Achievement

RPI IGERT trainee Y.W. Chen (Electrical engineering) and Ms. Meilin Kuo (Physics) under the guidance of Dr. P. Han and IGERT faculty X.-C. Zhang (Physics) designed and developed a multi-layer silicon microstructure for the purpose of broadband antireflection in terahertz frequencies. The uniqueness lies in the engineerable refractive indices. To achieve the desired refractive index for each layer, a certain percentage of silicon is removed from the layer by etching air columns into silicon; different air-to-silicon volume ratio is used for each layer. This way, the refractive index for each layer can be individually tuned and controlled, making it possible to achieve optimum and flexible design. The overall bandwidth of the device goes from 0.2 THz to 7.3 THz, covering almost the entire terahertz region. The device can operate at a large incident angle (20 degrees) and is polarization independent. The work was published in Applied Physics Letters in 2009.