A solid-state optical amplifier is described, having an active core and doped cladding in a single chip. An active optical core runs through a doped cladding in a structure formed on a substrate. A light emitting structure, such as an LED, is formed within and/or adjacent to the optical core. The cladding is doped, for example, with erbium or other rare-earth elements or metals. Several exemplary devices and methods of their formation are given.

A configuration is provided with a laser medium 1 of a refractive index nc that is an isotropic medium and includes an upper surface and a lower surface, where at least one of the upper surface and the lower surface is bonded with a cladding 2 having a refractive index satisfying a relationship of no<nc<ne or ne<nc<no. This allows selective output of only polarized light generated by a refractive index in the cladding 2 smaller than the refractive index nc at a desired wavelength (e.g. 1535 nm) which can be implemented by using the isotropic medium.

An intra-cavity doubled OPS-laser has a laser-resonator including a birefringent filter (BRF) for coarse wavelength-selection, and an optically nonlinear (ONL) crystal arranged for type-II frequency-doubling and fine wavelength-selection. Laser-radiation circulates in the laser-resonator at one of a range of fundamental wavelengths dependent on the resonator length. The ONL crystal has a transmission peak-wavelength dependent on the crystal temperature. Reflection of circulating radiation from the BRF is monitored. The reflection is at a minimum when the ONL crystal transmission-peak wavelength is at the circulating radiation wavelength. The temperature of the ONL crystal is selectively varied to maintain the monitored reflection at about a minimum.

An ultrastable laser system is based on a polarization-maintaining optical fiber. The ultrastable laser system comprises a laser device; acousto-optic modulators, a first beam splitter, a polarizer, an optical fiber interferometer comprising a second beam splitter, an optical fiber delay line, a third acousto-optic modulator, and a beam combiner; a beam combiner, a polarization beam splitter, photoelectric detectors, a frequency synthesizer, frequency mixers, a servo feedback circuit and a piezoelectric ceramic. The temperature interference is eliminated based on the characteristic that refractive indexes of a fast axis and a slow axis of the polarization-maintaining optical fiber differently change with a temperature, a vacuum structure can be avoided, and the ultrastable laser system has low cost, small system, simple structure and high signal stability.

The invention is a passively mode-locked ultrashort pulse fiber laser for generating ultrashort laser pulses, including a resonator in a figure-of-eight configuration, wherein the resonator has a main ring and a secondary ring optically coupled thereto designed as a non-linear Sagnac interferometer, and wherein the main ring and the secondary ring are constructed of polarization-maintaining optical fibers, and the main ring and/or secondary ring have a fiber section designed as a laser-active medium, wherein the laser-active medium is optically pumped through an externally-coupled pump light source which is also comprised, wherein the ultrashort pulse fiber laser is developed in that a separate optical unit is provided in the resonator as a dispersion compensation unit for compensating a group delay dispersion of the ultrashort laser pulses.

A method and a system for measurement of high laser field intensity, the method comprising tight focusing a non-Gaussian azimuthally polarized laser mode beam to a focusing spot, measuring a spectral line shape of a selected ionization state induced by a longitudinal oscillating magnetic field created by the tight focusing in the focusing spot; and determining the laser intensity from the spectral line shape. The system comprises a laser source of a peak power in a range between 100 terawatt and 10 petawatt; a converter unit; a tight focusing optics; and spectral measurement means; wherein the converter unit polarizes a main laser beam from the laser source into a non-Gaussian azimuthally polarized laser mode beam; the tight focusing optics focuses the azimuthally polarized laser mode beam to a focusing spot, yielding a longitudinal oscillating magnetic field of an intensity proportional to the laser intensity, the spectral measurement means measuring a line shape of a selected ionization state induced by the longitudinal oscillating magnetic field in focusing spot.

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.

A method and system for delivering laser pulses achieves the delivery of high quality laser pulses at the location of an application. The method includes the steps of: generating laser pulses, amplifying the laser pulses, temporally stretching the amplified laser pulses, and propagating the amplified laser pulses through an optical delivery fiber of desired length, wherein the laser pulses are temporally compressed in the optical delivery fiber and wherein the laser pulses undergo nonlinear spectral broadening in the optical delivery fiber.

Methods and apparatuses for determining the polarization state and for providing polarization control in optical fiber lasers and amplifiers. One embodiment of the invention is an optical fiber amplifying system including a circulator (260) having a first optical port (260a), a second optical port (260b) that is configured to output radiation received from the first optical port, and a third optical port (260c) that is configured to output radiation received from the second optical port; one or more amplifier stages (216) connected in series, together having an optical input (216a) optically coupled to the second port of the circulator, and an optical output (216b); and a polarization detector (240) having an optical input optically coupled to the third port of the circulator. Thereby the polarization state of the amplified radiation can be determined using radiation backscattered from the amplifying stage.

An example of the disclosure is a laser apparatus including a master oscillator capable of outputting a pulse laser beam, a plurality of optical amplifiers disposed on an optical path of the pulse laser beam outputted from the master oscillator and configured to sequentially amplify the pulse laser beam, an optical reflector capable of passing the pulse laser beam therethrough and reflecting a self-oscillation beam generated in one of the plurality of optical amplifiers, and an optical absorber capable of receiving and absorbing the self-oscillation beam reflected by the optical reflector.