Tailoring a sub-diffraction optical focus via a straightforward interferometric approach

NEYRA, ENRIQUE G; VAVELIUK, PABLO

Journal of Optics

Institute of Physics

Año: 2021 vol. 23 p. 75604 - 75604

2040-8978

An approach for yielding light focuses below Abbe?s diffraction limit in Gaussian beams ispresented. The method uses only standard passive optical elements as lenses, filters and mirrorsand consists of a Michelson interferometric setup, where one of the light branches is modified inamplitude and/or phase. The focus narrowing process is carried out at the focal plane of aspherical lens by the interference of altered and unaltered light branches. The main focusfeatures, namely, the focus intensity and size as well as the sidelobe intensity, are adjusted byvarying two external parameters in a controllable manner under the conditions of puredestructive interference. Narrowing of the diffraction limit close to 40% with reduced intensitysidelobes (10%) is achieved. Due to the use of only lenses and mirrors, the approach does workwith laser beams within a broad optical bandwidth ranging from infrared to ultraviolet incontinuum regime as well as in ultra-short pulse regime. The method can also be implementedfor high-power lasers and temporal domains. The focus-narrowing process emerges as a naturalmechanism to the light interference, bringing a fresh perspective to applications from a fewcontrollable degrees of freedom. The good performance of the sub-diffraction optical focus andthe simplicity of the experimental setup promote new opportunities in fields ranging fromoptical manipulation of particles at sub-wavelength scale to optical writing and super-resolutionmicroscopy.