Transmission characteristics of femtosecond laser pulses in a polymer waveguide.

Abstract

Femtosecond lasers have been widely employed in scientific and industrial applications, including the study of material properties, fabrication of structures on the sub-micrometer scale, surgical and medical treatment, etc. In these applications, the ultrafast laser is implemented either in free space or via an optical fiber-based channel. To investigate the light-matter interaction on a chip-based dimension, laser pulses with extremely high peak power need to be injected into an integrated optical waveguide. This requires the waveguide to be transparent and linear at this power, but also capable of providing a highly efficient and reliable interface for fiber-chip coupling. Contrary to the common belief that polymer materials may suffer from stability issues, we show that a polymer waveguide fabricated under simple and low-cost technology using only commercial materials can indeed transmit femtosecond laser pulses with similar characteristics as low-power continuous-wave laser. The coupling efficiency with a lensed fiber is ∼76% per facet. The pulse broadening effect in the polymer waveguide is also well fitted by the material and waveguide dispersion without nonlinear behavior. This study paves the way for developing a low-cost, highly efficient, polymer-based waveguide platform for the investigation of ultrafast phenomena on a chip.