We have fabricated a bandgap-guiding hollow-core photonic crystal fiber (PCF) capable of transmitting and compressing ultrashort pulses in the green spectral region around 532 nm. When propagating subpicosecond pulses through 1 m of this fiber, we have observed soliton-effect temporal compression by up to a factor of 3 to around 100 fs. This reduces the wavelength at which soliton effects have been observed in hollow-core PCF by over 200 nm. We have used the pulses delivered at the output of the fiber to machine micrometer-scale features in copper.

We have demonstrated nonlinear propagation in a 3-cell hollow core photonic crystal fiber. The reduced core size increases the nonlinear coefficient of the guided mode. However, the reduction in the expected soliton energy is small (a factor of approximately 2) as the dispersion of this fiber is also increased by the smaller core. We also demonstrate soliton compression using a 35m 7-cell tapered fiber, compressing picosecond input pulses by over an order of magnitude.

A scalable and accurate technique for measuring the group index and dispersion of optical fibers is used to provide the first accurate measurements of dispersion slope in hollow-core photonic band-gap fibers. We present data showing group index, group-velocity dispersion and dispersion slope in hollow-core fibers guiding at both 800 nm and 1064 nm wavelength.

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The next generation high bandwidth optical links from earth to space will requirement the development of new high power WDM sources. In this paper G&H present the latest results of their ongoing development of these sources. Namely the development and testing of a 50W optical fibre amplifier that operates across much of Cband is presented as well as a high power wavelength division multiplexer, designed to combine multiple high power amplifiers outputs into a diffraction limited beam.