Graphene ultrathin flat lens for broad applications

The optical lenses are indispensable components in almost all aspects of science and technology including imaging, sensing, communications, medical diagnosis and treatment. Recently, the rapid development in nano-optics and on-chip photonic systems has placed stringent demand for ultrathin flat lenses with three-dimensional (3D) subwavelength focusing capability. In 2015, our research team at Swinburne University of Technology has invented an ultrathin (1000 thinner than a human hair) graphene microlens that can focus light tightly into a three-dimensional nanometric focal spot, leading to an over 100-times enhancement on the focusing efficiency. The discovery of the graphene lens enables a wide range of nanodevice applications requiring ultrahigh level of integration and outstanding performance, which are insurmountably challenging with the existing technology.

In addition, we further develop the theory to accurately design arbitrary ultrathin flat lenses for any immersion media and sizes. We have experimentally demonstrated graphene ultrathin flat lenses can be applied in harsh environments for different applications, including a low Earth orbit space environment, strong corrosive chemical environments (pH = 0 and pH = 14), and biochemical environment. The graphene lenses have extraordinary environmental stability and can maintain a high level of structural integrity and outstanding focusing performance under different test conditions. Thus, it opens tremendous practical application opportunities for ultrathin flat lenses. Currently we further develop the graphene ultrathin flat lenses with different functions for different applications.

Graphene ultrathin flat lens for high performance focusing

Graphene ultrathin flat lens for broad applications

References

  • Zheng, X.;  Jia, B.;  Lin, H.;  Qiu, L.;  Li, D.; Gu, M., Highly efficient and ultra-broadband graphene oxide ultrathin lenses with three-dimensional subwavelength focusing. Nature communications 2015.
  • Cao, G.;  Gan, X.;  Lin, H.; Jia, B., An accurate design of graphene oxide ultrathin flat lens based on Rayleigh-Sommerfeld theory. Opto-Electronic Advances 2018, 1 (07), 180012.
  • Cao, G.;  Lin, H.;  Fraser, S.;  Zheng, X.;  Del Rosal, B.;  Gan, Z.;  Wei, S.;  Gan, X.; Jia, B., Resilient graphene ultrathin flat lens in aerospace, chemical, and biological harsh environment. ACS applied materials & interfaces 2019.

Graphene metamaterials for advance photonic devices

Graphene-based metamaterials have been theoretically demonstrated as an enabler for applications as perfect absorbers, photodetectors, light emitters, modulators, and tunable spintronic devices. However, challenges associated with conventional film deposition techniques have made the multilayered metamaterial difficult to fabricate, which have severely limited experimental validations. We experimentally demonstrated the phototunable graphene-based multilayered metamaterials on diverse substrates by a transfer-free, solution-phase deposition method. The optical properties of the metamaterials are tuned dynamically by controllable laser-mediated conversion from graphene oxide layers into graphene counterparts, which exhibit different degrees of conversion, which would offer huge potential for devices design and fabrication. The converted graphene layers present comparable (within 10%) optical conductivity to their chemical vapor deposited analogues. Moreover, laser patterning leads to functional photonic devices such as ultrathin flat lenses embedded in the lab-on-chip device, which maintains consistency and exhibits subwavelength focusing resolution in aqueous environments without any noticeable degradation compared with the original lens. This graphene-based metamaterial provides a new experimental platform for broad applications in on-chip integrated photonic, biomedical, and microfluidic devices.

Based on the unique optical properties, we experimentally demonstrate a 12.5 cm2, 90-nm-thick graphene metamaterial with approximately 85% absorptivity of unpolarized, visible and near-infrared light covering almost the entire solar spectrum (300–2,500 nm). The metamaterial consists of alternating graphene and dielectric layers; a grating couples the light into waveguide modes to achieve broadband absorption over incident angles up to 60°. The very broad spectral and angular responses of the absorber are ideal for solar thermal applications, as we illustrate by showing heating to 160 °C in natural sunlight. These devices open a novel approach to applications of strongly absorbing large-area photonic devices based on two-dimensional materials.

Now we further develop the fundamental science and applications based on the multilayer graphene metamaterials.

Schematic of the fabrication process of graphene metamaterial

Light tuning of graphene metamaterial

Graphene metamaterial perfect absorber

References

  • Yang, Y., et al., Graphene-based multilayered metamaterials with phototunable architecture for on-chip photonic devices. ACS Photonics, 2019.
  • Lin, H., et al., A 90-nm-thick graphene metamaterial for strong and extremely broadband absorption of unpolarized light. Nature Photonics, 2019. 13(4): p. 270-276.

Light interaction with 2D materials

Based on the unique light-matter interaction in 2D materials, we use laser beams to tune and control the properties of 2D materials. In this way, we are able to study the nonlinearity of 2D materials and fabricate functional devices.

Laser tuning properties of 2D materials

Graphene metamaterial perfect absorber

Polarization dependent nonlinearity in 2D materials

References

  • Zheng, X., et al., In Situ Third‐Order Non‐linear Responses During Laser Reduction of Graphene Oxide Thin Films Towards On‐Chip Non‐linear Photonic Devices. Advanced Materials, 2014. 26(17): p. 2699-2703.
  • Zheng, X., et al., Laser trimming of graphene oxide for functional photonic applications. J Phys D Appl Phys, 2017. 50: p. 074003.
  • Ren, J., et al., Giant third-order nonlinearity from low-loss electrochemical graphene oxide film with a high power stability. Applied Physics Letters, 2016. 109(22): p. 221105.
  • Yang, T., H. Lin, and B. Jia, Two-dimensional material functional devices enabled by direct laser fabrication. Frontiers of Optoelectronics, 2018. 11(1): p. 2-22.
  • Yang, T., et al., Anisotropic third-order nonlinearity in pristine and lithium hydride intercalated black phosphorus. ACS Photonics, 2018. 5(12): p. 4969-4977.

Integrated all-optical communication devices

The advent of graphene-based two-dimensional (2D) materials, which are composed of one single or a few atomic layers, has resulted in the demonstration of a range of unique optical, mechanical and electrical properties remained in the nanometre-scale that would not exist in their bulk morphologies. Graphene metamaterials (GM), comprising alternating graphene and dielectric layers, are artificially structured materials designed to attain an extremely high optical response that can enhance optical modulation. Recent researches have suggested that these materials can be useful in the photonics area. We have developed a low cost, solution-phase method that is able to build phototunable multilayered metamaterials in a layer-by-layer (LBL) manner by using 2D materials as the building blocks has been developed, which can lead to reconfigurable functional photonic devices.

Hybrid waveguide integrated with GM

FWM spectra of the hybrid GM integrated waveguide

Schematic of a GM-coated integrated waveguide polarizer, Raman spectra of the integrated chip with and without GM. Measured GM film thickness versus GM layer number.

References

  • Highly nonlinear BiOBr nanoflakes for hybrid integrated photonics, L Jia, D Cui, J Wu, H Feng, Y Yang, T Yang, Y Qu, Y Du, W Hao, B Jia, APL Photonics 4 (9), 090802 (2019)
  • Observation of third-order nonlinearities in graphene oxide film at telecommunication wavelengths, X Xu, X Zheng, F He, Z Wang, H Subbaraman, Y Wang, B Jia, RT Chen, Scientific reports 7 (1), 9646, 2017
  • Giant third-order nonlinearity from low-loss electrochemical graphene oxide film with a high power stability, J Ren, X Zheng, Z Tian, D Li, P Wang, B Jia, Applied Physics Letters 109 (22), 221105, 2016
  • Enhanced optical nonlinearities of hybrid graphene oxide films functionalized with gold nanoparticles, S Fraser, X Zheng, L Qiu, D Li, B Jia, Applied Physics Letters 107 (3), 031112, 2015
  • In Situ Third-Order Non-linear Responses During Laser Reduction of Graphene Oxide Thin Films Towards On-Chip Non-linear Photonic Devices, X Zheng, B Jia, X Chen, M Gu, Advanced Materials 26 (17), 2699-2703, 2014
  • Nanostructured plasmonic medium for terahertz bandwidth all-optical switching, M Ren, B Jia, JY Ou, E Plum, J Zhang, KF MacDonald, AE Nikolaenko, Advanced Materials 23 (46), 5540-5544, 2011
  • Highly non-linear quantum dot doped nanocomposites for functional three-dimensional structures generated by two-photon polymerization, B Jia, D Buso, J Van Embden, J Li, M Gu, Advanced Materials 22 (22), 2463-2467

Opto-magnetization study

We control the opto-magnetization by manipulating the polarization states of the incident light with amplitude or phase modulations, as well as the unique material properties, such as birefringence. In this way, we are able to create 3D super-resolved with pure longitudinal magnetization or transverse magnetization. These studies open up broad applications in magnetic-optical devices such as confocal and multifocal magnetic resonance microscopy, 3D ultrahigh-density magneto-optic memory, and light-induced magneto-lithography.

Opto-magnetization

Opto-magnetization in birefringence media

Manipulation of the magnetization states

References

  • Nie, Z.-Q., et al., Three-dimensional super-resolution longitudinal magnetization spot arrays. Light: Science & Applications, 2017. 6(8): p. e17032.
  • Lin, S., et al., All-optical vectorial control of multistate magnetization through anisotropy-mediated spin-orbit coupling. Nanophotonics, 2019

Advanced laser 3D nanoprinting

Three-dimensional laser nanoprinting techniques, especially the additive manufacturing or 3D printing have revolutionized the entire field of manufacturing. By using a focusing laser beam it is possible to fabricate 3D structures at micro/nanoscale in different materials, which have found broad applications in medical, biology, electronics and photonics. We focus on the development of 3D micro/nanofabrication platform based on the laser writing technique. It is aimed to develop a fully automatic platform with the capability of sample preparation and fast fabrication by implement the dynamic laser printing technique.

Examples of laser 3D nanoprinted structure

Dynamic parallel laser nanoprinting setup and the printed split ring resonator arrays.

Super-resolution laser nanoprinting

References

  • Lin, H. and M. Gu, Creation of diffraction-limited non-Airy multifocal arrays using a spatially shifted vortex beam. Applied Physics Letters, 2013. 102(8): p. 084103.
  • Lin, H., B. Jia, and M. Gu, Dynamic generation of Debye diffraction-limited multifocal arrays for direct laser printing nanofabrication. Optics letters, 2011. 36(3): p. 406-408.
  • Gan, Zongsong, Yaoyu Cao, Richard A. Evans, and Min Gu. “Three-dimensional deep sub-diffraction optical beam lithography with 9 nm feature size.” Nature communications 4 (2013): 2061.
  • Turner, M. D., Saba, M., Zhang, Q., Cumming, B. P., Schröder-Turk, G. E., & Gu, M. (2013). Miniature chiral beamsplitter based on gyroid photonic crystals. Nature Photonics, 7(10), 801.
  • Tabrizi, Sahar, Yaoyu Cao, Benjamin P. Cumming, Baohua Jia, and Min Gu. “Functional optical plasmonic resonators fabricated via highly photosensitive direct laser reduction.” Advanced Optical Materials 4, no. 4 (2016): 529-533.
  • Biomimetic gyroid nanostructures exceeding their natural origins, Zongsong Gan, Mark D. Turner and Min Gu, Science Advance 2 (5), (2016); doi: 10.1126/sciadv.1600084