Picosecond Fiber MOPA Pumped Supercontinuum Source With 39 W Output Power

We report a picosecond fiber MOPA pumped supercontinuum source with 39 W output, spanning at least 0.4-2.25 µm at a repetition rate of 114.8 MHz. The 2m long PCF had a large, 4.4 µm diameter core and a high-delta design which led to an 80% coupling efficiency, high damage threshold and rapid generation of visible continuum generation from the picosecond input pulses. The high and relatively uniform power density across the visible spectral region was ~31.7 mW/nm corresponding to peak power density of ~12.5 W/nm for the 21 ps input pulses. The peak power density was increased to 26.9 W/nm by reducing the repetition rate to 28 MHz. This represents an increase in both average and peak power compared to previously reported visible supercontinuum sources from either CW pumped or pulsed-systems

Soliton transmission and supercontinuum generation in holey fiber using a diode pumped ytterbium fiber source

We report linear dispersion compensation, soliton pulse formation, soliton compression, and ultra-broad supercontinuum generation in a holey fiber with anomalous dispersion at wavelengths above 800nm. The holey fiber was seeded with ultrashort pulses from a diode pumped, Ytterbium (Yb)-doped fiber source operating at 1.06µm. The results highlight the compatibility of the rapidly developing holey fiber technology with short pulse Yb-doped fiber lasers for wide application

Optimisation of short pulse multi-stage Yb fiber amplifier systems using commercial gain-modelling software

We demonstrate the accuracy of commercial telecommunications industry software for modelling Yb-fiber amplifiers. Simulations enabled optimisation of a broad bandwidth ultra-short pulse four-stage amplifier system. The predicted results were confirmed by experiments

Supercontinuum generation with femtosecond pulse fiber amplified VECSELs

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

Robust, high peak power, thulium-doped fiber chirped-pulse amplification system using a dissipative soliton seed laser

We report a dissipative soliton seeded, thulium-doped fiber chirped pulse amplification system at 1950 nm. The amplified pulses are compressed to 545 fs and have an energy of 0.85 μJ corresponding peak power of 1.56 MW.</p

Simulations and experiments showing the origin of multi-wavelength mode locking in femtosecond, Yb-fiber lasers

A stable and self-starting femtosecond breathing-pulse Yb-fiber oscillator is reported, modelocked using the nonlinear polarisation evolution mechanism. A bifurcation between two distinct modes of operation is demonstrated experimentally, producing pulses with a single central wavelength in one state, or following adjustment of the intra-cavity waveplates, the emission of pulses with three distinct central wavelengths. The maximum bandwidth was 72 nm at the -10 dB level and the pulses were compressible externally to 70 fs with energies of 0.75 nJ. The multi-wavelength pulses reported here are significantly shorter than the pico-second pulses previously observed from similar modelocked multi-wavelength sources. Vector simulations based on the nonlinear Schrödinger equation show that the multi-wavelength behaviour is produced by overdriving the nonlinear polarisation evolution based saturable absorber at the peak of the pulse, leading to transmission of the two wings of the strongly chirped pulse. This new insight shows clearly that the three pulses output in the multi-wavelength state are coherent. The agreement between simulation and experimental data shows nonlinear polarisation evolution based modelocked fiber lasers are a suitable platform for studying the nonlinear dynamics underlying the bifurcation of the output

Ultrashort-pulse Yb3+-fiber-based laser and amplifier system producing &gt;25-W average power

We have demonstrated an ultrashort-pulse Yb3+-fiber laser and amplifier system that produces &gt;400-nJ pulses at a repetition rate of 62 MHz (&gt;25-W average power). The output pulses were recompressed to a duration of 110 fs with good pulse quality by use of a standard bulk grating-based compressor

Determination of the mid-IR femtosecond surface-damage threshold of germanium

To assess the potential uses of germanium as a nonlinear material in the mid IR we have measured the surface-damage threshold of germanium optical windows using femtosecond pulses at a wavelength of 3.9 µm. By working with a wavelength corresponding to a photon energy of less than half the band-gap energy, free-carrier generation due to one- and two-photon absorption was eliminated. The laser pulses had an energy of 5.5 µJ, a duration of 255 fs, and were focused to a waist size of approximately 100 µm. The multi-shot damage threshold of the germanium windows was estimated to be approximately 94 GW/cm2. The data should be of immediate benefit to industrial laser researchers and applications engineers working in the mid-IR region

Efficient high-harmonic generation from a stable and compact ultrafast Yb-fiber laser producing 100 micro-joule, 350 fs pulses based on bendable photonic-crystal fiber

The development of an Yb3+-fiber based chirped-pulse amplification system and the performance in the generation of extreme ultraviolet (EUV) radiation by high-harmonic generation is reported. The fiber laser produced 100 µJ, 350 fs output pulses with diffraction limited beam quality at a repetition rate of 16.7 kHz. The system used commercial single-mode, polarization maintaining fiber technology. This included a 40 µm core, easily packaged, bendable final amplifier fiber in order to enable a compact system, to reduce cost, and provide reliable and environmentally stable long term performance. The system enabled the generation of 0.4 µW of EUV at wavelengths between 27-80 nm with a peak at ~45 nm using xenon gas. The EUV flux of ~1011 photons per second for a driving field power of 1.67 W represents state-of-the-art generation efficiency for single-fiber amplifier CPA systems, corresponding to a maximum calculated energy conversion efficiency of 2.4 x 10-7 from the infra-red to the EUV. The potential for high average power operation at increased repetition rates and further suggested technical improvements are discussed. Future applications could include coherent diffractive imaging in the EUV, and high-harmonic spectroscopy

Cladding pumped Ytterbium-doped fiber laser with holey inner and outer cladding

We have fabricated an ytterbium doped all-glass double-clad large mode area holey fiber. A highly efficient cladding pumped single transverse mode holey fiber laser has been demonstrated, allowing continuous-wave output powers in excess of 1W with efficiencies of more than 80%. Furthermore both Q-switched and mode-locked operation of the laser have been demonstrated