title: Characterization of light collection through a subwavelength aperture from a point source.
abstract: We experimentally measure and theoretically model the light transmission characteristics of subwavelength apertures. The characterization consists of translating a point source at varying vertical height and lateral displacement from the aperture and measuring the resulting transmission. We define the variation of the transmission with lateral source displacement as the collection mode point spread function (CPSF). This transmission geometry is particularly relevant to subwavelength aperture based imaging devices and enables determination of their resolution. This study shows that the achieved resolutions degrade as a function of sample height and that the behavior of sensor devices based on the use of apertures for detection is different from those devices where the apertures are used as light sources. In addition, we find that the measured CPSF is dependent on the collection numerical aperture (NA). Finally, we establish that resolution beyond the diffraction limit for a nominal optical wavelength of 650 nm and nominal medium refractive index of 1.5 is achievable with subwavelength aperture based devices when the aperture size is smaller than 225 nm.
authors.affiliation: Department of Electrical Engineering (MC136-93), California Institute of Technology, Pasadena, CA 91125, USA. xin@caltech.edu
authors.forename: Xin
authors.initials: X
authors.lastname: Heng
authors.forename: Xiquan
authors.initials: X
authors.lastname: Cui
authors.forename: David W
authors.initials: DW
authors.lastname: Knapp
authors.forename: Jigang
authors.initials: J
authors.lastname: Wu
authors.forename: Zahid
authors.initials: Z
authors.lastname: Yaqoob
authors.forename: Emily J
authors.initials: EJ
authors.lastname: McDowell
authors.forename: Demetri
authors.initials: D
authors.lastname: Psaltis
authors.forename: Changhuei
authors.initials: C
authors.lastname: Yang