Coherent Optics Everywhere: a New Dawn for Photonic Networks

Project Information

COYOTE

Grant agreement ID: 804769

DOI

10.3030/804769

Project closed

EC signature date 12 September 2018

Start date 1 January 2019

End date 31 December 2023

Funded under

• EXCELLENT SCIENCE - European Research Council (ERC)

Total cost

€ 1 500 000,00

EU contribution

€ 1 500 000,00

Coordinated by

AIT AUSTRIAN INSTITUTE OF TECHNOLOGY GMBH
Austria

Periodic Reporting for period 4 - COYOTE (Coherent Optics Everywhere: a New Dawn for Photonic Networks)

Reporting period: 2023-07-01 to 2023-12-31

Summary of the context and overall objectives of the project

The Digital Age imposes an enormous challenge on telecommunication networks. Global data traffic shows a skyrocketing tendency while the growth rate in data generation and processing has started to exceed that of the transport network capacity. Optical telecommunications and, in particular, coherent optics have proven its impressive performance in high-rate, long-reach data transmission. Furthermore, photonic technology greatly contributes to the energy efficiency of ICT networks.
However, the telecommunication technology as found in optical long-reach metro and core networks cannot be simply applied to any arbitrary network segment since practical deployment remains strictly cost-driven. The incremental advances in these cost-limited segments are thus not able to cope with the surging traffic demand, which calls for a disruptive rather than a graceful technological migration in these bottleneck frontiers.
This is where COYOTE kicks in and explores radically new methodologies for coherent data transmission, which are key to obtain high spectral efficiency and data rates. Coherent communications remove the performance roadblocks set by direct-modulation / direct-detection. COYOTE aims to bring coherent technology to short-reach networks by meeting the requirements for lean component technology, thus offering the credentials not only for scalable performance but also for practical deployment.

Examples for the accomplishments of the ERC Action include:
(i) Flexible analogue coherent optical reception using a polarization-multiplexed and balanced segmented detector configuration at low power consumption,
(ii) Analogue coherent reception and transmission of mm-wave radio signals in full-duplex mode and demonstration of photonic signal up- and down-conversion,
(iii) Simultaneous bidirectional data transmission over the same wavelength and the same frequency at the same time, resulting in a highly efficient use of optical network resources,
(iv) the seamless integration of quantum optics or neuromorphic signal processing in coherent transceiver engines.

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

COYOTE has demonstrated a novel coherent homodyne transceiver engine, which obviates the need for digital signal processing despite the use of free-running light sources. Fast coherent receiver locking in the nanosecond scale as required for intra-datacenter applications, and full-duplex transmission over the same opto-electronic transceiver element has been demonstrated for wired and wireless communication scenarios: optical access, analogue radio-over-fiber and radio-over-air in order to support 5G & beyond deployment. Stokes vector modulation and detection are further being investigated as a simple alternative to phase-sensitive higher-order formats.

Examples for the results include:
(i) Analogue coherent reception for up to 124.8 Gb/s/λ at an energy consumption of 4.4 pJ/bit,
(ii) Analogue coherent reception and transmission of Ka-band (34.3 GHz) 64-QAM OFDM radio signals, with concurrent DSP-less photonic up- and down-conversion to sub-6GHz frequencies,
(iii) Simultaneous full-duplex bidirectional data transmission over the same wavelength and the same frequency at the same time, resulting in a highly efficient use of optical network resources, including demonstrations over a free-space optical link with a budget equivalent to a reach of 100 meters, as well as 25/25 Gb/s full-duplex transmission for broadband links
(iv) the seamless integration of quantum optics or neuromorphic signal processing in coherent transceiver engines, such as shown for quantum random number generation and quantum key distribution or neuromorphic receptors.

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)

A main result of COYOTE is the analogue realization of coherent optical signal detection. The homodyne method of converting signals from the optical to the electrical domain ensures frequency- and phase stability for this process. This greatly simplifies coherent systems, which up to now are typically laid out in the digital domain and therefore faces a complexity roadblock with respect to their direct-detection counterparts when it comes to practical deployment. The obtained opto-electronic signal conversion at low error ratios without additional means for digital signal processing greatly contributes to the energy- and cost-efficiency, which is an important merit for sensitive short-reach network segments.
Moreover, state-of-the-art realizations are bound to dedicated transmitter and receiver sub-systems, while COYOTE realizes coherent transceiver functionality in a single element. Towards this direction, full-duplex transmission has been conducted with the same laser-modulator device for digital and analogue data transmission and investigated in view of possible transmission impairments.
Having demonstrated its key concepts, COYOTE will aim at blending opto-electronics and electronics in its next phase, in order to raise key performance indicators such as supported bandwidth, reception sensitivity and energy efficiency for its coherent data transmission. Towards this direction, the ERC Action has demonstrated for the first time,
- analogue coherent reception for >100 Gb/s/λ with flexible detect / transmit mode of its photonic engine,
- full-duplex radio signal transmission over the same wavelength and the same frequency at the same time,
- energy harvesting of 0-bits within a data stream to power optical telecommunication subsystems,
- a silicon light source as optical power supply for all-silicon photonic integrated circuits.

photonic integrated circuit of an analogue coherent receiver