An approach for yielding light focuses below Abbe’s diffraction limit in Gaussian beams is presented. The method uses only standard passive optical elements as lenses, filters and mirrors and consists of a Michelson interferometric setup, where one of the light branches is modified in amplitude and/or phase. The focus narrowing process is carried out at the focal plane of a spherical lens by the interference of altered and unaltered light branches. The main focus features, namely, the focus intensity and size as well as the sidelobe intensity, are adjusted by varying two external parameters in a controllable manner under the conditions of pure destructive interference. Narrowing of the diffraction limit close to 40% with reduced intensity sidelobes (10%) is achieved. Due to the use of only lenses and mirrors, the approach does work with laser beams within a broad optical bandwidth ranging from infrared to ultraviolet in continuum regime as well as in ultra-short pulse regime. The method can also be implemented for high-power lasers and temporal domains. The focus-narrowing process emerges as a natural mechanism to the light interference, bringing a fresh perspective to applications from a few controllable degrees of freedom. The good performance of the sub-diffraction optical focus and the simplicity of the experimental setup promote new opportunities in fields ranging from optical manipulation of particles at sub-wavelength scale to optical writing and super-resolution microscopy.

提出了一种在高斯光束中产生低于阿贝衍射极限的光聚焦的方法。该方法仅使用标准的无源光学元件作为透镜、滤光片和反射镜，并由迈克尔逊干涉测量装置组成，其中一个光分支在振幅和/或相位上进行了修改。通过改变和未改变的光分支的干涉，在球面透镜的焦平面上进行聚焦变窄过程。在纯相消干涉条件下，通过可控地改变两个外部参数来调整主聚焦特征，即聚焦强度和大小以及旁瓣强度。衍射极限缩小到接近 40%，同时降低了强度旁瓣 (10%)。由于只使用镜头和镜子，该方法确实适用于从红外到紫外连续区以及超短脉冲区的宽光带宽内的激光束。该方法还可用于高功率激光器和时间域。焦点缩小过程是光干涉的一种自然机制，从几个可控的自由度为应用带来了全新的视角。亚衍射光学焦点的良好性能和实验装置的简单性促进了从亚波长尺度的粒子光学操纵到光学写入和超分辨率显微镜等领域的新机遇。该方法还可用于高功率激光器和时间域。焦点缩小过程是光干涉的一种自然机制，从几个可控的自由度为应用带来了全新的视角。亚衍射光学焦点的良好性能和实验装置的简单性促进了从亚波长尺度的粒子光学操纵到光学写入和超分辨率显微镜等领域的新机遇。该方法还可用于高功率激光器和时间域。焦点缩小过程是光干涉的一种自然机制，从几个可控的自由度为应用带来了全新的视角。亚衍射光学焦点的良好性能和实验装置的简单性促进了从亚波长尺度的粒子光学操纵到光学写入和超分辨率显微镜等领域的新机遇。