Record-high sensitivity compact multi-slot sub-wavelength Bragg grating refractive index sensor on SOI platform

S. HEINSALU*, Y. ISOGAI, Y. MATSUSHIMA, H. ISHIKAWA, K. UTAKA

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

In this paper, a high sensitivity compact multi-slot sub-wavelength Bragg grating refractive index (RI) sensor was investigated. The structural parameters were optimized for higher sensitivity to RI change of the surrounding medium from viewpoints of a wavelength shift, an extinction ratio and a transmission loss, and a record-high sensitivity was experimentally demonstrated with a compact size. In this sensor, the first side-lobe at the Bragg grating (BG) stop-band end was focused as a sensing peak wavelength for moderate transmission loss and efficient sensing. To realize the compactness, a period count of the BG was kept as small as 20. By increasing the RI of the surrounding medium, the sensing peak shifts toward a longer wavelength side; thus due to the high sharpness and easy tracing of the first side-lobe, the device worked as an efficient RI sensor. The structural optimization was carried out by using 3D finite-difference time-domain (FDTD) simulation approach, and also influences of the structural parameters to sensitivities were discussed. Based on these optimized parameters, the devices were fabricated using the lift-off technique. By exposing the sensor to various liquid samples with different RIs such as pure water, sugar-dissolved water with various concentrations, acetone and isopropyl alcohol (IPA), a record-high sensitivity of 730 nm/RIU was attained for a sensor fabricated on SOI platforms with a length of as small as 9.5 μm and a transmission loss of 3 dB.

Original languageEnglish
Article number402672
JournalOptics Express
Volume28
Issue number19
DOIs
Publication statusPublished - 2020 Sep

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Fingerprint

Dive into the research topics of 'Record-high sensitivity compact multi-slot sub-wavelength Bragg grating refractive index sensor on SOI platform'. Together they form a unique fingerprint.

Cite this