1. MS 0603, Sandia National Laboratories, PO Box 5800, Albuquerque, New Mexico 87185, USA
2. Ames Laboratory, Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA

Correspondence to: S. Y. Lin¹ Correspondence and requests for materials should be addressed to S.Y.L. (e-mail: Email: slin@sandia.gov).

Abstract

Three-dimensional (3D) metallic crystals are promising photonic bandgap^{1, 2, 3} structures: they can possess a large bandgap^{4, 5, 6}, new electromagnetic phenomena can be explored^{7, 8, 9}, and high-temperature (above 1,000 °C) applications may be possible. However, investigation of their photonic bandgap properties is challenging, especially in the infrared and visible spectrum, as metals are dispersive and absorbing in these regions¹⁰. Studies of metallic photonic crystals have therefore mainly concentrated on microwave and millimetre wavelengths^{8, 11, 12}. Difficulties in fabricating 3D metallic crystals present another challenge, although emerging techniques such as self-assembly^{13, 14} may help to resolve these problems. Here we report measurements and simulations of a 3D tungsten crystal that has a large photonic bandgap at infrared wavelengths (from about 8 to 20 m). A very strong attenuation exists in the bandgap, 30 dB per unit cell at 12 m. These structures also possess other interesting optical properties; a sharp absorption peak is present at the photonic band edge, and a surprisingly large transmission is observed in the allowed band, below 6 m. We propose that these 3D metallic photonic crystals can be used to integrate various photonic transport phenomena, allowing applications in thermophotovoltaics and blackbody emission.