Abstract: Speckle effect in imaging applications is reduced by generating additional speckle patterns on the screen such that the speckle patterns are overlapped and the overlapped speckle patterns average out on the screen to appear as a noise background to the viewers. The speckle patterns are generated by discrete optical signals of a visible frequency comb. A visible frequency comb having discrete optical signals is generated through modulation-instability processes, phase-conjugation processes, and Bragg-scattering processes using a non-linear optical material and a wavelength converter.

Abstract: A method for reducing speckle noise in a coherent imaging system includes applying a time varying phase gradient across a sample beam of the system to convert spatial distortion to temporal noise, recording a plurality of measurements of the sample beam, and averaging the plurality of measurements to reduce the temporal noise. Another method includes acquiring a plurality of sample scans while modulating a numerical aperture of a sample beam, and concatenating the plurality of scans such that speckle noise is decorrelated from adjacent scans of the plurality of scans. An apparatus for reducing speckle noise includes an optical element for applying a time varying phase gradient across a sample beam of the system to convert spatial distortion to temporal noise, a detector for recording a plurality of measurements of the sample beam, and circuitry for averaging the plurality of measurements to reduce the temporal noise.

Abstract: A method and apparatus is disclosed for optic signal power control to maintain a desired or optimum optic signal power level. During start-up, a default or target value from memory may be utilized to bias or otherwise control operation of an optic signal generator or driver. During operation, pre-stored values may continue to be utilized or an open loop or closed loop control system may be utilized. An open loop control system may incorporate a temperature module or a timer module to account for changes in environment or changes due to aging that may undesirably affect system operation. A closed loop control system may incorporate one or more feedback loops that generate a compensation value to account for detected changes. In one configuration one or more peak values of the actual optic signal, or a portion thereof, are detected and processed to generate the compensation signal.

Abstract: A master oscillator power amplifier (MOPA) laser system includes a symmetrical master oscillator and an amplifier each having an optically pumped solid-state gain rod. An optical relay is located between the laser resonator and the amplifier gain rod. When the oscillator and amplifier gain media are equally optically pumped, the magnification and the distances from the optical relay to the resonator and the amplifier gain rod can be selected such that amplifier efficiency is maximized, independent of optical pump power, even if the diameters of the oscillator and amplifier gain rods are different.

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 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 laser oscillator and an output of a laser amplifier.

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: A method and apparatus for operating a very high repetition gas discharge laser system magnetic switch pulsed power system is disclosed, which may comprise a solid state switch, a charging power supply electrically connected to one side of the solid state switch; a charging inductor electrically connected to the other side of the solid state switch; a deque circuit electrically in parallel with the solid state switch comprising a deque switch; a peaking capacitor electrically connected to the charging inductor, a peaking capacitor charging control system operative to charge the peaking capacitor by opening the deque switch and leaving the solid state switch open and then shutting the solid state switch. The solid state switch may comprise a plurality of solid state switches electrically in parallel.

Abstract: A laser system includes a laser diode that oscillates in a multi-mode and has characteristics in which its oscillation wavelength varies with temperature, a grating that receives a light beam emitted from the laser diode and returns a diffracted beam to the laser diode, a mechanism that changes the wavelength of the diffracted beam returned to the laser diode, a wavelength detector that detects the wavelength of an output beam which is the same as that of the diffracted beam returned to the laser diode, a temperature regulator that maintains the laser diode at a predetermined temperature, and a control unit that controls the mechanism so that the output beam having a predetermined wavelength is output and controls the temperature regulator so that the laser diode oscillates at the predetermined wavelength.

Abstract: A method of operating a laser source comprising is provided. The method reduces speckle contrast in a projected image by creating a plurality of statistically independent speckle patterns. The method comprises generating a plurality of sub-beams that define an optical mode. The method further comprises controlling the phase of selected sub-beams to continuously sequence the laser source through a plurality of orthogonal optical modes. The plurality of orthogonal modes create a corresponding number of statistically independent speckle patterns, thus reducing speckle contrast in a image projected using the laser source by time averaging.

Abstract: The invention discloses an optical transmission module with digital adjustment and method thereof. The module includes a laser (21), a laser driver (22), an automatic power adjustment circuit (23), an automatic temperature adjustment circuit (24), a digital adjustment circuit (25) and a memory (26). The digital adjustment circuit, consisted of a digital-to-analog converter or a digital adjustment potentiometer, receives a digital adjustment signal and outputs, respectively, a extinction ratio adjustment signal and a cross point adjustment signal to the laser driver, an optical power adjustment signal to the automatic power adjustment circuit and an optical wavelength adjustment signal to the automatic temperature adjustment circuit. The memory stores data, using for on-line adjustment of the optical transmission module, at least including parameters of said optical transmission module and said laser emitting optical power parameters, to be reported upward.

Abstract: In a solid-state laser device, a single outer casing (1) having an approximately sealed structure is included; a single or a plurality of inner casings (2) are provided inside the outer casing (1); in some or all of the inner casings (2), an air cleaning unit (4) is included in which the air within the outer casing (1) is made clean and supplied into the inner casings (2); inside the outer casing (1), there disposed are a laser light-source (5, 6, 7) having a solid-state laser medium (501) and a light resonator, and an optical system (10, 11, 901) that transmits or interrupts a laser beam (8) emitted from the laser light-source; in addition, the laser light-source (5, 6, 7) and the optical system (10, 11, 901) or part of them are contained inside the inner casings (2); thus, in a simple, compact and inexpensive configuration, it is possible to prevent degradation of optical components and dew condensation thereon, and to stably supply a laser beam.

Abstract: A novel approach for providing temperature compensation for semiconductor lasers is disclosed. This approach utilizes reflectivity characteristics in the at least one of the mirrors of the semiconductor laser to provide temperature compensation to the device.

Abstract: A gas laser oscillator (1), which generates a laser beam by exciting laser gas in discharge tubes (7) with a laser power supply (4) and detecting an abnormality thereof, includes a storage unit (12) for storing the relationship between the output command and the DC current of the laser power supply (4) during the normal operation of the oscillator (1), an output command generating unit (13) for generating an output command corresponding to the peak current value in the relationship between the output command and the DC current, a current detection unit (19) for detecting the current during the operation of the laser power supply (4) based on the output command in the standby operation mode of the gas laser oscillator (1), and an abnormality judging unit (15) for judging that the discharge load of the gas laser oscillator (1) has an abnormality based on the detection current detected by the current detection unit (19) and the peak value of the current in the relationship between the output command and the DC c

Abstract: A laser power control circuit that is constituted by CMOS transistors reduces variations in a laser power that is emitted from a semiconductor laser, which are caused by a mismatch of the transistors. An offset amount of a differential amplifier is digitally calculated using an A/D converter that is located on the same chip, and a voltage value of a variable voltage source is controlled for applying a voltage in a direction opposite to the offset voltage of the differential amplifier to correct the offset voltage of the laser power control circuit, thereby reducing the variations in the laser power emitted from the semiconductor laser.

Abstract: The present invention generally relates to dynamic thermal management of a device. In one aspect, a method for thermally controlling a device is provided. The method includes setting a value of a set point in a thermoelectric cooler, wherein the set point corresponds to a first operating state. The method also includes monitoring a condition of the device to determine if the device is in the first operating state or a second operating state. Additionally, the method includes dynamically altering the value of the set point according to an algorithm upon determination that the device is in the second operating state. In another aspect, a method for dynamically controlling a device having a thermoelectric cooler is provided. In yet a further aspect, a system for dynamic thermal management of a device is provided.

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: A pulsed laser for machining, has a mode switch, e.g. Q-switch device (15, 30, 40), in a resonant optical cavity (20) capable of supporting a given lasing mode, e.g. a transverse mode of oscillation when lasing action is started, arranged to induce, e.g. temporarily, a localized change, e.g. loss, in the cavity. The latter alters the given lasing mode, e.g. causes the oscillation to hop to a higher transverse mode temporarily, which on its hand may be extinguished by an aperture limiting diaphragm (5) or equivalent and subsequently reduce the induced loss temporarily, to return the oscillation to the given transverse mode and output the laser pulse. A modulator can be used for inducing the temporary loss for a first transverse lasing mode and extinguishing the higher transverse mode with a diaphragm. The induced loss can be over a localized area much smaller than the dimensions of a beam of the laser, so that a miniaturized modulator can be used. In this way pulsed operation may be achieved.

Abstract: A semiconductor optical device where the leak current due to the double injection of carriers may be suppressed and a simplified process to form the device are disclosed. The device 10 provides, on the n-type InP substrate, a mesa and a burying region formed so as to bury the mesa. The mesa includes the first cladding layer, the active layer, the tunnel junction layer and the second cladding layer on the n-type InP substrate in this order. The tunnel junction layer comprises an n-type layer coming in contact with the active layer and a p-type layer between the active layer and the n-type layer. The n-type layer has a carrier concentration higher than that of the second cladding layer, while, the p-type layer may have the band gap energy greater than that of the second cladding layer.

Abstract: A novel method and apparatus for suppressing ASE and/or parasitic oscillation modes in a laser is introduced. By roughening one or more peripheral edges of a solid-state crystal or ceramic laser gain media and by bonding such edges to a predetermined electromagnetic absorbing material arranged adjacent to the entire outer surface of the peripheral edges of the roughened laser gain media, ASE, parasitic oscillation modes and/or residual pump energy can be effectively suppressed.

Abstract: An optical disk apparatus uses a laser driver which can measure the frequency of the high-frequency superimposed current of the semiconductor laser simply and accurately. The apparatus includes a semiconductor laser which emits a laser beam onto the optical disk, a laser driver which drives the semiconductor laser with a current, with the high-frequency current being superimposed thereon, and measures the frequency of the high-frequency current, and a main controller which controls the frequency of the high-frequency current produced by the laser driver by using the frequency measured by the laser driver.

Abstract: Compactness is preserved while enabling beam monitoring of optical properties of an output beam by employing a combination of reflection and diffraction. An input beam is reflected, divided using reflection/diffraction, and re-reflected. As a consequence, both a light source and one or more beam monitoring detectors may be disposed along a single side of an optical module. In one embodiment, an input beam is introduced from a first side of an optical module, is reflected by a 45 degree mirror, and is divided by a diffraction grating which redirects a minor portion of the beam energy back to the 45 degree mirror. Following the second reflection from the mirror, the returned portion of the beam is used to measure one or more optical properties.

Abstract: An improved beaconless adaptive optics system and process. A target is illuminated with a high energy laser beam of a directed energy laser. Wave front measurements are made of high energy laser beam reflections from the target. These wave front measurements are analyzed by a high speed processor to determine both high frequency phase components and low frequency phase components in the wave front data. (Applicants' experiments have shown that there is a direct correlation between beam spot size on the target and the phase variance of the reflected laser beam. The correlation is: the greater the phase variance the smaller the beam spot size.) Applicants have developed a technique for providing special control algorithms that provide very high speed control of the elements of a deformable mirror using this phase variance as a feedback parameter. Applicants have also developed algorithms to correct a limited number of Zernike modes associated with the wave front control.

Abstract: There is provided a light receiving circuit capable of preventing an output variation of the light receiving circuit due to a change in ambient temperature with a simple configuration. The light receiving circuit is provided with a photodiode 4 for LD power monitoring and an I-V amplifier 5 connected with a feedback resistor 13, wherein a light receiving section 16 of the photodiode 4 is covered with a protective film 19. Temperature dependences between a light transmittance of the protective film 19 in accordance-with a shift of a wavelength of a laser beam due to a change in ambient temperature, and a resistance value of the feedback resistor 13 are set in such a way that they may be mutually compensated and an output voltage from the light receiving circuit may be constant for a temperature change.

Abstract: A technique for reducing the vibration sensitivity of laser-stabilizing optical reference cavities is based upon an improved design and mounting method for the cavity, wherein the cavity is mounted vertically. It is suspended at one plane, around the spacer cylinder, equidistant from the mirror ends of the cavity. The suspension element is a collar of an extremely low thermal expansion coefficient material, which surrounds the spacer cylinder and contacts it uniformly. Once the collar has been properly located, it is cemented in place so that the spacer cylinder is uniformly supported and does not have to be squeezed at all. The collar also includes a number of cavities partially bored into its lower flat surface, around the axial bore. These cavities are support points, into which mounting base pins will be inserted. Hence the collar is supported at a minimum of three points.

Abstract: An optical module, such as a package for a vertical cavity surface emitting laser diode (VCSEL) or other light emitting device, includes monitoring of the emitted optical power by tapping the transmitted beam. The module includes a substrate, which carries the light emitting device and an optical monitor. In addition, the module includes a transparent plate with at least two reflective regions that together redirect part of the light from the light emitting device to the optical monitor.

Abstract: A laser diode is controlled such that a writing operation can be performed readily even at a low temperature and equal to or below the operation guarantee temperature range of the laser diode. A laser diode control device includes a temperature sensor for detecting temperature of a laser diode. If a detected temperature by the temperature sensor is equal to or below the operation guarantee temperature range, a current equivalent to a threshold current value is supplied to the laser diode. After a predetermined time lapses, laser light is outputted to increase temperature of the laser diode to the operation guarantee temperature thereof. Finally, a writing operation is then carried out.

Abstract: The present invention provides an optical transmitting module, in which a laser diode and a termination resistor are provided without sizing up the package thereof and degrading the thermal characteristic due to heat generation by the termination resistor. The transmitting module of the present invention includes the semiconductor laser diode, and the resistor. The laser diode is mounted on the side surface of the block extruding from the base. The resistor is mounted on the flat side portion of the end of the lead. The lead is secured in the through hole provided in the base with seal glass being filled in the gap between the through hole and the lead. In the transmitting module thus configured, the laser diode is thermally isolated from the heat generated by the resistor due to the seal glass.

Abstract: An optical arrangement includes a laser, and a chromatic error correcting device arranged in a beam path of the laser. The chromatic error correcting device includes a pulse stretcher.

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

Abstract: A method for producing stimulated emission of gamma radiation comprising: 1] providing at least first and second gamma-radiation sources, both sources being in recoil-free first-excited nuclear levels and the second source being in resonance with the first source and the gamma radiation from the first source being incident on the second source, 2] during the lifetime of its excited state, abruptly moving the first source through a distance equal to ½ the wavelength of the radiation emitted therefrom, thereby inducing a ?-phase-shift gamma radiation transparency in the second source whereby the ?-phase-shifted gamma radiation stimulates the excited nuclear resonant state of the second source to emit gamma radiation.

Abstract: An automatic power control system provides a control signal that regulates the output power of at least one laser diode. Coarse adjustment of the control signal is provided by a first means, preferably a digital variable resistor, while fine adjustment and compensation is provided by a second means, preferably by a digital-to-analog converter that receives an input signal proportional to a sensed control system parameter. The control system includes an operational amplifier having a first input coupled to sense output power, and a second input coupled to a DAC to provide finer resolution control. Memory can store system parameter or system parameter variations that can be coupled to the DAC and/or variable resistor to enhance system stability over ambient variations.

Abstract: Undoped layers are introduced in the passive waveguide section of a butt-joined passive waveguide connected to an active structure. This reduces the parasitic capacitance of the structure.

Abstract: A method for compensating for changes in output power or wavelength of an optical source with temperature. Many optical sources have power and/or wavelength variations with temperature which can be compensated by open- or closed-loop methods if a method of accurately measuring the optical source temperature is available. The voltage across a semiconductor junction varies with temperature. Measuring the optical source power or wavelength variation with temperature and tracking the voltage across the semiconductor junction provides a means for compensating an instrument for temperature induced optical output power or wavelength variations. An important field of application is optical density or turbidity measurements in cellular media.

Abstract: The present invention provides an apparatus for monitoring a laser. The apparatus includes a plurality of sensors and a monitoring device capable of communicating with the plurality of sensors and configured to monitor an operating status of a laser. The plurality of sensors includes an optical power sensor, a first temperature sensor, and a power sensor and/or a current supply sensor. The present invention also provides a method for monitoring a laser. The method includes measuring an output optical power of the laser, measuring a temperature of the laser and/or a lasing medium exciting device, measuring an amount of current supplied to the exciting device and/or an amount of laser cavity excitation, and determining a current and/or predicted health status of the laser based on at least one of the optical power, the temperature of the laser, the temperature of the exciting device, the current and the driver power.

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

Abstract: Amplified spontaneous emission (ASE) ducts are disclosed for use with various gain media. An ASE duct may be configured and arranged to remove ASE from solid state or liquid gain media and transmit the ASE to an exterior optical medium. The refractive index of an ASE duct is selected as desired based on the refractive index of a gain medium and an exterior optical medium. An ASE duct may include first and second boundary surfaces joined at a vertex having an included angle that allows ASE (light) reflected off on one boundary surface to be incident on the another boundary surface at less than the critical angle and transmitted outside of the ASE duct. Laser systems using ASE ducts and methods of using and manufacturing ASE ducts are disclosed.

Abstract: Aspects of the present invention are directed to the use of optical gain structures that include alternating layers of gain medium and transparent heat conductors in which the gain medium itself functions as a correction optic. The gain medium changes to an optimum or desired shape because of the thermal changes occurring as the materials of the optical gain structure(s) reach a desired optical output condition. At the desired optical output conditions, the gain medium conforms to a desired shape. The desired shape may be, for example, that of an optical surface of a transparent heat conductor. By designing the initial shape of the gain medium such that the physical contact with the transparent heat conductor is maximized at the desired optical output conditions, conductive heat transfer between the gain medium and heat conductor(s) is maximized at the desired optical output condition.

Abstract: An external cavity laser may be swept rapidly in frequency and cavity length to prevent formation of modes providing improved spectral response and light characteristics.

Abstract: Laser light is emitted from a laser oscillator, and the laser light is made to enter a beam expander optical system including a concave lens through a correction lens. The laser oscillator, the correction lens and the concave lens are disposed so that, when an emission point of the laser oscillator is a first conjugate point, a point at which an image at the first conjugate point is formed through the correction lens is a second conjugate point, a distance between the correction lens and the second conjugate point is b, a focal length of the concave lens is f, and a distance between the correction lens and the concave lens is X, the X satisfies b?3|f|?X?b+|f|.

Abstract: A method and apparatus for compensating for temperature characteristics of a laser diode are disclosed. The laser diode may be used in a transmitter unit of a transceiver for optical signal transmission. The transceiver includes the laser diode and a monitor photodiode. In such a method, a modulation current is derived from an input voltage and arbitrary variables. Variations of overall modulation resistance values corresponding to an operation temperature range are evaluated by a relation between the modulation current and the overall modulation resistance, and the overall modulation resistance values are determined according to the variations. Also, variations of overall bias resistance values corresponding to the temperature range are evaluated by a current Impd of the photodiode, which is derived at specific optical power arbitrarily chosen in the temperature range. The overall bias resistance values are determined according to the variations.

Abstract: A method and apparatus for temperature stabilization of a wavelength of a laser compensate for thermal instability of a internal etalon of the wavelength using the results of measuring the wavelength with an external wavelength meter.

Abstract: An automatic power control system provides a control signal that regulates the output power of at least one laser diode. Coarse adjustment of the control signal is provided by a first means, preferably a digital variable resistor, while fine adjustment and compensation is provided by a second means, preferably by a digital-to-analog converter that receives an input signal proportional to a sensed control system parameter. The control system includes an operational amplifier having a first input coupled to sense output power, and a second input coupled to a DAC to provide finer resolution control. Memory can store system parameter or system parameter variations that can be coupled to the DAC and/or variable resistor to enhance system stability over ambient variations.

Abstract: The present invention relates to a method for revising a wavelength of the EML by controlling a working temperature based on arithmetic functional relations between the DC-Offset voltage and the wavelength and between the working temperature and the wavelength, and a computer-readable recording medium thereof. The method includes the steps of: re-setting initial values of a working temperature, a amplifying voltage and the DC-Offset voltage; determining a wavelength with respect to the re-set DC-Offset voltage based on a functional relation between the DC-Offset voltage and the wavelength of the EML; and determining the revising working temperature for the determined wavelength based on the functional relation between the working temperature and the wavelength of the EML, and re-setting the working temperature with the revising working temperature.

Abstract: An optical module, such as a package for a vertical cavity surface emitting laser diode (VCSEL) or other light emitting device, includes monitoring of the emitted optical power by tapping the transmitted beam. The module includes a substrate, which carries the light emitting device and an optical monitor. In addition, the module includes a transparent plate with at least two reflective regions that together redirect part of the light from the light emitting device to the optical monitor.

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

Abstract: Submount substrates are connected to both sides of a laser diode via hard solders. The lower submount substrate and a heat sink are connected together by a soft solder. The heat sink and a presser electrode are fixed with a predetermined gap therebetween via an insulating spacer. A coil electrode is fitted in a V-shaped groove of the presser electrode. As the coil electrode is deformed slightly elastically, the coil electrode is pressed against the upper submount substrate.

Abstract: A monolithic, side pumped, passively Q-switched, solid-state laser (10) includes a laser resonator structure (16) that includes a laser gain medium (12) having an output face bonded to a passive Q-switch (14). The gain medium (12) has a side face (12A) for receiving pump light. The pump light is preferably generated by a laser diode array (20). In a further embodiment, a non-linear optical material (22), such as frequency doubling KTP, is optically coupled to an output face of the Q-switch for providing output wavelength conversion. A method is also disclosed for fabricating the monolithic, side pumped, passively Q-switched, solid-state laser. Techniques are included for providing compensation from thermal aberrations during operation of the laser.

Abstract: A laser oscillation apparatus includes a wavelength change unit for driving a wavelength selection element in a band-narrowing module and changing the oscillation wavelength of a laser beam to a target value, and an oscillation history memory for storing the oscillation state of the laser beam as an oscillation history. The wavelength change unit drives the wavelength selection element on the basis of the oscillation history and changes the oscillation wavelength of the laser beam to the target value.

Abstract: There is provided a phase control portion for controlling phase of a laser beam resonated in a resonator based on detected results by two optical detectors. The phase control portion adjusts the longitudinal mode positions by a feedback control so that a ratio of intensities detected by the two optical detectors comes to a predetermined reference value. To one of the optical detectors, part of a laser beam outputted from the resonator is irradiated as it is, whereas, to the other one of the optical detectors, part of the laser beam outputted from the resonator is irradiated after passing through an etalon. An FSR of the etalon is a double of that of another etalon in the resonator.

Abstract: A solid state zig-zag slab laser amplifier in which depolarization occurring at total internal reflection from opposed lateral faces of the amplifier slab is controlled by selecting a complex evanescent coating that provides a selected phase retardance that results in minimization of depolarization. Without use of the complex coating, small changes in incidence angles can result in phase retardance changes large enough to increase depolarization significantly, especially when the amplifier is operated at higher powers. Appropriate selection of the complex evanescent coating allows a desired phase retardance angle to be maintained relatively constant over a small range of angles of incidence, at a given wavelength, and therefore permits minimization of depolarization and birefringence effects.