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Metal-organic frameworks (MOFs) are an emerging kind of laser material, yet they remain a challenge in the controlled fabrication of crystal nanostructures with desired morphology for tuning their optical microcavities. Herein, the shape-engineering of pure MOF microlasers was demonstrated based on the coordination-mode-tailored method. The one-dimensional (1D) microwires and 2D microplates were selectively fabricated through changing the HCl concentration to tailor the coordination modes. Both the single-crystalline microwires and microplates with strong optical confinement functioned as low-threshold MOF microlasers. Moreover, distinct lasing behaviors of 1D and 2D MOF microcrystals confirm a typical shape-dependent microcavity effect: 1D microwires serve as Fabry-Pérot (FP) resonators, and 2D microplates lead to the whispering-gallery-mode (WGM) microcavities. These results provide a special pathway for the exploitation of MOF-based micro/nanolasers with on-demand functions.

Lasing signals with easily distinguishable readout and cavity-geometry-dependent output are emerging as novel cryptographic primitives for two-dimensional (2D) optical encryption, while their practical application is restricted by the challenge of integrating different lasing elements onto an identical 2D pattern. Herein, a lithographic template-confined crystallization approach was proposed to prepare large-scale perovskite microstructures with any desired geometries and locations, which enabled them to serve as 2D lasing patterns for reliable encryption and authentication. These prepatterned perovskite microstructures realized whispering-gallery-mode lasing and also demonstrated outstanding reproducibility of lasing actions. Benefiting from the feature of their cavity-geometry-dependent lasing thresholds, we achieved controllable laser output from different shaped elements, which was further utilized for the proof-of-concept demonstration of a cryptographic implementation. The remarkable lasing performance and feasible preparation of 2D microlaser patterns with customized geometries and locations provide us deep insights into the concepts and fabrication technologies for 2D optical encryption.

Laser displays, which offer wide achievable color gamut and excellent color rendering, have emerged as a promising next-generation display technology. Constructing display panels composed of pixelated microlaser arrays is of great significance for the actualization of laser displays in the flat-panel sector. Here, we report microscale light-emitting electrochemical cell (LEC) arrays that operate as both optically pumped lasers and electroluminescence devices, which can be applied as self-emissive panels for high quality displays. Optically pumped red, green, and blue laser emissions were achieved in individual circular microcells consisting of corresponding conjugated polymers and electrolytes, suggesting that the microstructures can act as resonators for coherent outputs. As-prepared microstructures possess a narrowed recombination region, which dramatically increases the current density by 3 orders of magnitude under pulsed operation, compared with the corresponding thin-film devices, representing a promising solution-processed device platform for electrical pumping. Under programmable electrical excitation, both static and dynamic displays were demonstrated with such microscale LEC arrays as display panels. The prominent performance of the demonstrated structures (microlaser arrays embedded in LEC devices) provide us deep insight into the concepts and device constructions of electrically driven laser displays.

Constructing three-dimensional (3D) metamaterials from functional nanoparticles endows them with emerging collective properties tailored by the packing geometries. Herein, we report 3D supercrystals self-assembled from upconversion nanorods (NaYF4:Yb,Er NRs), which exhibit both translational ordering of NRs and orientational ordering between constituent NRs in the superlattice (SL). The construction of 3D reciprocal space mappings (RSMs) based on synchrotron-based X-ray scattering measurements was developed to uncover the complex structure of such an assembly. That is, the two main orthogonal sets of hexagonal close-packing (hcp)-like SLs share the [110]SL axis, and NRs within the SL possess orientational relationships of [120]NR//[100]SL, [210]NR//[010]SL, and [001]NR//[001]SL. Notably, these supercrystals containing well-aligned NRs exhibit collectively anisotropic upconversion fluorescence in two perpendicular directions. This study not only demonstrates novel crystalline superstructures and functionality of NR-based 3D assemblies but also offers a unique tool for deciphering a wide range of complex nanoparticle supercrystals.

Wavelength switchable micro/nanoscale laser is essential to construct various ultracompact photonic devices. However, traditional semiconductors as the gain media generally provide only monochromatic laser output due to their continuous energy band structures. For luminescent conjugated molecules, the broad emission band usually contains a series of vibronic peaks, which is very helpful for extending the lasing spectrum to several different wavelengths. Here we propose a novel strategy to realize wavelength switchable lasers based on the controlled competition of dual-wavelength vibronic lasing in single-component organic microcrystals. The vibrationally structured fluorescence property of the single-crystal organic microdisks brings dual-wavelength lasing at different vibronic bands. Their relative optical gain intensity was modulated by controlling the population on the certain vibronic level of the ground state with varied temperature, which consequently enabled the reversible switching of the dual-wav...

The outcoupling of whispering-gallery-mode (WGM) lasers is crucial for the realization of various photonic functionalities, yet present material structures still suffered the unexpected surface damages or contaminations in the multistep micro/nanofabrications. Here, we propose a strategy to achieve controlled outcoupling of WGM lasers in self-assembled organic single-crystalline microrings. The microrings with molecular-smooth surfaces functioned as organic crystalline whispering-gallery-mode microlasers with a lasing threshold of ∼14.2 μJ cm–2 and a quality factor on the order of 103 to 104. The circular self-assembly allowed us to design different derived ring-based structures toward desired outcoupling of the WGM lasers, including unidirectional laser output from wire-ring coupled structures, and single-mode lasing in double-ring coupled systems. The results would provide an alternative avenue to construct versatile organic nanoscale lasers and related components with specific photonic applications.

Miniaturized lasers with high spectra purity and switchable output are of crucial importance for various ultracompact photonic devices. However, it still remains a great challenge to simultaneously control the wavelength and mode purity of microscale lasers due to the insensitive response of traditional materials to external stimuli. In this work, we propose a strategy to realize switchable single-mode microlasers in perovskite microwires (MWs) coupled with responsive organic microdisk cavities. The perovskite MW therein serves as an excellent laser source to deliver multiple lasing modes, while the microdisk functions as a spectral filter to achieve single-mode outcoupling. Furthermore, on account of the sensitive responsiveness of organic materials, reversible wavelength-switching of single-mode laser can be realized through adjusting the resonant modes of the microdisk cavity filter. The results will provide guidance for the rational design of nanophotonic devices with novel performances based on the characteristic of organic materials.