Metalenses can directly encode point spread functions (PSFs) using subwavelength nanostructures, enabling complex optical systems to become more compact. However, their performance under extreme temperature conditions is often limited by the thermo-optic effect and thermal expansion of the constituent materials. Temperature variations can simultaneously induce structural deformation and refractive-index changes, thereby disturbing the carefully designed phase distribution. This leads to focal shifts and accumulated wavefront aberrations, ultimately causing significant degradation in imaging quality.
To address this challenge, the research team led by Prof. Chongxin Shan and Prof. Peinan Ni at Zhengzhou University proposed and experimentally demonstrated a diamond-based metalens platform. Benefiting from diamond’s extremely small thermo-optic coefficient and very low thermal expansion, the thermally induced wavefront errors over a wide temperature range were suppressed to an ultralow level in simulations. The team further fabricated two types of diamond metalenses with engineered PSFs, namely a point PSF and a vortex PSF with a topological charge of L = 1, for experimental verification. This can be understood as engraving the “phase code” of a metalens onto an exceptionally thermally stable material platform, so that the phase profile remains almost unchanged even under large temperature fluctuations, allowing the focal profile and imaging capability to remain stable against environmental drift.
The key quantitative results of this work include the following: the diamond metalens maintained consistent diffraction-limited imaging performance over a temperature range from −100 °C to 500 °C. Numerical simulations showed that the thermally induced aberrations of the point PSF and vortex PSF were only about 0.0061λ and 0.0087λ, respectively. Experiments using a temperature-controlled platform further demonstrated that the focal length, full width at half maximum, and focusing efficiency of both the point PSF and vortex PSF remained nearly unchanged across the wide temperature range. Moreover, under incoherent illumination, the authors achieved edge-enhanced imaging by subtracting the imaging results of the point PSF and vortex PSF, and showed that this edge-enhancement performance remained stable from −100 °C to 500 °C. This work supports the development of compact and reliable imaging systems for extreme environments, such as deep-space missions, cryogenic experiments, and high-temperature industrial applications.
This work, entitled “Diamond Metalens Enabled Robust Imaging Across Broad Temperature Range,” was published in Laser & Photonics Reviews on February 26, 2026.
