Main author: Muhsin Ali
Other authors: Guillermo Carpintero, Alejandro Rivera-Lavado, Álvaro Jiménez
The move towards the sixth generation (6G) of mobile networks is well underway. With the recent publication of the IMT-2030 standard, ambitious targets have been defined: data rates of 200 Gb/s, latencies below 1 ms and a spectral efficiency of 50 Mbit/s/Hz. With such high requirements, the way forward is to explore new frequency bands beyond 100 GHz, where the available spectrum allows the development of very high performance solutions.
Since NTT’s landmark demonstration at the 2008 Beijing Olympics, using the 120 GHz band to transmit at 10 Gbps [1], the world has set its sights on sub-THz and THz spectrum as a way to enable ultra-fast connections. This trend has been consolidated with key regulatory decisions: in 2015, Japan allocated the 116-134 GHz band to commercial communications, and in 2019 the FCC in the US released more than 21 GHz for unlicensed use in bands up to 246 GHz [2]. Today, the 6G ecosystem is already targeting Terahertz (300 GHz – 3 THz), looking to exploit spectrum above 275 GHz.
Accessing this range is not straightforward: the ‘Terahertz Gap’ marks a complex transition between electronics and photonics, where free-space losses and the low power of compact sources pose major challenges [3]. Historically, these have been overcome by using large, high-gain antennas, but such solutions are incompatible with consumer electronics and mobile communications, which require electronic beam steering.
This is where LeapWave Technologies is making a difference. Without the technology offered by the Spanish company, there is a high risk of not achieving the goals set, stagnating the technology because of the limits present.
LeapWave: Innovation at the Heart of the Wireless Future
Based in Madrid and founded in 2022, LeapWave Technologies was created as a technology spin-off specialising in the development of semiconductor guides for 6G communications in the high frequency range above 100 GHz. Backed by private capital and committed to collaborative research, LeapWave is involved in multiple national and European projects that are shaping the future of telecommunications.
LeapWave’s differentiating proposition is based on its proprietary broadband waveguide technology, which can be used in more complex systems, such as phased arrays at sub-THz frequencies. These solutions not only allow power to be efficiently extracted from semiconductor chips, but also enable critical functionalities such as electronic beam steering, which is key to advanced mobile communications.
Proprietary Technology for a Photonics-based THz Ecosystem
Photonics technology has positioned itself as the most promising way to efficiently generate and manage THz signals, thanks to its low losses and immunity to interference. LeapWave integrates into this ecosystem with a key solution: antennas based on dielectric waveguides (DRW) specially designed to operate in conjunction with state-of-the-art photonic emitters.
Figure 1. Block diagram of a photonics-based terahertz transmitter with phased array. It uses optical heterodyning for signal generation and beam shaping using real-time delays to control the resulting beam [4].
Using optical heterodyning techniques, signals from microwaves to terahertz can be generated by mixing two wavelengths in a high-speed photodiode [5]. This is coupled with the use of Optical Beam Forming Networks (OBFNs), which allow each element of the array to be fed with the necessary phase shift to steer the signal. This architecture provides exceptional control, ideal for ultra-wideband phased arrays [6].
From Theory to Reality: DRW Antennas for THz Transmitters
In collaboration with Fraunhofer HHI, LeapWave has developed THz emitter modules that integrate antenna chips with high-speed InP-based photonic chips. These chips incorporate four photodiodes fed by optical waveguides and bow-tie antennas, capable of operating up to 1 THz. To overcome the limitations of traditional flat antennas – which require silicon lenses and make beam steering difficult – LeapWave implements its compact, high-efficiency DRW (Dielectric Rod Waveguides) antenna solution.
Figure 2. Image of the DRW 1×4 antenna array, fabricated on a silicon wafer, using effective index technology to achieve a monolithic component with discrete antennas [4].
Less than 1 mm² in size, DRWs allow dense and compact arrays to be built, maximising performance without compromising space. The structure, optimised using effective index technology, allows multiple waveguides to be integrated into a single piece of silicon. This innovation simplifies assembly, improves radiation efficiency and reduces manufacturing costs.
Figure 3. THz emission module with DRW antennas mounted on a high-speed InP photodiode. The chips are encapsulated in a metal housing with an aperture for antenna protrusion [7].
Each DRW features a tapered transition to air, which ensures excellent impedance matching and efficient THz energy coupling. The resulting emitter module – as shown in Figure 3 [7] – operates between 100 GHz and 330 GHz, offering stable and reliable performance over the entire range.
Electronic Beam Steering: A Leap Towards 6G
Tests with DRW modules show broad (±20°) and consistent radiation patterns between elements, even when exciting each antenna separately. When activated simultaneously with appropriate phase offsets, the resulting beam can be electronically steered in different directions, including ±20°, thus meeting the key requirements for phased arrays.
This behaviour has been experimentally validated (Figure 4 [4]), confirming that LeapWave technology is not only viable, but ideal for high-demand applications in 6G networks.
Figure 4. Radiation patterns emitted from the 1×4 DRW array at a frequency of 210 GHz and the demonstration of the beam control functionality. (a) Individual patterns corresponding to each of the four individual antennas. (b) Combined patterns with simultaneous excitation with pointing angles at 0°, -20° and 20° [4].
Ready for the Future: Ultra-Wide Phase Arrays
The combination of photonics technology with DRW antennas positions LeapWave as a key player in the development of advanced 6G communications systems. Its approach enables the construction of high-density 2D phased arrays, compatible with both electronic and photonic technologies, opening the door to compact, scalable and highly efficient solutions.
With their compact footprint, wide performance and semiconductor chip compatibility, LeapWave’s DRW antennas are emerging as a strategic solution for the deployment of future ultra-high-speed wireless networks.
A European Project with a Global Vision
LeapWave Technologies actively participates in reference research initiatives, including the European projects Tera6G (Grant Agreement No. 101096949) and TERAWAY (Grant Agreement No. 871668), as well as the CONEX-Plus programme, co-funded by Universidad Carlos III de Madrid and the European Union (Grant Agreement No. 801538). In this context, it collaborates closely with the UC3M GOTL research group, contributing with real solutions to the advancement of THz technologies in Europe.
LeapWave Technologies is building today the antennas that will enable tomorrow’s communications. With a clear vision, cutting-edge technology and a solid scientific foundation, we are poised to lead the future of 6G.
References
[1] Hirata, A. et al “120-GHz-band Wireless link Technologies for Outdoor 10-Gbit/s Data Transmission,” IEEE Trans. Microwave Theory and Tech., vol. 60, no. 3, pp. 881-895 (2012).
[2] Marcus, M.J. “Progress in opening access to spectrum above 100 GHz,” IEEE Wireless Communications. 2019.
[3] G. Carpintero et al., “RF Phase Arrays for the Millimeter/Terahertz Range Enabled by Photonics,” 2025 International Conference on Mobile and Miniaturized Terahertz Systems (ICMMTS), Dubai, United Arab Emirates, 2025.
[4] C. M. Carter, “The truth about Terahertz,” in IEEE Spectrum. 2012, p. 36.
[5] E García-Muñoz et al “Photonic-based integrated sources and antenna arrays for broadband wireless links in terahertz communications,” 2019 Semicond. Sci. Technol. 34 054001.
[6] C. Tsokos et al., “True Time Delay Optical Beamforming Network Based on Hybrid Inp-Silicon Nitride Integration,” in Journal of Lightwave Technology, vol. 39, no. 18, pp. 5845-5854, Sept.15, 2021.
[7] G. Carpintero et al., “Photonic-Enabled Terahertz Phase Arrays Using Dielectric Rod Waveguides for 6G Wireless Communications,” 2024 IEEE/MTT-S International Microwave Symposium – IMS 2024, Washington, DC, USA, 2024.