<inline-formula> <tex-math notation="TeX">$L_{n}$</tex-math></inline-formula> Slot Photonic Crystal Microcavity for Refractive Index Gas Sensing

• Main Authors: Kezheng Li, Juntao Li, Yanjun Song, Guisheng Fang, Chao Li, Ziying Feng, Rongbin Su, Biaohua Zeng, Xuehua Wang, Chongjun Jin
• Format: Article
• Language: English
• Published: IEEE 2014-01-01
• Series: IEEE Photonics Journal
• Subjects: Photonic Crystals; Sensors; Microcavity devices
• Online Access: https://ieeexplore.ieee.org/document/6910213/

We propose and experimentally demonstrate a series of <inline-formula> <tex-math notation="TeX">$L_{n}$</tex-math></inline-formula> slot photonic crystal (PhC) microcavities, which operate as refractive index (RI) gas sensors. The cavities are simply composed of a silicon slab triangular photonic crystal with <inline-formula> <tex-math notation="TeX">$n$</tex-math></inline-formula> holes replaced by a slot, which do not require sophisticated design or high fabrication resolution. With the increase in <inline-formula> <tex-math notation="TeX">$n$</tex-math></inline-formula>, the quality factor of the cavity exponentially increases, which is explained by the envelope of electric field approaching a Gaussian profile. An <inline-formula> <tex-math notation="TeX">$L_{9}$</tex-math></inline-formula> slot PhC microcavity with a quality factor exceeding 30&#x00A0;000, sensitivity of 421 nm per RI unit (RIU), and detection limit down to <inline-formula> <tex-math notation="TeX">$1\times 10^{-5}$</tex-math></inline-formula> RIU was experimentally demonstrated. The performance of the device is comparable with other fine-tuned PhC microcavity structures. Due to its simple structure and high fabrication tolerance, it could have wide applications in optical sensors.