Terahertz Waveform Synthesis and Analysis Using Hybrid Photonic-Electronic Circuits

Project Information

TeraSHAPE

Grant agreement ID: 773248

DOI

10.3030/773248

Project closed

EC signature date 22 February 2018

Start date 1 May 2018

End date 31 January 2024

Funded under

• EXCELLENT SCIENCE - European Research Council (ERC)

Total cost

€ 2 498 954,00

EU contribution

€ 2 498 954,00

Coordinated by

KARLSRUHER INSTITUT FUER TECHNOLOGIE
Germany

Periodic Reporting for period 4 - TeraSHAPE (Terahertz Waveform Synthesis and Analysis Using Hybrid Photonic-Electronic Circuits)

Reporting period: 2022-11-01 to 2024-01-31

Summary of the context and overall objectives of the project

Generation, detection, and processing of electrical and electromagnetic waveforms is one of the most important technical foundations of modern society. In particularly digital signal processing (DSP) has revolutionized many areas of science and engineering, with widespread applications in communications, radar and navigation, industrial metrology and sensing, chemical analysis, or medical diagnostics. Over the previous decades, the processing power of digital computing systems increased by orders of magnitude, mainly driven by the tremendous evolution and the outstanding scalability of complementary metal-oxide-semiconductor (CMOS) electronics. This has opened a door towards real-time processing of data streams of hundreds of gigabits per second, exploiting massively parallel computation on tens of billions of transistors at comparatively low internal clock speed. In contrast to this, the analogue bandwidth of electronic circuits is much more difficult to scale due to limited switching speed of semiconductor devices, strongly increased transmission line losses at high frequencies, and the considerable complexity associated with high-speed circuit packaging and assembly.
The goal of TeraSHAPE was to overcome these limitations by establishing the methodological and technological foundations of novel signal processing concepts in the frequency range between 100 GHz and 1 THz. By combining massively parallel processing in digital electronic circuits with synthesis and analysis of broadband waveforms in the optical domain, signal processing bandwidths of hundreds of gigahertz come into reach. This approach could capitalize on great progress in the fields of photonic integrated circuits (PIC) and optical frequency combs, which act as precise references for broadband signal generation and detection. Specifically, we exploited powerful PICs for spectrally sliced processing of phase-locked optical carriers that are derived from chip-scale frequency comb sources. To convert waveforms between optical and THz frequencies, TeraSHAPE explored novel concepts for ultra-fast electro-optic modulators and photodetectors with bandwidths of hundreds of gigahertz. Advances on the device level were complemented by scalable assembly concepts for high-performance systems, where TeraSHAPE focussed on three-dimensional additive fabrication techniques both for hybrid photonic integration and for THz system assembly. The viability and the application potential of the TeraSHAPE concepts were explored and demonstrated in dedicated experiments that target selected applications of high relevance, comprising, e.g. high-speed wireless communications in future sixth generation (6G) wireless networks or THz signal processing for scientific applications. The project has built the technology base of several start-up companies that transfer the scientific results to industrial use cases.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The project activities started from a quantitative analysis of system concepts based on dedicated models for photonic-electronic synthesis and analysis of signals with bandwidths beyond 100 GHz. These models were experimentally tested and built the base of photonic-electronic arbitrary waveform generation and measurement, which was applied to both optical and electrical signals. We have further implemented and demonstrated the key technologies and devices for integrated photonic-electronic signal processing systems, comprising high-speed signal optical-to-THz and THz-to-optical signal converters, as well as hybrid photonic multi-chip modules that rely on 3D-printed coupling elements. Building upon our technologies developed for 3D printing in photonic packaging, we have established and experimentally demonstrated 3D-printed passive THz components such as chip-chip transitions, suspended THz antennas, or THz probes, which pave the path towards novel system architectures with unprecedented functionality. The viability of all these approaches has been demonstrated in a series of proof-of-concept experiments, covering broadband signal generation and detection both in the optical and the electrical domain. In the optical domain, we have demonstrated both optical arbitrary waveform generation (OAWG) and optical arbitrary waveform measurement (OAWM) systems with record-high bandwidth. Regarding electrical signal generation and analysis, we managed to demonstrate a photonic-electronic ADC that relies on Kerr soliton combs and that offers a record-high acquisition bandwidth of 320 GHz. These experiments have been complemented by photonic-electronic synthesis of ultra-broadband electrical waveforms by so-called IQ multiplexing. With respect to application demonstrations, we have focused on wireless THz communications, which might play a key role in future sixth generation (6G) wireless networks. We have demonstrated single-carrier wireless transmission at record-high data rates of up to 250 Gbit/s, and we are transferring the technology to other application fields such as test and measurement equipment and scientific experiments that are, e.g. related to high-field electron paramagnetic resonance (EPR) spectroscopy.
The results of the project bear significant scientific and innovation potential, which is on the one hand witnessed by a series of publications in high-rank journals in the field of Optica & Photonics, as well as in contributions to internationally leading conferences. On the other hand, the project stands out due to its strong innovation potential, that was, e.g. leveraged through the incorporation of several start-up companies. Further technology transfer activities are currently ongoing, e.g. in the context of an ERC Proof-of-Concept grant.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Within the project, we demonstrated important progress beyond the state of the art in a series of aspects that are related to components, systems, as well as applications. A key success on the component level was, e.g. the advancements of silicon-organic hybrid (SOH) and plasmonic-organic hybrid (POH) electro-optic modulators for THz-to-optical conversion. This progress was the base for the incorporation of SilOriX GmbH, a start-up company geared towards exploiting SOH technology for high-speed optical transceivers. Moreover, we have developed and demonstrated silicon-plasmonic integrated circuits that offer unprecedented bandwidth for THz signal generation and detection. These activities were complemented by advancing 3D-printing techniques for optical packaging and assembly and by expanding the approach to functional THz elements that can be fabricated with unprecedented accuracy. On a system level, we have developed and demonstrated novel concepts for optical arbitrary waveform generation (OAWG) and optical arbitrary waveform measurement (OAWM) that offer unprecedented bandwidth and that lend themselves to integration into compact assemblies. These concepts have been the base for our application demonstration of a photonic-electronic analogue-to-digital converter (ADC) that offers a record-high acquisition bandwidth of 320 GHz and that has been used for digitizing ultra-broadband data signals. Moreover, we performed a series of demonstrations of photonic-electronic signal processing in wireless THz communications, where we reached record-high data rates of up to 250 Gbit/s. The results of the projects have built the base for a series of follow-up projects and are subject to technology transfer to several start-up companies.

Application scenario of THz signals in future wireless communication networks