gain of the feedback loop is relatively high, the overall transfer function of the system is primarily dependent on the feedback loop gain block, which is substantially linear. This is accomplished by incorporating a relatively large bandwidth photo-detector at the back facet of the laser that both monitors the output power of the system and provides a feedback signal to the linearization control circuit, as well as an amplifier.

Abstract: A laser power controller for performing an auto power control to control the laser power of an optical pick-up unit (OPU) includes: a sample/hold circuit used for sampling and holding a front photodiode output signal to generate an analog feedback signal; an analog-to-digital converter (ADC) electrically coupled to the sample/hold circuit for transferring the analog feedback signal into a digital feedback signal; and a digital control circuit electrically coupled to the ADC for generating a power control signal and outputting the power control signal to the OPU in order to control the laser power of the OPU. The front photodiode output signal corresponds to the laser power of the OPU.

Abstract: An apparatus and method for controlling power of a laser diode (LD) are provided, which allow the power of the laser diode (LD) affecting a performance of an optical recording apparatus to be constantly maintained at an optimum state, regardless of a variation in temperature. The method for controlling power of a laser diode (LD) used for an optical recording apparatus to record data in an optical recording device comprises: a) sampling the LD's power generated when data is recorded; and b) compensating for a variation of the LD's power changed according to sampling locations.

Abstract: The present invention proposes a method of controlling the laser power of a semiconductor laser that, in this method of controlling the laser power of a semiconductor laser by applying a power source voltage to between the collector and emitter of an output transistor and a serial circuit of the output transistor and a semiconductor laser, enables decreasing the power consumption of the output transistor. The present invention is arranged to apply a variable power source voltage Vcc to a serial circuit of an output transistor (Qb) and a semiconductor laser (SL) and thereby control the variable power source voltage Vcc such that a difference between the variable power source voltage Vcc and the peak hold voltage of an operating voltage of the semiconductor laser (SL) becomes substantially constant.

Abstract: A method and related apparatus for feedback control of laser power provided by a pick-up head of an optical disk drive. The pick-up head can adjust a cross-voltage of a laser generator according to a signal level of a control signal such that the laser power is changed correspondingly. The method includes updating the signal level of the control signal according to feedback of the cross-voltage or the control signal, such that the laser power is adjusted accordingly.

Abstract: A control system for operating a laser, including: a laser driver and a controller for providing the laser driver with a first electrical input indicative of a desired value for an output characteristic of the laser. The laser driver is arranged to control a second electrical input from the laser driver to the laser on the basis of the first electrical input with reference to a first electric reference. The controller is arranged to control the first electrical input on the basis of an electrical indicator of an actual value of the output characteristic of the laser with reference to a second electrical reference of greater reliability than the first electrical reference, so as to compensate for any variations of the first electrical reference.

Abstract: A power system for ultraviolet lighting includes a first network transformer structured to be powered from a first medium voltage power source and to output a first low voltage output; and a second network transformer structured to be powered from a second medium voltage power source and to output a second low voltage output. A first network protector inputs the first low voltage output of the first network transformer and outputs a third output. A second network protector inputs the second low voltage output of the second network transformer and outputs a fourth output. A spot network is powered from the third output of the first network protector and from the fourth output of the second network protector. A number of sag ride thru devices include an input powered from the spot network and an output structured to power a number of ultraviolet lights.

Abstract: A laser includes an Nd:YVO4 crystal end-pumped with diode-laser light having a wavelength at which the absorption coefficient for Nd:YVO4 is less than about 0.35 (35%) of the absorption coefficient at 808 nm.

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: The present invention provides for a method for configuring a laser operating system. More specifically, the system utilizes a graphical user interface (GUI) to allow an operator to interact with an embedded controller and set parameters for an optical communications transceiver. The system adjusts parameters such as laser bias and modulation currents, wavelength, qualification tests, and file management. In other words, the GUI manages configurations of a transceiver operating system. The system provides for an efficient method to design a laser transceiver and to perform and manage qualification tests. The embedded controller may contain a real time operating system that controls multiple functions in the transceiver and an optical channel. The GUI interacts with an operating system to download embedded firmware into an embedded micro controller unit (MCU). Downloading of firmware allows for multiple special programs from different sources to be integrated.

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: Methods of sensing lasers in real time for monitoring and control are disclosed. In one aspect, a method may include applying a perturbation current to a laser for a plurality of consecutive modulation cycles. Power of light emitted by the laser over the plurality of consecutive modulation cycles may be detected. Then, the perturbation current may be changed. The power of light emitted by the laser over a plurality of consecutive modulation cycles may be detected after changing the perturbation current. Then, an operating characteristic of the laser may be determined based, at least in part, on a change in the power of light detected before and after the change in the perturbation current. Sensors and systems incorporating the sensors are also disclosed.

Abstract: The invention relates to adjustment of optical output power and extinction ratio. A laser cuts resistors to obtain a desired resistance value, thereby adjusting an automatic power control loop circuit. Since several cuttable resistors and other components can be welded with Surface Mount Technology (SMT), process is simplified, the stability of products is increased and the production costs are reduced.

Abstract: A tuneable multi-section semiconductor laser 100 is characterized by applying currents in step-wise increments to sections 101, 102, 103 of the laser respectively and measuring power output by the laser to determine values of the applied currents corresponding to stable operating conditions for which the laser emits radiation at wavelengths remote from mode boundaries 51, 52; 141, 142 of the laser. The wavelength of the emitted radiation is measured and variations in the applied currents required to cross a mode boundary such that the laser undergoes a mode jump to emit radiation at a significantly different wavelength are also measured. These values are stored in a look-up table for use of the laser under the characterizing conditions and state of ageing of the laser. The applied currents are changed, to cause a predetermined incremental change in wavelength of the emitted radiation, within the said mode boundaries, and the further values are also stored.

Abstract: The present invention provides a cable assembly and method of making thereof for use with HDMI/DVI connectors. The cable assembly of the present invention includes a flat extruded cable jacket that includes an oblong cross section. Parallel oblong orifices lie across the cross section of the extruded jacket, extend the length of the jacket and provide a means for the insertion of solid straight conductors extending through the oblong orifices. The alignment of the oblong orifices in conjunction with a cylindrical orifice provides a means to attach the conductors to a HDMI/DVI connector. The oblong configurations as associated with the present invention are also applicable for Firewire cable and provides for a flat cable assembly for use therein.

Abstract: A charging voltage Vosc applied to a main capacitor C0 disposed in an oscillating high-voltage pulse generator 12 of an oscillating laser 100 is subject to constant control such that a pulse energy Posc of the oscillating laser 100 becomes a lower limit energy Es0 or more of an amplification saturation region. And, a charging voltage Vamp applied to a main capacitor C0 disposed in an amplifying high-voltage pulse generator 32 of an amplifying laser 300 is controlled, and pulse energy Pamp of the amplifying laser 300 is determined as target energy Patgt. Thus, the pulse energy of a two-stage laser is controlled to stabilize the pulse energy.

Abstract: A low-noise laser diode module comprises a laser diode for emitting light with a wavelength in the range from UV to IR, a drive circuit for injecting electrical current into said diode, and an automatic power control circuit for monitoring and adjusting laser output power using front-facet photodiode external to the laser assembly and a feedback loop. Said drive circuit produces injection current modulated by an RF signal with variable degrees, depending on the wavelength to be stabilized, the desired spectral bandwidths of the laser output, and/or other applications. Said RF signal can be a sine wave, a distorted sine wave, a rectified sine wave, a non-sine wave, a series of narrow pulses, or repetitive shunt. The present invention encompasses a method for producing stable, broadband, and low-coherent laser. The present invention also encompasses a method for producing stable narrowband or single longitudinal mode laser.

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

Abstract: A method of performing eye safety measurements on laser devices is disclosed. The laser is contained within a housing having a central bore. The method uses an optical detector having at least two zones to make separate measurements of both a direct power coming from the laser and an indirect power reflected off of the central bore. The first zone measuring the direct power is smaller than the second zone measuring the indirect power. The measurement of the first power is then used to adjust the power of the laser to be within a specified optical standard, such as the class 1 standard. In one exemplary embodiment, the laser is an 850 nanometer Vertical Cavity Surface Emitting Laser (VCSEL).

Abstract: An optical transmitter includes an external cavity laser array formed in a PLC, a trench-based detector array and an AWG. The external cavity laser is formed using an array of substantially similar laser gain blocks and an array of gratings formed in waveguides connected to the gain blocks. Each grating defines the output wavelength for its corresponding external cavity laser. Each detector of the detector array includes a coupler to cause a portion of a corresponding laser output signal of the laser array to propagate through a first sidewall of a trench and reflect off a second sidewall of the trench to a photodetector. In one embodiment, the photodetector outputs a signal indicative of the power level of the reflected signal, which a controller uses to control the laser array to equalize the power of the laser output signals.

Abstract: The invention relates to the stabilization of high power semiconductor laser diode sources as they are extensively used in the field of optical communication. Such lasers are mostly employed as so-called pump laser sources for fiber amplifiers, e.g. erbium-doped fiber amplifiers, and are designed to provide a narrow-bandwidth optical radiation with a stable power output in a given frequency band. To improve the wavelength locking range of such laser sources when operating without an active temperature stabilizing element, an external reflector providing very high relative feedback is used. The reflectivity bandwidth of the external reflector is broadened for improving the stability of the laser source. In commonly employed optical fibers for conducting the laser beam, the external reflector is formed by one or a plurality of appropriately designed fiber Bragg gratings.

Abstract: A system contains a laser output measurement circuit used in a laser control system (210). The circuits contain a photodiode (109), sample and hold amplifier (202), IC with synchronizer and delay circuits (206), and an analog to digital converter (204). The circuits measure the laser light output (107) while the laser Module (106) transmits signals. The measurement circuit tracks and stores the laser light output (107) signal using a Photodiode Sensor (109) and with a Sample/hold (202). The methods calculate the value of the laser light output (107) from mathematical relationships, which correlate the light output (107) of the laser Module (106) to the current value of the drive signal (100). Some of the distinguishing features in the present invention are 1) feedback information from the photodiode is obtained in a synchronous manner as a snapshot of the laser performance, and 2) the measurements are precise and calibrated, and 3) no disruption of the signal transmission occurs.

Abstract: A method for locking the wavelength of a laser uses a non-planar etalon, for example a non-parallel etalon, to produce a periodic spatial interference pattern, typically in the light reflected from the non-planar etalon. At least three different portions of the interference pattern are detected to generate at least three respective detection signals. A feedback signal is generated using the detection signals, and the operating wavelength of the laser is adjusted in response to the feedback signal.

Abstract: Provided is an apparatus for controlling a laser output comprising a common-anode laser diode having a first light emitting and receiving units and a common-cathode laser diode having a second light emitting and receiving units. Further, the apparatus comprises an automatic power controller (APC) that operates in either one of two modes. In the first mode the APC controls the amount of light emitted from the first light emitting unit by comparing a first feedback voltage corresponding to an amount of light received by the first light receiving unit and a reference voltage. In the second mode, the APC controls the amount of light emitted from the second light emitting unit by comparing a second feedback voltage corresponding to an amount of light received by the second light receiving unit and a reference voltage.

Abstract: Optical energy is provided to an optical amplifier by a first and a second pump laser. The optical energy that is provided is used as a basis for generating a gain associated with the optical amplifier. An error associated with the first pump laser may be identified. One or more parameters associated with the second pump laser may be controlled in response to the error such that the second pump laser increases an optical power output provided to the optical amplifier to compensate for the full or partial failure of the first pump laser. The adjustment in optical power output is used by the optical amplifier to substantially maintain the gain associated with the optical amplifier.

Abstract: A method, apparatus and system for controlling operation of a laser driver to limit emission levels of laser diodes each producing different monitor photocurrents are disclosed. In one embodiment, a laser driver controller includes a control signal generator configured to generate a single control signal to concurrently regulate an average power of the emission levels to a target average power level, and to generate a monitored output power reference to determine whether an output power of the emission levels exceeds an output power limit. The control signal generator can more accurately limit the emission levels than if the monitored output power reference is adjusted independent of regulating the average power.

Abstract: An optical device, including a monolithically integrated diode laser and semiconductor optical amplifier, that has reduced linewidth and improved side mode suppression for a given output power target. In a preferred embodiment, the diode laser is detuned from a gain peak wavelength to an emission wavelength. The semiconductor optical amplifier has an active region that is bandgap shifted to move its gain peak towards the emission wavelength of the laser diode, thus reducing its linewidth enhancement factor. The diode laser is preferably either a gain-coupled or index-coupled distributed feedback laser. The bandgap shift can be effected by known bandgap shifting methods, such as ion implantation, dielectric cap disordering, and laser induced disordering.

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

Abstract: A laser system for a spectroscopic catheter system utilizes an overmoded cavity in order to reduce mode hoping induced power fluctuations during wavelength scanning. In the preferred embodiment, a semiconductor gain medium is used to reduce cost. A fiber pigtail is used to define the laser cavity, which has a tight cavity mode spacing of less that 15 Gigahertz. A diffraction grating is used as the tuning element. A cylindrical lens is used to reduce alignment tolerances and thereby increase manufacturability.

Abstract: An apparatus and method for controlling the power of a laser beam is described. In one embodiment a rotatable Brewster element, rotated by a drive means, is disposed in the propagation path of a laser beam and is aligned along the an axis parallel to the direction of propagation of the laser beam. At least one stationary Brewster element is also disposed in the propagation path of the laser beam. Measuring means is provided to determine the power of the laser beam downstream of the rotatable Brewster element and to generate an actual power value. A control means receives the actual power value from the measuring means, compares it with the desired power value, and provides a control signal for the drive means. The drive means rotates the rotatable Brewster element in response to the control signal in order to minimize the difference between the actual power value and the desired power value.

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: A laser power controller for performing an auto power control to control the laser power of an optical pick-up unit (OPU) includes: a sample/hold circuit used for sampling and holding a front photodiode output signal to generate an analog feedback signal; an analog-to-digital converter (ADC) electrically coupled to the sample/hold circuit for transferring the analog feedback signal into a digital feedback signal; and a digital control circuit electrically coupled to the ADC for generating a power control signal and outputting the power control signal to the OPU in order to control the laser power of the OPU. The front photodiode output signal corresponds to the laser power of the OPU.

Abstract: A laser diode monitoring system, including a thermistor, a monitoring unit, and a laser diode is disclosed. Thermistor is to receive a temperature for outputting an electrical temperature signal. The monitoring unit is coupled to the thermistor, and for receiving the electrical temperature signal to output a control signal. Laser diode, coupled to the monitoring unit, is for receiving the control signal to output a laser beam, wherein the temperature is determined based on the output power of the laser beam.

Abstract: The present invention provides for a method for configuring a laser operating system. More specifically, the system utilizes a graphical user interface (GUI) to allow an operator to interact with an embedded controller and set parameters for an optical communications transceiver. The system adjusts parameters such as laser bias and modulation currents, wavelength, qualification tests, and file management. In other words, the GUI manages configurations of a transceiver operating system. The system provides for an efficient method to design a laser transceiver and to perform and manage qualification tests. The embedded controller may contain a real time operating system that controls multiple functions in the transceiver and an optical channel. The GUI interacts with an operating system to download embedded firmware into an embedded micro controller unit (MCU) Downloading of firmware allows for multiple special programs from different sources to be integrated.

Abstract: A semiconductor laser module including a semiconductor laser device having an integrated diffraction grating configured to output a multiple mode laser beam in the presence of a driving current, an optical fiber configured to guide the multiple mode laser beam to an output of the laser module, and an optical attenuation device configured to attenuate the multiple mode laser beam by an amount sufficient to provide a predetermined output power from the output of the laser module. The optical attenuation device may be an optical coupling lens offset from an optimum coupling position by an amount sufficient to provide the predetermined output power, or an optical attenuator interrupting the optical fiber and configured to attenuate the multiple mode laser beam by an amount sufficient to provide the predetermined output power.

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

Abstract: An object of the present invention is obtaining a semiconductor film with uniform characteristics by improving irradiation variations of the semiconductor film. The irradiation variations are generated due to scanning while irradiating with a linear laser beam of the pulse emission. At a laser crystallization step of irradiating a semiconductor film with a laser light, a continuous light emission excimer laser emission device is used as a laser light source. For example, in a method of fabricating an active matrix type liquid crystal display device, a continuous light emission excimer laser beam is irradiated to a semiconductor film, which is processed to be a linear shape, while scanning in a vertical direction to the linear direction. Therefore, more uniform crystallization can be performed because irradiation marks can be avoided by a conventional pulse laser.

Abstract: A current output of a drive signal, modulated between two current settings, is applied to a laser diode, e.g. VCSEL. The settings are selected such that laser diode's power output meets the average power and peak power limits of the eye safety standards. The drive signal having a duty cycle toggling between the two settings. The duty cycle is selected such that the average and peak power limits are met for the given upper current setting. The drive circuit may include an analog modulator or digital analog converter (DAC) for maintaining the lower and upper current settings. When the drive circuit is implemented as an integrated circuit, the DAC may be incorporated into the IC. The sensitivity of the DAC is selected to maintain the desired lower and upper current settings.

Abstract: A diode pumped, multi axial mode, intracavity doubled, intracavity tripled laser, includes at least two resonator mirrors defining a resonator cavity. A laser crystal and a doubling crystal are positioned in the resonator cavity. A tripling crystal is also positioned in the resonator cavity. A diode pump source supplies a pump beam to the laser crystal and produces a laser crystal beam with a plurality of axial modes that are incident on the doubling crystal. This produces a frequency doubled output beam. Further, a diode pumped, multi axial mode, intracavity nonlinearly-converted laser is provided and includes at least two resonator mirrors defining a resonator cavity, a laser crystal and a nonlinear conversion apparatus positioned in the resonator cavity. A nonlinear conversion apparatus is also positioned in the resonator cavity.

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

Abstract: The present invention is directed to a system and method which provide a Raman pump which is spectrally tailored in response to feedback from control structure associated with the Raman pump source. In certain embodiments of the present inventions, an incoherently beam combined laser (IBC) is utilized to provide a spectrally tailored Raman pump. In these embodiments, emitters in an emitter array are either individually addressable or block addressable to facilitate adjustment of emitter output power. By adjustment of the output power, the Raman pump may be spectrally tailored. The spectral tailoring can occur by employing suitable control algorithms to algorithms to dynamically maintain reasonably flat Raman gain.

Abstract: A laser control unit, a laser control circuit and a laser-power adjustment method are provided which are capable of controlling laser power precisely, even if an error is produced in the duty of an optical pulse.

Abstract: According to the present invention, an optical transmitting system, which enables a precise control of the power and the extinction ratio of the optical output without a small amount of the preset data, will be provided. The system comprises a laser module and a control system that supplies a bias current and a modulation current to the laser module. In the present invention, one of the bias current and the modulation current of the semiconductor laser in the laser module is varied to maintain the power and the extinction ratio of the optical output, and the other of the bias current and the modulation current is calculated based on the specific function. Only coefficients of the specific function are stored in the control system. Therefore, the present invention does not need a large size of the storage in which both the bias current and the modulation current are stored as a table.

Abstract: A power monitoring and correction to a desired power level of a laser or group of lasers utilizes two photodetectors which are employed to accurately determine the amount of output power from the front end or “customer” end of a laser or a plurality of such lasers. During power detection, which may be accomplished intermittently or continuously, the laser is modulated with a tone of low frequency modulation. One photodetector at the rear of the laser is employed to detect the DC value of the frequency tone, i.e., a value or number representative of the AC peak-to-peak swing, amplitude or modulation depth of the tone. Also, the rear photodetector may be employed to determine the optical modulation index (OMI). In either case, these values may be employed in a closed loop feedback system to adjust or otherwise calibrate the value of the low tone frequency relative to the total desired bias current applied to the laser.

Abstract: A method for controlling a laser beam power balance in a laser scanning unit is disclosed. The method of present invention comprises the steps of obtaining a first voltage value and a second voltage value corresponding to detection time points of a first laser beam and a second laser beam, respectively, emitted from the laser scanning unit. The first voltage value and the second voltage value are recorded in the laser scanning unit. After the laser scanning unit is mounted on a image forming apparatus, a third voltage value and a fourth voltage value are obtained corresponding to the detection time points of the first laser beam and the second laser beam, respectively, emitted from the laser scanning unit by driving the laser scanning unit mounted on the image forming apparatus. The third voltage value and the fourth voltage value are compared with the first voltage value and the second voltage value, respectively, thereby correcting the control voltage controlling the laser scanning unit by that variation.

Abstract: A method embodiment of the invention includes a scheme for trimming and compensation of a laser emitter in a fiber optic link. A laser emitter is provided. Also a reference optical power value is determined using data models of laser emitter performance generated by statistical analysis of sample population of lasers that are similar to the subject laser emitter. The performance of the subject laser is measured and qualified optical power levels for the subject laser emitter are determined using the reference operating power value and measured performance of the subject laser emitter. The driving current of the subject laser emitter is adjusted to compensate for changes in temperature until the optical power of the subject laser emitter obtains a desired qualified optical power level. Related methods of determining qualified optical power levels for a laser emitter in a fiber optic link are also disclosed.