Femtosecond pulses at 20 GHz repetition rate through spectral masking of a phase modulated signal and nonlinear pulse compression.

We present a laser system capable of producing 190 femtosecond pulses at a repetition rate of 20 GHz. The spectral masking of a phase modulated diode laser is used to produce a train of picosecond pulses which are compressed using a fibre-grating compressor followed by subsequent adiabatic soliton compression to the femtosecond regime using a tapered photonic crystal fiber.

Mid-infrared Raman-soliton continuum pumped by a nanotube-mode-locked sub-picosecond Tm-doped MOPFA.

We demonstrate a mid-infrared Raman-soliton continuum extending from 1.9 to 3 µm in a highly germanium-doped silica-clad fiber, pumped by a nanotube mode-locked thulium-doped fiber system, delivering 12 kW sub-picosecond pulses at 1.95 µm. This simple and robust source of light covers a portion of the atmospheric transmission window.

All-fiber integrated 10 GHz repetition rate femtosecond laser source based on Raman compression of pulses generated through spectral masking of a phase-modulated diode.

We report the development of a 10 GHz repetition rate all-fiber integrated femtosecond source tunable around 1.55 µm. A phase modulator and sharp spectral filter are used to convert the output of a tunable CW diode to a 10 GHz pulse train. These pulses are compressed using Raman soliton adiabatic compression in a 21 km long length of fiber to generate sub-300-fs duration pulses at a 10 GHz repetition rate. By tuning the wavelength of the diode and appropriate filtering, similar performance was achieved over a 20 nm bandwidth.

Amplification of picosecond pulses and gigahertz signals in bismuth-doped fiber amplifiers.

We demonstrate the capability for amplification of picosecond pulses in two bismuth-doped alumosilicate fibers. A spectrally filtered supercontinuum source is used to provide a train of picosecond pulses at discrete wavelengths within the gain bandwidth of bismuth fiber amplifiers. With a 30 m length of active fiber, a small signal gain at 1160 nm of over 20 dB is observed. In addition, we assess the viability of amplification of high repetition rate signals in such amplifiers, applying a 10 GHz modulation to a continuous wave Raman fiber laser operating at 1178 nm, finding that such signals are amplified without noticeable distortion.

Long wavelength extension of CW-pumped supercontinuum through soliton-dispersive wave interactions.

A supercontinuum spanning over 700 nm with an average spectral power of 1.7 mW/nm and flatness of 6 dB was produced in a solid core, double zero dispersion wavelength photonic crystal fiber pumped with a high power, continuous-wave ytterbium fiber laser. The spectrum displays a strong feature centered around 1980 nm. Through numerical simulations we demonstrate that this feature is initially generated through the shedding of Cherenkov radiation by solitons at the second zero dispersion wavelength, and then extended by a four-wave mixing process between this generated dispersive component and other solitons forming the continuum.