The innovative architecture combines low noise dual-wavelength Brillouin laser with resonant tunneling diodes to achieve high power terahertz outputs
March 31, 2026
Terahertz oscillators with low-phase noise and high output power are required in many fields in science and engineering. However, terahertz operation presents unique challenges based on the method of generation, achieving either high output power or low noise. To address these issues, a new study presents a hybrid approach where a waveguide RTD is injection-locked using a photomixed DWBL. This innovative approach shows a promising route towards practical 1 THz oscillators.
Terahertz (THz) oscillators with low phase noise have applications in a variety of fields, ranging from radio astronomy and radar to wireless communications and microscale molecular spectroscopy. However, the development of such oscillators has been hindered by the unique challenges associated with operation in the THz frequency range based on the method of generation.
One promising approach uses a dual-wavelength Brillouin laser (DWBL), which exhibits extremely low phase noise. In this method, two optical wavelengths are photomixed to generate THz radiation. While this approach provides excellent spectral purity, it produces relatively low usable output power. To address these limitations, studies have explored compact electronic oscillators such as resonant tunnelling diodes (RTDs) as a promising alternative. RTDs can generate higher output power at THz frequencies, but they typically suffer from comparatively high phase noise.
To resolve these issues, a new study published in the IEEE Journal of Quantum Electronics on January 12, 2026, presents a novel hybrid solution where a waveguide RTD is injection-locked using a photomixed DWBL to achieve high power, low-phase noise THz outputs. The authors note that previous studies have shown that injecting an RTD with a low-phase noise photomixed source can considerably improve the linewidth of an RTD. But current setups offer low output power. The present hybrid approach is described as effectively addressing these limitations.
To build the proposed RTD injection locking amplifier, the researchers first comprehensively analysed the free-running RTD phase noise and frequency fluctuations to identify the sources of noise. Using this analysis, they developed a theoretical model based on the Leeson effect to describe the phase noise behavior of the RTD oscillator.
Building on these insights, the researchers then constructed the RTD injection locking amplifier using low-loss waveguide components and measured its residual phase noise. They
also proposed a new method for predicting the phase noise of RTD oscillators, with results that matched well with experimental observations. The study describes this work as one of the most comprehensive analyses of RTD terahertz radiation phase noise, with measurements conducted over a wide bandwidth. It further highlights that the free-running phase noise and quality factor of the RTD are key parameters for evaluating the performance of future RTD injection-locking amplifiers.
By optimizing the injection locking phase, the researchers were able to achieve over 40 decibels (dB) of amplification of a 260 GHz wave for nanowatt-level input power. The authors further indicate that combining photomixing and injection-locking provides a promising route towards low- phase-noise, and high power 1 THz radiation sources.
The proposed architecture could enable the development of advanced THz oscillators that benefit a wide range of scientific and engineering applications.
Reference
Authors James Greenberg1, Brendan M. Heffernan1, William F. McGrew1, and Antoine Rolland1
Title of original paper: Terahertz Amplification by Injection Locking of Waveguide Resonant Tunneling Diode
Journal: IEEE Journal of Quantum Electronics
DOI: 10.1109/JQE.2026.3652530
Affiliations 1Imra America Inc., Boulder Research Laboratories, USA
Additional information for EurekAlert
Latest Article Publication Date: January 12, 2026
Method of Research: Experimental study
Subject of Research: Not Applicable
Conflicts of Interest Statement: N/A
Image Title: Experimental setup for hybrid RTD injection-locked terahertz oscillator
Image Caption: Photograph of the experimental setup used in the study, showing a waveguide resonant tunnelling diode (RTD) integrated with injection-locking components. This hybrid system combines photomixing and electronic amplification to achieve improved output power and reduced phase noise in terahertz (THz) oscillators.
Image Credit: Dr. James Greenberg from IMRA America Incorporation, Boulder Research Laboratories, USA
Image source link: N/A
License type: Original content
Usage restrictions: Credit must be given to the creator.
Press Release Source: IEEE Photonics Society Media Contact First Name: Laura A. Media Contact Last Name: Lander Media Contact Email: l.lander@ieee.org Media Contact Phone Number: 1 (732)-465-6479 State of Origin: New York, USA
