Investigation of silver-only and silver / TOPAS ® coated hollow glass waveguides for visible and NIR laser delivery

Hollow Glass Waveguides (HGWs) present a viable option for the low-loss transmission of radiation over a broad range spanning from visible to far-infrared wavelengths. Cyclic Olefin Copolymer (COC), a commercially available polymer known as TOPAS ® , is chosen for this study due to its exceptionally low absorption losses throughout the spectrum, particularly in the visible and near-infrared (NIR) regions. While silver-coated HGWs are capable of transmitting visible and NIR radiation with low losses, theory predicts that the addition of a uniform dielectric thin film of quarterwavelength thickness will reduce these losses for both straight and bent configurations, while additionally providing a potentially more desirable modal output for laser applications. In this paper, the procedures for the deposition of the silver and subsequent COC films are outlined. Spectroscopy is used to obtain the thickness of the polymer film. The theoretical attenuation losses of the silver and Ag/COC HGWs are explored and experimental values are obtained using various visible and IR lasers. Moreover, the modal output of the silver and Ag/COC HGWs is qualitatively compared. The possibility of use of these Ag/COC HGWs at midand far-IR wavelengths is discussed.