Abstract: In an example, the present invention provides a high intensity pulse laser generation system. The system has a variety of elements. The system has an optical cavity maintained in a vacuum, e.g., 300 Torr and less. In an example, the optical cavity is configured to increase an intensity of a laser beam comprising a pulse from a first energy power intensity to a second higher energy power intensity propagating on a first optical path configured within the optical cavity by circulating or reciprocating at least a portion of the laser beam.

Abstract: Physiological parameter detecting apparatuses and methods of detecting the physiological parameters are provided. A physiological parameter detecting apparatus includes: a light source configured to emit a light onto a region of an object; an optical path converter configured to receive the light returning from the object and convert an optical path of the received light; an optical detector configured to detect the light that has the converted optical path; and a controller configured to extract physiological information of the object from the detected light.

Abstract: Differentiating traffic signals from filler channels in optical networks includes obtaining power measurements of optical spectrum on an optical section in the optical network; analyzing the power measurements to differentiate signal type between traffic signals and Amplified Stimulated Emission (ASE) channel holders; and applying appropriate treatment to the optical spectrum based on the signal type. The analyzing is performed locally without any notification from upstream nodes of the optical spectrum.

Abstract: In an example, the present invention provides a high intensity pulse laser generation system. The system has a variety of elements. The system has an optical cavity maintained in a vacuum, e.g., 300 Torr and less. In an example, the optical cavity is configured to increase an intensity of a laser beam comprising a pulse from a first energy power intensity to a second higher energy power intensity propagating on a first optical path configured within the optical cavity by circulating or reciprocating at least a portion of the laser beam.

Abstract: Various example embodiments for supporting supervision in optical communication systems are presented. Various example embodiments for supporting supervision in optical communication systems may be configured to support supervision of an optical path including a remote optically pumped amplifier (ROPA) and, thus, supervision of the ROPA. Various example embodiments for supporting supervision of an optical path including a ROPA may be configured to support supervision of the optical path including the ROPA based on a pair of optical supervisory paths configured to extract a pair of optical supervisory signals from an optical path in a first direction and to insert the pair of optical supervisory signals into an optical path in a second direction. Various example embodiments for supporting supervision of an optical path including a ROPA may be configured to support supervision of the optical path including the ROPA based on a pair of optical time-domain reflectometer (OTDR) paths.

Abstract: A method and system is described. A signal indicative of a failure of a first channel within a plurality of channels of a transmission signal traversing a signal working path in a network is received. The signal working path has a headend node, a tail-end node and an intermediate node. The first channel has a frequency band and a power level prior to failing. The signal working path is associated with a protection path. The protection path includes the intermediate node, optical cross-connects, and a transmitter supplying (ASE) light. The transmitter is activated to supply the ASE light within a frequency band and having a power level corresponding to the frequency band and power level associated with the first channel. The ASE light is supplied to a cross-connect, such that the cross-connect provides a transmission signal including the ASE light.

Abstract: A method of depositing a nanoscale-thin film onto a substrate is disclosed. The method generally comprises depositing a layer of a solid or gaseous state functionalizing molecule onto or adjacent to the first surface of the substrate and exposing the first surface to a source of ionizing radiation, thereby functionalizing the first surface of the substrate. Once the layer of functionalizing molecule is removed, a nanoscale-thin film is then deposited onto the functionalized first surface of the substrate.

Abstract: A method for precise working of material, particularly organic tissue, comprises the step of providing laser pulses with a pulse length between 50 fs and 1 ps and with a pulse frequency from 50 kHz to 1 MHz and with a wavelength between 600 and 2000 nm for acting on the material to be worked. Apparatus, in accordance with the invention, for precise working of material, particularly organic tissue comprising a pulsed laser, wherein the laser has a pulse length between 50 fs and 1 ps and with a pulse frequency of from 50 kHz to 1 MHz is also described.

Abstract: A laser system may include a controller configured to direct a plurality of temporally spaced-apart electrical pulses to a device that optically pumps a lasing medium, and a lasing medium configured to output a quasi-continuous laser pulse in response to the optical pumping. The plurality of temporally spaced-apart electrical pulses may include (a) a first electrical pulse configured to excite the lasing medium to an energy level below a lasing threshold of the lasing medium, and (b) multiple second electrical pulses following the first electrical pulse. The quasi-continuous laser pulse is output in response to the multiple second electrical pulses.

Abstract: A flow channel structure includes a substrate including a supply flow channel that guides a measurement target liquid toward inside; a separation element accommodating unit that accommodates a separation element that separates components included in the measurement target liquid; and a detection unit that guides the measurement target liquid passing through the separation element accommodating unit, wherein measuring light for measuring information about the components is to be irradiated onto the measurement target liquid. The detection unit includes a measurement flow channel part that guides the measurement target liquid, an incident part that is provided at an end of the measurement flow channel part and that guides the measuring light toward inside the measurement flow channel part, and an emission part that is provided at the other end of the measurement flow channel part and that derives the measuring light from the measurement flow channel part.

Abstract: The present invention relates to an optical module configured to be optically coupleable to a laser amplifier module, the optical module comprising an inner optical element having a plurality of M inner reflective elements arranged around a center of the inner optical element; and a plurality of N outer reflective elements arranged around the inner optical element, the plurality of N outer reflective elements being configured to face the inner optical element, wherein the plurality of M inner reflective elements and the plurality of N outer reflective elements are configured to provide an optical path for a laser beam.

Abstract: A high-efficiency high-power ring laser amplifier includes four polarizers, four amplifiers, fours lens, two filter apertures, two electro-optic switches, a mirror, a wavefront corrector. A bidirectional ring laser amplifier configuration with twin pulses is suitable for any type of gain media and pumping configurations. This amplifier configuration can effectively improve the extraction efficiency of the gain medium. The amplification configuration proposed by the present invention patent can realize the ring amplification for any number of rounds in principle, and can effectively control quality of the output laser beam and relax the restriction on the injected energy. The two spatial filters in the novel high-efficiency high-power ring laser amplifier of the present invention patent can effectively removing the spatial modulations in the laser beams, and the first and second spatial filters reimage the beam at wavefront corrector to mirror which can effectively inhibit the diffraction effect.

Abstract: A light source arrangement is provided. The light source arrangement may include a plurality of semiconductor laser light sources arranged in such a way that the laser light emitted by the semiconductor laser light sources is aligned in parallel, and a deflection unit configured to collect and influence all beam paths of the laser light emitted by the semiconductor laser light sources so as to form a beam. The deflection unit has a first mirror element with a concavely curved surface, which is embodied to capture and reflect the laser light emitted by the semiconductor laser light sources by the surface. The light source arrangement may further include a second mirror element with a convexly curved surface, which is embodied to capture and focus the laser light reflected by the first mirror element.

Abstract: An optical amplifier which integrates a pre-amplifier and a power amplifier in a single rectangular active medium to enable amplification of low power ultra-short pulses to optimal power levels. A seed beam passes through the amplification medium along a first pre-amplification path making multiple traverses of the medium. It is imaged back along the first path to make a double pass of the medium as a pre-amplifier. The beam is then re-imaged into the medium again on a second power amplification path, making multiple traverses of the medium in a single pass. The paths are independent but overlap so that efficient power extraction is achieved. Embodiments based on all passive components are described.

Abstract: The present invention provides an optical amplifying device which can be easily downsized, increased in output, and stabilized. An optical amplifying device 1A includes an optical amplifier 10A and an energy supplier 30. The optical amplifier 10A includes an optical amplifying medium 11 and a transparent medium 12. The energy supplier 30 supplies excitation energy (for example, excitation light) to the optical amplifying medium 11. The optical amplifying medium 11 is supplied with the excitation light to amplify light and output it. To-be-amplified light passes through the transparent medium 12 in the optical amplifying medium 11 a plurality of times. The transparent medium 12 can propagate the to-be-amplified light, for example, zigzag inside.

Abstract: A system for generating a shaped optical pulse is disclosed. The system includes a master oscillator for generating an initial optical pulse, which is then directed to a semiconductor optical amplifier to amplify a portion of the initial optical pulse. The amplified pulse is reflected from a fiber Bragg grating to spectrally clean the amplified pulse and the reflected portion is returned back through the semiconductor optical amplifier. The semiconductor optical amplifier is activated a second time to amplify the reflected portion of the pulse. The time delay between the two activations of the semiconductor optical amplifier is selected to generate an output pulse with desired duration and/or amplitude profile over time.

Abstract: A spatial filter includes a first filter element and a second filter element overlapping with the first filter element. The first filter element includes a first pair of cylindrical lenses separated by a first distance. Each of the first pair of cylindrical lenses has a first focal length. The first filter element also includes a first longitudinal slit filter positioned between the first pair of cylindrical lenses. The second filter element includes a second pair of cylindrical lenses separated by a second distance. Each of the second pair of cylindrical lenses has a second focal length. The second filter element also includes a second longitudinal slit filter positioned between the second pair of cylindrical lenses.

Abstract: The various laser architectures described herein provide increased gain of optical energy as well as compensation of optical phase distortions in a thin disk gain medium. An optical amplifier presented herein provides for scalable high energy extraction and gains based on a number of passes of the signal beam through a gain medium. Multiple, spatially separate, optical paths may also be passed through the same gain region to provide gain clearing by splitting off a small percentage of an output pulse and sending it back through the amplifier along a slightly different path. By clearing out the residual gain, uniform signal amplitudes can be obtained.

Abstract: A chirped pulse amplification system includes a laser source providing an input laser pulse along an optical path. The input laser pulse is characterized by a first temporal duration. The system also includes a multi-pass pulse stretcher disposed along the optical path. The multi-pass pulse stretcher includes a first set of mirrors operable to receive input light in a first plane and output light in a second plane parallel to the first plane and a first diffraction grating. The pulse stretcher also includes a second set of mirrors operable to receive light diffracted from the first diffraction grating and a second diffraction grating. The pulse stretcher further includes a reflective element operable to reflect light diffracted from the second diffraction grating. The system further includes an amplifier, a pulse compressor, and a passive dispersion compensator disposed along the optical path.

Abstract: The various laser architectures described herein provide increased gain of optical energy as well as compensation of optical phase distortions in a thin disk gain medium. An optical amplifier presented herein provides for scalable high energy extraction and gains based on a number of passes of the signal beam through a gain medium. Multiple, spatially separate, optical paths may also be passed through the same gain region to provide gain clearing by splitting off a small percentage of an output pulse and sending it back through the amplifier along a slightly different path. By clearing out the residual gain, uniform signal amplitudes can be obtained.

Abstract: A regenerative amplifier according to one aspect of this disclosure is used in combination with a laser device, and the regenerative amplifier may include: a pair of resonator mirrors constituting an optical resonator; a slab amplifier provided between the pair of the resonator mirrors for amplifying a laser beam with a predetermined wavelength outputted from the laser device; and an optical system disposed to configure a multipass optical path along which the laser beam is reciprocated inside the slab amplifier, the optical system transferring an optical image of the laser beam at a first position as an optical image of the laser beam at a second position.

Abstract: A main amplifier system includes a first reflector operable to receive input light through a first aperture and direct the input light along an optical path. The input light is characterized by a first polarization. The main amplifier system also includes a first polarizer operable to reflect light characterized by the first polarization state. The main amplifier system further includes a first and second set of amplifier modules. Each of the first and second set of amplifier modules includes an entrance window, a quarter wave plate, a plurality of amplifier slablets arrayed substantially parallel to each other, and an exit window. The main amplifier system additionally includes a set of mirrors operable to reflect light exiting the first set of amplifier modules to enter the second set of amplifier modules and a second polarizer operable to reflect light characterized by a second polarization state.

Abstract: The various laser architectures described herein provide increased gain of optical energy as well as compensation of optical phase distortions in a thin disk gain medium. An optical amplifier presented herein provides for scalable high energy extraction and gains based on a number of passes of the signal beam through a gain medium. Multiple, spatially separate, optical paths may also be passed through the same gain region to provide gain clearing by splitting off a small percentage of an output pulse and sending it back through the amplifier along a slightly different path. By clearing out the residual gain, uniform signal amplitudes can be obtained.

Abstract: A regenerative amplifier according to one aspect of this disclosure is used in combination with a laser device, and the regenerative amplifier may include: a pair of resonator mirrors constituting an optical resonator; a slab amplifier provided between the pair of the resonator mirrors for amplifying a laser beam with a predetermined wavelength outputted from the laser device; and an optical system disposed to configure a multipass optical path along which the laser beam is reciprocated inside the slab amplifier, the optical system transferring an optical image of the laser beam at a first position as an optical image of the laser beam at a second position.

Abstract: Method and laser oscillator for the generation of a laser beam—According to the invention with a view to adjusting, inside said laser oscillator (1), the phase of each of the N elementary laser beams (FLE.1, FLE.2, FLE.N) generated on the basis of said laser oscillator (1) in such a way that said elementary laser beams are in phase, the deviation between the phase of an individual elementary laser beam (FLE.1) and the phases of the N?1 other elementary laser beams (FLE.2, FLE.N) is converted into a level of luminous intensity by means of at least one optical filtering element to which at least a part of each elementary laser beam is directed.

Abstract: A master oscillator power-amplifier stages includes multiple stages of fiber-amplification with a final power amplifier stage in the form of a multi-pass amplifier. With a thin-disk gain medium in one example the thin-disk amplifier includes a common optical arrangement for providing multiple incidences of radiation to be amplified and multiple incidences of a pump-radiation beam on the thin-disk gain medium.

Abstract: A light amplifier includes first and second multi-pass amplifiers, an excitation light source, and a beam splitter. The second multi-pass amplifier includes a light attenuation portion provided in an optical path for a light pulse to travel to pass through a light amplification medium a plurality of times, for attenuating energy of the input light pulse. In addition, an excitation light pulse from the excitation light source is split by the beam splitter into two light pulses. These two pulses are input to the first and second multi-pass amplifiers, respectively. Thus, fluctuation in energy of the light pulse output from the light amplifier can be less than fluctuation in energy of the excitation light pulse.

Abstract: An edge photo-pumped semiconductor slab amplifier including an undoped semiconductor slab. A first gain structure is formed on an upper surface of the slab and a second gain structure is formed on a lower surface of the slab. The gain structures can be resonant periodic gain structures including a plurality of stacked quantum well layers. Confining layers are coupled to the gain structures to confine a signal beam within the semiconductor slab. Heat sinks are thermally coupled to the confining layers. Optical pump sources are provided along the side edges or coupled to the end edges of the slab so that pump light is introduced into the slab through the edges to provide gain for the quantum well layers.

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 radiation system includes a target material supply configured to supply droplets of target material along a trajectory, and a laser system that includes an amplifier and optics. The optics are configured to establish a first beam path which passes through the amplifier and through a first location on the trajectory, and to establish a second beam path which passes through the amplifier and through a second location on the trajectory. The laser system is configured to generate a first pulse of laser radiation when photons emitted from the amplifier are reflected along the first beam path by a droplet of target material at the first location on the trajectory. The laser system is configured to generate a second pulse of laser radiation when photons emitted from the amplifier are reflected along the second beam path by the droplet of target material at the second location on the trajectory.

Abstract: The present invention relates to a method of amplification based on spatio-temporal frequency drift for a pulse laser comprising a so-called CPA (Chirped Pulse Amplification) frequency-shift amplifying chain, the various spectral components spatially spread. The various components separately amplified.

Abstract: A high extraction efficiency laser system. The novel laser system includes a laser amplifier and a laser source adapted to provide a laser beam to the amplifier such that polarization states for incident and reflected light within the amplifier are perpendicular one to another. In an illustrative embodiment, the laser beam is input to the amplifier such that the beam reflects back and forth between the side walls of the amplifier with an angle of incidence of about 45 degrees, and the laser beam is linearly polarized in the plane of incidence. This arrangement reduces interference fringes in the amplifier. In an alternative embodiment, the system includes an aberrator adapted to add time-varying aberrations in the laser beam at a rate exceeding an inversed lifetime of an inverted population in the amplifier to increase spatial homogenization of saturation and extraction patterns in the amplifier.

Abstract: The various laser architectures described herein provide increased gain of optical energy as well as compensation of optical phase distortions in a thin disk gain medium. An optical amplifier presented herein provides for scalable high energy extraction and gains based on a number of passes of the signal beam through a gain medium. Multiple, spatially separate, optical paths may also be passed through the same gain region to provide gain clearing by splitting off a small percentage of an output pulse and sending it back through the amplifier along a slightly different path. By clearing out the residual gain, uniform signal amplitudes can be obtained.

Abstract: An apparatus includes a first plurality of concave reflecting surfaces; a second plurality of reflecting surfaces facing the first plurality of concave reflecting surfaces such that a region is defined between the first and second pluralities; and an input for an optical beam to enter the region and an output for the optical beam to exit the region. The first and second pluralities of reflecting surfaces are arranged relative to each other so that the optical beam is re-imaged at a reflecting surface of one of the pluralities after only one reflection from a reflecting surface of the other of the pluralities and so that overlap of two or more optical beams on each of the reflecting surfaces is avoided.

Abstract: A high peak intensity laser amplification system and the method therein implemented are provided. In a first aspect of the invention, the laser system includes at least one optical member (27) operably introducing a phase function into a high peak intensity laser pulse (25). A further aspect includes introducing destructive interference in an unchirped laser pulse prior to amplification and reconstructive interference in the output laser pulse after amplification. Dynamic pulse shaping is employed in another aspect of the present invention.

Abstract: A tunable laser includes an optical gain medium, a first resonator, a periodically tunable optical filter, and a second resonator in which light of a laser wavelength exhibits a round trip time T. The optical filter is arranged between the first resonator and the second resonator and is tuned with a period t. The period t is governed by t=(n/m) T, where n and m are integers and m/n is not an integer.

Abstract: A device for amplifying high-energy ultrashort light pulses, includes a generator (1), a first amplifying/time-stretching element (2) including a time-stretching element (3), a regenerative amplifier (4), a multipass amplifier (5) and a compressor (6). The device further includes a second amplifying/time-stretching element (11), arranged at the output of the generator (1), amplifying and time-stretching the initial light pulses (7) to generate amplified and time-stretched pulses (13), and a filtering element (12) arranged between the second amplifying/time-stretching element (11) and the amplification unit (2), blocking the low-amplitude light signals (14) of the amplified and time-stretched pulses (13).

Abstract: A main amplifier system includes a first reflector operable to receive input light through a first aperture and direct the input light along an optical path. The input light is characterized by a first polarization. The main amplifier system also includes a first polarizer operable to reflect light characterized by the first polarization state. The main amplifier system further includes a first and second set of amplifier modules. Each of the first and second set of amplifier modules includes an entrance window, a quarter wave plate, a plurality of amplifier slablets arrayed substantially parallel to each other, and an exit window. The main amplifier system additionally includes a set of mirrors operable to reflect light exiting the first set of amplifier modules to enter the second set of amplifier modules and a second polarizer operable to reflect light characterized by a second polarization state.

Abstract: The various laser architectures described herein provide increased gain of optical energy as well as compensation of optical phase distortions in a thin disk gain medium. An optical amplifier presented herein provides for scalable high energy extraction and gains based on a number of passes of the signal beam through a gain medium. Multiple, spatially separate, optical paths may also be passed through the same gain region to provide gain clearing by splitting off a small percentage of an output pulse and sending it back through the amplifier along a slightly different path. By clearing out the residual gain, uniform signal amplitudes can be obtained.

Abstract: A device is described herein which may comprise an oscillator having an oscillator cavity length, L0, and defining an oscillator path; and a multi-pass optical amplifier coupled with the oscillator to establish a combined optical cavity including the oscillator path, the combined cavity having a length, Lcombined, where Lcombined=(N+x)*L0, where “N” is an integer and “x” is a number between 0.4 and 0.6.

Abstract: A laser oscillator includes a ring resonator. The ring resonator includes an optical circulator having first, second, third, and fourth ports and a first optical amplification fiber connected to the optical circulator. Light incident on the first port is exited from the second port, and light incident on the second port is exited from the third port. The fourth port provides an exciting light and injects the exciting light into the ring resonator through the first port. The first optical amplification fiber amplifies light exited from the third port with the exciting light provided by the fourth port. The laser oscillator also includes an optical member connected to the optical circulator. The optical member reflects at least a part of the light exited from the second port and injects the same into the second port again.

Abstract: A spatial filter includes a first filter element and a second filter element overlapping with the first filter element. The first filter element includes a first pair of cylindrical lenses separated by a first distance. Each of the first pair of cylindrical lenses has a first focal length. The first filter element also includes a first slit filter positioned between the first pair of cylindrical lenses. The second filter element includes a second pair of cylindrical lenses separated by a second distance. Each of the second pair of cylindrical lenses has a second focal length. The second filter element also includes a second slit filter positioned between the second pair of cylindrical lenses.

Abstract: An acousto-optic module is provided, including a number of partially coupled optical resonators distributed within a dielectric medium and at least one acoustic transducer mounted on a surface of the dielectric medium for injecting an acoustic wave into the optical resonators so as to diffract light passing therethrough by means of Bragg diffraction. This acousto-optic module has been applied in particular to an improved tuneable optical filter in which an acoustic shear wave is generated and which travels through the acousto-optic module in a direction substantially parallel with a polarized light signal passing therethrough. The acousto-optic module is also applied to an improved optical frequency shifter.

Abstract: The present invention provides an optical amplifying device which can be easily downsized, increased in output, and stabilized. An optical amplifying device 1A includes an optical amplifier 10A and an energy supplier 30. The optical amplifier 10A includes an optical amplifying medium 11 and a transparent medium 12. The energy supplier 30 supplies excitation energy (for example, excitation light) to the optical amplifying medium 11. The optical amplifying medium 11 is supplied with the excitation light to amplify light and output it. To-be-amplified light passes through the transparent medium 12 in the optical amplifying medium 11 a plurality of times. The transparent medium 12 can propagate the to-be-amplified light, for example, zigzag inside.

Abstract: A laser oscillator includes a ring resonator. The ring resonator includes an optical circulator having first, second, third, and fourth ports and a first optical amplification fiber connected to the optical circulator. Light incident on the first port is exited from the second port, and light incident on the second port is exited from the third port. The fourth port provides an exciting light and injects the exciting light into the ring resonator through the first port. The first optical amplification fiber amplifies light exited from the third port with the exciting light provided by the fourth port. The laser oscillator also includes an optical member connected to the optical circulator. The optical member reflects at least a part of the light exited from the second port and injects the same into the second port again.

Abstract: Methods and apparatus for providing amplification to coarse wave division multiplexing channels or signals are disclosed. According to one aspect of the present invention, an arrangement that adds gain to a set of signals that may be divided into a first band including signals of lower wavelengths and a second band including signals of higher wavelengths includes a multiplexer, first and second optical amplifiers, and a processing arrangement. The multiplexer multiplexes the set of signals. The first optical amplifier has a first gain peak and provides amplification to the set of signals, while the second optical amplifier has a second gain peak and provides amplification to the second band but not to the first band. The processing arrangement passes the second band from the first optical amplifier to the second optical amplifier, and substantially prevents the first band from passing from the first optical amplifier to the second optical amplifier.

Abstract: A device for amplifying high-energy ultrashort light pulses, includes a generator (1), a first amplifying/time-stretching element (2) including a time-stretching element (3), a regenerative amplifier (4), a multipass amplifier (5) and a compressor (6). The device further includes a second amplifying/time-stretching element (11), arranged at the output of the generator (1), amplifying and time-stretching the initial light pulses (7) to generate amplified and time-stretched pulses (13), and a filtering element (12) arranged between the second amplifying/time-stretching element (11) and the amplification unit (2), blocking the low-amplitude light signals (14) of the amplified and time-stretched pulses (13).

Abstract: To extend the temperature range for a stable operation without mode hopping and obtain a stable laser oscillation, a laser oscillator is provided. The laser oscillator includes: an optical circulator in which light incident on a first port is exited from the second port, light incident on the second port is exited from a third port, and light incident on a fourth port is exited from the first port; a first optical amplification fiber that amplifies the light exited from the third port because of being excited by an exciting light and injects the same into the first port; a reflective optical filter that reflects light with a predetermined wavelength among the light exited from the second port and injects the same into the second port again; and an pump light source that generates an exciting light to excite the first optical amplification fiber.

Abstract: Methods and apparatus are disclosed for directing optical radiation to make multiple passes across an extended region of an electro-optic material, where during each pass the electro-optic material converts a portion of the optical radiation into terahertz radiation, and where the optical radiation is directed into the electro-optic material to cause an amplitude of the terahertz radiation generated from one or more earlier passes of the optical radiation to be constructively enhanced by the terahertz radiation generated from a later pass of the optical radiation.

Abstract: The invention relates to a method of amplifying a laser beam which includes steps consisting in performing an optical pumping of an amplifying crystal so as to inject into the crystal an optical pumping energy Etotal, amplifying the laser beam by means of the amplifying crystal and an optical system with N passes, that is, designed to inject the laser beam into the amplifying crystal N times, N being an integer>1. The optical pumping is temporally divided into n partial pumpings, the optical energy of a partial pumping being a fraction of Etotal, n being an integer 2?n?N and in that the laser beam is injected into the amplifying crystal at least once after each partial pumping.