Nanometer scale uniform optical tunnel generating method and device

Abstract

The invention discloses a nanometer scale uniform optical tunnel generating method and device. The method comprises the steps that a laser beam is enlarged, collimated and converted into a linearly polarized laser beam; a reflection-type pure phase spatial light modulator is used to carry out quadratic special fan-shaped partition phase modulation on the collimated and enlarged linearly polarized laser beam to acquire a phase-modulated linearly polarized vortex beam; the phase-modulated linearly polarized vortex beam is converted into a phase-modulated radially polarized vortex beam by a radially polarized light converter; a 4F imaging system is used to image the phase-modulated radially polarized vortex beam to the rear aperture plane of a focusing objective lens; the objective lens focuses the phase-modulated radially polarized vortex beam to acquire a nanometer scale uniform optical tunnel in a focal area. The uniform optical tunnel is formed by optimizing and splicing four same optical tunnels produced by quadratic special fan-shaped partition phase modulation. The longitudinal intensity uniformity of the optical tunnel is within 10 wavelengths, and the intensity fluctuation error is less than three percent.

Description

technical field [0001] The invention relates to the field of far-field beam focusing control, and in particular to a method and device for generating a nanoscale uniform optical tunnel, which generates an optical tunnel with a super large aspect ratio in the field of view of a microscopic objective lens. Background technique [0002] It has always been a very important research hotspot to realize the adjustment of the spot or light field in the field of view of the objective lens by modulating the laser beam. Different light fields or spots have special applications in many fields such as super-resolution lithography, ultra-high-density optical data storage, laser processing of micro-nano scale structures, super-resolution imaging of fluorescent samples, and manipulation of micron or even nanoscale substances. Among them, the donut ring-shaped spot and the ellipsoidal solid spot are more important. When two lasers with appropriate wavelengths are used to focus on the same o...

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Problems solved by technology

[0004] In order to overcome the lack of prior art to produce nanometer-sized optical tunnels with high long-diameter ratio and good longitudinal intensity uniformity, the present invention proposes to use a reflective pure phase spatial light modulator to phase-modulate the focused beam to generate a linearly polarized vortex beam, and then Use the radial polarization converter to perform polarization modulation on the phase-modulated linearly polarized vortex beam to obtain the phase-modulated radially polarized vortex beam, and then use the 4F Fourier transform imaging system to image the above beam to the rear aperture plane of the focusing objective lens focus

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