Mie-lithography: self-guiding nonlinear laser printing for deep ultraviolet to near-infrared nano dispersion devices

Abstract

Nanoscale control of optical dispersion is essential for applications ranging from miniaturized spectrometers to color printing, all of which demand broadband spectral tunability. However, the Kramers-Kronig relations impose a fundamental trade-off between dispersion and loss, strictly limiting the design ability of single-material devices across the deep ultraviolet (DUV) to near-infrared (NIR) regimes. Consequently, the fabrication of miniaturized dispersion devices heavily relies on costly nanofabrication or heterogeneous integration. Here we overcome these limitations by shifting the light-matter interaction from solid structure into air-filled voids. We introduce a fabrication strategy termed "Mie-lithography", in which laser printed seed nanocavities excite Mie resonances in air and the resulting localized field enhancement drives the self-assembly of three-dimensionally tunable void-type optical resonators. Because the resonant modes are primarily confined within air voids, this architecture effectively circumvents material-imposed dispersion-loss constraints, allowing on-demand customization of the broadband spectral response. This approach enables single-step, high-throughput (>= 10^6 pixels/s) printing of dispersion units with a resolution of 63,500 DPI. As a proof of concept, we demonstrate a DUV-NIR nano spectrometer integrated in a single material covering an unprecedented range from 200 nm to 800 nm. Our approach can be extended into a platform for ultra-broadband nano devices fabrication and design, opening avenues for high-pixel-density displays and miniaturized spectrometers.

Figures (4)

• Figure 1: Mechanism of Mie-lithography. a The schematic illustrates the localized resonant modes excited by cavities of different sizes, which drive a self-guiding feedback loop between the incident laser beam and the laser-ablated nanocavities. b Simulation results demonstrate that the initial cavity formed by laser ablation provides strong light confinement for ultraviolet lasers. c Multipole analysis of Mie resonators. As the size of Mie resonators increases, higher-order multipole modes emerge within the UV spectral range, thereby sustaining the self-guiding feedback loop. $\mathrm{ED:}$ electric dipole, $\mathrm{EQ:}$ electric quadrupole, $\mathrm{MD:}$ magnetic dipole, $\mathrm{MQ:}$ magnetic quadrupole.d, f Electric field intensity profiles of cavities with distinct sizes under 800 nm (d) and 343 nm (f) laser beam illumination. The width of the cavities used in simulations is 300 nm. e, g Experimental verification (Silicon) that Mie resonance excited by the 343 nm laser beam drive self-assembly growth of Mie resonators. At non-resonant wavelengths (800 nm), cavity evolution is suppressed due to strong scattering despite silicon's larger skin depth (h) at 800 nm. i, j The influence of laser wavelength on cavity evolution with increasing pulse number. The 343 nm laser beam enables direct fabrication of high-aspect-ratio nanostructures, which is attributed to the self-guiding feedback mechanism that tightly confines light at the cavity bottom. Scale bars in e and g are 500 nm.
• Figure 2: Controllable printing of Mie resonators via Mie-lithography. a Controlled growth of Mie resonators achieved by varying pulse energy, polarization and pulse number of laser beam. The depth of the resonators increases with the pulse number increasing, while higher pulse energy leads to larger ablation cavity width. The polarization state of the laser beam determines both the symmetry and the orientation of the resulting Mie resonators. Scale bars are all 200 nm. b Performance comparison between Mie lithography and four established nanofabrication techniques in terms of cost, resolution, material selectivity, throughput, and simplicity of setup (Detailed parameters can be found in Suppl. Section 1). c Optical image of a large-scale arrays of Mie resonators fabricated via Mie lithography. d-f show the influence of laser pulse number and pulse energy on the aspect ratio, width and depth-to-width ratio of the Mie resonators.
• Figure 3: Ultra-broaden light field manipulation with Mie resonators. a Schematic of light field modulation with Mie resonators under reflection mode. Key parameters governing the light-matter interaction include: the length ($l$), width ($w$), orientation ($\phi$) and depth ($d$) of the asymmetric Mie resonators, refractive index contrast between the interior ($n_1$) and exterior ($n_2$) of the resonators. The asymmetric Mie resonators exhibit optical anisotropy to linearly polarized light, with an analyzer extracting distinct polarization components. Scale bars are 200 nm. b Experimentally measured reflectance of Mie resonators on the silicon substrates. As the size of the Mie resonators increases, the contribution ratio of different fundamental modes changes, accompanied by a red shift of characteristic resonance peaks. Scale bars are 300 nm. c Experimental characterization reveals polarization-dependent resonant spectral shifts. d shows the Mie lithography-fabricated color palettes experimentally recorded in air ($n_1=1$) and water ($n_1=1.33$), which exhibit color tuning with the increasing polarization angle. Asymmetric Mie resonators oriented at 45° were fabricated with fixed pulse number (PN = 20) and pulse energy varied from 20 nJ to 55 nJ. Black squares were used to guide the eye . During optical characterization, the analyzer angle was maintained at 90°. e CIE chromaticity diagram comparing colors of silicon-based Mie resonators in water (stars) and in air (circles). f Chromatic wheel with continuously adjustable brightness with orthogonal polarizer–analyser combinations. g The microscope image of the oil painting Girl with a Pearl Earring. h The microscope image of a still-life sketch. Mie resonators with different orientations exhibit distinct shading states. The length of each resonator is 650 nm, width is 350 nm. Scale bars of g and h are 50 $\mu$m.
• Figure 4: DUV-NIR nano spectrometers based on resonance in air. a Current miniaturized spectrometers utilize dispersion generated by resonance in high-refractive-index nanopillars or multilayer thin-film, which is constrained by material absorption, particularly in the ultraviolet region. In contrast, our "resonance-in-air" concept effectively circumvents the strong absorption inherent to high-index materials from DUV to NIR. b illustrates the principle of the miniaturized spectrometer based on resonance for encoding spectral information. Each unit in the resonators arrays is engineered to support diverse spectral responses R($\lambda$). When the incident light with unknown spectrum F($\lambda$) is transmitted through nano resonators, the encoded optical signal ($I$) is captured in a single camera exposure. However, the weak spectral response in the UV range results in a severely attenuated signal that is often dominated by noise (c). d A comparison between our device and reported miniaturized spectrometersyu2025miniaturizedbian2024broadbandyang2019singleyoon2022miniaturizedfan2024dispersion. e Schematic of the neural network for spectral reconstruction. Input: the reflected signal from our fabricated nano spectrometer, captured by a UV camera. Output: reconstructed spectra covering 200–800 nm wavelengths. f Correlation coefficients matrix computed from the reflectance of 100 resonator arrays in our nano spectrometer. g Narrowband spectral reconstruction results compared with measurements from a commercial spectrometer. h Complex spectral reconstruction. i Experimental spectral resolution demonstrating discrimination of mixed narrowband spectra with peaks separated by 3 nm.