My Note: I am on vacation and will be posting from my Ipad this week. Just FYI. this story is not new news but has some interesting discussion.

Researchers at Cornell University (Ithaca, NY) have developed tunable solid-state terahertz sources that employ inexpensive CMOS technology. This chip-based approach, according to the scientists, could enhance medical imaging applications and may even allow for the development of scanners capable of identifying skin cancer indicators that are invisible to the naked eye.

The Cornell researchers have strayed from the path typically taken by current methods of generating terahertz radiation, which often entail the use of large or costly lasers, vacuum tubes, or special circuits that must be cooled near absolute zero, for example. Instead, the team, led by Ehsan Afshari, assistant professor of electrical and computer engineering at Cornell, explored the possibility of generating terahertz signals on an inexpensive silicon chip.

"We present a solid-state tunable terahertz source that exploits the theory of coupled oscillators to simultaneously achieve high output power and frequency tuning," the researchers explain in an abstract for the American Physical Society. "Our proposed structure effectively generates and combines high-power harmonics from multiple synchronized solid-state oscillators in a loop configuration. We study the dynamics of the system, find the stable modes, and show how the structure can dynamically select a desired coupling mode. Using this method, we fabricated 0.29- and 0.32-THz tunable sources with peak output powers of 0.76 and 0.5 mW both in a standard 65-nm bulk complementary metal-oxide semiconductor technology."

Using this novel method yielded a power level approximately 10,000 times larger than that previously achieved at terahertz frequencies on a silicon chip, according to the researchers. These promising early results demonstrate promise for the use of such a technology for a variety of future medical applications.