The objective of the research is to design and develop a suite of electronic devices operating at terahertz frequencies. The approach is based on the active control of metamaterial structures using plasma wave resonant behavior of the gated two-dimensional electron gas in the channel of GaAs HEMT devices.
Intellectual Merit: The research is focused on the creation of unique metamaterial/pHEMT hybrid devices to fill the "terahertz gap," where very few components exist today. The fundamental approach uniquely combines the emerging field of electromagnetic metamaterials with novel plasma wave electronic transport phenomena in transistors. The plasma wave behavior in sub-micron transistors offers the unique possibility to detect and modulate terahertz frequency signals. Modulator and demodulator device architectures will be developed to facilitate wireless communications in the terahertz regime with targeted data rates exceeding hundreds of gigabits per second.
Broader Impacts: The research will help catalyze development in diverse areas such as high data rate wireless communications, terahertz spectroscopy for cancer detection and tools for homeland security. The project will establish research and teaching laboratories at Boston College and Tufts University in the area of metamaterials and terahertz electronics. The project will support diversity and outreach activities through research programs for undergraduates and summer programs for students from under-represented groups, The researchers also plan to offer lectures at local high schools primarily in minority-dominated neighborhoods, and participate actively in K-12 student-teacher mentorship programs established at Tufts University and Boston College.
The goal of this program was to develop a metamaterial film that could assist in the evaluation of pigmented skin lesions, including atypical moles, which have one or more clinical or historical characteristics of melanoma. To enhance the effectiveness of the imaging system for detection of skin cancer we developed a metamaterial that acts as an intermediate matching layer between the air/skin boundary which is intended to improve the contrast between healthy and cancerous skin cells at THz frequencies. Our metamaterial consists of two metallic layers separated by a thin polyimide layer. The overall thickness of the MM film is only 25 μm making it very flexible to allow for it to conform to the contours of skin. In order to test the relative enhancement of THz signal and validate the approach we performed computer simulations. Our models examined the effectiveness of the metamaterial layer against skin with inclusions of cancerous cells. Through the use of the metamaterial impedance matching layer our simulations showed that we were able to achieve a noticeable enhancement in the returned THz signal. Our simulations showed that when compared to skin with no cancer present the difference between the measured THz signal reflection of a skin/cancer interface and no metamaterial present is 0.8%. However the use of our prototype MM film increased this difference by over 4 times to 3.8% Prototype metamaterial films based on designs based on our simulations were created and two undergraduate researchers have been actively involved in all aspects of the project.
