Planar waveguide-coupled, high-index-contrast, high-Q resonators in chalcogenide glass for sensing

Abstract

High-index-contrast, compact microdisk resonators in thermally evaporated As 2 S 3 and Ge 17 Sb 12 S 71 chalcogenide glass films are designed, fabricated using standard UV lithography and characterized. Our pulley coupler configuration demonstrates coupling of the resonators to monolithically integrated photonic wire waveguides without resorting to demanding fine-line lithography. Microdisk resonators in As 2 S 3 support whisperinggallery-mode with cavity quality factors (Q) exceeding 2 × 10 5 , the highest Q value reported in resonator structures in chalcogenide glasses to the best of our knowledge. We have successfully demonstrated a lab-on-a-chip prototype sensor device with the integration of our resonator with planar microfluidic systems. The sensor shows a refractive index sensitivity of 182 nm/RIU (refractive index unit) and a wavelength resolution of 0.1 pm through resonant peak fit. This corresponds to a refractive index detection limit of 8 × 10 -7 RIU at 1550 nm wavelength, which could be further improved

Integrated photonics for infrared spectroscopic sensing

“…Compared to the conventional coupler configuration, the pulley coupler design improves the fabrication tolerance by increasing the coupling strength [78]. Figure 4a shows the TE polarization transmission spectrum of the resonator.…”

Mid-infrared integrated optics: versatile hot embossing of mid-infrared glasses for on-chip planar waveguides for molecular sensing

“…Thus the group of Luther-Davies has reported postprocessing problems of crystallization of As-S rib waveguides which had been formed in thermally evaporated As-S films on a substrate of oxidized Si. 33 In addition, Hu et al 34 reported that they coated thermally evaporated As-S with SU8 polymer to "prevent surface oxidation of devices in As-S." Moreover, Hu et al 15 postheat-treated waveguides to "stabilize the glass structure." Yet no such problems were reported when they applied similar processing to form Ge-Sb-S rib waveguides, in which, purposefully, no additional upper cladding layer was added.…”

Substrate-blind photonic integration based on high-index glass materials

“…Subsequent device fabrication on ChG films were performed using lift-off 15 or thermal nanoimprint [16][17][18] . Both methods are capable of generating sub-micron single-mode optical waveguides.…”