Terahertz (THz) waves are often called the last undeveloped region of the electromagnetic spectrum. Only in recent decades have they become accessible for use, and they are expected to support high-speed Beyond 5G communications and high-resolution sensing. Their transmission through materials and millimetre-scale resolution make it possible to inspect plastic packages and acquire tomographic information from samples. However, conventional experimental systems remain expensive and difficult to deploy in practice.
A major reason is that generating and propagating signals in this frequency band is extremely difficult with conventional electronic devices alone. We therefore combine optical, materials, and semiconductor technologies to develop THz devices and systems for real-world applications.
Integrated Terahertz Sensors Based on Resonant Tunnelling Diodes (RTDs)
We develop compact, integrated terahertz sensors based on resonant tunnelling diodes (RTDs). By using their oscillation and detection capabilities, we simplify large and complex THz measurement systems and pursue practical on-chip THz sensing. Device characteristics and signal processing are designed together to build a sensitive, fast, and stable platform for material measurement.
High-Function Three-Dimensional Imaging Systems Using Photonic Technologies
Photonic THz generation and integration are attracting attention as alternatives to conventional electronic devices for creating and propagating high-frequency THz signals. Their benefits include wide bandwidths above 100 GHz, high speed, and low noise. We use UTC-PD devices to generate THz signals from the difference frequency of two optical waves, and silicon waveguides to confine those signals. This enables complex optical configurations to be integrated on a silicon wafer, including three-dimensional imaging of objects such as a coin enclosed in a sample.