High sensitivity liquid sensing by optimized slot photonic crystal ring resonator
Sprache des Titels:
Proc. of SPIE Integrated Photonics: Materials, Devices, and Applications IV
In this work we present a design to enhance absorption of infrared light by a fluid analyte being in contact with a slot
photonic crystal ring resonator (slot-PCRR). For this purpose, we propose a new PCRR design facilitating higher
interaction between guided mode and analyte. These types of PCRRs are based on two-dimensional photonic crystals,
which consist of an array of holes in a silicon slab being arranged in a hexagonal lattice. The holes will be filled with
liquid analyte. A slot is embedded in this hexagonal ring cavity to create a slot-PCRR. The strong confinement of light in
the low index region, occupied by the analyte, is the key advantage of the slot- PCRR. We also calculate the relative
intensity change in the transmission spectrum due to the absorption in the analyte. The maximum change obtained is
given by a mode which has most of the electromagnetic field energy in the region the region filled with the analyte.
Furthermore, this mode is well separated from neighboring bands, which has the advantage that impinging light with
specified frequency is less likely to spuriously couple to other modes with the same frequency, which would decrease the
amount of energy coupled to desired mode. The slot-PCRR yields a higher relative change due to absorption compared
to the PCRR without a slot. In this work, the radii of six rods at the outer PhC were tuned to enhance the quality factor of
slot-PCRR. Using these optimum values of radii, the Q-factor rises up to 80000.