Highly birefringent silicate glass photonic-crystal fiber with polarization-controlled frequency-shifted output: A promising fiber light source for nonlinear Raman microspectroscopy.

A highly birefringent silicate glass photonic-crystal fiber (PCF) is employed for polarization-controlled nonlinear-optical frequency conversion of femtosecond Cr: forsterite laser pulses with a central wavelength of 1.24 mum to the 530--720-nm wavelength range through soliton dispersion-wave emission. The fiber exhibits a modal birefringence of 1.2.10(-3) at the wavelength of 1.24 mum due to a strong form anisotropy of its core, allowing polarization switching of the central wavelength of its blue-shifted output by 75 nm. Polarization properties and the beam quality of the blue-shifted PCF output are shown to be ideally suited for polarization-sensitive nonlinear Raman microspectroscopy.