Nanograting-Enhanced Optical Fibers for Visible and Infrared Light Collection at Large Input Angles

The efficient incoupling of light into particular fibers at large angles is essential for a multitude of applications; however, this is difficult to achieve with commonly used fibers due to low numerical aperture. Here, we demonstrate that commonly used optical fibers functionalized with arrays of metallic nanodots show substantially improved large-angle light-collection performances at multiple wavelengths. In particular, we show that at visible wavelengths, higher diffraction orders contribute significantly to the light-coupling efficiency, independent of the incident polarization, with a dominant excitation of the fundamental mode. The experimental observation is confirmed by an analytical model, which directly suggests further improvement in incoupling efficiency through the use of powerful nanostructures such as metasurface or dielectric gratings. Therefore, our concept paves the way for high-performance fiber-based optical devices and is particularly relevant within the context of endoscopic-type applications in life science and light collection within quantum technology.

Automated summary

The efficiency of light incoupling in commonly used optical fibers can be improved by functionalizing them with arrays of metallic nanodots, resulting in enhanced large-angle light-collection performance at multiple wavelengths. Higher diffraction orders at visible wavelengths contribute significantly to the light-coupling efficiency, with the potential for further improvement through the use of powerful nanostructures such as metasurfaces or dielectric gratings. This concept opens up possibilities for high-performance fiber-based optical devices, particularly in endoscopic-type applications in life science and light collection within quantum technology.