3C fiber technology advances the performance frontier of practical, high-pulse-energy fiber lasers by providing very large core fibers with the handling and packaging benefits associated with single mode fibers. First-generation fibers demonstrate scaling to > 240 W average power coincident with 100-kW peak power in 1-mJ, 10-ns pulses while maintaining single-mode beam quality, polarized output, and efficiencies > 70%. Peak powers over 0.5 MW with negligible spectral distortion can be achieved with sub ns, near-transform-limited pulses. In-development second-generation 3C Yb-fiber based on core sizes around 55 μm1 have produced >8 mJ, 13 ns pulses with peak powers exceeding 600 kW.
3C (Chirally-Coupled Core) optical fiber establishes a technological platform for high brightness, power scalable lasers
with an engineerable fiber geometry that enables robustly single-mode performance of large core diameter fibers. Here
we report the demonstration of robust polarization preserving performance of 35 μm core 3C fiber for short pulse
systems. A polarization extinction ratio (PER) of ~ 20 dB is stably maintained with ambient temperatures varying over a
50°C range from a Yb-doped double clad 3C fiber amplifier. We also demonstrate that this high-PER polarization
output is insensitive to temperature gradients and mechanical perturbations in the 3C fiber amplifier. The ability to
deliver high peak power pulses at high average powers while maintaining exceptional beam quality and a stable
polarization state in an easily integrated format makes 3C fiber laser systems extremely attractive for harmonic
generation to visible and UV wavelengths.
We report the energy scaling of mode-locked fiber lasers using a large-mode area chirally-coupled core fiber. This is a
demonstration of the scaling of ultrafast fiber oscillators to large cores in an all-solid glass package that holds the lowest
order fiber mode while maintaining compatibility with fiber fusion technology. An all-normal dispersion cavity design
yields pulse energies above 40 nJ that dechirp to durations below 200 fs. Using lower net dispersion, pulses dechirping
close to 100 fs are obtained with pump limited energies. Effectively single-mode operation is confirmed by beam quality
as well as spectral interference measurements.
It is shown that nanosecond to picosecond fluorescence relaxation phenomena can be accessed for imaging after double pulse saturation excitation. This new technique has been introduced before as fluorescence lifetime imaging (DPFLIm) (Mueller et al, 1995). An OPA laser system generating ultra short, widely tunable, high power optical pulses provides the means for the selective excitation of specific fluorophores at sufficient excitation levels to obtain the necessary (partial) saturation of the optical transition. A key element in the developed method is that the correct determination of fluorescence relaxation times does allow for non-uniform saturation conditions over the observation area. This is true for the validation demonstration experiments reported here as well as for imaging applications at a later stage. Measurements on bulk solutions of Rhodamine B and Rhodamine 6G in different solvents confirm the experimental feasibility of accessing short fluorescence lifetimes with this technique. As only integrated signal detection is required no fast electronics are needed, making the technique suitable for fluorescence lifetime imaging in confocal microscopy, especially when used in combination with bilateral scanning and cooled CCD detection.
A three stage optical parametric amplifier is pumped by a 250-kHz (mu) J level Ti:sapphire regenerative amplifier system. Broad-bandwidth pulses are produced by tuning each stage of the OPA system to amplify adjacent frequency components of a white-light continuum source. These broad-band pulses may be compressed with a standard prism compressor to pulse- widths of less than 30 fs.
Microjoule pulse energies are achieved from a single stage upconversion fiber amplifier for the first time in this demonstration of chirped pulse amplification using a multimode Tm:ZBLAN fiber. A Ti:sapphire laser system provides the seed pulse for the upconversion fiber amplifier which produces subpicosecond pulse trains with energies as great as 16 (mu) J at repetition rate of 4.4 kHz. The compressed pulse peak power is more than 1 MW, and the pulse is characterized both temporally and spatially.