Abstract
The design and modeling of a highly sensitive sensor based on a slot photonic crystal waveguide (slot-PCWG) is presented. The structure consists of cylindrical air rods drilled in a dielectric slab on a triangular lattice, which are filled with SiO2. The waveguide is formed by removing elements from the regular photonic crystal grid in a row, and embedding a slot in the center position. This concept allows for a vast enhancement of the evanescent field ratio, leading to a strong overlap between the field of the waveguide mode and the analyte. In the present work, we show that the sensitivity at the constant slab thickness of the slot-PCWG modes is greatly enhanced, up to a factor of 7.6 compared with the corresponding PCWG modes or Si-slab WGs. The finite-difference time-domain (FDTD) technique and plane wave expansion (PWE) methods were used to study the dispersion and profile of the PCWG mode. The simulation results show the potential of this design, which will be fabricated and tested in the following steps of the project.
Highlights
Integrated optical sensing technology is expected to play an increasing role in lab-on-a-chip applications, because of their small size [1,2]
Many photonic devices have been proposed as optical sensors, such as micro-ring resonators [3,4,5], slot waveguides [6,7], and photonic crystals [8,9], as well as those based on Bragg gratings [10,11]
Changing the slot width allows for tuning the energy of the slotted photonic crystal waveguide (SPCWG) mode and the evanescent field ratio
Summary
Integrated optical sensing technology is expected to play an increasing role in lab-on-a-chip applications, because of their small size [1,2]. Photonic crystals (PhCs) are among the most important candidates for improving the performance of slab-based guided-wave devices They can confine and guide light through narrow channeled waveguides and around very tight bends, with sizes in the order of optical wavelengths. Optimized values for the thickness and the length of the waveguide can be found by calculating the maximum change of the normalized power of the guided mode This allows for defining a sensitivity (figure of merit) using the following equation [16],.
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