A Closer Look at Photonic Nanojets in Reflection Mode: Control of Standing Wave Modulation

The photonic nanojet phenomenon is commonly used both to increase the resolution of optical microscopes and to trap nanoparticles. However, such photonic nanojets are not applicable to an entire class of objects. Here we present a new type of photonic nanojet in reflection mode with the possibility to control the modulation of the photonic nanojet by a standing wave. In contrast to the known kinds of reflective photonic nanojets, the reported one occurs when the aluminum oxide hemisphere is located at a certain distance from the substrate. Under illumination, the hemisphere generates a primary photonic nanojet directed to the substrate. After reflection, the primary nanojet acts as an illumination source for the hemisphere, leading to the formation of a new reflective photonic nanojet. We show that the distance between the hemisphere and substrate affects the phase of both incident and reflected radiation, and due to constructive interference, the modulation of the reflective photonic nanojet by a standing wave can be significantly reduced. The results obtained contribute to the understanding of the processes of photonic nanojet formation in reflection mode and open new pathways for designing functional optical devices.

Automated summary

A new type of reflective photonic nanojet is proposed in this study, with the modulation of the photonic nanojet controlled by a standing wave. The primary nanojet generated by the hemisphere under illumination leads to the formation of a new reflective photonic nanojet after reflection, and the modulation of the reflective photonic nanojet can be significantly reduced by constructive interference. The findings contribute to understanding the formation processes of photonic nanojets in reflection mode and provide new pathways for designing functional optical devices.