Free-space creation of ultralong anti-diffracting light beam with multiple energy oscillations adjusted using optical pen

TL;DR

This paper introduces a novel method to create ultralong anti-diffracting light beams in free space by controlling multiple energy oscillations with an optical pen, overcoming the finite power barrier.

Contribution

It presents a new approach using energy oscillations and an optical pen to generate tunable, long-distance non-diffracting beams in free space, surpassing previous power limitations.

Findings

Achieved ultralong anti-diffracting propagation in free space.

Developed an optical pen to manipulate energy oscillations.

Generated light beams with tunable energy oscillations and wavy trajectories.

Abstract

A light beam propagating with an infinite anti-diffracting distance requires infinite power to preserve its shape. However, the fundamental barrier of finite power in free space has made the problem of diffraction insurmountable over the past few decades. Here, to overcome this limitation, we report an approach that employs the multiple energy oscillation mechanism, thereby permitting the creation of a light beam with an ultralong anti-diffracting distance in free space. The anti-diffracting distance is no longer restricted by finite power in free space but instead depends on the number of energy oscillations. This unprecedented propagation behavior is attributed to a new understanding of non-diffractive light beam: when an anti-diffracting light beam completely discharges its energy, it cannot recharge again. A versatile optical pen is therefore developed to manipulate the number, amplitude, position and phase of energy oscillations for an arbitrary numerical aperture of a focusing lens so that energy recharge can occur in free space and multiple energy oscillations can be realized. A light beam with a tunable number of energy oscillations is eventually generated in free space and propagates along a wavy trajectory. This work will enable extending non-diffractive light beams to an expanded realm and facilitate extensive developments in optics and other research fields, such as electronics and acoustics.