Abstract: A laser system using ultrashort laser pulses is provided. In another aspect of the present invention, the system includes a laser, pulse shaper and detection device. A further aspect of the present invention employs a femtosecond laser and binary pulse shaping (BPS). Still another aspect of the present invention uses a laser beam pulse, a pulse shaper and a SHG crystal.

Abstract: Techniques and devices to stabilize a passively mode-locked laser against the timing jitter by using a feedback control signal based on a signal component at a high harmonic frequency of the laser pulse repetition frequency in the laser output to control the optical path length of the laser resonator.

Abstract: The present invention generally concerns the use of Bragg optical fibers in chirped pulse amplification systems for the production of high-pulse-energy ultrashort optical pulses. A gas-core Bragg optical fiber waveguide can be advantageously used in such systems to stretch the duration of pulses so that they can be amplified, and/or Bragg fibers can be used to compress optical signals into much shorter duration pulses after they have been amplified. Bragg fibers can also function as near-zero-dispersion delay lines in amplifier sections.

Abstract: Laser apparatus including two different, pulsed MOPAs, one having a fundamental wavelength of 1064 nm and the other having a fundamental wavelength of 1564 nm, provide trains of optical pulses. The 1064-nm pulses are frequency tripled to 355 nm and the 1564-nm pulses are frequency doubled to 782 nm. The 355-nm and 782-nm pulses are mixed to provide 244-nm pulses. The 244-nm pulses are mixed with residual 1064-nm pulses to provide 198-nm output pulses of the apparatus. The output pulses can be either digitally modulated or amplitude modulated by controlling the phase relationship between the 1064-nm and 1564-nm pulses.

Abstract: An EUV light generation system and method is disclosed that may comprise a droplet generator producing plasma source material target droplets traveling toward the vicinity of a plasma source material target irradiation site; a drive laser; a drive laser focusing optical element having a first range of operating center wavelengths; a droplet detection radiation source having a second range of operating center wavelengths; a drive laser steering element comprising a material that is highly reflective within at least some part of the first range of wavelengths and highly transmissive within at least some part of the second range of center wavelengths; a droplet detection radiation aiming mechanism directing the droplet detection radiation through the drive laser steering element and the lens to focus at a selected droplet detection position intermediate the droplet generator and the irradiation site.

Abstract: The present invention relates generally to multi-faceted wavelength conversion devices and laser projection systems incorporating the same.

Abstract: A laser and monitoring system is provided. In another aspect of the present invention, the system includes a laser, pulse shaper and detection device. A further aspect of the present invention employs a femtosecond laser and binary pulse shaping (BPS). Still another aspect of the present invention uses a laser beam pulse, a pulse shaper and a SHG crystal. In yet another aspect of the present invention, a multiphoton intrapulse interference phase scan (hereinafter “MIIPS”) method is used to characterize the spectral phase of femtosecond laser pulses and to correct them. A further aspect of the system of the present invention is employed to monitor environmental chemicals and biological agents, including toxins, explosives, and diseases.

Abstract: A solar module patterning apparatus comprises a laser oscillator, a homogenizer and a scanner. The laser oscillator generates a laser beam having a predetermined wavelength. The homogenizer homogenizes an intensity distribution of the generated laser beam provided from the laser oscillator. The scanner scans the laser beam to a solar module. The laser beam is output from the homogenizer and passed through a mask with a predetermined pattern.

Abstract: Techniques, apparatus and systems for providing compensation mechanisms for mode-locked lasers and optical amplifiers and a dispersion compensation mechanism to allow a mode-locked laser and an optical amplifier to be optically coupled to each other and to share a common diffraction grating for a dispersion compensation element for the laser and a separate dispersion compensation element for the amplifier.

Abstract: A control system and apparatus for use with an ultra-fast laser is provided. In another aspect of the present invention, the apparatus includes a laser, pulse shaper, detection device and control system. A multiphoton intrapulse interference method is used to characterize the spectral phase of laser pulses and to compensate for any distortions in an additional aspect of the present invention. In another aspect of the present invention, a system employs multiphoton intrapulse interference phase scan. Furthermore, another aspect of the present invention locates a pulse shaper and/or MIIPS unit between a spectral dispersion point in a laser oscillator and an output of a laser amplifier.

Abstract: The present invention provides a laser oscillator using an electroluminescent material that can enhance directivity of emitted laser light and resistance to a physical impact. The laser oscillator has a first layer including a concave portion, a second layer formed over the first layer to cover the concave portion, and a light emitting element formed over the second layer to overlap the concave portion, wherein the second layer is planarized, an axis of laser light obtained from the light emitting element intersects with a planarized surface of the second layer, the first layer has a curved surface in the concave portion, and a refractive index of the first layer is lower than that of the second layer.

Abstract: An apparatus for adjusting the wavelength of a laser capable of lasing at multiple wavelengths by using a single acousto-optical modulator and a pair of optical reflectors inside a laser cavity. By adjusting the frequency and amplitude of the radio-frequency source to the acousto-optical modulator, undesired wavelengths are suppressed in the laser cavity, leaving appreciable gain only at the desired wavelength.

Abstract: A WDM communication system having two optical-frequency comb sources (OFCSs) that are substantially phase-locked to one another, with one of these OFCSs used at a transmitter to produce a WDM communication signal and the other OFCS used at a receiver to produce multiple local-oscillator signals suitable for homodyne detection of the WDM communication signal received from the transmitter. In one embodiment, the transmitter has (i) a first OFCS adapted to generate a first frequency comb and (ii) an optical modulator adapted to use the first frequency comb to generate a WDM communication signal having at least two beacon lines for transmission to the receiver. The receiver has a second OFCS adapted to produce a second frequency comb having the beacon frequencies, with the phases of the corresponding comb lines being locked to the phases of the beacon lines of the received WDM signal.

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

Abstract: An apparatus is described that includes an optical storage cavity comprising a planar mirror and a spherically curved mirror that form an optical path therebetween. A pump laser introduces optical pulses into the cavity. A folding mirror is disposed in the optical path between the planar mirror and the spherically curved mirror such that a beam waist is formed between the folding mirror and the second spherically curved mirror. The optical pulses preferably interact with selected particles disposed in the optical path at the waist. The apparatus further comprises a first transducer which adjusts the distance between the spherical mirror and the folding mirror to change a characteristic of the beam waist. A second transducer adjusts the distance between the planar mirror and the spherical mirror to change the optical path length of the cavity. The optical cavity is arranged such that the change in path length due to the second transducer does not significantly affect the characteristic of the beam waist.

Abstract: The direct integration of light and optical control into microfluidic systems presents a significant hurdle to the development of portable optical trapping-based devices. A simple, inexpensive fiber-based approach is provided that allows for easy implementation of diode-bars for optical particle separations within flowing microfluidic systems. Models have also been developed that demonstrate the advantages of manipulating particles within flow using linear geometries as opposed to individually focused point traps as traditionally employed in optical-trapping micromanipulation.

Abstract: A system for laser amplification includes a dual-crystal Pockels cell which is used to control emission of laser pulses from an ultra-fast laser. The Pockels cell is constructed to enable adjustment of the rotational orientation of one crystal relative to the other crystal. The rotational orientation of one or both crystals in the Pockels cell is adjusted to control sidebands in the laser pulse.

Abstract: A laser annealing apparatus comprises a laser oscillator having a Q switching action, one or a plurality of partially reflective mirrors for split a laser beam emitted from the laser oscillator into a plurality of laser beams, a plurality of optical fibers which respectively transmit the plurality of laser beams split by the partially reflective mirrors, and whose respective emission ends are arranged linearly in one direction, a first optical system for synthesizing and homogenizing the plurality of laser beams emitted from the optical fibers, and a second optical system for focusing the laser beam emitted from the first optical system on the work piece surface as a rectangular laser beam whose beam shape is long in the lateral direction and short in the longitudinal direction.

Abstract: In the laser system of the present invention, an acoustic grating (AG) established in an SBS cell by an initial laser pulse is forced into oscillation from noise. Since the process is nonlinear, SBS Phase Conjugation does not take place until a specific level is achieved based on several factors such as the physical conditions and the SBS media. The invention segments the initial laser pulse with a zonal lenslet array that produces a set of beams that have their foci distribute in space. By coupling this segmented lenslet array with a master lens, the separation of the foci from each other can be controlled. At a large separation distance each foci independently produces an associated AG. As each AG forms from a local noise source the coherence between the segmented beams has been lost. However, the master lens controls the entire focal envelope and hence the separation distance between the foci. Increasing the power of the master lens causes the separation between the foci to decrease.

Abstract: The infrared image generation device, method and system generate realistic infrared images to accurately test infrared sensors. The device and system include a laser light source, at least one scanner, a processor and a target plate. The scanner(s) receive and redirect the laser light. The processor controls operation of the scanner(s) to generate at least one infrared image and the target plate receives the redirected light from the scanner(s) and, as such, the infrared image(s) are generated on the target plate. For instance, the target plate may display an infrared image having at least one portion that represents a temperature of at least 1000 Kelvin. The target plate may be made of a transparent heat sink layer facing the scanner(s), an insulator layer adjacent to the transparent heat sink layer, and an emissive layer that is at least opaque and is adjacent to the insulator layer.

Abstract: A semiconductor optical amplifier, an acousto-optic tunable filter, a phase shifter, a lens, and an internal etalon are arranged in a resonator. Outside the resonator, two lenses, two beam splitters, two photo-detectors, and an external etalon are arranged. The internal etalon is a quartz etalon and the external etalon is a crystal etalon. Therefore, the rate of change in transmission peak wavelength of the internal etalon to a temperature change is greater than that of the external etalon.

Abstract: To provide an image processing method including at least one of recording an image onto a thermoreversible recording medium in which transparency or color tone reversibly changes depending upon temperature, by applying a laser beam with the use of a CO2 laser device so as to heat the thermoreversible recording medium, and erasing an image recorded on the thermoreversible recording medium, by heating the thermoreversible recording medium, wherein an intensity distribution of the laser beam applied in the image recording step satisfies the relationship represented by Expression 1 shown below, 1.59<I1/I2?2.00 ??Expression 1 where I1 denotes an irradiation intensity of the applied laser beam in a central position of the applied laser beam, and I2 denotes an irradiation intensity of the applied laser beam on a plane corresponding to 80% of the total irradiation energy of the applied laser beam.

Abstract: A combined laser source includes: a plurality of semiconductor lasers which contain emission elements emitting a plurality of laser beams and being separately and hermetically sealed; a plurality of collimator lenses which collimate the plurality of laser beams emitted from the emission elements of the plurality of semiconductor lasers; an optical condensing system which receives, condenses, and optically combines the plurality of laser beams collimated by the plurality of collimator lenses; and one or more deflection members which are arranged between the optical condensing system and one or more of the plurality of collimator lenses, and deflect one or more of the plurality of laser beams collimated by the one or more of the plurality of collimator lenses so that the one or more of the plurality of laser beams propagate parallel to an optical axis of the optical condensing system.

Abstract: The present invention provides a laser oscillator using an electroluminescent material that can enhance directivity of emitted laser light and resistance to a physical impact. The laser oscillator has a first layer including a concave portion, a second layer formed over the first layer to cover the concave portion, and a light emitting element formed over the second layer to overlap the concave portion, wherein the second layer is planarized, an axis of laser light obtained from the light emitting element intersects with a planarized surface of the second layer, the first layer has a curved surface in the concave portion, and a refractive index of the first layer is lower than that of the second layer.

Abstract: Systems and methods are described for controlling flow disturbances emanating from a protrusion, such as a beam propagating device. In one embodiment, a method includes positioning a flow control element at least partially around a base portion of a protrusion, wherein the flow control element includes at least one flow expanding feature. A reduced pressure zone is generated proximate an aft portion of the protrusion by expanding at least a portion of a flowfield. One or more flow disturbances emanating downstream from the protrusion are deflected using the at least one reduced pressure zone.

Abstract: Information on the side of the body of an exposure apparatus is effectively used on the side of the laser light source apparatus. There is provided a laser light source apparatus which supplies a laser beam to a body of an exposure apparatus which exposes a wafer, and includes a controller adjusting an operation condition of the laser light source apparatus based on exposure information about the exposure operation supplied from the body of the exposure apparatus. The exposure information is exemplified by information on the waiting time until the light emission start or light emission continuation time and the operation condition is exemplified by the gas pressure in an emission chamber in which a laser beam is emitted, the temperature in the emission chamber and a number of revolutions of a blower in the emission chamber.

Abstract: For optical data storage applications, for example, for holographic storage applications, a radiation beam (12) with a flat intensity profile is needed. The radiation source device (1) of the invention comprises a beam shaper element (5) and a collimating element (7) between a semiconductor laser (3) and an output coupler (9) and provides such a radiation beam (12) with an increased efficiency. An external resonator is thereby provided. Further, a relatively fast tuning of the wavelength of the output radiation beam (12) can be provided.

Abstract: A laser system comprises a source, a laser medium, first and second mirrors, a Q-switch, and a control system. The source produces input energy. The laser medium converts the input energy to an output beam. The first and second mirrors are disposed on opposing sides of the laser medium. The output beam reflects between the first and second mirrors. The first mirror is an output mirror for releasing a pulsed laser beam having an energy level. The Q-switch is made of material that has an alterable optical property in response to a Q-switch input signal. The control system selectively varies the Q-switch input signal to control the energy level of the pulsed laser beam. A first Q-switch input signal produces a pulsed laser beam for a plurality of pulses at a maximum power level, while a second Q-switch input signal produces a pulsed laser beam at an intermediate power level.

Abstract: A rectangular beam having the energy density distribution homogenized in its short-side direction is formed in a beam homogenizer wherein two light reflection surfaces are parallel-provided in a beam progression optical waveguide with a predetermined space so as to face each other at surfaces along the beam progression direction and a course change reflection surface for changing the beam progression direction is formed at a surface in the direction intersected with the light reflection surfaces. The beam enters a cylindrical lens array and a cylindrical lens sequentially to homogenize the energy density distribution in its long-side direction. Then, the irradiation laser from the cylindrical lens is projected onto a non-single crystalline semiconductor film to perform annealing.

Abstract: A device of detection of gas in trace amounts by a semiconductor laser coupled to a resonant optical cavity containing a chemical species to be analyzed. The device comprises a resonant optical cavity containing a chemical species to be analyzed; a semiconductor laser, coupled by optical feedback to the optical cavity and capable of being frequency-scanned; a means for adjusting the laser-cavity coupling rate; a means for finely adjusting the optical feedback phase; and a means for measuring the light transmitted by the cavity.

Abstract: A laser system using ultrashort laser pulses is provided. In another aspect of the present invention, the system includes a laser, pulse shaper and detection device. A further aspect of the present invention employs a femtosecond laser and a spectrometer. Still another aspect of the present invention uses a laser beam pulse, a pulse shaper and a SHG crystal. In yet another aspect of the present invention, a multiphoton intrapulse interference phase scan system and method characterize the spectral phase of femtosecond laser pulses. Fiber optic communication systems, photodynamic therapy and pulse characterization tests use the laser system with additional aspects of the present invention.

Abstract: A light source that emits light includes light source units, each emitting a plurality of light beams parallel to one another, the plurality of light beams including first and second light beams, and a beam distance adjustment element that is an optical element made of a light-transmissive material. The beam distance adjustment element is configured to adjust the distance between the first and second light beams. The beam distance adjustment element includes a first incidence plane on which the first light beam is incident, a first exit plane that is parallel to the first incidence plane and from which the first light beam exits, a second incidence plane on which the second light beam is incident, and a second exit plane that is parallel to the second incidence plane and from which the second light beam exits. The first and second light beams intersect in the beam distance adjustment element.

Abstract: A beam mixer for increasing intensity symmetry along a selected axis of a beam (wherein the beam extends from a first edge to a second edge along the axis) is disclosed and may include a plurality of mirrors establishing a spatially inverting path. For the beam mixer, the inverting path may have a beginning and an end and may be characterized in that a part of the beam near the first beam edge at the beginning of the path translates to the second beam edge at the end of the path. For this aspect, the beam mixer may further include an optic dividing the beam into first and second beam portions, the optic placing the first portion onto the inverting path and recombining the first and second portions onto a common path after the first portion has traveled along the inverting path thereby mixing the beam.

Abstract: A method for controlling operation of a transistor includes the following steps: providing a bipolar transistor having emitter, base and collector regions; applying electrical signals to the transistor to produce light emission from the transistor; effecting photon-assisted tunneling of carriers in the transistor with self-generated photons of the light emission, and controlling operation of the transistor by controlling the photon-assisted tunneling.

Abstract: The present invention provides a beam homogenizer being able to form a rectangular beam spot having homogeneous energy distribution in a direction of its major axis without using the optical lens requiring to be manufactured with high accuracy. In addition, the present invention provides a laser irradiation apparatus being able to irradiate the laser beam having homogeneous energy distribution in a direction of its major axis. Furthermore, the present invention provides a method for manufacturing a semiconductor device being able to enhance crystallinity in the surface of the substrate and to manufacture TFT with a high operating characteristic. The beam homogenizer, one of the present invention, is to shape the beam spot on the surface to be irradiated into a rectangular spot having an aspect ratio of 10 or more, preferably 100 or more, and comprises an optical waveguide for homogenizing the energy distribution of the rectangular beam spot in the direction of its major axis.

Abstract: A line narrowing module includes an elliptical mirror, a diffraction grating disposed at a first focus of the mirror for separating an incident beam into different lines, and a laser beam dispersion and extraction unit. The laser beam dispersion and extraction unit disperses incident laser over the diffraction grating and selectively extract from the resulting lines a laser beam having a desired narrowed bandwidth. A light source that employs the line narrowing module also includes a laser oscillator for generating the beam, and a light returning unit that returns one fraction of the beam extracted from the laser oscillator back to the laser oscillator. Another fraction of the beam is extracted from the laser oscillator through a front window of the laser oscillator, and undergoes line narrowing in the module. The laser beam having the narrowed bandwidth is immediately output as the exposure light from the module.

Abstract: A laser spark distribution and ignition system that reduces the high power optical requirements for use in a laser ignition and distribution system allowing for the use of optical fibers for delivering the low peak energy pumping pulses to a laser amplifier or laser oscillator. An optical distributor distributes and delivers optical pumping energy from an optical pumping source to multiple combustion chambers incorporating laser oscillators or laser amplifiers for inducing a laser spark within a combustion chamber. The optical distributor preferably includes a single rotating mirror or lens which deflects the optical pumping energy from the axis of rotation and into a plurality of distinct optical fibers each connected to a respective laser media or amplifier coupled to an associated combustion chamber. The laser spark generators preferably produce a high peak power laser spark, from a single low power pulse.

Abstract: Optical gain of a nonpolar or semipolar Group-III nitride diode laser is controlled by orienting an axis of light propagation in relation to an optical polarization direction or crystallographic orientation of the diode laser. The axis of light propagation is substantially perpendicular to the mirror facets of the diode laser, and the optical polarization direction is determined by the crystallographic orientation of the diode laser. To maximize optical gain, the axis of light propagation is oriented substantially perpendicular to the optical polarization direction or crystallographic orientation.

Abstract: Methods and systems for control and monitoring processing of semiconductor materials with a focused laser beam. Laser light may be focused on a sample to excite optical emission at the sample surface during processing, which may include laser processing. Optical emission spectra produced may be analyzed for various properties effectively during the process. For example, process effects such as chemical composition analysis, species concentration, depth profiling, homogeneity characterization and mapping, purity, and reactivity may be monitored by optical spectral analysis. The wavelength may be selected to be appropriate for the process effect chosen.

Abstract: A semiconductor laser device incorporates a beam control layer for reducing far field and beam divergence. Within the beam control layer, a physical property of the semiconductor material varies as a function of depth through, the beam control layer, by provision of a first sub-layer in which the property varies gradually from a first level to a second level, and a second sub-layer in which the property varies from said second level to a third level. In the preferred arrangement, the conduction band edge of the semiconductor has a V-shaped profile through the beam control layer.

Abstract: An upper limit and a lower limit are preliminarily set for a spectral line width common to a plurality of narrow-band laser devices. When delivered or subjected to maintenance, the narrow-band laser device is caused to laser oscillate to detect its spectral line width before it is used as a light source for semiconductor exposure. A spectral line width adjustment unit provided in the narrow-band laser device is adjusted so that the spectral line width assumes a value between the upper limit and the lower limit. The present invention is able to suppress the variation in spectral line width such as E95 bandwidth caused by machine differences during the manufacture of the laser device, or by replacement or maintenance of the laser device, whereby the quality of integrated circuit patterns formed by the semiconductor exposure tool can be stabilized.

Abstract: A tunable laser comprising: a foundation including a first side and an oppositely facing second side and including a hole extending from the first side to the second side; a tuning assembly including a base, a fine tuning arm and a rotational flex bearing disposed adjacent the first side of the foundation; wherein the base is disposed adjacent to the first side of the foundation; wherein one end of the flex bearing is secured to the base; wherein the other end of the flex bearing is secured to the fine tuning arm; wherein a portion of the fine tuning arm extends at least partially into the hole; an external cavity laser including a gain medium, a dispersion medium and a reflective member disposed adjacent to the second side of the foundation; wherein the gain medium and the dispersion medium grating are secured in a fixed relation relative to the each other; wherein the reflective member is secured to the portion of the arm extending into the hole; and a piezoelectric device with one end secured to the base a

Abstract: Provided is a semiconductor laser device comprising a substrate, a light emitting structure including a first clad layer, an active layer, and a second clad layer sequentially stacked on the substrate, and a scattering portion formed on the bottom surface of the substrate in order to scatter light. As such, the semiconductor laser device may emit higher quality laser light.

Abstract: A laser resonator for generating a laser beam having beam quality along two transverse axes that is determined primarily by the mode discrimination characteristics of one axis. The apparatus including a means for providing a collimated beam of electromagnetic energy with a predetermined orientation with respect to a line of sight thereof, and, a means for rotating the beam such that a transverse mode selection therefor is the same for two orthogonal directions thereof.

Abstract: An EUV light generation system and method is disclosed that may comprise a droplet generator producing plasma source material target droplets traveling toward the vicinity of a plasma source material target irradiation site; a drive laser; a drive laser focusing optical element having a first range of operating center wavelengths; a droplet detection radiation source having a second range of operating center wavelengths; a drive laser steering element comprising a material that is highly reflective within at least some part of the first range of wavelengths and highly transmissive within at least some part of the second range of center wavelengths; a droplet detection radiation aiming mechanism directing the droplet detection radiation through the drive laser steering element and the lens to focus at a selected droplet detection position intermediate the droplet generator and the irradiation site.

Abstract: A method and system decrease the amount of undesired laser radiation reaching a workpiece from a laser having a laser cavity and a Q-switch. The laser operates at any given time in one of at least two modes. In a first mode the laser emits pulses at a PRF (pulse repetition frequency) for selectively irradiating targets on or within a workpiece, and the pulses propagate along a propagation path to the workpiece. In a second mode less or no laser radiation desirably reaches the workpiece. The method is operable during the second mode. The method opens the Q switch more than the Q switch is open in the first mode, thereby limiting the amount of energy that builds up in the laser cavity and decreasing the peak energy of the laser radiation emitted in the second mode.

Abstract: Provided is a semiconductor laser device, a semiconductor laser device package including the semiconductor laser device and methods of manufacturing the same. A semiconductor laser device may include a light emission structure including a first clad layer, an active layer and a second clad layer sequentially deposited on a substrate, a submount to which the light emission structure bonded, and a light shield plate in the submount, wherein the light shield plate blocks an end of the substrate on a light emission face of the light emission structure and blocks light leaked through the end of the substrate.

Abstract: A surface emitting semiconductor laser includes a laminate of semiconductor layers emitting multimode laser light, and a block member blocking light of a specific mode among the multimode laser light emitted from the laminate.

Abstract: YAG laser can simultaneously emit a plurality of laser beams having different wavelengths from each other. By simultaneously irradiating the laser beams having different wavelengths from each other to a same region of a non-single crystal semiconductor film, an interference influence is suppressed to obtain a more uniform laser beam. For example, by simultaneously generating second and third harmonics of YAG laser to irradiate the same region through suitable optical system, a laser beam having higher uniformity and having an energy in which interference is highly suppressed is obtained.

Abstract: The invention features an apparatus and an associated method for illuminating a target area. The apparatus includes reflectors defining a first optical cavity. The first optical cavity defines a first set of longitudinal modes. The apparatus includes a first gain medium defining a first gain band. The first gain medium is configured to cause a plurality of the longitudinal modes of the first set to oscillate over an oscillation band within the first gain band when the first gain medium is pumped at an operative level. The apparatus includes a first optical waveguide positioned within the first optical cavity. The first optical waveguide has a length selected to cause a temporal coherence length of light emitted from the first optical cavity to be shorter than a scattering distance associated with the target area.