In a groundbreaking development at the intersection of nanofabrication and topological photonics, researchers have achieved a room-temperature topological laser that operates directly in the visible spectrum at 523 nanometers. This novel laser is fabricated using nanoimprint lithography (NIL), marking a significant stride toward scalable, cost-effective production of photonic devices that harness the power of topological physics. Unlike conventional patterning methods, NIL circumvents the need for resource-intensive etching processes, providing a high-throughput pathway for the creation of intricate nanostructures necessary for advanced photonic functionalities.
Nanoimprint lithography’s capacity for large-area patterning combined with its financial efficiency makes it an attractive alternative to traditional electron-beam lithography and focused-ion-beam etching. However, fabricating visible-band nanodevices has historically been hampered by the stringent requirement for near-perfect structural fidelity—a standard challenged by the presence of defects introduced during the demolding phase of NIL. This barrier is particularly significant when solution-processed gain media, such as organic dyes or colloidal semiconductor nanocrystals, are involved, given their sensitivity to fabrication imperfections.
Addressing these challenges, the emerging field of topological photonics brings new theoretical and practical tools that promise exceptional resilience to fabrication defects, leveraging concepts rooted in topology—a branch of mathematics concerned with properties maintained under continuous deformations. Harnessing topological invariants allows photonic devices to maintain robust operational characteristics even in the presence of considerable disorder. This foundational principle inspired the development of topological lasers, devices that can maintain lasing action despite imperfections in their fabrication.
This latest work has introduced a topological laser that operates at visible wavelengths through a single, hand-crafted NIL step, employing cesium lead halide (CsPbBr₃) perovskite nanocrystals as the active lasing medium. These all-inorganic perovskite nanocrystals are notable for their excellent optical gain properties and environmental stability, which are critical for the realization of practical photonic devices at room temperature. The successful integration of perovskite NCs into a topologically engineered nanostructure via NIL represents a remarkable leap forward in materials and device engineering.
Central to the device’s design is a meticulously engineered two-dimensional Kagome lattice structure. This lattice type is known in physics for its ability to support unconventional electronic and photonic states arising from its unique geometric configuration. Utilizing tight-binding modeling alongside finite-element method simulations, the research team identified multiple higher-order topological corner states (HOTCS) supported by this lattice. These HOTCS extend the concept of topological protection beyond edge states, localizing light at the corners of the lattice structure in modes that are robust against scattering and fabrication imperfections.
The experiment detailed the spectral signatures of these corner states using stimulated-emission spectroscopy, verifying not just the existence of the previously reported type-I and type-II corner states but also demonstrating, for the first time in the visible spectral range, lasing action originating from type-III corner states. The observation and exploitation of type-III HOTCS for laser emission mark a novel advance in topological photonics, expanding the typology of accessible robust states that can be engineered for device applications.
One of the standout features of the nanoimprinted topological laser is its pronounced robustness to nanofabrication defects. Experimental results underscore the device’s ability to sustain lasing despite the typical disorder and irregularities inherent in hand-fabricated NIL processes. This robustness is a testament to the protective nature of topological corner states, which serve as fault-tolerant modes impervious to many types of structural perturbations that would ordinarily degrade laser performance or prevent lasing altogether.
This groundbreaking realization signifies an important expansion of topological photonics research into practical visible-band devices and notably highlights NIL’s untapped potential for the cost-effective, high-volume fabrication of topological lasers and potentially other photonic components. The use of low-refractive-index materials like perovskite nanocrystals in such devices amplifies the versatility of NIL as a fabrication method, broadening the horizons for industry adoption of these robust photonic architectures.
The research team acknowledges that while these results are promising, additional inquiry is necessary to comprehensively map the limits of fabrication defect tolerance within these topological frameworks. A thorough and systematic quantification of the upper bounds of allowable disorder across diverse topological configurations is needed to fully harness the reliability offered by such designs. Such ongoing and future investigations will be critical in translating this fundamental science into scalable manufacturing protocols for integrated photonic systems.
The implications of this work extend beyond the immediate demonstration of a topological laser. It paves the way for the design of resilient photonic devices capable of maintaining functionality under real-world manufacturing and operational imperfections. This robustness is especially critical as the photonics industry advances toward more complex, multifunctional circuitry where defect-induced failure modes could otherwise limit performance or yield.
Moreover, the synergy between solution-processed nanocrystal materials and topological design principles offers an exciting platform to explore new lasing mechanisms and photonic device architectures. The incorporation of perovskite nanocrystals into topologically non-trivial lattice configurations via scalable nanoimprinting aligns with the broader trend toward hybrid materials and innovative manufacturing methods in photonics, potentially revolutionizing how optical devices are conceived and realized.
In conclusion, this research sets a new benchmark in topological photonics, demonstrating the feasibility of low-cost, high-volume fabrication of visible-wavelength topological lasers through nanoimprint lithography. The innovative exploitation of higher-order topological corner states combined with durable nanocrystal gain media heralds a new era of robust and efficient photonic components, providing a compelling template for future advancement in both fundamental research and practical application domains.
Subject of Research: Nanoimprint lithography, topological photonics, higher-order topological corner states, perovskite nanocrystals, visible-wavelength lasers
Article Title: Nanoimprinted Topological Laser in the Visible
Web References: 10.1016/j.scib.2026.02.037
Image Credits: ©Science China Press
Keywords: Nanoimprint lithography, topological laser, higher-order topological corner states, perovskite nanocrystals, visible light photonics, Kagome lattice, robust photonic devices, fabrication tolerance, cesium lead halide, room-temperature lasing, scalable nanofabrication, topological photonics
