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

Abstract

We propose and experimentally demonstrate a series of L n 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 n holes replaced by a slot, which do not require sophisticated design or high fabrication resolution. With the increase in n, the quality factor of the cavity exponentially increases, which is explained by the envelope of electric field approaching a Gaussian profile. An L 9 slot PhC microcavity with a quality factor exceeding 30 000, sensitivity of 421 nm per RI unit (RIU), and detection limit down to 1 Â 10 À5 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.

Surface-sensitive diamond photonic crystals for high-performance gas detection

“…Since there is no chemisorption reaction expected between N 2 and diamond, the frequency shift can be attributed to a change of the refractive index of the surrounding medium of the PhC. From the value of the refractive index of nitrogen at ambient temperature, namely n nitrogen 1.00028, we estimate a sensitivity S Δλ∕Δn ≈ 0.1∕2.8 × 10 −4 360 nm∕RIU (refractive index unit), a value similar to that obtained with silicon photonic crystals [2,19,20]. We also calculated the slotted PhC sensitivity with 3D-FDTD simulations.…”

Optical Refractive Index Sensors with Plasmonic and Photonic Structures: Promising and Inconvenient Truth

“…For example, L 13 PCC has the RI sensitivity of 51.27 nm/RIU, which is higher than that of L 7 PCC (37.4 nm/RIU) and L 3 PCC (24.5 nm/RIU) [521]. To improve the sensitivity, some modifications to the L n PCCs have been proposed, such as inserting holes [506,523], integrating slots in the cavity [96,524], or modifying the locations and sizes of the neighboring holes [507]. As shown in Figure 11, panel C, a, by introducing a single-hole defect in the L 3 cavity, the single-hole defect L 3 PCC exhibited the 11% enhancement in the RI sensitivity, and it was further enhanced by 18% with three holes defect [506].…”

“…(WGM) resonator sensors [92][93][94][95]. On the other hand, the highest FoM is reaching 100,000 RIU −1 , which appears for various dielectric-based RI sensors such as PCC sensors [96,97] and WGM resonator sensors [98][99][100]. Fourthly, majority of dielectric-based photonic RI sensors operate at near infrared (NIR) wavelength range, whereas metal-based plasmonic RI sensors expand its working wavelength from visible to NIR.…”

Progress of infrared guided-wave nanophotonic sensors and devices

“…Slot PhC cavities combine the advantages of the spatial confinement by slot and the temporal confinement by PhC cavity. Hetero [83,84] and Ln [85] slot PhC cavities have been demonstrated for biochemical sensing applications. The slot design has also been adopted in a phaseshifted Bragg grating sensor [86].…”