6G & Communication Research

Terahertz technologies

Enabling the next generation of wireless connectivity

The race toward THz communication is on. Future high-speed wireless links are expected to deliver data rates beyond 100 Gbit/s, ultra-low latency, and seamless connectivity between multiple devices.

But the electromagnetic spectrum used by today’s wireless systems from Wi-Fi to 5G is nearing exhaustion.

To achieve these ambitious goals, research has moved into the terahertz (THz) frequency band, between roughly 100 GHz and 1 THz. This region offers massive bandwidth, sufficient for terabit-per-second wireless links. Harnessing it requires cutting-edge THz test and measurement technologies, precisely where laser-based systems from TOPTICA make the difference. In the past years, research in this field has been fueled by the exciting prospect that terahertz links could be integrated into a future-generation network.

Why THz matters for high-speed wireless links

As communication engineers move from millimeter-wave to terahertz frequencies, they unlock new opportunities:

Unprecedented bandwidth enabling data rates above 100 Gbit/s.
Miniaturized components, i.e. antennas and waveguides shrink with higher carrier frequencies.
Improved spatial resolution for advanced beamforming and localization.

Yet, the THz regime also poses challenges. Conventional electronic signal generators and detectors struggle to maintain low phase noise and broadband tunability above 100 GHz. This is where photonics-based THz systems, driven by precise laser sources, enable breakthroughs in both measurement and communication research.

From lasers to THz waves: The photomixing principle

At the core of modern THz communication research lies optoelectronic photomixing. Two continuous-wave lasers with slightly different optical frequencies are combined and illuminate a so-called photomixer, a special type of high-speed photodiode. The optical beat between them creates a coherent, tunable THz signal, the frequency of which equals precisely the laser frequency difference.

By tuning one or both lasers, the THz frequency can be adjusted continuously. In systems like TOPTICA’s TeraScan 1550 or TeraScan ultra, the tuning range covers four to six octaves (50 GHz – 1.2 THz or >3 THz, respectively).

This method combines wide tunability for exploring multiple frequency bands, narrow linewidths and ultra-low phase noise, both of which critical criteria for coherent links.

The TeraScan ultra, in particular, offers a flexible and stable test platform perfectly suited to 6G research, antenna calibration, and propagation studies.

Most stable terahertz signals with comb-locked sources

In the TeraScan ultra, the two THz-generating lasers are locked to a frequency comb. The system thus transfers the ultra-low phase noise of optical oscillators into the THz domain.

This approach delivers:

Continuous tunability from 20 GHz to >5 THz
Frequency accuracy and resolution down to 1 Hz
A single-source single-receiver concept without the need for swapping frequency extenders.

Such precision enables high-fidelity channel sounding, spectrum analysis, and component characterization in frequency ranges unmatched by purely electronic techniques.

Broadband component characterization

Even though most THz communication links use narrowband cw-THz signals, pulsed THz systems such as TOPTICA’s TeraFlash pro play an essential role in component development.

Using a broadband THz pulse and time-domain detection, engineers can obtain both amplitude and phase information over > 5.5 THz bandwidth, with a spectral resolution down to 300 MHz. This makes it ideal for analyzing waveguides, reflectors, filters, or absorbers used in THz communication hardware.

In practice, pulsed and continuous-wave THz systems complement each other: pulsed setups are preferred for broadband characterization, cw systems for high-resolution communication and device testing.

Conclusion – Making the future of THz communication measurable

Terahertz communication is transforming from a visionary concept to experimental reality. With laser-based THz systems such as TOPTICA’s TeraScan 1550, TeraScan ultra, and TeraFlash pro, researchers can:

Generate, measure, and analyze tunable, ultra-stable THz signals.
Characterize devices and channels with metrology-grade precision.
Broaden the frequency ranges of wide-band VNAs and SAs for full test coverage.

As data demands grow exponentially, THz technologies will define the foundation of 6G and beyond.

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