ROHM has developed a 2nd Generation terahertz (THz) wave oscillation device using semiconductor elements known as Resonant Tunneling Diodes (RTDs). The company is making the device available via the RTD-EVK-G2 Terahertz Wave Device Evaluation Kit, which includes a sample device, cable, and evaluation board. The kit enables companies and research institutions to evaluate THz wave oscillation and detection in a compact development environment.
Occupying the frequency region between radio waves and light, terahertz waves combine the penetrating properties of radio waves with the straight-line propagation of light. Because they exhibit unique absorption characteristics for polymers, moisture, and other substances, they are expected to be used in non-destructive testing without ionizing radiation, medical and healthcare applications, and high-resolution radar sensing. However, conventional terahertz systems require large equipment and high implementation costs, making it difficult for new companies and research institutions to enter the field or pursue commercialization.
Since the late 2000s, ROHM has engaged in joint research with the Institute of Science Tokyo, Osaka University, and many other universities and research institutions to develop THz wave oscillation and detection devices using RTDs. In 2024, ROHM began offering samples of 1st Generation products, achieving substantial downsizing and cost reduction compared with conventional methods.
What’s New in the 2nd Gen Wave Oscillation Device?
To address the growing demand for improved signal quality in application development, ROHM has now developed a 2nd Generation terahertz wave oscillation device. The device maintains the same compact 0.5×0.5mm chip size as the 1st Generation product while adopting an internal structure that enables higher output power. As a result, output power has been increased to approximately 4 times that of the 1st Generation product, reaching a maximum of 40µW. The higher output power improves the detectability of THz waves after transmission through or reflection from target objects – making the device well suited for applications such as sensing and imaging that require high signal quality.
The device is mounted in the same 4.0×4.3mm PLCC package, maintaining the industry’s smallest footprint. This enables evaluation environments to be built even in space-constrained settings. In addition, compared with other THz generation methods, the RTD approach generates less heat and consumes less power. This reduces application development load at both companies and research institutions. Sales of the RTD-EVK-G2 evaluation kit, which includes samples of the 2nd Generation wave oscillation device, are scheduled to begin later this year at $3,300 per set.
By enabling evaluation at a lower cost than other methods, the kit supports the development of a wide range of applications. This includes non-destructive testing; imaging and sensing in the medical and healthcare sectors; material identification; and moisture detection. ROHM will also continue sales of 1st Generation devices for applications that prioritize low power consumption. For further information, please contact a sales representative or visit the contact page on ROHM’s website. Purchase of the evaluation kit requires signing a non-disclosure agreement (NDA) with ROHM.
Expanding THz Wave Applications
Sharing his views on the development, Professor Safumi Suzuki, Laboratory for Future Interdisciplinary Research of Science and Technology, Institute of Integrated Research, Institute of Science Tokyo, said, “Terahertz waves are expected to be applied in a wide range of fields, including non-destructive testing, imaging and sensing, and wireless communications. At the same time, commercialization continues to face major challenges, such as the need for large-scale equipment and high implementation costs.
Conventional methods for generating terahertz waves include the ‘frequency multiplication’ method. This converts the frequency of an electrical signal into an integer multiple for output. The “photomixing” method that produces terahertz waves from the difference frequency created when two laser beams of different wavelengths are mixed in a photo-mixer. Both approaches necessitate large or medium sized costly equipment to generate terahertz waves.
“The RTD terahertz wave device, developed through many years of joint research with ROHM is compact, power saving, and does not require cooling. It can also be introduced at low cost, helping companies and research institutions begin terahertz wave research. With the launch of the 2nd Generation device featuring significantly improved oscillation output, I expect development of applications requiring higher signal quality to accelerate,” added Suzuki.
“With the launch of RTD-EVK-G2, we expect to make another major step forward toward the practical implementation of terahertz technology. Feedback from users of the 1st Generation device revealed strong demand for higher-output devices. With this 2nd Generation product, we have succeeded in increasing oscillation output to approximately 4 times that of the 1st Generation device while maintaining a compact size, bringing us closer to meeting those needs. Terahertz technology is steadily progressing toward real-world implementation,” mentioned Ken Nakahara, General Manager of ROHM Research & Development Center, ROHM Co., Ltd.
The Smallest Terahertz Wave Device Now Becomes Smarter!
Innovative oscillation and detection devices have been ROHM’s forte. Readers will remember that last year, the company introduced the first generation of the industry’s smallest THz wave oscillation and detection devices utilizing RTDs. Its extremely compact size, typically less than one-thousandth that of conventional oscillators, enabled this innovation to ensure easy development of terahertz wave applications, even in space-constrained environments.
By positioning the antenna surfaces of the oscillation and detection devices facing each other 10mm apart, a dynamic range of 40dB (typ.) was easily achievable. Both oscillator and detector maintain a drive power consumption of 10mW (typ.), while their ability to oscillate and detect terahertz waves at room temperature eliminates the need for cooling equipment required with some conventional methods. These compact, power-saving devices are almost unaffected by the operating environment, enabling use in a wide range of applications.
Going forward, ROHM intends to continue diversifying the possibilities for THz wave application development and contribute to the early commercialisation and real-world implementation of terahertz technology. This will help accelerate its deployment across a broad range of industries. “ROHM will continue working together with customers, partners, universities, research institutions, and government agencies to support the development of terahertz wave applications and contribute to the realization of a sustainable society,” averred Nakahara.
