Abstract: 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.

Abstract: 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.

Abstract: The present invention is directed to a chirped dichroic mirror comprising a stack of alternating high refractive index and low refractive index layers, a front end portion including an antireflective coating followed by an impedance matching region in which the ratio of the optical thickness of a high refractive index layer to the optical thickness of the next following low refractive index layer is adiabatically increasing to a first value, the impedance matching region being followed by a chirped mirror region where the Bragg wavelength of the layer pair is generally increasing or generally decreasing, characterized in that the layers in a back end region form a second impedance matching region in which the ratio of the optical thickness of a high refractive index layer to the optical thickness of the next following low refractive index layer starts at the value of this ratio in the adjacent chirped mirror region and is then adiabatically decreasing in order to provide matched impedance to the surrounding m

Abstract: A balanced optical-RF phase detector for the extraction of low-jitter radiofrequency (RF) signals from optical pulse trains is demonstrated. The extraction of the low-jitter radiofrequency signals is based on the precise phase detection by use of a differentially biased Sagnac-loop interferometer and synchronous detection. The phase-error signal from this balanced optical-RF phase detector, which is robust against drifts and photodetector nonlinearities, is used to regenerate low-jitter radiofrequency signals from optical pulse trains. Alternatively, the phase-error signal is used to generate a low-jitter optical pulse train, synchronized with a master radiofrequency signal or to synchronize multiple modelocked lasers with each other.

Abstract: The carrier-envelope phase in a train of optical pulses is varied utilizing the dispersive properties of lossless plates while the total dispersion in transmission is maintained practically constant. The plates include sloped surfaces and are mounted for displacement such that the ratio of the thicknesses of the two plates through which the optical pulses will pass can be varied by displacing the plates so as to shift the carrier-envelope phase in the optical pulses. In one embodiment, the plates include a barium fluoride wedge and a fumed silica wedge, wherein the wedges are bond together to form a composite structure with thicker and thinner portions of the wedges inversely matched.

Abstract: The phase spectrum of an ultrashort pulse is measured based on two-dimensional spectral shearing interferometry with zero delay. The measurement is performed utilizing an optical source pulse from which is extracted a short pulse and from which a chirped component is generated. The chirped component is split into first and second chirped pulses. The first and second pulses are then mixed with the short pulse in a nonlinear medium to produce up-converted and spectrally sheared copies of the first and second chirped pulses, which are measured in a spectrometer. A plurality of path lengths for the first second chirped pulses is provide to generate delays and shift the relative positions of the first and second chirped pulses for additional measurements. The apparatus and methods are uniquely suited for characterizing single-cycle pulses.

Abstract: A simple and low-cost apparatus amplifies short optical pulses (e.g., in the femtosecond domain) to high pulse energies using energy stored in an enhancement cavity. The enhancement cavity is first filled with pump light from a pump laser; and a signal laser then directs a signal pulse into the cavity, where the signal pulse and pump laser both pass through a non-linear medium for parametric amplification of the signal pulse, wherein energy from the aggregated pump light is transferred to the signal pulse, which then exits the enhancement cavity.

Abstract: A laser system for generating self-starting few cycle laser pulses or widely tunable laser pulses is provided. The laser system includes a modelocked pump source that provides a pulsed pump signal. A gain medium receives the pulsed pump signal. A resonator structure includes the gain medium and a plurality of mirrors. The resonator structure defines a laser operated in a CW-modelocked regime generating few-cycle laser pulses having a duration less then 30 fs.

Abstract: An x-ray source that can produce high-brilliance x-rays at a low cost and from a small footprint includes a radiofrequency (RF) photoinjector, an accelerator module (such as a linear superconducting accelerator moducle), a high-power optical laser apparatus, and a passive enhancement cavity. A stream of photons generated by the laser apparatus is accumulated in the enhancement cavity, and an electron stream from the photoinjector are then directed through the enhancement cavity to collide with the photons and generate high-brilliance x-rays via inverse-Compton scattering.

Abstract: A beam splitter includes a substrate. A thin film layer stack is formed on the substrate to achieve the same group delay dispersion (GDD) for both reflection and transmission from any input port and output port of said beam splitter.

Abstract: An opto-electronic modulator includes a Mach-Zehnder structure that comprises p+in+-diodes in both arms of the Mach-Zehnder structure. The Mach-Zehnder structure is formed by waveguides so as to confine an optical mode in the opto-electronic modulator.

Abstract: A RF-synchronization system includes a laser that creates pulse trains for synchronization. A modulation means transfers the timing information of the pulse train into an amplitude modulation of an optical or electronic system. A synchronization module changes the driving frequency of the modulation means until it reaches a phase-locked state with the pulse train.

Abstract: An optical semiconductor includes a first semiconductor layer and at least one reflective element that is formed on the semiconductor layer. The at least one reflective element comprises alternating layers of high and low index layers. A crystalline semiconductor layer is formed on the at least one reflective element.

Abstract: An optical reflector includes an optical reflective element that comprises alternating layers of high and low index layers. A new substrate is bonded on the optical reflective element. The sequence of layers in the reflective element is reversed in order such that the layers grown first with lowest surface roughness are exposed to the highest electric field strength, and the layer grown last, of highest roughness, are buried deep in the multilayer stack.