Open AccessA refractive index sensor design based on grating-assisted coupling between a strip waveguide and a slot waveguide
Author(s) -
Qing Liu,
Jack Sheng Kee,
Mi Kyoung Park
Publication year - 2013
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.21.005897
Subject(s) - waveguide , optics , refractive index , materials science , grating , slot waveguide , sensitivity (control systems) , slotted waveguide , coupling (piping) , wavelength , arrayed waveguide grating , radiation mode , optoelectronics , optical fiber , wavelength division multiplexing , photonics , physics , single mode optical fiber , slot antenna , silicon photonics , telecommunications , electronic engineering , directional antenna , antenna (radio) , computer science , engineering , metallurgy
In this paper, we present a design of a refractive index sensor based on grating-assisted light coupling between a strip waveguide and a slot waveguide. The slot waveguide serves as the sensing waveguide while the strip waveguide is used for light launching and detection. The wavelength at which the light is coupled from the strip waveguide to the slot waveguide serves as a measure of the refractive index of the external medium. The sensitivity of the sensor is ~1.46 × 10(3) nm/RIU (refractive index unit) and can be almost doubled by isolating the strip waveguide from the external medium. The effects of the slot-waveguide parameters on the sensitivity have also been investigated. In particular, it is found that the sensor can achieve extraordinarily high sensitivity (on the order of 10(5) nm/RIU) when the group indices of two waveguides are close. The temperature dependence of the sensor is also investigated and a sensor with very low temperature dependence can be achieved with a polymer isolation layer.