Gottingen, Germany
Gottingen, Germany

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Patent
Coherent GmbH | Date: 2015-11-11

MOPA apparatus includes a mode-locked fiber laser delivering seed-pulses to a regenerative amplifier. The seed-pulses are transported via one of two lengths of optical fiber. One of the lengths of fiber is significantly longer than the other, and significantly increases the duration of the seed-pulses. Amplified seed-pulses are compressed in a pulse-compressor. The pulse compressor delivers pulses having a pulse-duration of either a few picoseconds, or less than one picosecond, depending on whether the seed pulses are transported respectively by the longer or shorter of the lengths of optical fiber.


Patent
Coherent GmbH | Date: 2013-02-27

A master oscillator power amplifier (MOPA) system includes an oscillator having a neodymium-doped gadolinium vanadate gain-medium and delivering seed-pulses. A length of single mode fiber is used to broaden the spectrum of the seed pulse. An amplifier having a neodymium-doped yttrium vanadate gain-medium amplifies the spectrally broadened seed-pulses. The gain-spectrum of the amplifier partially overlaps the broadened pulse-spectrum, providing spectral selection of the seed-pulses in addition to amplification. This provides amplified output-pulses having a duration about one-third that of the corresponding seed-pulses.


A frequency-doubled OPS-laser having a desired output wavelength of 532 nm is tunable about that wavelength by a temperature tuned birefringent filter (BRF). The temperature of the BRF is varied while measuring transmission of a sample of the output through a Nd:YAG crystal having an absorption peak at a wavelength of about 532.4 nm. The peak is detected as a minimum of transmission and the temperature at which that minimum occurs is recorded. From wavelength-change-versus-temperature data for the BRF a temperature is calculated at which the output wavelength has the desired value and is maintained at that value to stabilize the output wavelength.


Patent
Coherent GmbH | Date: 2015-07-20

An apparatus for temporally dividing pulses from a train of optical pulses into angularly-separated beam paths is disclosed. The apparatus includes no more than one acousto-optic modulator (AOM) for each beam path. The AOMs are configured and arranged to maximize the angular separation of the beam paths and to maximize the energy of each divided pulse. Pulses on the separated beam paths have equal pulse energies and may be gated independently.


Patent
Coherent GmbH | Date: 2013-03-27

In a master oscillator plus power amplifier (MOPA) system, the oscillator is a passively Q-switched laser. The laser is triggered into passively Q-switched operation by operating an optical switch to resonantly couple back into the laser amplified stimulated emission generated by the amplifier.


Patent
Coherent GmbH | Date: 2013-07-12

A laser-resonator is terminated between an outcoupling mirror and a semiconductor saturable absorbing mirror (SESAM). A beam-translator including two spaced-apart mirrors is located in the laser resonator in a beam-path of laser radiation circulating in the laser-resonator. The two spaced apart mirrors are selectively rotatable as a pair about two axes perpendicular to each other for selectively translating an incidence point of the laser radiation on the SESAM.


Patent
Coherent GmbH | Date: 2013-09-09

A solid-state MOPA includes a mode-locked laser delivering a train of pulses. The pulses are input to a fast E-O shutter, including polarization-rotating elements, polarizing beam-splitters, and a Pockels cell that can be driven alternatively by high voltage (HV) pulses of fixed long and short durations. A multi-pass amplifier follows the E-O shutter. The E-O shutter selects every Nth pulse from the input train and delivers the selected pulses to the multi-pass amplifier. The multi-pass amplifier returns amplified seed-pulses to the E-O shutter. The shutter rejects or transmits the amplified pulses depending on whether the HV-pulse duration is respectively short or long. Transmitted amplified pulses are delivered to a transient amplifier configured for separately suppressing first-pulse over-amplification and residual pulse leakage.


An optically pumped laser oscillator or amplifier includes a laser head having a gain medium exhibiting polarization-dependent absorption along two crystallographic axes and a pump source producing a pump beam. The mediums absorption coefficients along both said crystallographic axes are equal or the difference between the absorption coefficients relative to the lowest absorption coefficients R=Abs(_(c)-_(a))/(min(_(c), _(a))) is reduced at least by a factor of two compared to the same relative difference between the two absorption coefficients at the mediums absorption peaks, used for conventional pumping by pumping with unpolarized or partially polarized pump light at a wavelength around which the average absorption coefficients along both of said crystal-lographic axes are equal or present a relative difference that is reduced by a factor of two or better compared to conventional pumping around the mediums absorption peaks.


Patent
Coherent GmbH | Date: 2012-07-02

Two excimer lasers have individual pulsing circuits each including a storage capacitor which is charged and then discharged through a pulse transformer to generate an electrical pulse, which is delivered to the laser to generate a light pulse. The time between generation of the electrical pulse and creation of the light pulse is dependent on the charged voltage of the capacitor. The capacitors are charged while disconnected from each other. The generation of the electrical pulses is synchronized by connecting the capacitors together for a brief period after the capacitors are charged to equalize the charging voltages. The capacitors are disconnected from each other before they are discharged.


Apparatus for homogenizing and projecting two laser-beams is arranged such that the projected homogenized beams are aligned parallel to each other in a first transverse axis and partially overlap in second transverse axis perpendicular to the first transverse axis. The projected homogenized laser-beams have different intensities in the second axis and the degree of partial overlap is selected such that the combined intensity of the laser beams in the second axis has a step profile.

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