We demonstrate broadband wavelength conversion of a 40 Gb/s return-to-zero signal by cross-phase modulation in a newly developed chalcogenide glass waveguide based photonic chip. These new serpentine As_2S_3 waveguides offer a nonlinear coefficient ≈1700 W^-1km^-1 with 5× lower propagation loss over a length of 22.5 cm which ensures the full propagation length contributes towards the nonlinear process. This reduces the peak operating power thereby allowing a ×4 increase in the data rate compared with previous results. Spectral measurements show the device operates over a span of 40 nm while system measurements show just over 1 dB of power penalty at a bit-error rate of 10^-9. This is primarily due to the compact planar waveguide design which minimizes the effect of groupvelocity dispersion.