White Cyphochilus insulanus beetles, exhibiting both environmental camouflage display and radiative cooling functions, serve as a good prototype for biomimetic fabrication. As inspired, this work presents a femtosecond (fs) laser-based biomimetic fabrication strategy that takes full use of the synthesized radiative cooling nanomaterials for a groundbreaking stimuli-responsive infrared (IR) impressionistic camouflage display. The proposed technique is capable of readily transforming various substrates (quartz glass and metals including Ti, Al, Zr, and W) into self-assembled porous networks (aerogels) consisting of oxygen-vacancy-rich oxide nanoparticles. Surprisingly, the emissions of all as-prepared porous particle-networks in the radiative-cooling long-wavelength infrared (LWIR) band are above 95%, with the SiO₂ aerogels reaching a maximum of 99.6%. Benefiting from the far-from-equilibrium thermodynamic kinetics, metastable phases of anatase TiO₂, tetragonal zirconia (t-ZrO₂), and monoclinic WO₃ (Pc) are synthesizable, opening up opportunities for exploring their optical applications. Taking the low-temperature metastable phase WO₃ (Pc) as representative for systematic studies, it is found that (1) the ratio WO₃ (Pc) phase to that of room-temperature phase of WO₃ (P2₁/n) can be tailored by modulation of processing parameters; (2) laser synthesized aerogels with hybrid phases of WO₃ (Pc) and WO₃ (P2₁/n) have a brighter visible whiteness, higher visible/near-infrared (NIR) spectral selectivity than the natural prototype of white Cyphochilus insulanus beetles but with comparable LWIR emittance. White WO₃ aerogel in situ deposited during flexibly fs laser artistic patterning can blur the painting features due to its radiative cooling effect, allowing a colorful impressionistic IR display in the heating mode. What’s more, invisible painting features concealed by the white deposited WO₃ aerogel are clearly/faintly distinguishable by introducing external stimuli of a human hand and sample heating, respectively, catalyzing progress in optical encryption and selectively stimuli-responsive decryption display in the infrared band.

Black wings of butterfly Ornithoptera goliath and infrared-band radiative cooling function of Rapala dioetas butterfly wings are associated with black pigment (e.g., melanin) and unique hierarchical micro/nanostructures, greatly stimulating biomimetic fabrication of functional photonic structures but mainly targeted to one prototype. Targeted at two-prototype integrated biomimetic fabrication from fully compositional/structural/functional aspects, femtosecond (fs) laser subtractive/additive-integrated hierarchical micro/nano-manufacturing technique is proposed in this work. This technique can one-step transfer refractory metals (e.g., W, Mo, Nb, Ta) into black non-stoichiometric oxide nanomaterials with abundant oxygen vacancies and simultaneously enable the realization of in situ quasi-controllable micro/nanoscale hierarchical aggregation and assembly, all displaying black color but with tunable infrared emission. Adjusting the scan interval for biomimetic manufacturing can tailor the structural oxidation degree, the emission in the long-wave infrared (LWIR) band while keeping the blackness of hierarchical aggregates, and the confined height between the covering quartz plate and the ablated sample. The blackening efficiency of this technique can reach ~11.25 cm²·min⁻¹, opening opportunities for high-throughput optical/thermal applications. Selectively patterned Chinese characters, Arabic numbers, and English letters are easily fabricable, which are intrinsically invisible-infrared dual-band encrypted but decryptable via static/dynamic environment stimuli (e.g., sample heating/cooling, introducing external hot/cold sources including human hands). The self-evolution from ‘orderless’ structuring to ‘ordered’ functionalization is validated for the proposed fs laser subtractive/additive-integrated biomimetic manufacturing, specifically from the synthesis of diverse black nanomaterials and the seemingly disordered micro/nano-aggregates to the ordered optical/thermal regulation capacities for a delicate modulation of information encryption and decryption, unveiling a new concept for future exploration and extension.

Exsolution, as an effective approach to constructing particle-decorated interfaces, is still challenging to yield interfacial films rather than isolated particles. Inspired by in vivo near-infrared laser photothermal therapy, using 3 mol% Y₂O₃ stabilized tetragonal zirconia polycrystals (3Y-TZP) as host oxide matrix and iron-oxide (Fe₃O₄/γ-Fe₂O₃/α-Fe₂O₃) materials as photothermal modulator and exsolution resource, femtosecond laser ultrafast exsolution approach is presented enabling to conquer this challenge. The key is to trigger photothermal annealing behavior via femtosecond laser ablation to initialize phase transition from monoclinic zirconia (m-ZrO₂) to tetragonal zirconia (t-ZrO₂) and induce t-ZrO₂ columnar crystal growth. Fe-ions rapidly segregate along grain boundaries and diffuse towards the outmost surface, and become ‘frozen’, highlighting the potential to use photothermal materials and ultrafast heating/quenching behaviors of femtosecond laser ablation for interfacial exsolution. Triggering interfacial iron-oxide coloring exsolution is composition and concentration dependent. Photothermal materials themselves and corresponding photothermal transition capacity play a crucial role, initializing at 2 wt%, 3 wt%, and 5 wt% for Fe₃O₄/γ-Fe₂O₃/α-Fe₂O₃ doped 3Y-TZP samples. Due to different photothermal effects, exsolution states of ablated 5 wt% Fe₃O₄/γ-Fe₂O₃/α-Fe₂O₃-doped 3Y-TZP samples are totally different, with whole coverage, exhaustion (ablated away) and partial exsolution (rich in the grain boundaries in subsurface), respectively. Femtosecond laser ultrafast photothermal exsolution is uniquely featured by up to now the deepest microscale (10 μm from 5 wt%-Fe₃O₄-3Y-TZP sample) Fe-elemental deficient layer for exsolution and the whole coverage of exsolved materials rather than the formation of isolated exsolved particles by other methods. It is believed that this novel exsolution method may pave a good way to modulate interfacial properties for extensive applications in the fields of biology, optics/photonics, energy, catalysis, environment, etc.