Enhancing the signal-to-noise ratio of an infrared photodetector with a circular metal grating.
We use finite-difference time-domain (FDTD) simulations to demonstrate enhanced infrared absorption in a photodetector covered with a microstructured metal film consisting of a metal-plasmon grating collector/ concentrator and sub-wavelength detector well; for circular gratings we use radial FDTD, and for linear gratings we use two-dimensional FDTD. We identify a figure of merit to quantify the improvement in signal-to-noise ratio of such a detector scheme. We optimize grating parameters for a circular grating surrounding a simple hole, showing that the signal-to-noise ratio can be improved by a factor of as much as 5.2, whereas the signal-to-noise improvement for comparable linear gratings is at most 1.7. In the case of the circular grating, this result is achieved with more than 400 times as much light absorbed in the hole as with a metal film but no grating.
Bhat
Ravi D
RD
Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA. rbhat@cumsl.msl.columbia.edu
Panoiu
Nicolae C
NC
Brueck
Steven R
SR
Osgood
Richard M
RM
D003198:Computer Simulation; D017076:Computer-Aided Design; D020342:Finite Element Analysis; D007259:Infrared Rays; D008027:Light; D008670:Metals / Q000737:chemistry; D008962:Models, Theoretical; D010783:Photometry / Q000295:instrumentation* / Q000379:methods; D012031:Refractometry / Q000295:instrumentation*; D012680:Sensitivity and Specificity; D014159:Transducers
D008670:Metals