Color-changing refractive index sensor based on Fano-resonant filtering of optical modes in a porous dielectric Fabry-Pérot microcavity.
Opt Express
; 28(19): 28226-28233, 2020 Sep 14.
Article
in En
| MEDLINE
| ID: mdl-32988098
ABSTRACT
Refractometry is a ubiquitous technique for process control and substance identification in the chemical and biomedical fields. Herein, we present an all-dielectric, wafer-scalable, and compact Fabry-Pérot microcavity (FPMC) device for refractive index (RI) sensing. The FPMC consists of a highly porous SiO2 microcavity capped with a thin, quasi-periodically patterned TiO2 hole array partial reflector that enables rapid, nanoliter-scale analyte transport to and from the sensor. Liquid (alcohols) or condensed-vapor (water from human breath) infiltration resulted in spectral redshifts up to 100 nm, highly apparent visible color change, rapid recovery (< 20 s), and RI sensitivity of up to 680 nm/RIU. The sensor can also be used in spectral or single-wavelength detection modes. Effective-medium and finite-difference time-domain optical simulations identified that Fano-resonant scattering modes induced by the quasi-periodic TiO2 outcoupling layer effectively filter higher-order Fabry-Pérot cavity modes and thereby confer an easily identifiable red-to-green color transition during analyte infiltration.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
Opt Express
Journal subject:
OFTALMOLOGIA
Year:
2020
Document type:
Article