Abstract: This disclosure relates to polarizing optical fibers and polarization maintaining optical fibers, including active and/or passive implementations. An embodiment includes a polarizing (PZ) optical fiber that includes stress applying parts (SAPs) disposed in a first cladding region, the SAPs comprising a material with a thermal expansion coefficient, ?SAP. A core region is at least partially surrounded by cladding features and the SAPs. The core includes glass with a thermal expansion coefficient, ?core. The arrangement of the SAPs satisfies: Rsc=dSAP/Dsc, where Dsc is the SAP center to core center distance, and dSAP is the average SAP diameter, and d?=|?SAP??core|, and where Rsc and d? may be sufficiently large to induce stress birefringence into the core and to provide for polarized output. Active fibers in which a portion of the fiber is doped may be implemented for application in fiber lasers, fiber amplifiers, and/or optical pulse compressors.

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: System for converting relatively long pulses from rep-rate variable ultrafast optical sources to shorter, high-energy pulses suitable for sources in high-energy ultrafast lasers. Fibers with positive group velocity dispersion (GVD) and self phase modulation are advantageously employed with the optical sources. These systems take advantage of the need for higher pulse energies at lower repetition rates so that such sources can be cost effective.

Abstract: Disclosed is a method for making a colloidal suspension of precious metal nanoparticles. The method comprises providing a target material comprising a precious metal in a liquid dispersion medium in an ablation container. The dispersion medium has an electrical conductivity within a predetermined conductivity range. Laser pulses are used to generate the nanoparticles from the target in the container. While generating the nanoparticles the electrical conductivity of the dispersion medium is monitored and maintained within the predetermined range and thereby the generated nanoparticles are produced within a predetermined size range. The generated nanoparticles are used to form a colloidal suspension.

Abstract: The described embodiments provide an energy storage device that includes a positive electrode including an active material that can store and release ions, a negative electrode including an active material that is a lithiated nano-architectured active material including tin and at least one stress-buffer component, and a non-aqueous electrolyte including lithium. The negative electrode active material is nano-architectured before lithiation.

Abstract: In one aspect, the present disclosure describes a fiber laser system for the generation and delivery of femtosecond (fs) pulses in multiple wavelength ranges. For improved versatility in multi-photon microscopy, an example of a dual wavelength fiber system based on Nd fiber source providing gain at 920 and 1060 nm is described. An example of a three-wavelength system is included providing outputs at 780 nm, 940 nm, and 1050 nm. The systems include dispersion compensation so that high quality fs pulses are provided for applications in microscopy, for example in multiphoton microscope (MPM) systems.

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: Examples of robust self-starting passively mode locked fiber oscillators are described. In certain implementations, the oscillators are configured as Fabry-Perot cavities containing an optical loop mirror on one cavity end and a bulk mirror or saturable absorber on the other end. The loop mirror can be further configured with an adjustable line phase delay to optimize modelocking. All intra-cavity fiber(s) can be polarization maintaining. Dispersion compensation components such as, e.g., dispersion compensation fibers, bulk diffraction gratings or fiber Bragg gratings may be included. The oscillators may include a bandpass filter to obtain high pulse energies when operating in the similariton regime. The oscillator output can be amplified and used whenever high power short pulses are required. For example the oscillators can be configured as frequency comb sources or supercontinuum sources. In conjunction with repetition rate modulation, applications include dual scanning delay lines and trace gas detection.

Abstract: Compact optical frequency sources are described. The comb source may include an intra-cavity optical element having a multi-material integrated structure with an electrically controllable active region. The active region may comprise a thin film. By way of example, the thin film and an insulating dielectric material disposed between two electrodes can provide for rapid loss modulation. In some embodiments the thin film may comprise graphene. In various embodiments of a frequency comb laser, rapid modulation of the CEO frequency can be implemented via electric modulation of the transmission or reflection loss of an additional optical element, which can be the saturable absorber itself. In another embodiment, the thin film can also be used as a saturable absorber in order to facilitate passive modelocking. In some implementations the optical element may be formed on a cleaved or polished end of an optical fiber.

Abstract: A femtosecond laser based laser processing system having a femtosecond laser, frequency conversion optics, beam manipulation optics, target motion control, processing chamber, diagnostic systems and system control modules. The femtosecond laser based laser processing system allows for the utilization of the unique heat control in micromachining, and the system has greater output beam stability, continuously variable repetition rate and unique temporal beam shaping capabilities.

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 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: Methods for ultrashort pulse laser processing of optically transparent materials. A method for scribing transparent materials uses ultrashort laser pulses to create multiple scribe features with a single pass of the laser beam across the material, with at least one of the scribe features being formed below the surface of the material. This enables clean breaking of transparent materials at a higher speed than conventional techniques. Slightly modifying the ultrashort pulse laser processing conditions produces sub-surface marks. When properly arranged, these marks are clearly visible with side-illumination and not clearly visible without side-illumination. In addition, a method for welding transparent materials uses ultrashort laser pulses to create a bond through localized heating. The ultrashort pulse duration causes nonlinear absorption of the laser radiation, and the high repetition rate of the laser causes pulse-to-pulse accumulation of heat within the materials.

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. In at least one embodiment a coherent dual scanning laser system (CDSL) includes two passively modelocked fiber oscillators. In some embodiments an effective CDSL is constructed with only one laser. At least one embodiment includes a coherent scanning laser system (CSL) for generating pulse pairs with a time varying time delay. A CDSL, effective CDSL, or CSL may be arranged in an imaging system for one or more of optical imaging, microscopy, micro-spectroscopy and/or THz imaging.

Abstract: A method for scribing transparent materials uses ultrashort laser pulses to create multiple scribe features with a single pass of the laser beam across the material, with at least one of the scribe features being formed below the surface of the material. This enables clean breaking of transparent materials at a higher speed than conventional techniques.

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: The invention describes classes of robust fiber laser systems usable as pulse sources for Nd: or Yb: based regenerative amplifiers intended for industrial settings. The invention modifies adapts and incorporates several recent advances in FCPA systems to use as the input source for this new class of regenerative amplifier.

Abstract: An electronic circuit for controlling a laser system consisting of a pulse source and high power fiber amplifier is disclosed. The circuit is used to control the gain of the high power fiber amplifier system so that the amplified output pulses have predetermined pulse energy as the pulse width and repetition rate of the oscillator are varied. This includes keeping the pulse energy constant when the pulse train is turned on. The circuitry is also used to control the temperature of the high power fiber amplifier pump diode such that the wavelength of the pump diode is held at the optimum absorption wavelength of the fiber amplifier as the diode current is varied. The circuitry also provides a means of protecting the high power fiber amplifier from damage due to a loss of signal from the pulse source or from a pulse-source signal of insufficient injection energy.

Abstract: Various embodiments include large cores fibers that can propagate few modes or a single mode while introducing loss to higher order modes. Some of these fibers are holey fibers that comprise cladding features such as air-holes. Additional embodiments described herein include holey rods. The rods and fibers may be used in many optical systems including optical amplification systems, lasers, short pulse generators, Q-switched lasers, etc. and may be used for example for micromachining.

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.