Researchers at Pohang University of Science and Technology (POSTECH) have developed an ultra-fine 3D printing technique for fabricating vertically aligned nanolasers directly on semiconductor substrates. The approach enables high-density placement of optical components and is intended for use in future optical integrated circuits for computing, communications, and display technologies.
The work was led by Ji Tae Kim, Professor in the Department of Mechanical Engineering, and Junsuk Rho, with Shiqi Hu as first author. The research was published in ACS Nano.
Manufacturing constraints in on-chip nanolasers
Nanolasers are considered a key component for optical information processing, where data is transmitted and processed using light rather than electrical signals. However, conventional semiconductor fabrication methods such as photolithography are primarily suited to planar, repetitive structures and offer limited flexibility in device geometry and placement. These processes can also be costly and complex when applied at the nanoscale.
Most existing on-chip lasers are fabricated in horizontal configurations, which occupy surface area on the substrate and can suffer from optical losses due to light leakage into the underlying material. These factors limit achievable device density and efficiency in optical integrated circuits.
Vertical nanolasers via electrohydrodynamic 3D printing
To address these limitations, the POSTECH team developed an ultra-fine electrohydrodynamic 3D printing process capable of depositing material with attoliter-scale resolution. The method uses electrical voltage to control the ejection and placement of nanoscale ink droplets, enabling direct-write fabrication without the need for subtractive patterning steps.
Using this approach, the researchers fabricated vertically oriented, pillar-shaped nanostructures from perovskite, a semiconductor material known for its strong light-emission properties. The structures were printed directly at specified locations on the substrate, forming vertical nanolasers with dimensions significantly smaller than a human hair.
Surface quality was identified as a critical factor for device performance. By integrating the printing process with gas-phase crystallization control, the team produced nanostructures with smooth surfaces and near single-crystalline alignment. This reduced optical scattering and loss, enabling stable laser operation with improved efficiency.
Tunable emission and optical security features
The researchers also demonstrated wavelength control by adjusting the height of the printed nanostructures, allowing the emission color of the nanolasers to be tuned. Using this capability, the team created laser-based security patterns that are not visible under normal viewing conditions and can only be detected using specialized optical equipment.
According to the researchers, the ability to directly fabricate vertical nanolasers at high density could simplify the integration of optical components on semiconductor chips and support future developments in optical computing and security-related photonic devices.
3D printed photonics for optical computing
Recent research has explored how additively manufactured photonic systems could support next-generation optical computing and signal processing, particularly where conventional semiconductor fabrication limits design freedom. Studies have examined the use of 3D printed photochromic materials to enable all-optical information processing, light-controlled switching, and reconfigurable photonic functions.
Other work has reviewed how 3D printed photonic architectures may allow greater control over geometry, material composition, and spatial arrangement of optical components, supporting more compact and application-specific device designs. Within this broader research landscape, vertical nanolaser architectures represent one approach to increasing component density while reducing optical losses associated with planar layouts.
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Featured image shows FE-SEM images showing electrohydrodynamically printed single perovskite nanowires, including MAPbI₃, MAPbBr₃, and MAPbCl₃ (scale bar: 1 μm). Image via Hu et al.
