National University of Singapore (NUS) engineers say they have developed a technique to miniaturize and simplify terahertz (THz) emitters.

Traditional methods of generating terahertz waves often require bulky high power lasers or extremely expensive and sophisticated device fabrication processes, says Wu Yang, first author of the study published in the journal Advanced Materials. "Our team’s terahertz emitters have displayed better performance compared to existing devices in many aspects," he says. At the same time, "we have also developed a fabrication process to produce these novel terahertz emitters in large quantities at a low cost."

(Read "Terahertz Waves: Poised for a Breakthrough?")

Yang Hyunsoo (right) and Wu Yang from the NUS Faculty of Engineering and NUS Nanoscience and Nanotechnology Institute.Terahertz waves, which fit into the electromagnetic spectrum between microwaves and infrared light waves, are non-ionizing and non-destructive. Since they can pass through non-conducting materials such as clothing, paper, wood, and brick they are natural candidates for such applications as cancer diagnosis, detection of chemicals, drugs and explosives, coding analysis, and quality control of integrated circuit chips.

"Traditional methods of generating terahertz waves, such as through the exciting of electro-optical crystals or photoconductive antennas, often require expensive and bulky high power lasers or extremely expensive and sophisticated device fabrication processes," says Dr. Wu.

Their device is much more efficient because it can produce its output using a low-power laser. Based on a 12 nm metallic thin film heterostructure, it emits broadband terahertz waves with a higher power output than a standard 500-µm rigid electro-optical crystal emitter.

The emitters can be fabricated by depositing a wafer-scale film, which is then diced to produce a large quantity of ready-to-use devices.

The research team also tested their device on flexible surfaces and found that its performance was not compromised despite being subjected to a large bending angle. They could therefore be incorporated into wearable devices.

The team now plans to build a compact spectroscopy system based on its emitters. They are also looking into enhancing the emission at specific wavelengths, which will be useful for a wide range of applications.