Abstract: The inventive system for crystallizing an amorphous silicon (a-Si) film is configured with a quasi-continuous wave fiber laser source operative to emit a film irradiating pulsed beam. The fiber laser source is operative to emit a plurality of non-repetitive pulses incident on the a-Si. In particular, the fiber laser is operative to emit multiple discrete packets of film irradiating light at a burst repetition rate (BRR), and a plurality of pulses within each packet emitted at a pulse repetition rate (PRR) which is higher than the BRR. The pulse energy, pulse duration of each pulse and the PRR are controlled so that each packet has a desired packet temporal power profile (W/cm2) and packet energy sufficient to provide transformation of a-Si to polysilicon (p-Si) at each location of the film which is exposed to at least one packets.

Abstract: A pulsed fiber generator is configured with a unidirectional ring waveguide configured to emit a train of pulses. The ring waveguide includes multiple fiber amplifiers, chirping fiber components coupled to respective outputs of first and second fiber amplifiers, and multiple spectral filters coupled to respective outputs of the chirping components. The filters have respective spectral band passes centered around different central wavelengths so as to provide leakage of light along the ring cavity in response to nonlinear processes induced in the ring cavity. The pulse generator operates at a preliminary stage during which it is configured to develop a pitch to a signal, and at a steady stage during which it is configured to output a train of pulses through an output coupler at most once per a single round trip of the signal.

Abstract: A broad line red light generator is configured with a single mode (SM) pulsed ytterbium (“Yb”) fiber laser pump source outputting pump light in a fundamental mode (“FM”) at a pump wavelength which is selected from a 1030-1120 nm wavelength range. The disclosed generator further includes a SM fiber Raman converter spliced to an output of the Yb fiber laser pump source. The Raman converter induces an “n” order frequency Stokes shift of the pump light to output the pump light at a Raman-shifted wavelength within 1220 and 1300 nm wavelength range with a broad spectral line of at least 10 nm. The disclosed light generator further has a single pass second harmonic generator (“SHG”) with a lithium triborate (“LBO”) nonlinear optical crystal having a spectral acceptance linewidth which is sufficient to cover the broad spectral line of the pump light. The SHG generates a SM pulsed broad-line red light with a broad spectral line of at least 4 nm.

Abstract: A single mode fiber pulsed oscillator includes an all normal dispersion ring cavity provided with a mode-locking fiber loop component and a giant chirp generating fiber component. The mode-locking fiber loop component is configured with a hybrid of NOLM and NALM configurations which is operative to induce a first phase acquisition of a spectrally narrow pulse due to SPM. The giant chirp generating fiber loop component is configured to induce the additional phase acquisition to the pulse broadened in the mode-locking fiber component so as to generate a pulse with a giant chirp. The fiber loop components each include a fiber amplifier and a coil of fiber. The amplifiers each are configured with an active fiber provided with a core which supports multiple transverse mode in a range of wavelength except for the desired wavelength at which the core is configured to support a single fundamental mode.

Abstract: A high power fiber laser system includes a booster winch is configured as a fiber amplifier extending over free space, pump source and laser head including a reflective element which receives pump light and reflects toward the output end of the booster in a counter signal-propagating direction. The booster is configured with concentric and coextending frustoconically shaped (“MM”) core and cladding around the core. The core includes a mode transition region expanding between small diameter SM input and large diameter MM output core ends and configured so that amplification of high order modes is substantially suppressed as a single mode (“SM”) signal light propagates from the input to output core ends. The laser head receives output ends of respective pump light delivery fibers and signal fiber, respectively. The pump source is structured with a plurality of independent sub pumps arranged around the booster.

Abstract: A high power single mode (“SM”) laser system includes an amplifier configured with a monolithic fiber to rod fiber waveguide which is structured with a multimode (“MM”) core and at least one cladding surrounding the core. The MM core is configured with a small diameter uniform input region receiving and guiding a SM signal light, a mode-transforming frustoconical core region expanding outwards from the input region and a relatively large diameter uniform output portion. The high power laser system is further structured with a MM pump light delivery fiber having a numerical aperture NA2, which is at most equal to that one of the output core portion. The amplifier and pump light output fiber traverse an unconfined delivery cable and terminate upstream from a mirror which is configured to focus the incident pump light into the core of the amplifier in a counter-propagating direction.

Abstract: An optical fiber includes a monolithic elongated mosaic core having a longitudinal axis and configured with a silica-based medium with a uniform refractive index, and a plurality of coaxial elongated individual elements which do not waveguide light at a given wavelength and are received in the silica-glass medium. The refractive indices of the medium and individual anti- waveguiding elements together determine a cumulative effective refractive index of the mosaic core. The optical fiber further includes at least one cladding surrounding the mosaic core and provided with a cladding refractive index which is lower than the index of the mosaic core, so that the mosaic core waveguides the light at the given wavelength.

Abstract: A high power single mode (“SM”) laser system includes an amplifier configured with a monolithic fiber to rod fiber waveguide which is structured with a multimode (“MM”) core and at least one cladding surrounding the core. The MM core is configured with a small diameter uniform input region receiving and guiding a SM signal light, a mode-transforming frustoconical core region expanding outwards from the input region and a relatively large diameter uniform output portion. The high power laser system is further structured with a MM pump light delivery fiber having a numerical aperture NA2, which is at most equal to that one of the output core portion. The amplifier and pump light output fiber traverse an unconfined delivery cable and terminate upstream from a mirror which is configured to focus the incident pump light into the core of the amplifier in a counter-propagating direction.

Abstract: A laser illuminated projector system is configured with multiple Red, Green and Blue laser sources. The Green laser source has an all fiber master oscillator power amplifier configuration in which pump light is coupled into the output end of the fiber amplifier in a counter-propagation direction rendering the structure of the Green source and therefore projector system compact. The Green laser source is operative to emit signal light pulses at about 1064 nm wavelength with a pulse repetition reaching of up to about 3000 kHz, pulse duration between about a 100 fm to about 100 psec, an average power between 1.5 W to above 30 W, a peak power above 5 MW, a pulse energy exceeding 100 ?J and a beam quality parameter M2 ranging between 1.2 and 1.5. The thus configured Green laser source substantially reduces speckle otherwise visible on the laser illuminated screen.

Abstract: An ultra-high power fiber laser system includes a single-piece fiber booster configured with fiber and straight short rod fiber portions which have in common a core configured with a numerical aperture?0.1. The rod fiber portion has a length?a few tens of centimeters and has a frustoconical cross-section expanding from the uniformly configured fiber portion. The core extending along the fiber portion supports a single mode (SM) or very low number of HOMs, whereas the large-diameter end of the frustoconical core portion supports a fundamental mode and high order multiple modes. The disclosed booster is energized by a pump source configured to emit pump light with such a density that while amplification of the fundamental mode continues in the central area of the core, a peripheral non-overlapped area of the core is bleached. The disclosed booster emits signal light in substantially a fundamental mode.

Abstract: A high power pump ultra bright low-noise source is configured with a multimode (“MM”) seed source outputting a MM smooth, low-noise signal light at a desired wavelength in a wavelength range between about 974 and 1030 nm, a MM Yb fiber wavelength converter operative to convert emission of a plurality of high power (“HP”) semiconductor laser diodes at a sub-pump wavelength ?sp to a pump output at the desired wavelength ??, wherein ??=????sp<0/1?sp. The Yb-doped MM wavelength converter is configured with noise levels substantially identical to those of the low-noise signal light, brightness (“B”) substantially equal to ?×B, wherein n is a number HP semiconductor laser diodes, and B is brightness of each HP laser diode, and output power (“Po”) substantially equal to nPd, wherein Pd is a power of each HP laser diode, and n is the number thereof.

Abstract: The inventive system for crystallizing an amorphous silicon (a-Si) film is configured with a quasi-continuous wave fiber laser source operative to emit a film irradiating pulsed beam. The fiber laser source is operative to emit a plurality of non-repetitive pulses incident on the a-Si. In particular, the fiber laser is operative to emit multiple discrete packets of film irradiating light at a burst repetition rate (BRR), and a plurality of pulses within each packet emitted at a pulse repetition rate (PRR) which is higher than the BRR. The pulse energy, pulse duration of each pulse and the PRR are controlled so that each packet has a desired packet temporal power profile (W/cm2) and packet energy sufficient to provide transformation of a-Si to polysilicon (p-Si) at each location of the film which is exposed to at least one packets.

Abstract: A laser illuminated projector system is configured with multiple Red, Green and Blue laser sources. The Green laser source has an all fiber master oscillator power amplifier configuration in which pump light is coupled into the output end of the fiber amplifier in a counter-propagation direction rendering the structure of the Green source and therefore projector system compact. The Green laser source is operative to emit signal light pulses at about 1064 nm wavelength with a pulse repetition reaching of up to about 3000 kHz, pulse duration between about a 100 fm to about 100 psec, an average power between 1.5 W to above 30 W, a peak power above 5 MW, a pulse energy exceeding 100 ?J and a beam quality parameter M2 ranging between 1.2 and 1.5. The thus configured Green laser source substantially reduces speckle otherwise visible on the laser illuminated screen.

Abstract: A high power pump ultra bright low-noise source is configured with a multimode (“MM”) seed source outputting a MM smooth, low-noise signal light at a wavelength ?p in a wavelength range between about 900 and 940 nm, a MM Yb fiber wavelength converter operative to convert emission of a plurality of high power (“HP”) semiconductor laser diodes at a wavelength ?sp to a pump output at the desired wavelength ?p. The Yb-doped MM wavelength converter is configured with noise levels substantially identical to and lower than those of the low-noise signal light, brightness (“B”) substantially equal to n×B, wherein n is a number HP semiconductor laser diodes, and B is brightness of each HP laser diode, and output power (“Po”) substantially equal to nPd, wherein Pd is a power of each HP laser diode, and n is the number thereof.

Abstract: A high power fiber laser system emitting a substantially diffraction limited beam with a Gaussian intensity profile includes a single mode (“SM”) neodymium fiber pump source outputting a SM pump light; a seed laser operative to emit a SM signal light at a wavelength greater than that of the pump light; a SM DWM receiving and multiplexing the SM pump and signal lights. The disclosed system further includes a booster fiber amplifier which is configured with a frustoconically-shaped ytterbium (“Yb”) doped core receiving the pump and signal lights and configured with a small diameter input end which supports only a SM and a large diameter output end which is capable of supporting the SM and high order modes (:HOM”). The booster further has a cladding surrounding and coextending with the core, the core being configured for having intensity profiles of respective SMs of pump and signal lights overlap one another so that an overlap integral substantially equals to one (1) along an entire length of the core.

Abstract: An ultra-high power fiber laser system includes a single-piece fiber booster configured with fiber and straight short rod fiber portions which have in common a core configured with a numerical aperture equal to or higher than 0.1 and doped with ions of one or more rare earth elements across the entire cross-section thereof. The rod fiber portion is structured with a short length not exceeding about a few tens of centimeters and has a generally frustoconical cross-section expanding from the uniformly configured fiber portion. The core extending along the fiber portion is capable of supporting either a SM or a very low number of HOMs guided along the core in a propagating direction and coupled into the small diameter end of the rod fiber's frustoconically-shaped core. The opposite, large-diameter end of the frustoconical core supports multiple modes with a fundamental mode overlapping at least about 0.652 of the cross-section area of the core along the entire length thereof.

Abstract: A method and apparatus are operative to control the desired level of population inversion in a gain medium having an amplified spontaneous emission (ASE) spectrum which is characterized by distinct short- and long-wavelength regions. The control is realized by the apparatus configured to determine a relationship between the regions of the ASE spectrum represented by respective frequencies which are filtered by respective frequency discriminators. The apparatus includes a controller operative to process the filtered frequencies by determining a relationship between amplitudes of the respective filtered frequencies which represents a measured level of population inversion. Upon mismatch between the measured level and desired level of the population inversion, a control signal is coupled into a pulse generator or pump or both. In response, the pulse generator may output a pulse, or/and the pump may be completely shut down to lower the level of the measured inversion.

Abstract: A high power fiber laser system includes a booster winch is configured as a fiber amplifier extending over free space, pump source and laser head including a reflective element which receives pump light and reflects toward the output end of the booster in a counter signal-propagating direction. The booster is configured with concentric and coextending frustoconically shaped (“MM”) core and cladding around the core. The core includes a mode transition region expanding between small diameter SM input and large diameter MM output core ends and configured so that amplification of high order modes is substantially suppressed as a single mode (“SM”) signal light propagates from the input to output core ends. The laser head receives output ends of respective pump light delivery fibers and signal fiber, respectively. The pump source is structured with a plurality of independent sub pumps arranged around the booster.

Abstract: A method for contactless laser welding of a plurality of sheets of material stacked upon one another includes simultaneously delivering a laser beam and a stream of fluid through a laser head and further through an end cap which is removably mounted to the laser head. The end cap is configured with a stationary cylinder, which is coupled to the laser head, and a piston movable relative the cylinder. The piston moves in response to a pressure differential generated by the fluid in chambers above and below the piston. Once the pressure equilibrium is reached between the chambers, the pressure in the chamber below the piston is sufficient to reliably press the sheets of material against one another during a laser welding operation.

Abstract: A high power pump ultra bright low-noise source is configured with a multimode (“MM”) seed source outputting a MM smooth, low-noise signal light at a desired wavelength in a wavelength range between about 974 and 1030 nm, a MM Yb fiber wavelength converter operative to convert emission of a plurality of high power (“HP”) semiconductor laser diodes at a sub-pump wavelength ? sp to a pump output at the desired wavelength ??, wherein ??=????sp<0/1?sp. The Yb-doped MM wavelength converter is configured with noise levels substantially identical to those of the low-noise signal light, brightness (“B”) substantially equal to ?×B, wherein n is a number HP semiconductor laser diodes, and B is brightness of each HP laser diode, and output power (“Po”) substantially equal to nPd, wherein Pd is a power of each HP laser diode, and n is the number thereof.