Ultrafast optics in hollow-core fibers

01.01.2014, 00:00

Newsletter 7

The capture of ever-faster events, the conversion of light to higher frequencies and the attainment of strong effective nonlinearities are common themes in ultrafast optics. Although conventional optical fibers have provided remarkable advantages over bulk materials, gas-filled hollow-core fibre allows us to go to even more extreme intensities. By appropriate choice of gas pressure, the dispersion can be arranged to be anomalous at a pump wavelength of 1550 nm, permitting the excitation of a shape-preserving soliton, its duration being determined by the dispersion, pulse energy and core nonlinearity. Uniquely, a gaseous core makes these solitons possible even at ionizing intensities without damage to the system. A newly developed device enables a self-sustained interplay of extended ionization and soliton dynamics. Upon ionization, the abruptly dropping refractive index acts as a phase modulator, causing the soliton to experience a continuous upshift in frequency as it travels. The upshifting soliton adjusts adiabatically to the varying conditions at shorter wavelength by reducing its duration and increasing its peak intensity, causing further ionization. As a result, self-compression down to single-cycle durations together with simultaneous self-frequency-shifting by more than an octave can be obtained in an integrated all-fiber system. 

Contact: john.travers@mpl.mpg.de
Group: Russell Division
Reference: W. Chang et al., Opt. Lett.  38, 2984-2987 (2013).