Polarization-dependent blue-shifted emissions in microstructure fibers

Trefoil and quatrefoil channels between air holes of two microstructure fibers can strongly confine light field and act as highly nonlinear waveguides. Polarization-dependent blue-shifted emissions of femtosecond Ti:sapphire laser pulses were carried out in these channels. The spectra bandwidth of blue-shifted emissions in a trefoil channel is narrower than 10 nm and can be tuned slightly by altering the polarization state of pump light. Polarization-dependent blue-shifted emissions from a quatrefoil channel lie in a hollow beam having potential use in optical tweezers.