Generation of super-resolved optical needle and multifocal array using graphene oxide metalenses

Ultrathin flat metalenses have emerged as promising alternatives to conventional diffractive lenses, offering new possibilities for myriads of miniaturization and interfacial applications. Graphene-based materials can achieve both phase and amplitude modulations simultaneously at a single position due to the modification of the complex refractive index and thickness by laser conversion from graphene oxide into graphene like materials. In this work, we develop graphene oxide metalenses to precisely control phase and amplitude modulations and to achieve a holistic and systematic lens design based on a graphene-based material system. We experimentally validate our strategies via demonstrations of two graphene oxide metalenses: one with an ultra-long (similar to 16 lambda) optical needle, and the other with axial multifocal spots, at the wavelength of 632.8 nm with a 200 nm thin film. Our proposed graphene oxide metalenses unfold unprecedented opportunities for accurately designing graphene-based ultrathin integratable devices for broad applications.

Automated summary

Graphene-based metalenses offer new opportunities for precisely controlling phase and amplitude modulations, leading to unprecedented possibilities in lens design and applications. The conversion of graphene oxide into graphene materials allows for simultaneous modulation at a single position, enabling the demonstration of ultra-long optical needles and axial multifocal spots in graphene oxide metalenses.