Flexible Optical Amplifier for Visible-Light CommunicationsBased on Organic–Inorganic Hybrids

摘要

Visible-light communications (VLCs) based on white light-emitting diodes (LEDs) are emerging as a low-cost and energy-efficient alternative solution to wireless communications. As white emitting LEDs use a combination of a long-lived yellow emission combined with the faster response of a blue emitting LED (∼460 nm), VLC technology requires amplification of the blue component to improve the signal-to-noise ratio. We report the fabrication and characterization of planar and channel waveguides based on a blue-emitting polyfluorene conjugated polyelectrolyte, namely, poly[9,9-bis(4-sulfonylbutoxyphenyl)fluorene-2,7-diyl-alt-1,4-phenylene] (PBS-PFP) incorporated into diureasil organic–inorganic hybrids for optical amplification in VLC. Taking advantage of the diureasil host as a UV self-patternable material, direct UV laser writing was used to pattern channel waveguides with a larger refractive index (Δn=0.09) compared to the nonexposed region, enabling confinement and guidance of the PBS-PFP emission with a maximum optical gain efficiency value of 1.62 ± 0.02 cm μJ^–1. This value is among thebest figures of merit known for polymeric materials with additionaladvantages added by the diureasil hybrid host, namely, mechanicalflexibility, thermal stability, and low insertion losses due to thenearly null refractive index contrast between the optical fiber andthe amplification device, establishing the proposed approach as apromising cost-effective solution for optical amplification in VLCs.