Photonic Hook-Assisted Contrast-Enhanced Super-Resolution Imaging Using Janus Microspheres

Microsphere-assisted imaging is a promising label-free super-resolution imaging technique. Its performance is significantly affected by the photonic nanojet (PNJ) of microspheres. Recently, a new type of curved PNJ, i.e. the photonic hook (PH), was discovered, which shows promising potential for various applications. This Letter presented a contrast-enhanced super-resolution imaging technique utilizing the PHs generated by Janus microspheres. We demonstrated that the Janus microspheres can be fabricated using a one-step deposition process, they exhibit superior imaging performance to pristine microspheres, and their field-of-view and imaging contrast can be easily adjusted by changing the coating thickness. In addition, we demonstrated that the imaging contrast of Janus microspheres can be further enhanced by using polarized illumination.