Green Manufacturing of Electrically-Tunable Smart Light-Weight Planar Optics: A Review

Evolving demands for compact, light-weight, and versatile optical systems across various industries require the facile integration of planar diffractive optics. For the manufacturing of diffractive optics, green manufacturing becomes the prerequisite with timely considerations of Environmental, Social, and Governance (ESG). Conventional manufacturing processes such as semiconductor lithography or nano /micro imprinting utilize a large amount of harmful chemicals. Meanwhile, direct laser writing emerges as one of the key solution candidates, offering clear advantages over others, especially in terms of eco-friendliness due to the simple manufacturing process with less chemical usage. In this comprehensive review, we present recent advances in the analytical design, green manufacturing of electrically tunable smart light-weight planar optics, and their promising applications in space optics, photovoltaics, and optical imaging, highlighting the necessity for tunability in focal length, aberration, transparency, and beam propagation direction. Various types of electrically tunable diffractive optical elements utilizing active modulation of refractive index, geometrical shape, and bandgap have been discussed. Finally, this review concludes by proposing the integration of ultra-thin and light-weight diffractive optics presenting potential applications in micro-electronics, biomedical imaging, space exploration, and extended reality.