Feature: RF and microwave


Powering up THz systems with


injection-locked amplifiers By Greg Rankin, US-based technology writer


F


or decades the terahertz (THz) region of the electromagnetic spectrum (roughly 300GHz-3THz) has intrigued researchers with its potential to enable


faster wireless communications, ultra- high-resolution spectroscopy and more precise sensing. Yet, despite a solid understanding of the underlying physics, real-world THz systems have remained elusive. A major challenge has been the lack of THz sources capable of delivering both the output power and spectral purity required for practical applications. That may be starting to change.


Researchers at IMRA America have demonstrated a new THz source architecture that overcomes several long-standing limitations. By combining a resonant tunneling diode (RTD), a photomixed dual-wavelength Brillouin laser and a low-loss waveguide circulator, the team achieved gain over 40dB at 260GHz; see their setup in Figure 1. Just as importantly, these researchers


became the first to characterise the residual phase noise of an injection- locked RTD at this frequency, providing


32 April 2026 www.electronicsworld.co.uk Figure 1: IMRA RTD Setup


new insight into how high-power, low- noise THz oscillators can be built and scaled. Although this is only a proof of


principle, this architecture shows a clear path to combining power and spectral


purity at terahertz frequencies, which makes practical THz systems possible.


From diode to THz oscillator As shown in Figure 2, at the heart of the system is the RTD: a well-established


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