Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

A fully photonics-based coherent radar system


The next generation of radar (radio detection and ranging) systems needs to be based on software-defined radio to adapt to variable environments, with higher carrier frequencies for smaller antennas and broadened bandwidth for increased resolution1,2,3,4. Today’s digital microwave components (synthesizers and analogue-to-digital converters) suffer from limited bandwidth with high noise at increasing frequencies5,6,7, so that fully digital radar systems can work up to only a few gigahertz, and noisy analogue up- and downconversions are necessary for higher frequencies. In contrast, photonics provide high precision and ultrawide bandwidth8,9, allowing both the flexible generation of extremely stable radio-frequency signals with arbitrary waveforms up to millimetre waves10,11,12,13,14,15,16,17,18,19,20,21,22, and the detection of such signals and their precise direct digitization without downconversion23,24,25,26. Until now, the photonics-based generation and detection of radio-frequency signals have been studied separately and have not been tested in a radar system. Here we present the development and the field trial results of a fully photonics-based coherent radar demonstrator carried out within the project PHODIR27. The proposed architecture exploits a single pulsed laser for generating tunable radar signals and receiving their echoes, avoiding radio-frequency up- and downconversion and guaranteeing both the software-defined approach and high resolution. Its performance exceeds state-of-the-art electronics at carrier frequencies above two gigahertz, and the detection of non-cooperating aeroplanes confirms the effectiveness and expected precision of the system.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Figure 1: The photonics-based radar transceiver.
Figure 2: Architecture of the photonics-based radar.
Figure 3: Test results of the photonics-based RF generator.
Figure 4: Test results of the photonics-based ADC.
Figure 5: Test results of the field-trial demonstrator.

Similar content being viewed by others


  1. Skolnik, M. L. Introduction to Radar Systems 3rd edn (McGraw-Hill, 1980)

    Google Scholar 

  2. Haykin, S. Cognitive radar: a way of the future. IEEE Signal Process. Mag. 23, 30–40 (2006)

    Article  ADS  Google Scholar 

  3. Ravenni, V. Performance evaluations of frequency diversity radar system. Proc. Eur. Microwave Conf. 1715–1718, (2007)

  4. Tsui, J. B. Digital Techniques for Wideband Receivers 2nd edn (SciTech, 2004)

    Book  Google Scholar 

  5. Scheer, J. A. & Kurtz, J. L. Coherent Radar Performance Estimation (Artech House, 1993)

    Google Scholar 

  6. Richards, M. A., Scheer, J. A. & Holm, W. A. Principle of Modern Radar: Basic Principles (SciTech Publishing, 2010)

    Book  Google Scholar 

  7. Walden, R. Analog-to-Digital Conversion in the Early Twenty-First Century (Wiley Encyclopedia of Computer Science and Engineering, 2008)

    Book  Google Scholar 

  8. Capmany, J. & Novak, D. Microwave photonics combines two worlds. Nature Photon. 1, 319–330 (2007)

    Article  ADS  CAS  Google Scholar 

  9. Yao, J. Microwave photonics. J. Lightwave Technol. 27, 314–335 (2009)

    Article  ADS  CAS  Google Scholar 

  10. Goldberg, L., Esman, R. D. & Williams, K. J. Generation and control of microwave signals by optical techniques. IEEE Proc. J. 139, 288–295 (1992)

    Google Scholar 

  11. Khan, M. H. et al. Ultrabroad-bandwidth arbitrary radiofrequency waveform generation with a silicon photonic chip-based spectral shaper. Nature Photon. 4, 117–122 (2010)

    Article  ADS  CAS  Google Scholar 

  12. Serafino, G. et al. Stable optically generated RF signals from a fibre mode-locked laser. Proc. 23rd IEEE Photonics Soc. Ann. Meet. Abstr. TuK4, 193–194, (2010)

  13. Yilmaz, T., DePriest, C. M., Turpin, T., Abeles, J. H. & Delfyett, P. J. Toward a photonic arbitrary waveform generator using a modelocked external cavity semiconductor laser. IEEE Photonics Technol. Lett. 14, 1608–1610 (2002)

    Article  ADS  Google Scholar 

  14. Chou, J., Han, Y. & Jalali, B. Adaptive RF-photonic arbitrary waveform generator. IEEE Photonics Technol. Lett. 15, 581–583 (2003)

    Article  ADS  Google Scholar 

  15. McKinney, J. D., Leaird, D. E. & Weiner, A. M. Millimeter-wave arbitrary waveform generation with a direct space-to-time pulse shaper. Opt. Lett. 27, 1345–1347 (2002)

    Article  ADS  CAS  Google Scholar 

  16. Lin, I. S., McKinney, J. D. & Weiner, A. M. Photonic synthesis of broadband microwave arbitrary waveform applicable to ultrawideband communication. IEEE Microwave Wireless Components Lett. 15, 226–228 (2005)

    Article  Google Scholar 

  17. Chi, H. & Yao, J. P. An approach to photonic generation of high frequency phase-coded RF pulses. IEEE Photonics Technol. Lett. 19, 768–770 (2007)

    Article  ADS  Google Scholar 

  18. Li, Z., Li, W., Chi, H., Zhang, X. & Yao, J. Photonic generation of phase-coded microwave signal with large frequency tunability. IEEE Photonics Technol. Lett. 23, 712–714 (2011)

    Article  ADS  Google Scholar 

  19. Ghelfi, P., Scotti, F., Laghezza, F. & Bogoni, A. Phase coding of RF pulses in photonics-aided frequency-agile coherent radar systems. IEEE J. Quantum Electron. 48, 1151–1157 (2012)

    Article  ADS  CAS  Google Scholar 

  20. Ghelfi, P., Scotti, F., Laghezza, F. & Bogoni, A. Photonic generation of phase-modulated RF signals for pulse compression techniques in coherent radars. J. Lightwave Technol. 30, 1638–1644 (2012)

    Article  ADS  Google Scholar 

  21. Maleki, L. et al. High performance, miniature hyper-parametric microwave photonic oscillator. Proc. IEEE Freq. Control Symp. 558–563, (2010)

  22. Maleki, L. The optoelectronic oscillator. Nature Photon. 5, 728–730 (2011)

    Article  ADS  CAS  Google Scholar 

  23. Valley, G. C. Photonic analog-to-digital converters. Opt. Exp. 15, 1955–1982 (2007)

    Article  ADS  Google Scholar 

  24. Khilo, A. et al. Photonic ADC: overcoming the bottleneck of electronic jitter. Opt. Exp. 20, 4454–4469 (2012)

    Article  ADS  Google Scholar 

  25. Chou, J., Conway, J. A., Sefler, G. A., Valley, G. C. & Jalali, B. Photonic bandwidth compression front end for digital oscilloscopes. J. Lightwave Technol. 27, 5073–5077 (2009)

    Article  ADS  Google Scholar 

  26. Laghezza, F. et al. Jitter-limited photonic analog-to-digital converter with 7 effective bits for wideband radar applications. Proc. IEEE Radar Conf. 1–5, (2013)

  27. Photonic-based Fully Digital Radar (PHODIR). (2009)

  28. Ghelfi, P., Scotti, F., Nguyen, A. T., Serafino, G. & Bogoni, A. Novel architecture for a photonics-assisted radar transceiver based on a single mode-locking laser. IEEE Photonics Technol. Lett. 23, 639–641 (2011)

    Article  ADS  Google Scholar 

  29. Pierno, L. et al. Optical switching matrix as time domain demultiplexer in photonic ADC. Proc. Eur. Microwave Integr. Circuits Conf. Abstr. EuMIC03.3, INSPEC accession number 13990947. (2013)

  30. Ghelfi, P. et al. Photonic generation and independent steering of multiple RF signals for software defined radars. Opt. Exp. 21, 22905–22910 (2013)

    Article  ADS  Google Scholar 

Download references


This work was supported by the ERC projects PHODIR (contract number 239640) and PREPARE (contract number 324629), and by the EU NEXPRESSO programme through the project INSIDE with Selex Sistemi Integrati S.p.A. (now Selex ES S.p.A.).

Author information

Authors and Affiliations



A.B. coordinated all the activities of the PHODIR project. A.B. and P.G. designed the architecture of the photonics-based transceiver and wrote the paper. F.L., A.C. and F.B. defined the radar parameters and designed the RF front end. F.L., F.S., S.P., G.S., E.L. and D.O. implemented the photonic subsystems. S.P. designed and developed the electronic controls of the machine that separates the samples into parallel streams and of the front panels of the radar demonstrator. F.S. assembled the demonstrator. F.L. implemented the digital processing tools. P.G., G.S., M.S., E.L. and A.B. analysed and discussed the results from the photonics-based transmitter. P.G., F.L., F.S., S.P., D.O., A.M. and A.B. analysed and discussed the results from the photonics-based receiver. F.L., F.S., S.P., G.S. and D.O. collected and processed the data of the field trial. P.G., F.L., F.S., G.S., S.P., D.O. and A.B. analysed and discussed the results of the field trial. C.P., V.V., P.G. and A.B. discussed the possible development of the photonics-based transceiver with integrated photonics techniques. P.G., G.S., F.L., F.S. and A.B. commented on the manuscript.

Corresponding author

Correspondence to Antonella Bogoni.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

PowerPoint slides

Rights and permissions

Reprints and permissions

About this article

Cite this article

Ghelfi, P., Laghezza, F., Scotti, F. et al. A fully photonics-based coherent radar system. Nature 507, 341–345 (2014).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing