Abstract: Systems and methods for use with an optical communication beam are disclosed. The system allows the beam of light to operate at an adequate power level that provides a robust optical link while minimizing any safety risk to humans. The system calibrates and controls the gain for an avalanche photodiode detector (APD). A detector circuit is used to calibrate the APD. Once calibrated, the detector circuit further provides an electrical bias to the APD to process or condition the electrical signal to produce a detector output. The systems and methods disclosed herein attenuate the power level of an incoming communication beam to prevent oversaturation of an APD. The system further provides an alignment signal, which is effective over a wide dynamic range of incoming power levels.

Abstract: A laser transmitter with a laser diode and first and second feedback loops for maintaining a constant average laser power output and constant extinction level. A photo detector samples and detects transmitter laser light. The detector output is split, with one portion sent to a low-pass detector circuit for detecting the average laser power and using the detected signal to control a laser power current bias source. The other portion of the detector output is delivered to a high-pass detector circuit for detecting the amplitude of the modulation for outputting a signal to control a modulation laser current source that adds to the power current bias for a logic “1” state and does not add to the power bias for a logic “0” state.

Abstract: The invention relates to a method and a circuit arrangement for a laser control loop with automatic adaptation to the monitoring signal polarity. Use is made of a single-phase method which consists in that a signal produced by the monitor during the starting phase of the laser control loop is compared with a reference value, and in accordance with the result of the comparison the signal produced by the monitor is fed directly or inverted to the comparator for controlling the light power of the laser during the starting phase of the laser control loop. A signal is produced which initially feeds the comparator for controlling the light power the inverted monitoring signal, or directly feeds the monitoring signal, in a fashion always independent of the monitoring signal polarity, but dependent on the polarity of a reference value, and feeds it in a non-inverted fashion in the case of a monitoring signal running up to the reference value.

Abstract: An optical configuration to illuminate an etalon in a laser wavemeter with a minimum level of light intensity. The system includes optical components to direct a portion of the laser output beam representing the entire cross section of the beam, through an etalon positioned in an etalon housing and onto a photodetector. A first lens condenses the size of the beam sample, and a second lens re-collimates the beam which then passes into the etalon housing, ensuring that all of the spatial components of the beam are adequately sampled. A diffractive diffusing element is incorporated into the optical path. In a preferred embodiment, the diffractive diffusing element is placed within the etalon housing between said plano-concave lens and the etalon. In another preferred embodiment, the diffusing element is located up stream but outside the housing in the optical path.

Abstract: The present invention is for a ceramic calibration filter, in one embodiment a ceramic attenuator (410), for attenuating radiation between a light source (402) and a photodiode sensor (422). A laser signal is reduced by ceramic attenuator (410) to a low-level signal that can be measured the photodiode sensor (422). A focal plane (240) of the light source is offset from a face of the ceramic attenuator (410).

Abstract: A fiber optic arrangement includes a chip, and a first light emitter and a second light emitter formed on the chip. A guide is formed on the chip and in registration with an active region of the second light emitter. An optical fiber is coupled to the second light emitter for transmitting light from the second light emitter. The guide aligns the optical fiber relative to the active region of the second light emitter. A light-sensing device is provided. An optical element transmits light emitted from the first light emitter to the light-sensing device for controlling an output optical power of at least the second light emitter.

Abstract: Described embodiments provide a method and apparatus for transmission of optical communications. An embodiment provides an optical transmitter which includes a control circuit to enhance the stability of output power levels, a modulator circuit with precise impedance matching for high frequency performance, and an optical coupling mechanism that relaxes the alignment tolerances between the laser and the fiber and decreases the sensitivity of the gain medium to feedback from devices coupled to the fiber. These features allow the transmitter to deliver an optical output beam which can be modulated over a wide range of frequencies, duty cycles and amplitudes with very precise definition of the rising and falling edges of the waveform. In combination these features result in an optical transmitter that may be fabricated with relatively low cost and a reduced form factor when compared with prior art optical transmitters.

Abstract: An energy stabilization method and system includes an energy detector and simulating optics before the detector for forming a diagnostic portion of an output beam to simulate the beam profile of the working beam incident at the workpiece. Preferably, the simulating optics before the detector are selected to be identical or similar to beam transforming optics that the working beam traverses after the diagnostic portion is split off from the working beam, but before the working beam reaches the workpiece. The diagnostic beam portion is thus formed to have an identical or similar beam profile as the working beam at the workpiece. Alternatively, instead of providing transforming optics along the diagnostic beam path that are the same or similar to those encountered by the working beam, a processor configures the data received at the detector to simulate the beam profile of the working beam at the workpiece, after it traverses the transforming optics described above.

Abstract: A laser array system is described. The system includes a plurality of lasers, a switching mechanism, a wavelength locking mechanism, and a laser parameter feedback control. Each laser provides a collimated beam having certain wavelength and power. The beam has at least two parts, first part of the two parts used for stabilization of the wavelength and power. The switching mechanism is configured to receive and sequentially select the first part of the collimated beam from the plurality of lasers. The wavelength locking mechanism is configured to monitor and measure a drift of the wavelength and power of a selected laser. The laser parameter feedback control is configured to adjust laser parameters of the selected laser.

Abstract: Laser printers are designed assuming the actual laser operates at nominal values which are the average or central values of a large batch of such lasers. The nominal values are determined and stored in permanent memory. Similarly, the values of the laser actually in the printer are determined during manufacture and also stored in permanent memory. Data to the laser is adjusted to correlate the output called for by the data with the differences in response of the laser of the printer by determining the optical output called for by the data using the nominal values stored and then finding the power needed to achieve the same output using the actual values stored. This is particularly useful with extreme duty cycles.

Abstract: A technique for driving a laser diode on the basis of automatic power control (APC) is disclosed. The technique uses, for the bottom level feedback control, a constant reference voltage instead of a variable intermediate signal generated in the peak level feed back control. The constant reference voltage may be either a reference voltage for the peak level control or a separately generated voltage. A technique for setting the extinction ratio to 1/n is also disclosed.

Abstract: An optical system comprising a light source and a beamsplitter for splitting the beam of the light source into a primary output beam and a secondary output beam. The power of the secondary output beam is a substantially fixed small percentage (preferably less than 0.5%, such as less than 0.1%) of the power of the primary output beam, at least within a certain wavelength range. Thus, measuring the power of the secondary output beam provides a precise measure for the power of the primary output beam. May be used for controlling/adjusting the output power of the primary output beam, e.g. for keeping the power substantially constant. The fixed percentage is preferably invariant to wavelength variations, at least within a certain wavelength range. Preferably, a low variation in power (ripple) is induced.

Abstract: An integrated surface emitting laser and modulator device is disclosed that includes a detector for monitoring the optical power output of the laser and another detector for monitoring an extinction ratio of the modulator. A cleave physically and electrically separates the laser from the modulator device. The device has a collimating lens disposed on a top surface.

Abstract: A semiconductor laser system includes a reflector on the lid that directs light emitted from the front facet to the monitoring diode. Thus, even when the diode is installed behind the semiconductor laser chip, and as a result receives back facet light, the ratio of front facet to back facet light received by the monitoring diode is increased due to the operation of the reflector. This configuration improves power tracking in Bragg grating stabilized semiconductor laser systems, for example.

Abstract: A laser power control device, optical head and optical recording and/or reproducing apparatus to set and control the output power of laser light radiated from a plurality of laser sources. The laser power control device is provided with plural variable resistors associated with the plural laser sources, a photodetector unit associated with the plural laser sources, and a laser output stabilizing unit for controlling the laser light output power at a constant predetermined level. The resistance values of the variable resistors are set so that the output power of the laser light radiated from the laser sources is at the predetermined level.

Abstract: A beam delivery system for a laser emitting at a relevant wavelength of less than 200 nm is provided. The system includes a sealed enclosure connected to the laser and surrounding the path of the beam as it exits the laser resonator. The enclosure extends between the laser output coupler and a photodetector sensitive at the wavelength of the relevant laser emission. The interior of the enclosure, and thus the beam path between the output coupler and the detector, is substantially free of species that strongly photoabsorb radiation at the relevant laser emission wavelength. A beam splitting element diverts at least a portion of the beam for measurement by the detector. The beam splitting element preferably includes a beam splitting mirror, holographic beam sampler or diffraction grating. In addition, optics are preferably provided for filtering a visible portion of the diverted beam, so that substantially only a VUV portion of the diverted beam is received at the detector.

Abstract: A cavity length is determined on the basis of a relationship of electric drive power to a range of optical output power over 50 mW, for cavity length to be constant as a parameter in a range over 1000 &mgr;m, so that the electric drive power is vicinal to a minimum thereof in correspondence to a desirable optical output power. If the optical output is 360 mW for example, a cavity length of 1500 &mgr;m is determined to be selected.

Abstract: A laser device which repeats a cycle of burst mode operation in each of which continuous oscillating operations for continuously pulsatively oscillating laser light by a prescribed number of times and stopping operations for stopping the pulsative oscillation for a prescribed pausing time are alternately executed, controls the power supply voltage of the laser device so that each output energy of the pulsative oscillation can become coincide with a target value, finds the difference between the output voltage of each pulse and the target value at every pulse and, for a pulse for which the difference exceeds tolerance limits, corrects and updates the power supply voltage value stored in the voltage data table means corresponding to the pulse number of the pulse and the measured oscillation pausing time by using the control gain of a control gain setting means set in the block corresponding to the pulse number and the measured oscillation pausing time and the difference, so as to always make the pulse energy of

Abstract: A semiconductor laser control method and a semiconductor laser control apparatus allow an outgoing radiation power of a semiconductor laser to be accurately stabilized to a desired value even if a characteristic of the semiconductor laser changes due to temperature variations or deterioration of life. The characteristic of a semiconductor laser is measured by a semiconductor laser characteristic detection unit and a target value is corrected by a target value correction unit based on a threshold current and differential quantum efficiency obtained from the measurement result. A power control unit controls the semiconductor laser by comparing the corrected target value with the output of a power detection unit, making it possible to achieve a desired outgoing radiation power of the semiconductor laser with high accuracy even if the threshold current or differential quantum efficiency of the semiconductor laser changes due to temperature variations or deterioration of life.

Abstract: A laser is provided having a gain medium including a laser gas and a photoabsorbing species. The photoabsorbing species has at least one photoabsorption line within an output emission spectrum of the laser. When the laser is an ArF-excimer laser, the photoabsorbing species is preferably either atomic carbon or molecular oxygen, which are formed after carbon- or oxygen-containing molecules introduced into the gain medium with the laser gas interact within the gain medium. An absolute wavelength of a narrowed emission of the laser can be calibrated when a narrowed output emission of the laser is tuned through at least one photoabsorption line of the photo-absorbing species. Preferably, a processor communicates with a detector and a wavelength selection unit, as well as a power supply when output beam energy is held constant, to automatically perform the calibration.

Abstract: A method of producing a semiconductor laser module, and a semiconductor laser module including a semiconductor laser element having a front facet to emit output light and a rear facet to emit monitor light, an optical fiber on which the output light is incident, a light receiving element receiving the monitor light emitted from the rear facet, and a substrate for supporting the semiconductor laser element and the light receiving element. The method of producing the semiconductor laser module comprises a step of receiving the monitor light output from the semiconductor laser element by the light receiving element, and adjusting the position of the light receiving element with respect to the semiconductor laser element based on an amount of received light at the light receiving element, and a step of fixing the light receiving element to a substrate through a supporting member.

Abstract: Disclosed is an apparatus for controlling a semiconductor laser module wherein despite an increase in laser driving current owing to aging of the laser module, temperature control can be performed accurately so as to render constant the actual temperature of the laser module and prevent a change in lasing wavelength that accompanies a change in temperature. The apparatus includes a photodiode for sensing optical intensity of the laser; an APC circuit for controlling driving current of the laser in accordance with an output from the photodiode; a thermistor for sensing the temperature of the laser module; an ATC circuit for driving an electronic laser-cooling device in accordance with an output from the thermistor; and a current-quantity sensing circuit, which is connected to the APC and ATC circuits, for sensing the driving current of the laser output from the APC circuit.

Abstract: In the method and the arrangement, a ratio (p2/P3)—which is independent of the total optical power of the laser (1)—between a power (p2) essentially containing only the wavelength (&lgr;) to be stabilized, which power is filtered out from a portion (P2) of the total power (P0), and an additional portion (P3) is measured and compared to a desired value (S0), and, given a deviation from the desired value (S0), the temperature of the laser (1) is controlled to the desired value (S0).

Abstract: A top surface emitting vertical cavity laser with enhanced power handling capacity. The laser provides a patterned top electrode for uniformly injecting applied current to the active area. The diameter of the electrode relative to the vertical distance between it and the active layer is reduced by patterning. The result is an improved laser with significant power output.

Abstract: The present invention is for a ceramic calibration filter, in one embodiment a ceramic attenuator (410), for attenuating radiation between a light source (402) and a sensor (422). A laser signal is reduced by ceramic attenuator (410) to a low-level signal that can be measured the sensor (422).

Abstract: The bias current of the semiconductor laser 4 is adjusted corresponding to the amplitude of the modulation. A transmit signal is presented to the input 1, then amplified by an amplifier 2 and transmitted to the laser 4 via a blocking capacitor 3. A check photodiode 5 is optically coupled to the laser and a set of four resistors 6, 7, 8, 9 forms a bridge. A differential amplifier 10 having its inputs connected to the bridge ensures the supply of bias current through an inductance 11 intended to inhibit the passing of the modulation signal. A peak detector 12 measures the peak amplitude of the signal that drives the laser to check the conductance of a transistor 14 which operates in the variable conductance mode and is branched parallel to the branch 7 of the resistor bridge to modify the balance of the bridge and thus the value of the power transmitted by the laser.

Abstract: An optical recording/reproducing apparatus which controls the power of a laser diode (LD) and a method therefor. A current power level of an optical signal output by the LD is compared with a reference level and the output of the LD is controlled according to the comparison result. A photo detector (PD) monitors the current power level of the optical signal output by the LD. The current power level is compared with a reference level and power to the LD is controlled based on the comparison. Two different control loops are provided. In a first loop, comparison data is continually provided and in a second loop, sampled comparison data is provided based on a non return to zero inverted (NRZI) signal. Rapid change in an optical output is controlled using the different loops according to a kind and state of a medium such as a disc.

Abstract: In a light power modulating system for modulating output power of a laser diode, an output power of the laser diode is monitored and a voltage signal corresponding to the detected output power is output. An image signal output system is provided to form an image signal representative of a thickness density of an image to be formed, and a modifying system modifies the image signal such that a changing rate of the image signal between a lower value and a higher value is lowered. A differential amplifier outputs an amplified difference between the modified image signal and the voltage signal, and a driving current to be supplied to the laser diode is generated based on the amplified difference output by the differential amplifier.