Fig. 1. Schematic diagram of femtosecond laser 3D printing technology of inorganic materials. (a) Polymer hybrid; (b) reaction of functional precursor; (c) inter-nanoparticle bonding

Fig. 2. Precursor-modified two-photon polymerization printing methods. (a) Scanning electron microscope (SEM) and fluorescence images of 3D structures of quantum dots synthesized in situ after two-photon polymerization^[19]; (b) schematic diagram of metal precursor two-photon polymerization printing components^[18]; (c) schematic diagram of modified POSS resin used for two-photon polymerization printing and heat treatment of glass structure^[23]; (d) schematic diagram of TiO₂ precursor two-photon polymerization printing^[17]; (e) schematic diagram of YAG precursor two-photon polymerization printing components and optical-gain 3D structure^[31]

Fig. 3. Nanoparticle-based two-photon polymerization printing methods. (a) Schematic diagram of silica nanoparticle resin two-photon polymerization printing (top right: schematic diagram of silica nanoparticle resin; bottom right: schematic diagram of crystallization transformation after high-temperature sintering)^[38]; (b) schematic diagram of two-photon polymerization printing of magnetic Fe₃O₄ nanoparticles^[39]; (c) fluorescence and SEM images of two-photon polymerization printing structure containing red, green, and blue (RGB) quantum dots^[40]; (d) schematic diagram of two-photon polymerization printing of metal nanoparticles^[37]

Fig. 4. Functional precursor laser printing methods based on non-photopolymerization. (a) Schematic diagram of metal structure reduction by laser printing, including three stages of nucleation, growth and aggregation^[45]; (b) schematic diagram of 3D direct writing micro-nano glass structure based on HSQ^[48]; (c) schematic diagram of printing silicon structure based on laser reduction APTES^[49]; (d) schematic diagram of laser printing ZnO, Pt and Ag composition^[50]

Fig. 5. Schematic diagram of laser-induced bonding printing between nanoparticles. (a) Schematic diagram of light stimuli-induced ligand change mechanism of nanoparticles; (b) change of interaction force between nanoparticles^[51]

Fig. 6. Light-induced nanoparticle ligand desorption to achieve 3D micro-nano printing. (a) Schematic diagram of assembly mechanism of nanoparticles induced by photo-induced polarity change^[54]; (b) schematic diagram of printing device and laser-induced AuNC ligand desorption and pyrolysis^[55]

Fig. 7. Light-induced cross-linking between nanoparticles realizing 3D micro-nano printing. (a) Schematic diagram of PEB mechanism; (b) schematic diagram of 3D Pin mechanism; (c) SEM images of printed metal, oxide, and semiconductor micro-nano 3D structures; (d) EDS pictures of 3D printing structure by hybrid colloidal solution^[60]

Fig. 8. Laser printing of metal 3D micro-nano structures and their applications. (a) SEM image of direct writing silver wire on curved surface and pictures of micro-nano electric heater^[44]; (b) SEM image of printed metal structure and schematic diagram for holographic optical storage^[68]; (c) schematic diagrams of different types Ni micro-nano spiral robots (top) and images demonstrating their capabilities of load carrying (bottom)^[22]

Fig. 9. Laser printing of semiconductor 3D micro-nano structures and their applications. (a) Fluorescence images of RGB quantum dots pixel array printed by PEB (top) and quantum dot photodetector performance (bottom)^[57]; (b) SEM and performance image of Pt-ZnO-Ag diode structure (top) and SEM and structural diagrams of Pt-ZnO-Ag memristor (bottom) ^[50]; (c) CdS quantum dots woodpile structure shown by microscope and SEM images^[20]; (d) CdSe helical structure diagram (top left), chiral absorption spectrum (top right), simulated structure diagram (bottom left), and simulated chiral absorption spectrum (bottom right)^[60]

Fig. 10. Laser printing of dielectric 3D micro-nano structures and their applications. (a) Schematic diagram of titanium dioxide photonic crystal structure (top) and electron microscope image (middle), showing band gap blue shift with decreasing period (bottom)^[17]; (b) curves of hardness (left) and elastic modulus (right) of SiOC ceramic structure with different material ratios^[26]; (c) SEM (top left) and spectrum (top right) images of 3D structure of Nd-doped YAG, showing that optical gain capability increases after high annealing temperature increases transparency (bottom)^[31]

Fig. 11. Laser printing of silica 3D micro-nano structures and their applications. (a) Schematic diagram of DUV processing printed PDMS structure (top) and low RMS roughness glass lens diagrams (bottom)^[24]; (b) high transparency spectrum of printed POSS glass^[23]; (c) structure (top left) and performance (top right) demonstration of micro-annular whispering gallery modes optical resonator based on silica nanoparticles and emission spectrum of doped rare earth elements (bottom)^[38]; (d) demonstration of direct writing ring resonator (left), transmittance curve before and after heat treatment (middle), and optical fiber end face processing capabilities (right) based on HSQ^[48]

Fig. 12. Laser printing of heterogeneous materials. (a) Two-photon printing of polymer template (left), pyrolyzing template into conductive carbon structure (middle), electrodepositing nickel into carbon template, and milling excess metal with focused ion beam (right)^[81]; (b) schematic diagram of laser printing heterostructure humanoid robot and its control (left) and capturing particles (right)^[83]

Fig. 13. High-throughput laser 3D micro-nano printing and colloidal crystal laser printing. (a) Optical path schematic diagram (top) and printed structures image (bottom) of femtosecond pulses spatio-temporal focusing achieving high-precision and high-throughput printing ^[87]; (b) schematic diagram of light-sheet 3D micro-nano printing via two-colour two-step absorption and processing capabilities (top), printing parameter diagram (bottom left) and SEM image of printed structures (bottom right)^[90]; (c) perovskite colloidal crystals exhibiting superfluorescence emission (left), electron microscope image of colloidal crystal assembly (middle) and superfluorescence emission spectrum image (right)^[91]; (d) stable colloidal crystal structure based on bisazide molecules (left) and transmission electron microscope (TEM) image of assembly structure (right)^[94]; (e) nanoparticles with complementary DNA ligands achieving orderly assembly under photothermal action^[96]; (f) 3D colloidal crystal structure formed by sacrificial scaffold method (top) and demonstration of adjustable structural color (bottom)^[97]