Abstract: Architectures for coherently combining an array of fiber-based lasers are provided. By matching their lengths to within a few integer multiples of a wavelength, the spatial and temporal properties of a single large laser are replicated, while extending the average or peak pulsed power limit.

Abstract: There is provided a rotary disk laser module including disk comprised of at least one lasing material. The lasing material may be excited by a laser excitation source, such as an optical pump beam directed onto the disk. The laser gain region contains excited lasing material and extends between the first and second surfaces of the disk. A laser generator is formed when the gain region is brought into optical communication with a laser generator. A laser generator may be a laser oscillator or a laser amplifier. To create pulsed laser output, an optical modulator is positioned in the laser beam propagation path of the laser generator.

Abstract: A laser oscillator to generate a pulsed light beam includes an output coupler mirror, configured to reflect a reflected portion of the pulsed light beam back into the laser oscillator, and to couple an outputted portion of the pulsed light beam out from the laser oscillator; an end-mirror, configured to return the pulsed light beam into the laser oscillator; a gain material, positioned between the output coupler mirror and the end-mirror along an optical path, configured to amplify the pulsed light beam; a self-starting saturable absorber, configured to self-start a pulsed mode-locking operation of the laser oscillator; and a pulse-shaping saturable absorber, configured to shape pulses of the pulsed light beam into laser pulses with a pulse length of less than 1,000 femtoseconds.

Abstract: Provided is an apparatus for generating a single-polarization mode-locked laser capable of energy control. The apparatus for generating a single-polarization mode-locked laser is configured to adjust at least one of a focal length of a lens focusing laser light on a semiconductor saturable absorber mirror (SESAM) functioning as a saturable absorber, power of pump laser light, and reflectivity of an output coupler (OC) to set fluence, which is defined as energy density per unit area of the laser light incident on the saturable absorber, to be greater than reference fluence, which is energy density per unit area of the laser light incident on the saturable absorber when reflectivity of the saturable absorber is a maximum. Accordingly, it is possible to generate a single-polarization mode-locked laser, of which energy can be controlled, without generating multiple pulses.

Abstract: A method of sustaining a plasma, by focusing a first wavelength of electromagnetic radiation into a gas within a volume, where the first wavelength is substantially absorbed by a first species of the gas and delivers energy into a first region of a plasma having a first size and a first temperature. A second wavelength of electromagnetic radiation is focused into the first region of the plasma, where the second wavelength is different than the first wavelength and is substantially absorbed by a second species of the gas and delivers energy into a second region of the plasma region within the first region of the plasma having a second size that is smaller than the first size and a second temperature that is greater than the first temperature.

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: An optical coherence analysis system uses a laser swept source that is constrained to operate in a mode locked condition. This is accomplished by synchronously changing the laser cavity's gain and/or phase based on the round trip travel time of light in the cavity. Many high-speed wavelength swept laser sources emit pulses synchronized with the round trip time of the cavity as part of a nonlinear optical frequency red shifting process. Stable pulsation is associated with smooth tuning and low relative intensity noise. Addition of mode-locking methods to this class of lasers can control and stabilize these lasers to a low clock jitter and RIN state, and in specific cases allow long-to-short wavelength tuning in addition to the usual short-to-long (red shifting). The laser may comprise a SOA (410), a tunable Fabry-Perot-Filter (412) as one reflector and an Output coupler (405) in an optical fiber (406) to adjust the cavity length.

Abstract: A method for quasi-synchronous tuning of laser wavelength or frequency of grating external-cavity laser and a corresponding laser are provided. A grating or mirror is rotated around a quasi-synchronous tuning point (Pq) to achieve the quasi-synchronous tuning of frequency selections by grating and resonance cavity, wherein, on the xOy coordinate plane, from the perspective of actual physical space of the laser, the rotation center Pq(xq, yq) satisfying the quasi-synchronous tuning condition can be considered as being extended from the rotation center P0(x0, y0) under the conventional synchronous tuning condition to the region enclosed by two parabolas near P0. According to the present disclosure, approximately-synchronous tuning of laser is achieved with simple and flexible designs.

Abstract: The invention taught herein provides a method, device and system for modulating or switching electromagnetic radiation by controlling a state of the radiation, such as a polarization state. Radiation is directed at a reflective or transmissive structure, such that the radiation is incident on the structure. The structure includes a property that can be dynamically switched between two configurations, one of which is asymmetric and is configured to modify the polarization characteristic of the radiation. The dynamically configurable structure can be combined with polarization components to achieve modulation. Embodiments suitable for mode-locking a laser and for cavity dumping a mode-locked laser are also disclosed.

Abstract: An apparatus comprising: a processor for determining if a laser is operating in a single-mode state and for determining the degree to which one of one or more tunable parameters for the laser must be adjusted so that laser operates in a single-mode state if not operating in a single-mode state, wherein the one or more tunable parameters include the following parameters: the laser current and the wavelength of the output light. The apparatus may include a laser and/or a holographic storage medium. Also provided is a method for determining if a laser is operating in a single-mode state and for determining the degree to which one of one or more tunable parameters for the laser must be adjusted so that laser operates in a single-mode state if not operating in a single-mode state.

Abstract: A modular, compact and widely tunable laser system for the efficient generation of high peak and high average power ultrashort pulses. Peak power handling capability of fiber amplifiers is expanded by using optimized pulse shapes, as well as dispersively broadened pulses. Dispersive pulse stretching in the presence of self-phase modulation and gain results in the formation of high-power parabolic pulses. To ensure a wide tunability of the whole system, Raman-shifting of the compact sources of ultrashort pulses in conjunction with frequency-conversion in nonlinear optical crystals can be implemented, or an Anti-Stokes fiber in conjunction with fiber amplifiers and Raman-shifters are used. Positive dispersion optical amplifiers are used to improve transmission characteristics.

Abstract: A wavelength-tunable light source apparatus includes a first light source apparatus and a second light source apparatus. The first light source apparatus is capable of changing an oscillation wavelength and includes a resonator. The resonator includes an optical amplification medium for amplifying light and a waveguide having wavelength distribution. The second light source apparatus is connected to the waveguide and configured to introduce pulsed light as modulation light to the first light source apparatus. The oscillation wavelength is controlled by active mode locking employing cross-gain modulation using the modulation light. The pulse width of the modulation light has a duration shorter than a duration of a half period of a driving signal for generating the modulation light.

Abstract: A control system for improving and stabilizing Fourier domain mode locking (FDML) operation. The control system may also provide regulation of FDML operational parameters such as filter tuning, laser gain, polarization, polarization chromaticity, elliptical polarization retardance, and/or dispersion. The control system may be located internal to or external from the FDML laser cavity.

Abstract: Techniques and devices that lock and stabilize a laser to an optical resonator via self-injection locking based on a reflection feedback. A whispering gallery mode optical resonator can be implemented to provide both the optical filtering and injection feedback based on the reflection feedback from feedback optics outside the optical resonator.

Abstract: A laser system comprises a high-Q nonlinear optical resonator, a cavity comprising an amplifying element and a dispersive element, an optical delay line adapted to tune the length of the cavity, and a large pass-band filter adapted to tune the cavity's central oscillation wavelength, the nonlinear optical resonator being selected with a linewidth (LWR) comparable to the cavity free-spectral range (FSRC). There is provided a method for generating highly stable pulse streams, comprising providing a cavity comprising an amplifying element and a dispersive element; selecting a high-Q nonlinear optical resonator with a linewidth (LWR) comparable to the cavity free-spectral range (FSRC); tuning the length of the cavity; and tuning the cavity's central oscillation wavelength.

Abstract: The present invention provides a femtosecond laser apparatus using laser diode optical pumping. To provide a stable mode locking and improve power stability and beam stability in an ultrafast laser such as a femtosecond laser, optical mounts which have mounted thereon optical parts of a diode pumping unit are mechanically engaged using bars of low thermal expansion coefficients and form a pumping module, and the pumping module is maximally separated from a laser platform or case.

Abstract: Described herein is a tunable optical filter (1). The filter includes a phase manipulation layer in the form of a liquid crystal material (3) and a diffractive layer in the form of a diffraction grating (5) sandwiched between an upper glass layer (7) and lower silicon layer (9). Grating (5) includes a grating structure (11) etched therein for angularly diffracting an input optical signal into a plurality of constituent wavelength components according to wavelength. Material (3) includes a two-dimensional array of independently addressable pixels (13), each pixel configured for receiving a drive signal and, in response to the drive signal, selectively modifying the phase of the wavelength components incident onto each pixel to directionally steer the components along respective angularly separated paths. By suitable steering of the wavelength components, at least one wavelength component is coupled along a predetermined collection path to an optical system such as a laser cavity.

Abstract: In one embodiment, the invention relates to systems, methods and devices for improving the operation of an electromagnetic radiation source or component thereof. In one embodiment, the source is a laser source. A Fourier domain mode locked laser can be used in various embodiments. The sources described herein can be used in an optical coherence tomography (OCT) system such as a frequency domain OCT system. In one embodiment, laser coherence length is increased by compensating for dispersion. A frequency shifter can also be used in one embodiment to compensate for a tunable filter induced Doppler shift.

Abstract: Disclosed is a laser apparatus of amplifying a laser pulse output using an anisotropic laser crystal through chirped pulse amplification. The laser apparatus includes a laser resonator. The laser resonator includes a plurality of anisotropic laser crystals, generates a shorter femtosecond pulse by widening a spectrum bandwidth through a combination of different gain spectrum distributions using the anisotropic laser crystals, and allows a laser beam to travel in axial directions with different thermal characteristics of the anisotropic layer crystals in order to reduce a thermal effect.

Abstract: A frequency comb laser providing large comb spacing is disclosed. At least one embodiment includes a mode locked waveguide laser system. The mode locked waveguide laser includes a laser cavity having a waveguide, and a dispersion control unit (DCU) in the cavity. The DCU imparts an angular dispersion, group-velocity dispersion (GVD) and a spatial chirp to a beam propagating in the cavity. The DCU is capable of producing net GVD in a range from a positive value to a negative value. In some embodiments a tunable fiber frequency comb system configured as an optical frequency synthesizer is provided. In at least one embodiment a low phase noise micro-wave source may be implemented with a fiber comb laser having a comb spacing greater than about 1 GHz. The laser system is suitable for mass-producible fiber comb sources with large comb spacing and low noise. Applications include high-resolution spectroscopy.

Abstract: Systems and methods for producing high-energy, pico-second laser pulses are disclosed. Systems and methods include using a modelocked laser source to drive an OPO (optical parametric oscillator) and an OPA (optical parametric amplifier) such that the OPA and OPO self-synchronize without the use of separate synchronization components and produce high-energy output without requiring pulse stretchers or pulse compressors, making the laser system viable for portability and vehicle mounting from both cost and durability standpoints.

Abstract: The present invention is directed to providing an environmentally stable, ultra-short pulse source. Exemplary embodiments relate to passively modelocked ultra-short fiber lasers which are insensitive to temperature variations and which possess only negligible sensitivity to pressure variations. Further, exemplary embodiments can be implemented in a cost-effective manner which render them commercially practical in unlimited applications. Arbitrary fiber lengths (e.g., on the order of 1 millimeter to 1 kilometer, or greater) can be used to provide an ultra-short pulse with a cost-effective architecture which is commercially practical.

Abstract: Frequency standards based on mode-locked fiber lasers, fiber amplifiers and fiber-based ultra-broad bandwidth light sources, and applications of the same.

Abstract: A pulsed laser comprises an oscillator and amplifier. An attenuator and/or pre-compressor may be disposed between the oscillator and amplifier to improve performance and possibly the quality of pulses output from the laser. Such pre-compression may be implemented with spectral filters and/or dispersive elements between the oscillator and amplifier. The pulsed laser may have a modular design comprising modular devices that may have Telcordia-graded quality and reliability. Fiber pigtails extending from the device modules can be spliced together to form laser system. In one embodiment, a laser system operating at approximately 1050 nm comprises an oscillator having a spectral bandwidth of approximately 19 nm. This oscillator signal can be manipulated to generate a pulse having a width below approximately 90 fs.

Abstract: There is provided a light source including a mode-lock laser unit that includes a semiconductor laser and an external resonator unit and emits a laser beam having a predetermined frequency, the semiconductor laser including a saturable absorber unit that applies a reverse bias voltage and a gain unit that applies a gain current, a semiconductor optical amplifier that performs amplification modulation on the laser beam emitted from the mode-lock laser unit, a laser clock generating unit that generates a laser clock synchronized with the laser beam based on a signal detected from the saturable absorber unit when the laser beam oscillates in the mode-lock laser unit, and a modulating unit that generates a driving current synchronized with the laser clock and applies the driving current to the semiconductor optical amplifier.

Abstract: A saturable absorber (SA) based on a high-contrast grating (HCG) having a buried layer of quantum structures for absorption, and which is particularly well suited for use in a mode-locked application. The HCG-SA provides three times the bandwidth compared with traditional DBR structures, while exhibiting a lower saturation fluence due to the field enhancement inside the grating. Varying grating bar width over one or two axis provides lensing effects on the optical output, while chirping of the period and duty cycle changes optical phase relationships. Novel VCSEL embodiments with external or internal cavities are described using the HCG-SA.

Abstract: A wavelength-tunable, ultrafast laser includes a resonator having an optically-pumped gain-medium. The resonator includes a pair of group-delay-dispersion compensating prisms and a bandwidth limiting stop. Both prisms and stop are fixed in a predetermined position relative to one another. In one embodiment, a movable beam shifting reflector is placed between the prisms. The reflector shifts the dispersed beam with respect to the second prism and the stop. The stop is arranged, cooperative with the second prism, to select a pulse wavelength within the gain-bandwidth. Tuning of the selected pulse-wavelength is accomplished by translating the beam shifting reflector. Alternatively, a two-reflector arrangement may also select pulse-wavelengths, accomplished by a combination of rotation and translation of the two reflectors.

Abstract: In a mode-locked laser-diode-excited laser apparatus: a solid-state laser medium is arranged at a distance of at most twice the Rayleigh range from a saturable absorbing mirror with a depth of absorbing modulation of at least 0.4%; the total intracavity dispersion is smaller than zero and makes oscillating light have such a pulse bandwidth that the saturable absorbing mirror can suppress a background pulses other than soliton pulses repeated with a fundamental repetition period, and the magnitude of the total intracavity dispersion has a predetermined relationship with a pulse width of the oscillating light; and an output mirror is a negative-dispersion mirror in which high-index layers and low-index layers, having optical thicknesses randomly varying in the range of one-eighth to half of the predetermined wavelength, are alternately laminated, and the negative-dispersion mirror causes a mirror dispersion of ?1000 fsec2 to ?100 fsec2 and realizes a reflectance of 97% to 99.5%.

Abstract: A laser resonator cavity is presented. The laser resonator cavity comprises an optical manipulator of different longitudinal modes propagating along different optical paths. The optical manipulator is configured for adjusting a difference in optical lengths of the different optical paths thereby adjusting a frequency spacing between the different longitudinal.

Abstract: A laser apparatus for producing mode locked pulses includes a closed optical system adapted to connect to a fiber grain medium to form a laser cavity. The fiber gain medium is adapted to receive pulses characterized by a first state and to output pulses characterized by a second state. The closed optical system is adapted to receive the pulses in the second state and output pulses in a state similar to the first state.

Abstract: A monoblock laser cavity incorporates optical components for a short-pulse laser. These optical components are ‘locked’ into alignment forming an optical laser cavity for flash lamp or diode laser pumping. The optical laser cavity does not need optical alignment after it is fabricated, increasing the brightness of the monoblock laser.

Abstract: Method for suppressing side modes during use of a tunable laser of MGY type, having an amplification section, a phase section and a reflector section having a Y-branched waveguide, with a first a second branch, where the laser operation point is defined by feeding a respective current through the phase section, the first and the second branch, where possible combinations of these currents span a three-dimensional space, in which elongated volumes define combinations of currents for which the laser is operated in the same mode and where two-dimensional sections, defined by holding the current through the phase section constant and varying the currents through the branches, through a certain of the volumes constitute modeflats.

Abstract: Apparatus, systems, and methods having a frequency comb of large spacing can be used in a variety of applications. In various embodiments, a frequency comb is generated from a slave laser by injecting an optical output from a drive laser into the slave laser. One or more parameters of the drive laser and/or the slave laser can be adjusted such that a frequency comb can be generated at a multiple of the repetition rate of the drive laser. Additional apparatus, systems, and methods are disclosed.

Abstract: A laser and amplifier combination delivers a sequence of optical pulses at a predetermined pulse-repetition frequency PRF. An interferometer generates a signal representative of the carrier-envelope phase (CEP) of the pulses at intervals corresponding to the PRF. The signal includes frequency components from DC to the PRF. The signal is divided into high and low frequency ranges. The high and low frequency ranges are sent to independent high frequency and low frequency control electronics, which drive respectively a high-frequency CEP controller and a low frequency controller for stabilizing the CEP of pulses in the sequence.

Abstract: A laser system comprises a high-Q nonlinear optical resonator, a cavity comprising an amplifying element and a dispersive element, an optical delay line adapted to tune the length of the cavity, and a large pass-band filter adapted to tune the cavity's central oscillation wavelength, the nonlinear optical resonator being selected with a linewidth (LWR) comparable to the cavity free-spectral range (FSRC). There is provided a method for generating highly stable pulse streams, comprising providing a cavity comprising an amplifying element and a dispersive element; selecting a high-Q nonlinear optical resonator with a linewidth (LWR) comparable to the cavity free-spectral range (FSRC); tuning the length of the cavity; and tuning the cavity's central oscillation wavelength.

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: An photonic device, comprising one section of a material which is different from the material of another section such that the two sections present different optical birefringent index values. This causes a first set of polarization modes to move in a spectral space with a different velocity than a second set of polarization modes. A bias current, or voltage, is used for controlling the overall birefringence effect in the device. The biasing for controlling the birefringence effect is performed such the TE modes and the TM modes of the device are made to coincide in their respective spectral position. Thus the device is made insensitive, or presents substantially reduced sensitivity, to the polarization of any incoming optical signal.

Abstract: Modelocked fiber laser resonators may be coupled with optical amplifiers. An isolator optionally may separate the resonator from the amplifier. A reflective optical element on one end of the resonator having a relatively low reflectivity may be employed to couple light from the resonator to the amplifier. Enhanced pulse-width control may be provided with concatenated sections of both polarization-maintaining and non-polarization-maintaining fibers. Apodized fiber Bragg gratings and integrated fiber polarizers may also be included in the laser cavity to assist in linearly polarizing the output of the cavity. Very short pulses with a large optical bandwidth may be obtained by matching the dispersion value of the grating to the inverse of the dispersion of the intra-cavity fiber. Frequency comb sources may be constructed from such modelocked fiber oscillators. Low dispersion and an in-line interferometer that provides feedback may assist in controlling the frequency components output from the comb source.

Abstract: Laser devices are presented in which a graphene saturable absorber and an optical amplifier are disposed in a resonant optical cavity with an optical or electrical pump providing energy to the optical amplifier.

Abstract: Frequency standards based on mode-locked fiber lasers, fiber amplifiers and fiber-based ultra-broad bandwidth light sources, and applications of the same.

Abstract: Provided is a driving method of a mode-locked semiconductor laser device comprising a laminated structure in which a first compound semiconductor layer, a third compound semiconductor layer having an emission region and a second compound semiconductor layer are successively laminated, a second electrode, and a first electrode. The laminated structure is formed on a compound semiconductor substrate having polarity, the third compound semiconductor layer includes a quantum well structure having a well layer and a barrier layer. The well layer has a depth of 1 nm or more and 10 nm or less. The barrier layer has an impurity doping density of 2×1018 cm?3 or more and 1×1020 cm?3 or less. An optical pulse is generated in the emission region by passing a current from the second electrode to the first electrode via the laminated structure.

Abstract: A modelocked fiber laser is designed to have strong pulse-shaping based on spectral filtering of a highly-chirped pulse in the laser cavity. The laser generates femtosecond pulses without a dispersive delay line or anomalous dispersion in the cavity.

Abstract: The invention relates to a laser light source for generating narrow-band laser radiation with high coherence, comprising a laser diode (1), which forms an internal resonator (4), and an external resonator (7) coupled to the internal resonator (4). The object of the invention is to improve a laser source of the kind such that it generates narrow-band and coherent laser radiation with high output power and at the same time with high long-term stability. Furthermore, the laser light source is to be produced in a cost-effective manner. The object is achieved by the invention in that the laser diode (1) runs in an operating mode in which multimode laser radiation is generated, comprising a plurality of spectrally neighboring resonance modes (9) of the external resonator (7). The resonance modes are selected by adapting the spectral characteristics of the external (7) and internal (4) resonators.

Abstract: A control system for improving and stabilizing Fourier domain mode locking (FDML) operation. The control system may also provide regulation of FDML operational parameters such as filter tuning, laser gain, polarization, polarization chromaticity, elliptical polarization retardance, and/or dispersion. The control system may be located internal to or external from the FDML laser cavity.

Abstract: An intense optical high field generator capable of generating an intensive optical high field includes an optical amplification medium that converts optical energy for a wide band or plural bands and performs optical energy conversion into oscillating light oscillated from an optical resonator. The generator also includes: a negative dispersion element that imparts negative dispersion to a pulse light, which is the oscillating light; a mode locking unit that mode locks the optical resonator; a positive dispersion element that imparts positive dispersion on the pulse light; an optical system; and a vacuum chamber that accommodates the negative dispersion element, the mode locking unit, and the positive dispersion element 4, such that an intensive optical high field generating point takes in the pulse light from the negative dispersion element or the positive dispersion element and is formed within the vacuum chamber.

Abstract: A saturable absorber (SA) based on a high-contrast grating (HCG) having a buried layer of quantum structures for absorption, and which is particularly well suited for use in a mode-locked application. The HCG-SA provides three times the bandwidth compared with traditional DBR structures, while exhibiting a lower saturation fluence due to the field enhancement inside the grating. Varying grating bar width over one or two axis provides lensing effects on the optical output, while chirping of the period and duty cycle changes optical phase relationships. Novel VCSEL embodiments with external or internal cavities are described using the HCG-SA.

Abstract: The present invention provides a femtosecond laser apparatus using laser diode optical pumping. To provide a stable mode locking and improve power stability and beam stability in an ultrafast laser such as a femtosecond laser, optical mounts which have mounted thereon optical parts of a diode pumping unit are mechanically engaged using bars of low thermal expansion coefficients and form a pumping module, and the pumping module is maximally separated from a laser platform or case.

Abstract: A saturable absorber (SA) is constructed using a fiber taper embedded in a carbon nanotube/polymer composite. A fiber taper is made by heating and pulling a small part of standard optical fiber. At the taper's waist light is guided by the glass-air interface, with an evanescent field protruding out of the taper. Carbon nanotubes mixed with an appropriate polymer host material are then wrapped around the fiber taper to interact with the evanescent field. Saturable absorption is possible due to the unique optical properties of the carbon nanotubes. The device can be used in mode-locked lasers where it initiates and stabilizes the pulses circulating around the laser cavity. The SA can be used in various laser cavities, and can enable different pulse evolutions such as solitons, self-similar pulses and dissipative solitons. Other applications include but are not limited to optical switching, pulse cleanup and pulse compression.

Abstract: A chirped diode laser (ChDL) is employed for seeding optical amplifiers and/or dissimilar optical paths, which simultaneously suppresses stimulated Brillouin scattering (SBS) and enables coherent combination. The seed spectrum will appear broadband to suppress the SBS, but the well-defined chirp will have the coherence and duration to allow the active phasing of multiple amplifiers and/or dissimilar optical paths. The phasing is accomplished without optical path-length matching by interfering each amplifier output with a reference, processing the resulting signal with a phase lock loop, and using the error signal to drive an acousto-optic frequency shifter at the front end of each optical amplifier and/or optical path.

Abstract: A surface emitting laser emitting a laser beam in a single transverse mode irrespective of an emission area while one-dimensionally aligning polarization of the output beam, including a two-dimensional photonic crystal, having resonance modes in directions of the primitive translation vector a1 and a2, lengths |a1| and |a2| of the primitive translation vectors a1 and a2 satisfied |a1|=p×(?1/2neff1), |a2|=?2/2neff2 described by a resonance wavelengths ?1 and ?2 in the resonance modes in the a1 and a2 directions, effective refractive indexes neff1 and neff2 determined by the resonance modes in the a1 and a2 directions, an integer p of 2 or more, the resonance wavelengths ?1 and ?2 satisfy ?2?2×(neff2/(nout+neff2))×?1 described by the effective refractive index neff2 and a refractive index nout of an external medium located out of the surface emitting laser.