Third order nonlinearity of a PFCB polymer core rib waveguide

Abstract

PFCB is a semi-fluorinated polymer suitable for integrated optics due to its low absorption at the telecommunication wavelength range, compatibility with standard fabrication tools and processes, and thermomechanical robustness. In this work we report the fabrication and characterization of waveguides optimized for Kerr nonlinearity enhancement, comprised of PFCB core and optical-grade Cytop cladding having a 10% index contrast and supporting single-mode operation with an effective mode area of 4 µm2. Propagation loss of 0.9 dB/cm and 1 dB/facet coupling loss using lensed optical fibers having 2.5 µm spot size were obtained, leading to an effective length of Leff =0.82 cm. A nonlinear coefficient of γ=0.18 ± 0.03 (W·m)-1 was measured for both TE and TM polarizations using a four-wave mixing arrangement about 1.55 µm, with no observed nonlinear absorption. A relatively high Kerr coefficient of |n2|=1.9×10−15 cm2/W is derived for PFCB in the telecom wavelength range for the first time.