Dielectric microspheres superenhance backscattering of light from nanoparticles

Feb. 1, 2006
Enabling potential applications in visible-light ultramicroscopy and optical biosensing systems, in which nanoparticles consisting of as few as several hundred atoms could be tested and characterized, scientists at Northwestern University (Evanston, IL) have determined how and why the backscattering of light by nanoparticles from 1 to 100 nm in size positioned in close proximity to a dielectric microsphere is enhanced by 7 to 11 orders of magnitude.

Enabling potential applications in visible-light ultramicroscopy and optical biosensing systems, in which nanoparticles consisting of as few as several hundred atoms could be tested and characterized, scientists at Northwestern University (Evanston, IL) have determined how and why the backscattering of light by nanoparticles from 1 to 100 nm in size positioned in close proximity to a dielectric microsphere is enhanced by 7 to 11 orders of magnitude.

A plane-wave-illuminated (wavelength of 300 nm) microsphere with a 3-µm radius and refractive index of 1.73 produces a photonic nanojet of strongly localized optical fields at its shadow-side surface. If a nanoparticle is introduced into the nanojet (surface-to-surface distance between microsphere and nanoparticle is 25 nm), analytical and perturbation analysis show that the nanoparticle is first excited by the nanojet, boosting its scattering intensity by two orders of magnitude; the fields reradiated by the nanojet-excited nanoparticle then interact with the electromagnetic modes of the microsphere, elevating the backscattered intensity of the nanoparticle by four to nine additional orders of magnitude. Contact Zhigang Chen at z‑[email protected] or [email protected].

Sponsored Recommendations

Digitizer system available in seven different models

Nov. 26, 2023
The Star-Hub digitizer system can be used with any cards from the M5i.33xx PCIe digitizer family.

High-speed cameras offer UV-extended capability

Nov. 25, 2023
The Phantom T3610, T2410, and TMX high-speed cameras (TMX 7510/6410/5010) are available in a UV variant.

Linear voice coil motors offer peak force of 2.20 N

Nov. 24, 2023
The LVCM-013-032-02M and LVCM-013-032-02 are 12.7 mm diameter linear voice coil motors.

Image sensor has use in home and professional security

Nov. 23, 2023
The OS08C10 image sensor features both staggered high dynamic range (HDR) and single exposure dual analog gain (DAG).

Voice your opinion!

To join the conversation, and become an exclusive member of Laser Focus World, create an account today!