Abstract: A repetition frequency control device includes a slave photoelectric conversion unit which converts a slave laser light pulse into a slave electrical signal, a master photoelectric conversion unit which converts a master laser light pulse into a master electrical signal, a frequency change unit which changes the repetition frequency of the master electric signal by a predetermined value, a phase comparator which detects a phase difference between the slave electric signal and the output from the frequency change unit, and a loop filter which removes a high frequency component of an output from the phase comparator, where the repetition frequency of the master laser does not undergo control based on one or both of the master electric signal and the slave electric signal.

Abstract: A laser assembly is configured with a frequency conversion laser head operative to shift a fundamental frequency of input light to the desired frequency of an output light. The frequency conversion laser head includes a dump means operative to guide an unconverted output light at the fundamental frequency outside the case of the frequency conversion laser head. The dump means is configured with a guide optics operative to couple the output light at the fundamental frequency to a fiber terminating outside the case of the frequency conversion laser head.

Abstract: A single-mode, etched facet distributed Bragg reflector laser includes an AlGaInAs/InP laser cavity, a front mirror stack with multiple Fabry-Perot elements, a rear DBR reflector, and a rear detector. The front mirror stack elements and the rear reflector elements include input and output etched facets, and the laser cavity is an etched ridge cavity, all formed from an epitaxial wafer by a two-step lithography and CAIBE process.

Abstract: A transmissive active channel element is provided in each signal channel of a monolithic multi-channel TxPIC where each channel also includes a modulated source. The active channel element functions both as a power control element for both monitoring and regulating the output channel signal level of each signal channel and as a modulator for channel wavelength tagging or labeling to provide for wavelength locking the modulated sources. The power regulating function is also employed to control the channel signal power outputs of each channel to be uniform across the channel signal array. All of these functions are carried out by a feedback loop utilizing digital signal processing.

Abstract: An optical transmitter includes a light source that outputs light superposed with a pilot signal having a predetermined frequency; an optical modulating unit that modulates the light from the light source according to an input electric signal; a detecting unit that detects a high-output-side maximum value of signal light output from the optical modulating unit, a fluctuation width of the high-output-side maximum value, and a fluctuation width of a low-output-side minimum value; a bias-potential adjusting unit that adjusts a bias potential of an electric signal to be input to the optical modulating unit based on the detected maximum value; and an amplitude adjusting unit that adjusts an amplitude of the electric signal to be input to the optical modulating unit based on the fluctuation width of the high-output-side maximum value and the fluctuation width of the low-output-side minimum value.

Abstract: An apparatus/method may comprise a line narrowed pulsed lithography laser light source which may comprise: a seed pulse providing laser system which may comprise: a first pulsed seed laser producing seed pulses at a rate of X kHz; a second pulsed seed laser producing seed pulses at a rate of X kHz; an amplification system which may comprise: a first amplifier gain system which may comprise a first and a second pulsed gas discharge amplifier gain medium, each with a nominal center wavelength in the UV range, and each operating at ½X kHz on output pulses from the first seed laser; a second amplifier gain system which may comprise a first and a second pulsed amplifier gain medium, each with a nominal center wavelength in the UV range, and each operating at ½X kHz on output pulses from the second seed laser.

Abstract: Angle adjustment of a wavelength conversion element after assembly is eliminated to achieve a reduction in production cost with a simplified structure. An element holder provided on a base that supports the wavelength conversion element is provided with a mounting reference surface that positions the wavelength conversion element in parallel with an optical axis. The wavelength conversion element has a substantially parallelepiped shape. A bottom surface, which is one of the four surfaces adjacent to an incident surface and an output surface, is in contact with the mounting reference surface, such that a depth direction of inverted polarization regions is substantially orthogonal to the optical axis and the incident surface and the output surface are tilted at a predetermined tilt angle relative to a flat surface orthogonal to the optical axis.

Abstract: A photonic system and method are provided. The system includes an optical source configured to generate a carrier signal; and a modulator configured to modulate the carrier signal with a radio frequency, (“RF”) input signal to generate a modulated signal. The system also includes an optical filter configured to filter the modulated signal to generate a vestigial sideband modulated signal; and an optical detector configured to demodulate the vestigial sideband signal to generate an RF output signal. The system further includes a wavelength controller module configured to set an operating parameter of the optical source.

Abstract: Described is a method for controlling the wavelength of a laser in a wavelength division multiplexed (WDM) system. The method includes generating broadband light having a dithered optical power and a wavelength spectrum that includes a plurality of WDM wavelengths. The broadband light is spectrally filtered to generate a spectrally-sliced optical signal having a wavelength spectrum that includes one of the WDM wavelengths. The spectrally-sliced optical signal is injected into a laser and a dithered optical power of the laser is determined. A parameter of the laser is controlled in response to the determination of the dithered optical power to thereby align a wavelength of the laser to the wavelength spectrum of the spectrally-sliced optical signal.

Abstract: An apparatus includes a light source, a substrate, a temperature-based controller and an insulator. The light source is mounted to the substrate. The temperature-based controller is electrically coupled to the light source and causes the light source to provide a relatively constant light output. The insulator is positioned proximate the temperature based controller.

Abstract: The invention relates to scanning pulsed laser systems for optical imaging. Coherent dual scanning laser systems (CDSL) are disclosed and some applications thereof. Various alternatives for implementation are illustrated, including highly integrated configurations. In at least one embodiment a coherent dual scanning laser system (CDSL) includes two passively modelocked fiber oscillators. The oscillators are configured to operate at slightly different repetition rates, such that a difference ?fr in repetition rates is small compared to the values fr1 and fr2 of the repetition rates of the oscillators. The CDSL system also includes a non-linear frequency conversion section optically connected to each oscillator. The section includes a non-linear optical element generating a frequency converted spectral output having a spectral bandwidth and a frequency comb comprising harmonics of the oscillator repetition rates.

Abstract: Systems and methods for stabilizing laser frequency based on an isoclinic point of an atomic or molecular medium are provided herein. A system may include: a transmission cell containing a gas and configured to transmit light from the laser, the gas having an absorption spectrum with an isoclinic point; a photodiode generating an output based on an amplitude of transmitted laser light; and circuitry configured to tune the frequency of the laser to the isoclinic point of the absorption spectrum based on the output. The absorption spectrum may have first and second overlapping peaks respectively corresponding to first and second transitions of the gas, the isoclinic point being a saddle point between the first and second peaks. The first and second peaks may have substantially equal amplitude as one another and/or may broaden substantially equally as each other as a function of a physical parameter of the gas.

Abstract: High-power, phased-locked, laser arrays as disclosed herein utilize a system of optical elements that may be external to the laser oscillator array. Such an external optical system may achieve mutually coherent operation of all the emitters in a laser array, and coherent combination of the output of all the lasers in the array into a single beam. Such an “external gain harness” system may include: an optical lens/mirror system that mixes the output of all the emitters in the array; a holographic optical element that combines the output of all the lasers in the array, and an output coupler that selects a single path for the combined output and also selects a common operating frequency for all the coupled gain regions.

Abstract: A method and laser system for dynamically adjusting a transient wavelength of light pulses emitted by a laser includes sequential processing of transient photocurrent curves which are generated after interaction between each light pulse and wavelength-selective medium which is configured with a known spectral peak line selected in the range of the transient wavelength. The method further includes continuously processing parameters of sequentially generated curves until the processed parameters are repeatedly uniform.

Abstract: One embodiment of the invention includes an optical system. The optical system includes an optical cavity comprising a plurality of reflectors. The optical system also includes optics configured to provide a first optical signal and a second optical signal into respective inputs of the optical cavity to be substantially concurrently resonated within the optical cavity. The first and second optical signals can have distinct wavelengths.

Abstract: A broadband light source configured to emit a stable broadband optical beam is provided. The broadband light source includes at least one optical pump source, an optical system including a polarization beam combiner, and a solid state laser medium. The optical system is configured to receive at least one optical pump beam from a respective one of the at least one optical pump source. The solid state laser medium receives a substantially unpolarized pump beam from a first output of the optical system. Stable broadband amplified spontaneous emission is output from a second output of the optical system.

Abstract: A circuit controlling the gain of an amplifier in an optical transmitter used for optical communication, including a detection circuit for measuring the power of the RF input to a laser; a gain controller or controlling a gain of an amplifier, and a switch connected to the gain controller, wherein the gain controller is adapted, in response to an activation of a switch, to: (i) automatically vary gain of the amplifier, and (ii) set the gain of the amplifier at a level corresponding to a reduction in the noise and/or distortion associated with the transmitter.

Abstract: Systems and methods for stabilizing laser frequency based on an isoclinic point of an atomic or molecular medium are provided herein. A system may include: a transmission cell containing a gas and configured to transmit light from the laser, the gas having an absorption spectrum with an isoclinic point; a photodiode generating an output based on an amplitude of transmitted laser light; and circuitry configured to tune the frequency of the laser to the isoclinic point of the absorption spectrum based on the output. The absorption spectrum may have first and second overlapping peaks respectively corresponding to first and second transitions of the gas, the isoclinic point being a saddle point between the first and second peaks. The first and second peaks may have substantially equal amplitude as one another and/or may broaden substantially equally as each other as a function of a physical parameter of the gas.

Abstract: A method of controlling a frequency-converted laser source is provided where the laser source comprises a laser cavity, an external optical feedback component, a wavelength selective component, and a wavelength conversion device and the method comprises driving a gain section of the laser cavity with a gain signal that comprises a data component and a modulation component. The modulation component of the gain signal comprises a gain modulation amplitude IMOD that is sufficient to shift the available cavity modes in the spectral domain such that lasing at several different cavity modes sequentially is established as the gain signal is modulated.

Abstract: A method of optical communication includes generating an amplified optical signal from at least a portion of a first optical signal having a first carrier wavelength, ?1. The amplified optical signal is applied to Brillouin media to stimulate generation of a Brillouin effect signal at a wavelength ?2. The Brillouin effect signal is modulated to produce a second optical signal having a second carrier wavelength, ?2. In one embodiment, the first optical signal is a downstream optical signal and the second optical signal is an upstream optical signal of a passive optical network.

Abstract: An optical phase lock loop (OPLL) system is disclosed that includes a master external cavity laser (ECL), and a substantially identical slave ECL. The master and slave ECLs are fabricated using a planar semiconductor device with waveguide-integrated planar Bragg gratings (PBG). Both the master and slave ECLs have a narrow linewidth and a low frequency-noise. Each of the ECLs has their own controller-modulator circuits for thermal tuning or electrical tuning via direct modulation. A laser-select-logic (LSL) module receives and processes a filtered phase error signal from a loop filter coupled to an electronic PLL device, and directs the processed phase error signal to one or both of the master and slave controller-modulators according to a logical determination of a required mode of operation of the OPLL system in order to achieve a stable and identical phase performance of the master and the slave ECLs.

Abstract: A Fiber Bragg grating is sliced into small segments (such as 1 mm in length), the sliced fiber Bragg grating segments are used as external cavities for lasers to stabilize their center wavelength. In one embodiment, a semiconductor laser has an anti-reflection coating on the front facet and a high reflectivity coating on the back facet, a sliced fiber Bragg grating is used as a partial reflection mirror to form a lasing cavity. Since the sliced fiber Bragg grating has a very small wavelength drift with temperature change, the semiconductor laser has a stable center wavelength output. In the other embodiment, a solid state laser has an anti-reflection coating on the front facet and a high reflectivity coating on the back facet, a sliced fiber Bragg grating is used as a partial reflection mirror to form a lasing cavity. The solid state laser has a stable center wavelength output.

Abstract: A laser device capable of preventing deterioration of a light signal and a controlling method therefor are provided.

Abstract: Systems and methods for stabilizing laser frequency based on an isoclinic point of an atomic or molecular medium are provided herein. A system may include: a transmission cell containing a gas and configured to transmit light from the laser, the gas having an absorption spectrum with an isoclinic point; a photodiode generating an output based on an amplitude of transmitted laser light; and circuitry configured to tune the frequency of the laser to the isoclinic point of the absorption spectrum based on the output. The absorption spectrum may have first and second overlapping peaks respectively corresponding to first and second transitions of the gas, the isoclinic point being a saddle point between the first and second peaks. The first and second peaks may have substantially equal amplitude as one another and/or may broaden substantially equally as each other as a function of a physical parameter of the gas.

Abstract: An apparatus and source arrangement for filtering an electromagnetic radiation can be provided which may include at least one spectral separating arrangement configured to physically separate one or more components of the electromagnetic radiation based on a frequency of the electromagnetic radiation. The apparatus and source arrangement may also have at least one continuously rotating optical arrangement which is configured to receive at least one signal that is associated with the one or more components. Further, the apparatus and source arrangement can include at least one beam selecting arrangement configured to receive the signal.

Abstract: Techniques and devices that stabilize a laser to a whispering gallery mode optical resonator.

Abstract: An optical frequency comb generator includes a laser device arranged for generating input laser light having a predetermined input light frequency, a dielectric micro-resonator having a cavity exhibiting a third order nonlinearity, so that the micro-resonator is capable of optical parametric generation providing parametrically generated light, and a waveguide optically coupled to the micro-resonator, the waveguide being arranged for in-coupling the input laser light into the micro-resonator and out-coupling the parametrically generated light out of the micro-resonator, wherein the laser device, the waveguide and the micro-resonator being arranged for resonantly in-coupling the laser input light to a mode of the micro-resonator with a minimum power level so that an optical field inside the cavity exceeds a predetermined cascaded parametric oscillation threshold at which the parametrically generated light includes frequencies of frequency sidebands of the input light frequency and of the sidebands thereof.

Abstract: A semiconductor laser device comprising a laser diode with an integrated photodiode, wherein one of the components of the laser diode with the integrated photodiode is also used for heating the laser diode. A simpler design of a wavelength-controlled semiconductor laser is thus obtained.

Abstract: A method and system for stabilizing a laser to a frequency reference with an adjustable offset. The method locks a sideband signal generated by passing an incoming laser beam through the phase modulator to a frequency reference, and adjusts a carrier frequency relative to the locked sideband signal by changing a phase modulation frequency input to the phase modulator. The sideband signal can be a single sideband (SSB), dual sideband (DSB), or an electronic sideband (ESB) signal. Two separate electro-optic modulators can produce the DSB signal. The two electro-optic modulators can be a broadband modulator and a resonant modulator. With a DSB signal, the method can introduce two sinusoidal phase modulations at the phase modulator. With ESB signals, the method can further drive the optical phase modulator with an electrical signal with nominal frequency ?1 that is phase modulated at a frequency ?2.

Abstract: Among others, RF receivers based on whispering gallery mode resonators are described. In one aspect, a photonic RF device includes a laser that is tunable in response to a control signal and produces a laser beam at a laser frequency. The RF device includes a first optical resonator structured to support a whispering gallery mode circulating in the first optical resonator, the optical resonator being optically coupled to the laser to receive a portion of the laser beam into the optical resonator in the whispering gallery mode and to feed laser light in the whispering gallery mode in the optical resonator back to the laser to stabilize the laser frequency at a frequency of the whispering gallery mode and to reduce a linewidth of the laser. The RF device includes a second optical resonator made of an electro-optic material to support a whispering gallery mode circulating in the optical resonator.

Abstract: An optical transmitter is disclosed having a temperature stabilization system for an optical filter for maintaining constant the frequency response of the filter. The filter is mounted within a housing having a substantially higher thermal conductivity. The housing may include a copper-tungsten alloy and extend along the optical axis of the filter. The housing is in thermal contact with a thermo-electric cooler (TEC) and a temperature sensor. The TEC and temperature sensor are electrically coupled to a controller which adjusts the temperature of the TEC according to the output of the temperature sensor.

Abstract: A system and method for stabilising a plurality of output frequencies (wavelengths) of a plurality of lasers (106). The laser beams are combined using optical multiplexer (110) and coupled into length-imbalanced (armlength-mismatched) Mach-Zehnder interferometer (MZI) (114) having an optical modulator (e.g. AOM) (122) in one of its arms. The output of the MZI is divided into corresponding beams via optical demultiplexer (128) and each beam is detected by a respective photo-diode (PD) (134). The individual electric signals, so generated, are demodulated using a corresponding plurality of phase-responsive devices (138) and the resulting phase-signals are directed to a plurality of servo-controllers (148) to control the central frequency of the respective lasers (106) via a corresponding plurality of feedback loop circuits (150). The lasers (106) can have different central frequencies which can also be individually tunned using offset modules (141) in the phase-responsive devices (138).

Abstract: Laser light wavelength control is provided by periodically predicting a next position of a light controlling prism using a model of the prism's motion characteristics. The prediction is then updated if a measurement of laser output wavelength is obtained. However, because the predictions are made without waiting for a measurement, they can be made more frequently than the laser firing repetition rate and the prism can be repositioned at discrete points in time which can occur more frequently than the laser firing events. This also reduces performance degradation which may be caused by being one pulse behind a laser measurement and the resultant laser control signal being applied.

Abstract: A light source device for a display device for projecting an image on a screen is provided, the light source device for display device including a light source unit operable to output light; an image outputting unit operable to output an image by giving an image signal to the light; and a control circuit operable to switch the image output from the image outputting unit between a normal image and a mirror reversed image formed by reversing the normal image right and left by controlling the image signal, such that outputting type is switched between a front projection in which the image is projected onto the screen from a front on the same side as the viewing side, and a rear projection in which the image is projected onto the screen from a rear plane on the opposite side to the viewing side.

Abstract: It is an object to provide a laser apparatus, a laser irradiating method and a manufacturing method of a semiconductor device that make laser energy more stable. To attain the object, a part of laser beam emitted from an oscillator is sampled to generate an electric signal that contains as data energy fluctuation of a laser beam. The electric signal is subjected to signal processing to calculate the frequency, amplitude, and phase of the energy fluctuation of the laser beam.

Abstract: The present invention relates to an atomic frequency acquisition device comprising a gas cell (400) filled with an atomic gas, a laser light source (100) emitting a laser beam which enters the gas cell (40) and excites a first energy transition of the atomic gas, a local oscillator (700) for generating an oscillator frequency in a frequency range including a frequency of a HFS transition of the atomic gas, and a modulator (600) modulating the laser light source (100) so as to emit laser radiation modulated with the oscillator frequency. An optical reflector (500) is arranged behind the gas cell (400) to reflect the laser beam after passage through the atomic gas so as to re-enter the laser cavity. A photodetector (200) detects beat frequencies caused by self-mixing interference within the laser cavity.

Abstract: A laser oscillation device includes an oscillation unit oscillating a laser, a shutter unit covering the laser, and a connection unit covering the laser, connecting the oscillation unit and the shutter unit and including a first connection part supported by the oscillation unit and a second connection part supported by the shutter unit. The first and second connection parts are separated from each other, and one of the first and second connection parts covers at least a portion of the other one of the first and second connection parts.

Abstract: A method and apparatus may comprise a seed laser, along with an amplifier laser amplifying the output of the seed laser. A bandwidth metrology module may provide a bandwidth measurement and a bandwidth error signal may be provided using a bandwidth set point. A differential timing system responsive to the error signal can selectively adjust a differential firing time between the seed laser and amplifier laser. A beam dimension and center wavelength control system may adjust a beam dimension, within the cavity of the seed laser, to select bandwidth, and may adjust center wavelength at the same time, using a plurality of beam expansion prisms and at least one other prism or other optical element in the cavity to select center wavelength.

Abstract: An apparatus and method which may comprise a seed laser defining an optical cavity producing an output. An amplifier may amplify the seed laser output. A bandwidth error signal generator may provide a bandwidth error signal from measured bandwidth and a target. A bandwidth selection element, which may comprise an adjustable sized aperture external to the cavity of the seed laser may selectively alter the bandwidth of the seed laser output. A bandwidth control system may control the bandwidth control element and also selectively adjust a differential firing time between the seed laser and amplifier or another bandwidth selection actuator to cooperated (coarsely or finely) with the bandwidth selection element to control bandwidth of the laser system.

Abstract: An optical transmission control circuit includes: an analog input section which receives optical transmission states as an analog values; an A/D conversion section which converts the analog values into digital values; a value storage section which stores maximum value of the digital values provided by the A/D conversion section; an output register which outputs a value to a host apparatus; and a control section which controls the maximum value storage section to store the maximum value of the digital values therein and controls the output register to output the maximum value to the host apparatus.

Abstract: This invention relates to a monolithic folded F-P cavity used for semiconductor laser, which is composed of a monolithic optical element. The monolithic optical element is made of the material having low propagation loss for a certain spectrum range. Light entering through an input/output coupling surface of the monolithic optical element is reflected several times between the input/output coupling surface and at least two high reflection surfaces within the monolithic optical element, and then at least one part of the light exits through the input/output coupling surface along the path which is collinear with the incident light but in an opposite direction. By means of integrating reflecting and coupling parts of the folded F-P cavity within a single monolithic optical material, this invention greatly improves the reliability of the F-P cavity, and has other advantages, such as insensitive to outside interferences, smaller size, simpler structure and easy usage.

Abstract: Alerts, such as laser driver current alarms, are triggered in an optoelectronic device based on dynamic digital diagnostics, such as operating temperature. Optoelectronic devices may execute microcode structured to represent a formulaic relation between a first parameter (e.g., temperature) and an indicator value for a second parameter (e.g., laser driver current). The microcode may further be structured to cause the optoelectronic device to access the first parameter, calculate an indicator value for the second parameter based on the accessed first parameter using the formulaic relation, access the second parameter, and compare the indicator value with the second parameter to determine whether to trigger an alert. If the second parameter exceeds the indicator value, the alert may be triggered, and may be indicative of potentially imminent optoelectronic device failure.

Abstract: The present invention relates to an external-cavity laser module comprising a thermoelectric cooler (TEC) including an upper carrier plate having an upper surface, said TEC being configured to stabilize the temperature of the upper surface at a substantially constant temperature. The laser module further comprises a laser assembly mounted on an optical bench, which is in thermal coupling with said upper surface, said laser assembly comprising a gain medium for emitting an optical beam into the external cavity and an end mirror.

Abstract: Techniques and devices for providing optical locking of optical resonators and lasers.

Abstract: An apparatus and source arrangement for filtering an electromagnetic radiation can be provided which may include at least one spectral separating arrangement configured to physically separate one or more components of the electromagnetic radiation based on a frequency of the electromagnetic radiation. The apparatus and source arrangement may also have at least one continuously rotating optical arrangement which is configured to receive at least one signal that is associated with the one or more components. Further, the apparatus and source arrangement can include at least one beam selecting arrangement configured to receive the signal.

Abstract: The invention relates to a method for stabilizing the spectrum of a pulsed coherent optical source that comprises controlling the offset frequency ?0 and the repetition rate ?r in order to stabilize the frequencies of the comb lines constituting the optical spectrum thereof. The method comprises forming, from the pulsed coherent optical source (S1), a beam that is directed onto a reference resonant optical cavity (CR), and using the signal generated by the reference resonant optical cavity (CR) for controlling the offset frequency ?o or the repetition rate ?r, and probing, using a comb line, an atomic or molecular transition (AMT) in order to generate a driving signal for the repetition rate ?r or the offset frequency ?0.

Abstract: Disclosed is directed to a laser source based on Fabry-Perot laser diodes (FP-LDs) and seeding method using the same. The laser source comprises a plurality of FP-LDs, an optical filter, and at least a fiber mirror. The FP-LDs are aligned to their corresponding filter modes of the optical filter, and output their optical spectrums. The optical spectrums are filtered via the optical filter then reflected into the FP-LDs. Each of the FP-LDs further outputs its optical spectrum with a form of continuous wave (CW) of single longitudinal mode (SLM). The outputted CWs may be treated as injected laser light sources. They may also be applied to the transmission architecture in wavelength-division-multiplexed passive optical networks.

Abstract: A device for generating a high power frequency converted laser beam includes a nonlinear optical crystal having an entrance surface and a curved surface. The nonlinear optical crystal is configured to receive at least one laser beam at the entrance surface and provide a frequency converted beam through a frequency conversion process. The device also includes an optical coating coupled to the curved surface. The reflectance of the optical coating is greater than 50% at a wavelength of the frequency converted beam. Additionally, the far field divergence angle of the frequency converted beam increases after reflection off the curved surface. The device further includes a heat sink in thermal contact with the optical coating.

Abstract: An optical phase lock loop (OPLL) system is disclosed that includes a master external cavity laser (ECL), and a substantially identical slave ECL. The master and slave ECLs are fabricated using a planar semiconductor device with waveguide-integrated planar Bragg gratings (PBG). Both the master and slave ECLs have a narrow linewidth and a low frequency-noise. Each of the ECLs has their own controller-modulator circuits for thermal tuning or electrical tuning via direct modulation. A laser-select-logic (LSL) module receives and processes a filtered phase error signal from a loop filter coupled to an electronic PLL device, and directs the processed phase error signal to one or both of the master and slave controller-modulators according to a logical determination of a required mode of operation of the OPLL system in order to achieve a stable and identical phase performance of the master and the slave ECLs.

Abstract: Key technologies have been developed in realizing single longitudinal mode CW operation with a regular standing-wave cavity for intracavity frequency doubling and intracavity frequency conversions, so as to produce all solid-state, true cw devices with operation over wide spectral ranges including green, blue and UV. In one method laser arrangement, a beam expander (23 or 41) is applied to render a large mode waist and an improved beam divergence so as to greatly reduce the insertion losses for intracavity optical elements (17, 18 or 44). In another method laser arrangement, when spatial hole burning interference effect is minimized by using a pump head (12) with a thin gain zone (2) in contact with an end cavity mirror, then a low resolving-power spectral filter with low loss can be utilized.