We present a mode-locked VECSEL emitting 400-fs pulses at a 3 GHz repetition rate at 1040 nm, amplified by a cascaded ytterbium doped fiber amplifier system to an average power of 40 W. The 3-ps duration amplified pulses are recompressed to their original 400-fs duration using a high-throughput transmission grating compressor. The recompressed pulses are used to generate supercontinuum with two different photonic crystal fibers (PCFs); an all-normal dispersion PCF and a PCF with a zero-dispersion wavelength at 1040 nm, creating spectra with 20 dB bandwidths of 200 nm with 3.9 W average power and 280 nm with 2.5 W average power respectively.
We demonstrate a lithium triborate (LBO) optical parametric oscillator (OPO), which is synchronously pumped with a
pulse-compressed and frequency-doubled master-oscillator power-amplifier (MOPA) system consisting of a gain-switched
laser diode and a series of Ytterbium-doped fiber amplifiers. The 20ps pulses from the MOPA were
compressed in a transmission grating compressor down to 4.4ps with a throughput efficiency of ~70% and subsequently
frequency-doubled with an efficiency of ~60% in a 20mm long LBO to a maximum of ~25W. With a typical pump
power of 17W for the OPO, we obtained a maximum combined signal and idler output power of 2.5W (at 877nm) and
1.7W (at 1.3μm). Individually, a maximum signal power of up to 3.7W at 740 nm was obtained with a signal pulse
duration of ~3.2ps. The OPO was widely tunable from 651nm-1040nm (signal) and from 1081nm-2851nm (idler). To
the best of our knowledge, this is the highest output power from a green-pumped LBO OPO. The fiber-based pump
source can potentially be operated between 100MHz and 1GHz, which in combination with the few-picosecond pulses
and the near-IR tunability of the OPO is a very attractive source for nonlinear microscopy.
We report recent advances in the development of fibers for the delivery and generation of both single-mode and heavily
multimode laser beams as well as recent progress in fibers for supercontinuum generation in spectral regimes spanning
the visible to mid-IR.
We have performed numerical simulations to investigate the optimization of compound glass microstructured optical
fibers for mid IR supercontinuum generation beyond the low loss transmission window of silica, using pump
wavelengths in the range 1.55-2.25 mm. Large mode area fibers for high powers, and small core fiber designs for low
powers, are proposed for a variety of glasses. Modeling results showed that for Bismuth and lead oxide glasses, which
have nonlinearities ~10 x that of silica, matching the dispersion profile to the pump wavelength is essential. For
chalcogenide glasses, which have much higher nonlinearities, the dispersion profile is less important. The pump pulses
have duration of <1 ps, and energy <30 nJ. The fiber lengths required for generating continuum were <40 mm, so the
losses of the fibers were not a limiting factor. Compared to planar rib-waveguides or fiber-tapers, microstructured fiber
technology has the advantages of greater flexibility for tailoring the dispersion profile over a broad wavelength span, and
a much wider possible range of device lengths.
We review recent advances in Yb fiber lasers and amplifiers for high power short pulse systems. We go on to describe associated recent developments in fiber components for use in such systems. Examples include microstructured optical fibers for pulse compression and supercontinuum generation, and advanced fiber grating technology for chirped-pulse amplifier systems.
The combination of wavelength-scale features and design flexibility offered by holey fibers leads to a significanlty broader range of optical properties than is possible in conventional optical fibers. Of particular interest, holey fibers offer the combination of broadband single mode guidance and large mode areas, and such fibers are promising for high power delivery applications such as including laser welding and machining, and for fiber lasers and amplifiers. Holey fiber technology has now reached the point that km-lengths of polymer-coated fiber with less than 1 dB/km loss at 1550nm are possible. As well as being of fundamental scientific interest, the novel guidance properties of holey fibers can be exploited to develop technologically important devices. Here recent advances in holey fibers will be presented, with a particular focus on recent results in developing holey fiber-based lasers.