Abstract: A laser-diode-pumped solid-state laser apparatus includes a laser rod, and laser diode devices that generate pumping light. Optical unit such as a reflection mirror and an optical waveguide medium is provided at a position in a laser resonator near a laser optical axis and not blocking the optical axis. A photo-detector detects a quantity of fluorescence generated from solid-state laser medium. The fluorescence quantity is compared with a predetermined value or a previously measured value. Thus degradation status of a laser diode light source is constantly diagnosed.

Abstract: In the semiconductor laser module testing device, a temperature control power source changes a temperature of a wavelength locker module, and a wavelength monitoring bias circuit detects an output of a wavelength monitor in the changed temperature range and computes a correlation between a temperature of a semiconductor laser and a wavelength of light output therefrom. Moreover, the wavelength of the output light is locked by controlling the temperature of the wavelength locker module while feeding back the output of the wavelength monitor by a wavelength feedback circuit based on the obtained correlation between the temperature and the wavelength.

Abstract: A laser diode module includes a laser diode device, a first photo detector part for receiving, first divided light that is a first portion of light when at least one of light emissions of the laser diode device is divided into two portions of light each traveling a different optical path, a second photo detector part for receiving second divided light that is a second portion of light thus divided via at least a wavelength selective member, and a controller which controls the lasing wavelength of the laser diode device on the basis of outputs of the first and second photo detector parts. A beam splitter provided between the laser diode and the wavelength selective member divides light emitted from the laser diode into the first and second divided light and a quarter-wave plate is provided in an optical path between the beam splitter and the wavelength selective member.

Abstract: An optical transmission system is provided, which permits high-precision optical transmission of a signal even if the signal has a high accurate timing, an indefinite period, and a DC component. The transmitting side is provided with a rise edge detecting circuit 1 for detecting the rise edge of a transmitting signal waveform, a transmitting pulse generating circuit 2 for generating a transmitting pulse signal (b) constituted by a pair of opposite-polarity pulses inverting their polarities at the detected timing, and a light intensity modulation circuit 3 for generating a light intensity modulated signal (c) based on the pulse signal (b). The receiving side is provided with an AC-coupled receiving circuit 4 for receiving the light intensity modulated signal (c) and extracting therefrom only an AC component, and a discrimination circuit 5 for discriminating the rise timing from the received signal.

Abstract: An arrangement for tuning a micro-electro-mechanical (MEM) laser center wavelength to exactly match the passband of its associated filter. A dither wavelength locked feedback loop dynamically adjusts the position of the MEM element, and hence the laser, wavelength, to keep it nominally centered at the filter passband peak. The dither wavelength locked feedback loop compensates for many internal variables of the laser, filter, and the MEM with a single mechanism that stabilizes the laser and locks the wavelength to any desired value.

Abstract: An apparatus and method for controlling the phase of a tunable laser is provided. Stabilization of the mode of a laser beam is provided as the laser is tuned to a target frequency. For one embodiment, a laser generates a reference beam and an output beam. The power of each of beam is measured by optical detectors, and a ratio thereof is utilized to detect when a mode hop occurs as the laser is coarsely tuned. The average of the pre and post mode hop ratios is utilized as a control setpoint while finely tuning the laser to the target frequency. Wavelength lockers, optical power dividers and optical detectors are utilized to determine power levels of the reference and output beams while also monitoring frequency characteristics thereof. A control unit utilizes the outputs from the wavelength locker to control the operation of the extended cavity laser during and after tuning.

Abstract: The laser source comprises an optically-pumped solid state laser (10) enabling a first laser beam (2) of frequency f1 to be emitted, an absorption cell (7) containing an absorber chemical element and which, in operation, has the first laser beam (2) or a beam (4b) derived therefrom passing through it so that a transition (T) of the absorber chemical element is saturated, and locking means (9) designed to lock the frequency f1 of the first laser beam on said saturated transition (T) of the absorber chemical element by means of synchronous detection based on modulating said transition (T).

Abstract: The invention relates to a method that can be used to compensate the influence of the temperature on the optical output power (light power) of light emitting diodes and laser diodes without the need to measure the temperature or light power. The method is based on the fact that the current flowing through a light emitting or laser diode and the forward voltage drop on the diode are at a constant light power independent of the temperature in a functional correlation that is often linear and can be obtained. If it is known, it must only be achieved during operation that the current and the forward voltage exhibit this correlation in order to eliminate the temperature effect on the light power.

Abstract: A laser includes a first region with a first moveguide having a first diffraction grating, a second region with a second waveguide having a second diffraction grating, and a phase controlling region with a third waveguide and a phase control unit for controlling an effective refractive index of the third waveguide. The phase controlling region, the first region and the second region are coupled serially along a light propagation direction in this order, and are constructed such that light to the first region from the phase controlling region is enlarged relatively to light to the phase controlling region from the first region, or constructed such that a coupling coefficient of the first diffraction grating in the first region adjacent to the phase controlling region is smaller than a coupling coefficient of the second diffraction grating in the second region away from the phase controlling region.

Abstract: It is an object to provide a laser apparatus, a laser irradiating method and a manufacturing method of a semiconductor device that can perform uniform a process with a laser beam to an object uniformly. The present invention provides a laser apparatus comprising an optical system for sampling a part of a laser beam emitted from an oscillator, a sensor for generating an electric signal including fluctuation in energy of the laser beam as a data from the part of the laser beam, a means for performing signal processing to the electrical signal to grasp a state of the fluctuation in energy of the laser beam, and controlling a relative speed of an beam spot of the laser beam to an object in order to change in phase with the fluctuation in energy of the laser beam.

Abstract: A multilayer film includes alternately laminated, a first film with a refractive index of n1 and a second film with a refractive index of n2, the multilayer film having the first film in contact with an end face of a semiconductor laser element. The first film and the second film satisfy relations expressed by the formulas n1<(nc)1/2 and n2>(nc)1/2. The reflectivity characteristic of the multilayer film has a 1 maximum at a wavelength &lgr;1 in a wavelength region and minimums at wavelengths &lgr;2 and &lgr;3 on a shorter-wavelength side and a longer-wavelength side of the wavelength &lgr;1, respectively.

Abstract: A wavelength monitor comprises a cylindrical lens configured to allow a laser beam emitted from a semiconductor laser to pass therethrough, first and second photodetectors configured to receive the laser beam through the cylindrical lens, and a wavelength filter disposed in an optical path between the semiconductor laser and the first photodetector.

Abstract: A light frequency locker (10) able to accept a light beam (14) generated by a controllable light source (12) into a light diverter (16) and impart to it a transverse displacement characteristic which can be detected in a light detection unit (20) connected to a processor (22). The processor (22) then controls the light source (12). Optionally, a light diverger (18) may be provided to enhance angular resolution. The light diverter (16) and the light diverger (18) may either transmit or reflect the light. The light diverter (16) may particularly include a diffraction grating (116, 156), Fabry-Perot interferometer (216), multiple slit plate (316), or an acousto-optical unit (416).

Abstract: A laser package comprises a laser diode source having a first Fabry-Perot cavity between a highly reflective back facet and low reflective front facet for providing a first light output for an optical application. A light monitor is positioned adjacent to the back facet and aligned to receive a second light output from the laser diode back facet. A pigtail fiber having a lensed fiber input end is positioned from the laser diode front facet to form an optical coupling region and is aligned relative to the lasing cavity to receive the first light output into the fiber, the light output exiting the package for coupling to the application. A portion of the first light output from the lasing cavity is reflected off the lensed fiber input end with a portion directed back into the lasing cavity and another portion reflected off of the laser diode front facet.

Abstract: A wavelength stabilized laser module is provided which is so configured as to be simplified and smaller in size and is capable of emitting semiconductor laser light whose wavelength is stablized with high accuracy. The wavelength stablized laser module includes a semiconductor laser, a substrate, a lens to convert emitted semiconductor laser light to parallel luminous flux, a first photoelectric converter to receive a part of the parallel luminous flux and to convert it to electric signals, a filter to receive a part of the parallel luminous flux, a second photoelectric converter to receive light transmitted through the filter and to convert it to electric signals, wherein a control signal to be used for stabilization obtained by computations of electric signals fed from the converters is fed back to the semiconductor laser device and/or the substrate so that said semiconductor laser is able to stably emit laser light having a reference wavelength to be used as a target for stabilization.

Abstract: A method for frequency and mode stabilisation of a tuneable laser that has at least three sections, such as a Bragg laser or GCSR laser, where measurable magnitudes are measured and the laser has been characterised with respect to a number of operation points, and where the values of the measurable magnitudes are stored in a microprocessor or corresponding device. The invention is characterised in that the values of one or more of the measurable magnitudes (E) are caused to be non-extreme values; in that the measurable magnitudes include back power in addition to front power and frequency; and in that control currents (I1, I2, I3; I1, I2, I3, I4) for the gain section (P1), the phase section (N2; N3) and the reflector section (N3; N4) respectively of said laser, and when applicable also for the coupler section (N2) of said laser, are caused to be controlled on the basis of the measured values of said measurable magnitudes while keeping both the front power and back power constant.

Abstract: A system and method for spectral conditioning an optical signal. An optical filter has an input for receiving an emitted optical signal and an output providing a filtered optical signal. The filter has a corresponding filter profile which includes a high wavelength skirt at an upper wavelength region of the filter profile. A laser is optically coupled to the optical filter input and emits the emitted optical signal. The laser is controllable to emit the optical signal at a wavelength proximate to the optical filter high wavelength skirt.

Abstract: A solid-state laser device, comprising two or more resonators for outputting laser beams on a same axis, a first light emitter and a second light emitter for entering excitation light to each of the resonators, a photodetector for monitoring which monitors the outputted laser beams, and a control unit for performing constant output control of at least one of the first light emitter and the second light emitter based on a signal from the photodetector for monitoring.

Abstract: Systems and methods are described for laser array synchronization using master laser injection of broad area lasers. A method, includes: master laser injecting a plurality of broad area lasers; and externally cavity coupling the plurality of broad area lasers. A method, includes: master laser injecting a plurality of broad area lasers; and externally Q switch coupling the plurality of broad area lasers. A method, includes: injection synchronizing a plurality of pulsed broad area lasers using a signal source; modulating the plurality of pulsed broad area lasers using the signal source; and externally coupling the plurality of pulsed broad area lasers.

Abstract: An object of the invention is to provide a wavelength locker which has a wider locking range than that of the wavelength locker in the prior art and which can cope with a plurality of wavelengths. The aforementioned objects are achieved by a wavelength locker, which comprises a periodic filter, a detecting part for detecting the intensity of a laser beam through the periodic filter, and a controlling part for controlling the wavelength of the laser beam to a desired wavelength in accordance with the output of the detecting part. In this wavelength locker, the FSR of the periodical filter is controlled according to space between the wavelengths, and refers to the number of wavelength to be locked, so that the characteristics corresponding to output wavelengths that vary in every period twice the space of wavelengths and are complementary to each other, can be obtained, and the locking range will become wider.

Abstract: A three-cavity stabilized laser system is disclosed. The laser system includes a laser with rear and front ends surrounding a gain medium. First and second wavelength-selective reflective elements with respective first and second overlapping reflectivity bandwidths are optically coupled to the laser. The wavelength-selective reflective elements are arranged so that the laser system operates stably in the coherence collapse lasing regime.

Abstract: An optical transmitter having a packaging structure by which excellent optical transmitting waveform at high speed transmission is provided. An optical transmitter, comprising, a stem formed almost coaxial shape, a column fixed on said stem, a light emitting element chip provided on the column, terminals insulated with said stem and provided through the stem, and a connecting article connecting between the terminal and said light emitting element chip, wherein, the connecting article is formed by a line which is provided on an insulating substrate and is controlled to have predetermined characteristic impedance, and a resistive element for impedance matching connected to the line serially.

Abstract: The invention relates to the stabilization of 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 stability of such laser sources compared to prior art designs, a plurality of “external” cavities is provided. In the commonly employed optical fibers for conducting the laser beam, these cavities may be formed by a plurality of appropriately designed Bragg gratings. However, the cavities may as well be formed by other means reflecting a given amount of the energy back to the laser in a desired frequency band, thus effecting the stabilization of the laser's intensity and frequency.

Abstract: An optical transmitter having a packaging structure by which excellent optical transmitting waveform at high speed transmission is provided. An optical transmitter, comprising, a stem formed almost coaxial shape, a column fixed on said stem, a light emitting element chip provided on said column, terminals insulated with said stem and provided through said stem, and a connecting article connecting between said terminal and said light emitting element chip, wherein, said connecting article is formed by a line which is provided on a insulating substrate and is controlled to have predetermined characteristic impedance, and a resistive element for impedance matching connected to said line serially.

Abstract: An apparatus and method for flexibly and precisely varying temporal placement and duration of pulses, within a train of high speed, high power optical pulses. The invention includes optics adapted for focusing on a layer of an information storage media. An optical pulse generator is coupled with the layer through the optics for generating a train of optical pulses, wherein each pulse has a respective temporal placement within the train and has a respective pulse duration. The respective pulse duration of each pulse is controlled by an amount of an analog duration control voltage, in accordance with a WRITE STRATEGY, which is based on a physical property of the layer of the information storage media. Similarly the respective temporal placement of each pulse is controlled by an amount of an analog temporal placement control voltage, in accordance with the WRITE STRATEGY.

Abstract: A semiconductor laser module includes a single semiconductor laser device having a first light emitting stripe and at least one other light emitting stripe which are aligned to respectively emit a first laser beam and at least one other laser beam through one edge surface. It also includes a first lens positioned so that the first laser beam and the at least one other laser beam emitted from the semiconductor laser device are incident thereon, the first lens configured to separate the first laser beam and the at least one other laser beam. A beam synthesizing member is included and has a first input part on which the first laser beam is incident, at least one other input part on which the at least one other laser beam is incident, and an output part from which the first laser beam emerging from the first input part and the at least one other laser beam emerging from the at least one other input part are multiplexed and emitted as a multiplexed laser beam.

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: The medical laser unit (1) includes at least one laser body (3) being made of laser material (4). A first type of a pump light source (11) is designed and arranged to continuously excite the laser material (4) and to generate continuous laser radiation (7). A second type of a pump light source (16) is designed and arranged to excite the laser material (4) by pulses and to generate pulsed laser radiation (7). A transmitting unit is designed and arranged to transmit the continuous laser radiation (7) and the pulsed laser radiation (7) to a surgical application site. More particularly, the medical laser unit (1) has two modes of operation, a first mode for cutting with continuous laser radiation (7) and a second mode for fragmenting with pulsed laser radiation (7) of short time and high power laser pulses.

Abstract: The present invention utilizes two monitoring and feedback loops to track the performance of the laser output as it relates both to the environmental conditions and the effects that gradual changes in the efficiency slope of the laser performance curve have on the modulation amplitude of the laser. The first control loop operates to monitor the changes in the average power output of the laser resulting from the impact of environmental factors and to apply an adjustment thereby increasing or decreasing the drive current to maintain the average power output of the laser at a constant state. The second control loop operates periodically to determine the slope of the performance curve to determine the operating efficiency of the laser thereby providing feedback necessary to determine the drive current necessary to modulate the laser at a constant extinction ratio.

Abstract: Method to measure gain of a photonic inverter based on a semiconductor laser using two different modes of operation. In one mode, the device is operated as a photonic inverter device and in the other mode as a photogenerated current measurement device. While the device is operated in a photonic inverter mode, that is, pumped at a magnitude that supports photonic inverter operation, the optical output power is measured in the absence of an input signal and with an input signal that quenches the output of the photonic inverter. While the device is operated as a photogenerated current measurement device with an input optical signal, a reverse bias is applied to offset any forward bias induced by the injected input optical signal, the induced photocurrent is measured, and the wavelength of the input optical signal is measured.

Abstract: The invention relates to a method and system for wavelength stabilization of a broadband optical source. The method and system are based on utilizing an optical power divider to generate two optical signals for each of the broadband source and a reference wavelength source. The difference in the power ratio of the two optical signals derived from the broadband source and the power ratio of the two optical signals derived from the reference wavelength source is determined. Because the power ratios are similarly affected by component aging and changes in environmental factors such as temperature and incident radiation, the difference in the power ratios can be used to adjust the wavelength of the broadband source so that its center wavelength is stabilized to the center wavelength of the reference source.

Abstract: A laser-based light source includes a laser (26), two optical detectors (27), a diffraction grating (29) mounted in a can (28), and a controlling circuit (31). A plurality of parallel grooves (293) is defined in a bottom face (292) of the diffraction grating. Each groove has a depth “d.” A groove separation “a” is defined between any two adjacent grooves. A groove cycle “b” is defined as a sum of the distance a and a width of any one groove. A light intensity of light beams depends on the values of “d”, “a” and “b”. By selecting a desired duty cycle f=a/b for the diffraction grating, the reflected light beams are converged into ±1 order light beams. Almost all the ±1 order light beams are collected by the optical detectors, notwithstanding variations in operational temperature. The controlling circuit receives feedback signals from the optical detectors.

Abstract: The present invention provides a method for correcting a shift of an output wavelength of a light source. The output wavelength shift correcting method derives simple equations through experimental processes, predicts a shift degree of the output wavelength with respect to a varied input current using the equations whenever a drive current is reset later, and adjusts a drive temperature according to the predicted shift degree, thus correcting the shift of the output wavelength. The output wavelength shift correcting method is advantageous in that it provides a method of locking an output wavelength of each light source without continuously operating a wavelength locker or a wavelength measuring device, thus reducing the operating cost of the optical communication system.

Abstract: An optical output stabilizing circuit is disclosed, which comprises a pilot signal generator, a pilot signal amplitude adjusting circuit which adjusts an amplitude of a pilot signal, a laser driving circuit which modulates a driving pulse current of a semiconductor laser by an output signal of the adjusting circuit, and drives the laser by the modulated driving current, a pilot signal detecting circuit which detects a detection voltage corresponding to the amplitude of the pilot signal, a first error amplifier which generates a difference signal by comparing the first detection voltage with a first reference voltage, and which, on the basis of the difference signal, controls the adjusting circuit, and a reference voltage temperature compensating circuit which carries out temperature compensation of the reference voltage of the first error amplifier to decrease fluctuation of an extinction ratio of the output beam of the laser at the high temperature operation time.

Abstract: A die having a semiconductor laser driven by a differential drive circuit is provided. The die provides a matched load to the drive circuit by also having a balancing load with an impedance, including both resistive and reactive components substantially identical to the load impedance of the semiconductor laser fabricated on the die. With the balancing load and semiconductor laser pair, the die prevents impedance-mismatch-induced drive problems that occur in high frequency operation, e.g., above about 1 GHz. The semiconductor laser may be a vertical cavity surface emitting laser (VCSEL), for example, as are used in high bandwidth applications like Gigabit Ethernet and Fibre Channel Applications. Furthermore, the die can form an array of balancing and semiconductor laser pairs.

Abstract: System and method for detection of mode hops in the output of continuously tunable lasers according to variation in the period of an interference signal derived from laser output. The method comprises generating an interference signal from laser output, detecting variation in the period of the interference signal, and determining the presence of a mode hop or mode hops from the detected variation in the period of the interference signal. The methods may additionally comprise adjusting the cavity of the laser when a mode hop is detected.

Abstract: A method and apparatus to automatically control an output power of a laser diode, include generating an error voltage between an output voltage of the laser diode sampled during an automatic power control period and a reference voltage, and performing proportional-integral processing on the error voltage to generate a compensated control voltage and applying the compensated control voltage to the laser diode.

Abstract: The present invention relates to an optical module for light path conversion, which is used in the fields of optical communications, optical information processing and the like. The optical module of the present invention comprises a surface light emitting element and a light path converting reflective body formed from single-crystal silicon, which has an inclined face on which a light-reflecting film is formed, and is constructed by causing the light that is emitted from the surface light emitting element to be subjected to a light path conversion by the inclined face.

Abstract: A large area slab laser, wherein disharge is confined between two large area electrodes. A two dimensional array of inductors is placed across the electrodes so that the standing wave patterns associated with the propagation of the high frequency driving current are corrected. In one embodiment, the electrodes are planar, in another, the electrodes are annular.

Abstract: In a semiconductor laser diode module including a semiconductor laser diode having a front facet for emitting a light beam, a collimating lens for receiving the light beam to generate a collimated light beam and a coupling lens for receiving the collimated light beam and converging the collimated light beam to an optical fiber, a bandpass filter is provided for receiving a first part of the collimated light beam, and a light detector is provided to have a first portion for receiving the first part of the collimated light beam through the bandpass filter and a second portion for receiving a second part of the collimated light beam. Thus, a wavelength of the semiconductor laser diode is controlled in accordance with an output signal of the first portion of the light detector, and a light intensity of the semiconductor laser diode is controlled in accordance with an output signal of the second portion of the light detector.

Abstract: The present invention comprises a dense wavelength division multiplexing system which uses an automatic level control feedback circuit or loop (100) to maintain one of a plurality of selectable output power levels. In addition, to prevent the sidelobes of the individual channels from interfering with one another when power to the channel is increased, an optical bandpass filter (5) is placed in the optical feedback path of the ALC loop (100). Furthermore, if the frequency or wavelength drifts from the desired output wavelength, the output wavelength is tuned by cooling or heating the laser using a thermoelectric cooler (55) which is part of a thermoelectric cooler loop (110) that uses a calibration table to adjust for temperature/wavelength errors.

Abstract: A device to monitor light output from a light source, including a V-groove substrate with a reflective coating deposited on at least one surface, an optical fiber, a light source positioned so that an amount of the light emitted, which is less than 100%, enters the optical fiber, a light intensity or source detector positioned so that at least some of the light emitted from the light source, that did not enter the optical fiber impinges upon the light intensity detector, and feedback circuitry. A method of producing a device including the steps of coating a surface of a V-groove substrate with a reflective material, placing a light source in said V-groove substrate.

Abstract: In the initial state, any wavelength variation of the output signal light with a change of the current injected into the laser is monitored with a wavelength meter, the quantity of wavelength variation is fed back to the wavelength compensation circuit, a compensation voltage for maintaining the wavelength in the initial stage is figured out, and that voltage is recorded into a memory element or the like. A configuration to add this compensation voltage to a comparator makes it possible to compensate for fluctuations of the characteristics of the optical splitter, wavelength filter and light receiving elements and thereby to obtain a stable optical wavelength. By constantly monitoring the injected current applied to the laser when the optical transmitter is in operation and giving a compensation voltage matching the current variation to the comparator, stabilization of the optical wavelength can be realized.

Abstract: The invention relates to an improved method and system for synchronizing signals in a particle accelerator system. In one embodiment, a method and system is disclosed whereby a phase of laser pulses are monitored, and a high-frequency signal is adjusted as necessary to be substantially in-phase with the laser pulses. In another embodiment, a method and system is disclosed whereby a phase of an electromagnetic field in an electron gun is monitored, and a high-frequency signal is adjusted as necessary to be substantially in-phase with the electromagnetic field.

Abstract: A system and method for reducing peak power of a laser pulse and reducing speckle contrast of a single pulse comprises a plurality of beamsplitters, mirrors and delay elements oriented to split and delay a pulse or pulses transmitted from a light emitting device. The design provides the ability to readily divide the pulse into multiple pulses by delaying the components relative to one another. Reduction of speckle contrast entails using the same or similar components to the power reduction design, reoriented to orient received energy such that the angles between the optical paths are altered such that the split or divided light energy components strike the target at different angles or different positions. An alternate embodiment for reducing speckle contrast is disclosed wherein a single pulse is passed in an angular orientation through a grating to create a delayed portion of the pulse relative to the leading edge of the pulse.

Abstract: Embodiments of wavelength tunable lasers are disclosed. The wavelength tunable lasers include thermo-optic organic material that has an index of refraction that can quickly vary in response to changes in temperature. By controlling the temperature in the thermo-optic organic material through the use of heaters or coolers, the wavelength tunable lasers and the integrated optical components can be quickly and selectively tuned over a broad range of wavelengths with high spectral selectivity.

Abstract: The invention discloses an optical output power and output wavelength control system for use with a sampled grating distributed Bragg reflector (SGDBR) laser. The optical output power and output wavelength control system for use with a sampled grating distributed Bragg reflector (SGDBR) laser comprises a controller for providing current inputs to the laser controlling the optical output power and output wavelength and an external reference receiving an optical output from the laser and providing a reference output to the control, wherein the controller compares the optical output power and output wavelength of the laser to the reference output and locks the optical output power and output wavelength of the laser to the external reference.

Abstract: In a method and apparatus for synchronizing the output of two passively modelocked pulsed lasers, the output of each laser is sampled and delivered to two photodiodes, one for each laser. The output of the each photodiode is converted to a train of digital pulses having the pulse repetition frequency of each laser. The digital pulses are processed in a digital phase detector that generates from the digital pulses a first analog voltage representative of the phase difference at the photodiodes between corresponding pulses in each train. This analog voltage is summed with a second analog voltage representative of a desired phase relationship of the laser pulses at a target location remote from the photodiodes. The sum of the analog voltages provides an error signal that commands a device to adjust the length of the resonator of one of the lasers. When the error signal is minimized, pulses from each laser have the same repetition frequency and have the desired phase relationship at the target.

Abstract: An apparatus including a cavity optical length actuator to vary a cavity optical path length of a laser in response to an excitation signal having varying frequencies. The cavity optical length actuator induces intensity perturbations in an optical beam of the laser corresponding to the excitation signal. A sensor senses the intensity perturbations in the optical beam and generates a response signal corresponding to the intensity perturbations. A combiner combines the excitation signal and the response signal to generate an error signal.

Abstract: Disclosed is a method for obtaining feedback to drive a servo system for aligning and maintaining alignment in optical systems that bring light to an in vivo skin sample, for adjusting the focus of the optical system, and for adjusting the net depth of focus of the optical system within the in vivo system under characterization. These methods comprise adjusting the angle of incidence of electromagnetic radiation and/or providing a shielding lens to block scattered incident light, or otherwise limiting the field of view of the Raman scattered radiation collection system to exclude optical surfaces of the excitation delivery portion of the optical system. In one embodiment, the method comprises discriminating between Raman signals originating on outer portions of skin from signals originating from substances deeper within the skin or other tissues. In another embodiment, the invention provides a method for detecting skin abnormalities and for assessing the aging of skin and related tissues.