Optical-grade diamond: characteristics, synthesis, and recent research progress

Diamonds, characterized by their elegant tetrahedral arrangement of carbon atoms, exhibit outstanding thermal, mechanical, and electrical properties. In the fields of optics and photonics, diamonds are highly regarded for their exceptionally wide spectral transmission range, excellent thermo-optical properties, remarkable mechanical strength, and unique nonlinear optical characteristics. Recent advancements in chemical vapor deposition (CVD) technologies have enabled the production of synthetic diamonds with lower dislocation densities, reduced impurities, minimal residual stress, and low absorption coefficients, thereby meeting the stringent demands of optical applications, even under extreme conditions. Additionally, progress in diamond processing techniques—such as polishing, anti-reflection coatings, micro/nanostructuring, and color center engineering—has further enhanced the potential of optical-grade diamonds, expanding their applications in areas such as lasers, quantum technologies, and precision instrumentation. This review provides a comprehensive overview of recent research progress in diamond synthesis and processing technologies, with a focus on controlling dislocation density and impurity levels in optical-grade diamonds. Furthermore, it explores future development trends and advanced applications of diamonds, offering valuable insights and guidance for researchers dedicated to high-quality diamond crystal growth and its utilization.