A Hyperuniform Disordered Solid Waveguide for Gas Sensing

ABSTRACT Hyperuniform disordered solids (HUDS) are a class of emerging photonic bandgap materials that combine the macroscopic isotropy of disordered systems with the hidden long‐range order of hyperuniform systems, with great potential for applications in optoelectronics, optical communication, sensing, and spectroscopy. However, current HUDS waveguides typically possess weak evanescent fields, which limit the interaction between propagating light and its environment, thereby preventing chemical sensors from demonstrating their capabilities in HUDS‐based photonic integrated circuits. Here, we propose and demonstrate a subwavelength‐grating (SWG)‐embedded HUDS waveguide configuration to enhance evanescent fields of HUDS devices for highly sensitive on‐chip gas sensing. Our results show that the developed SWG‐embedded HUDS waveguide exhibits an enhanced external confinement factor of 0.42, accompanied by a propagation optical loss of 0.097 dB·µm −1 . By being functionalized with a CO 2 ‐sensitive material, polyhexamethylene biguanide hydrochloride (PHMB), a Mach‐Zehnder interferometer device with the SWG‐embedded HUDS waveguide exhibits a sensitivity of −2.91 pm·ppm −1 and a detection limit of ∼29 ppm for CO 2 refractive index sensing. Our study paves the way for developing chip‐integrated gas sensors with HUDS waveguide devices.