Showing papers by "Andreas Tünnermann published in 2002"
TL;DR: It is reported on the generation of linearly chirped parabolic pulses with 17-W average power at 75 MHz repetition rate and diffraction-limited beam quality in a large-mode-area ytterbium-doped fiber amplifier.
Abstract: We report on the generation of linearly chirped parabolic pulses with 17-W average power at 75 MHz repetition rate and diffraction-limited beam quality in a large-mode-area ytterbium-doped fiber amplifier. Highly efficient transmission gratings in fused silica are applied to recompress these pulses down to 80-fs with an efficiency of 60%, resulting in a peak power of 1.7 MW. Power scaling limitations given by the amplifier bandwidth are discussed.
244 citations
TL;DR: It is demonstrated that by changing only the writing speed, waveguides with a controllable mode number can be produced.
Abstract: With tightly focused femtosecond laser pulses, waveguides are fabricated in fused silica. The guiding and attenuation properties of these waveguides at wavelengths of 514 nm and 1.5 microm are studied. We demonstrate that by changing only the writing speed, waveguides with a controllable mode number can be produced.
219 citations
TL;DR: In this paper, a fiber-based amplification of a Q-switched Nd:YAG thin-disk laser was presented, achieving up to 4 mJ with diffraction-limited beam quality in a 30-μm Yb-doped large-mode-area fiber.
Abstract: We report on the fiber-based amplification of a Q-switched Nd:YAG thin-disk laser. At repetition rates between 3 and 50 kHz output powers up to 100 W are generated. Pulse energies up to 4 mJ, with diffraction-limited beam quality, are generated in a 30-μm Yb-doped large-mode-area fiber, furthermore pulse energies up to 8 mJ are achieved from a multimode fiber amplifier.
154 citations
TL;DR: In this article, spectral compression due to self-phase modulation was demonstrated for ultrashort pulses in a fiber amplifier with peak powers of several kW at a repetition rate of 74 MHz and diffraction-limited beam quality.
Abstract: In a fiber amplifier, spectral compression due to self-phase modulation is demonstrated for ultrashort pulses. We report the generation of near-transform-limited picosecond pulses with peak powers of several kW at a repetition rate of 74 MHz and diffraction-limited beam quality in a Yb-doped fiber amplifier when seeding with a negative chirped pulse.
42 citations
03 Feb 2002
TL;DR: In this paper, spectral compression due to self-phase modulation (SPM) is demonstrated for ultrashort pulses in a fiber amplifier. Butts et al. reported the generation of nearly transform-limited picosecond pulses with peak powers of several kW at a repetition rate of 74 MHz and diffraction-limited beam quality in an Yb-doped fiber amplifier when seeding with a negative chirped pulse.
Abstract: In a fiber amplifier spectral compression due to self-phase modulation (SPM) is demonstrated for ultrashort pulses. We report on the generation of nearly-transform- limited picosecond pulses with peak powers of several kW at a repetition rate of 74 MHz and diffraction-limited beam quality in an Yb-doped fiber amplifier when seeding with a negative chirped pulse.
35 citations
03 Feb 2002
TL;DR: In this paper, a diode-pumped ytterbium-doped low-NA large mode area fiber based chirped pulse amplification system was presented, which achieved 125 W average power at a repetition rate of 75 MHz and diffraction limited beam quality.
Abstract: We report on a diode-pumped ytterbium-doped low-NA large mode area fiber based chirped pulse amplification system delivering 125 W average power at a repetition rate of 75 MHz and diffraction limited beam quality. Femtosecond laser pulses at 1060 nm center wavelength are stretched in a single mode fiber and recompressed after amplification to 350 fs pulse duration.
21 citations
03 Feb 2002
TL;DR: In this paper, the suppression of higher order transverse modes in rare earth-doped multimode fiber amplifiers is analyzed and an efficient gain-loss-management single transverse mode operation can be enforced in fibers with core diameters up to several 10 μm to 100 μm.
Abstract: The suppression of higher order transverse modes in rare-earth-doped multimode fiber amplifiers is analyzed. Applying an efficient gain-loss-management single transverse mode operation can be enforced in fibers with core diameters up to several 10 μm to 100 μm.
16 citations
24 May 2002
TL;DR: In this paper, a double-closeness double-clad fiber was demonstrated at two separated diode laser wavelengths (808 nm and 940 nm) with a combined output at 1.1 /spl mu/m.
Abstract: Summary from only given. We report on a neodymium-ytterbium-codoped fiber which can be pumped at two separated diode laser wavelengths (808 nm and 940 nm). The combined output at 1.1 /spl mu/m represents a scalability of double-clad fiber lasers by a factor of 2.
13 citations
TL;DR: In this article, a praseodymium-ytterbium-doped multimode upconversion ZBLAN fiber laser with high brightness multimode diodes was demonstrated.
Abstract: A praseodymium-ytterbium-doped multimode upconversion ZBLAN fibre laser pumped with high brightness multimode diodes at 850 nm is demonstrated. With a pump power of 6.5 W an output power >2 W at 635 nm and 0.3 W at 520 nm has been achieved.
12 citations
24 May 2002
TL;DR: In this article, the first time to our knowledge, a multi millijoule system with repetition rates in the 10 kHz range has been reported, and the setup of the high power and high energy Yb-doped fiber amplifier is shown.
Abstract: Summary from only given. We report for the first time to our knowledge on a multi millijoule system with repetition rates in the 10 kHz range. The setup of the high power and high energy Yb-doped fiber amplifier is shown. As a nanosecond seed source a Q-switched Nd:YAG disk laser is applied the laser delivers average powers up to 2.5 W.
11 citations
TL;DR: An integrated-optical unbalanced Mach-Zehnder interferometer in lithium niobate is demonstrated for detecting wavelength shifts of light sources, such as laser diodes and superluminescentdiodes at lambda = 844 nm, with high accuracy over a temperature range from 10 degrees C to 40 degrees C.
Abstract: We demonstrate an integrated-optical unbalanced Mach-Zehnder interferometer in lithium niobate for detecting wavelength shifts of light sources, such as laser diodes and superluminescentdiodes at λ = 844 nm. The output signal can be used to stabilize the light source. Because of the temperature dependence of the effective refractive index and the thermal expansion of the substrate, the device acts also as a temperature sensor. The temperature sensitivity of the interferometer was compensated for by the combination of proton exchanged- and annealed proton exchanged-channel waveguides by approximately two orders of magnitude. The thermo-optic coefficients of the extraordinary effective refractive index in integrated optical channel waveguides in LiNbO3 have been measured with high accuracy over a temperature range from 10 °C to 40 °C.
24 May 2002
TL;DR: In this article, a femtosecond seed source was used as a femto-glass laser system, which consists of a passively mode-locked, diode-pumped solid-state oscillator, a fiber stretcher, an ytterbium-doped single-mode preamplifier, a large-mode-area power amplifier and a diffraction-grating compressor.
Abstract: Summary from only given. The high average power femtosecond laser system consists of a passively mode-locked, diode-pumped solid-state oscillator, a fiber stretcher, an ytterbium-doped single-mode preamplifier, a ytterbium-doped low-numerical aperture large-mode-area power amplifier and a diffraction-grating compressor. As a femtosecond seed source a passively mode-locked Nd:glass laser system is used.
19 May 2002
TL;DR: In this article, the authors have experimentally demonstrated waveguiding along defect channels in photonic crystal films made from low index materials, and showed that the waveguide losses are below 3.5 dB/mm.
Abstract: Summary from only given. We have experimentally demonstrated waveguiding along defect channels in photonic crystal films made from low index materials. The waveguiding losses are below 3.5 dB/mm. A proper design of the basic crystal allows for a polarization sensitive transmission of the guides.
01 Jan 2002
TL;DR: In this paper, the authors report on the 5 W average power, supercontinuum generation in different air-silica microstructered fibers using a compact largemode-area ytterbium-doped femtosecond fiber amplifier at 1060 nm center wavelength as the excitation source.
Abstract: We report on the 5 W average power, supercontinuum generation in different air-silica microstructered fibers using a compact large-mode-area ytterbium-doped femtosecond fiber amplifier at 1060 nm center wavelength as the excitation source. The flat continuum ranges from 1800 nm. The experimental results are confirmed by numerical simulations, revealing the evolution and fission of higher order solitons as the main contribution to the continuum.