Optical absorption modeling of thermal infrared detectors by use of the finite-difference time-domain method.

The optical absorption of thin-film thermal infrared detectors was calculated as a function of wavelength, pixel size, and area fill factor by use of the finite-difference time-domain (FDTD) method. The results indicate that smaller pixels absorb a significantly higher percentage of incident energy than larger pixels with the same fill factor. A polynomial approximation to the FDTD results was derived for use in system models.

Three-dimensional analysis of subwavelength diffractive optical elements with the finite-difference time-domain method.

We present a three-dimensional (3D) analysis of subwavelength diffractive optical elements (DOE's), using the finite-difference time-domain (FDTD) method. To this end we develop and apply efficient 3D FDTD methods that exploit DOE properties, such as symmetry. An axisymmetric method is validated experimentally and is used to validate the more general 3D method. Analyses of subwavelength gratings and lenses, both with and without rotational symmetry, are presented in addition to a 2 x 2 subwavelength focusing array generator.