Long Wave Infrared Light Modulation Based on Metalenses: Principles, Progress, and Challenges

ABSTRACT Long‐wave infrared (LWIR) metalenses, capable of precise wavefront modulation through subwavelength meta‐atoms, represent a transformative advancement in infrared optics, offering a compact alternative to conventional refractive elements. This work systematically examines the fundamental principles, typical designs, and fabrication challenges of LWIR metalenses, with an emphasis on different phase modulation strategies, presenting their distinct advantages and limitations. Recent breakthroughs in aberration correction, wide‐field imaging, and polarization‐sensitive functionalities are critically reviewed, alongside computational optimization approaches such as deep learning and topology algorithms. Fabrication techniques, including advanced lithography and etching, are evaluated for their scalability and precision in realizing high‐performance metasurfaces. Persistent challenges in efficiency, thermal stability, and large‐scale manufacturing underscore the need for novel materials, refined nanofabrication methods, and integrated design frameworks. By addressing these barriers, LWIR metalenses hold potential to revolutionize applications in thermal imaging, defense systems, and biomedical sensing, paving the way for next‐generation infrared technologies.