Researchers fabricate micron sized optical devices at the end of optical fibers

Researchers have shown that 3D laser printing can directly produce high-quality and complex polymer optical devices at the end of optical fibers. The details of this micro optical device are smaller than the diameter of a hair, which can provide an extremely compact and inexpensive way to customize light beams for various applications.

3D printed complex polymer optics

In the paper, the researchers described how they directly manufactured the micro multi-component beam shaper on the optical fiber. The device converts ordinary lasers into distorted Bessel beams, which carry orbital angular momentum and do not expand in space like typical beams. The researchers made the whole micro optical device in less than 5 minutes. The price of optical fiber and micro optical equipment is less than 100 dollars, about one tenth of the price of standard microscope objective lens performing similar functions.

"The ability to generate Bessel beams directly from optical fiber can be used for particle manipulation or fiber integrated stimulated emission loss STED microscope, which is a technology to generate super resolution images. Our manufacturing method can also upgrade smart small structures to higher quality smart lenses by printing them on cheap lenses." The researchers explained.

Precise planning

In order to manufacture this tiny optical device, the researchers used a manufacturing technology called 3D direct laser printing. The laser beam with femtosecond pulse generates two-photon absorption in the photosensitive optical material. Only tiny materials that undergo two-photon absorption become solid, providing a way to create high-resolution 3D structures.

Although this kind of 3D direct laser printing has been used for a period of time, it is difficult to obtain the correct proportion if such a small optical element is to be made on the fiber end. The researcher explained: "Before starting the manufacturing process, we overcame this obstacle by conducting high-precision 2D and 3D simulation. In addition, we must carefully consider how to integrate optical elements with each other and then align them with the fiber core."

After simulation and careful planning, researchers used commercial 3D direct laser writing system and high optical quality photosensitive polymer to print optical equipment with a diameter of 60 microns and a height of 110 microns at the end of single-mode fiber. The device comprises a parabolic lens for light collimation and a spiral axis prism for twisting light.

The propagation quality of light

In order to analyze the propagation quality of the fabricated optical devices, researchers have established an optical measurement system to capture the modified optical fiber transmission shaping beam. They observed very low diffraction in the beam, which means it can be used in applications such as STED microscopy and particle manipulation.

Reference from:hlomi Lightman et al, Vortex-Bessel beam generation by 3D direct printing of an integrated multi-optical element on a fiber tip, Optics Letters (2022). DOI: 10.1364/OL.470924

Source: Guangxingtianxia