Skip to main content

Thank you for visiting nature.com. 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.

  • Article
  • Published:

Modified uni-travelling-carrier photodiodes with 206 GHz bandwidth and 0.81 A W−1 external responsivity

Nature Photonics volume 19, pages 1301–1308 (2025)Cite this article

Subjects

Abstract

The accelerating demand for wireless communication necessitates wideband, energy-efficient photonic sub-terahertz sources to enable ultrafast data transfer. However, as critical components for terahertz photomixing, photodiodes face a fundamental trade-off between bandwidth and quantum efficiency, presenting a major obstacle to achieve high-speed performance with high optoelectronic conversion efficiency. Here we overcome this challenge by demonstrating an InP-based, waveguide-integrated modified uni-travelling-carrier photodiode with bandwidth exceeding 200 GHz and a bandwidth–efficiency product surpassing 130 GHz. Incorporating a spot-size converter together with optimized electric field distribution, balanced carrier transport and minimized parasitic capacitance, the device achieves a 3-dB bandwidth of 206 GHz and an external responsivity of 0.81 A W−1, setting a new bandwidth–efficiency product benchmark. Packaged with WR-5.1 waveguide output, it delivers radio-frequency power exceeding –5 dBm across the 127–185-GHz frequency range. As a proof of concept, we achieved wireless transmission over 54 m with a single-line rate of up to 120 Gbps, leveraging photonics-aided technology without requiring a low-noise amplifier. This work establishes a pathway to significantly enhance optical power budgets and reduce energy consumption, presenting a transformative step towards high-bandwidth, high-efficiency sub-terahertz communication systems and next-generation wireless networks.

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

Access options

Buy this article

  • Purchase on SpringerLink
  • Instant access to the full article PDF.

USD 39.95

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

Fig. 1: THz waveguide-integrated MUTC-PD.
Fig. 2: Measured static and dynamic performances of PDs.
Fig. 3: WR-5.1-waveguide-packaged MUTC-PD module and the results of photonics-aided sub-THz communication without a THz amplifier.
Fig. 4: Performance comparison of waveguide-coupled and surface-illuminated PDs.

Similar content being viewed by others

Data availability

All data supporting the findings of this study are provided within the Article. Source data are available via Figshare at https://doi.org/10.6084/m9.figshare.28659041 (ref. 54) and are provided with this paper. Additional data related to this work are available from the corresponding authors upon reasonable request.

References

  1. Nagatsuma, T., Ducournau, G. & Renaud, C. C. Advances in terahertz communications accelerated by photonics. Nat. Photon. 10, 371–379 (2016).

    Article  ADS  Google Scholar 

  2. Sung, M. et al. Design considerations of photonic THz communications for 6G networks. IEEE Wirel. Commun. 28, 185–191 (2021).

    Article  Google Scholar 

  3. Zhang, H. et al. Tbit/s multi-dimensional multiplexing THz-over-fiber for 6G wireless communication. J. Lightwave Technol. 39, 5783–5790 (2021).

    Article  ADS  Google Scholar 

  4. Kang, G. et al. Frequency comb measurements for 6G terahertz nano/microphotonics and metamaterials. Nanophotonics 13, 983–1003 (2024).

    Article  ADS  Google Scholar 

  5. Zhang, L., Pang, X., Jia, S., Wang, S. & Yu, X. Beyond 100 Gb/s optoelectronic terahertz communications: key technologies and directions. IEEE Commun. Mag. 58, 34–40 (2020).

    Article  Google Scholar 

  6. Seddon, J. P. et al. Photodiodes for terahertz applications. IEEE J. Sel. Topics Quantum Electron. 28, 3801612 (2022).

    Article  Google Scholar 

  7. Ishibashi, T., Muramoto, Y., Yoshimatsu, T. & Ito, H. Unitraveling-carrier photodiodes for terahertz applications. IEEE J. Sel. Topics Quantum Electron. 20, 79–88 (2014).

    Article  ADS  Google Scholar 

  8. Ummethala, S. et al. THz-to-optical conversion in wireless communications using an ultra-broadband plasmonic modulator. Nat. Photon. 13, 519–524 (2019).

    Article  ADS  Google Scholar 

  9. Zhu, M. et al. Ultra-wideband fiber-THz-fiber seamless integration communication system toward 6G: architecture, key techniques, and testbed implementation. Sci. China Inf. Sci. 66, 113301 (2023).

    Article  Google Scholar 

  10. Ishibashi, T. et al. Uni-traveling-carrier photodiodes. In Ultrafast Electronics and Optoelectronics UC3 (Optica Publishing Group, 1997).

  11. Ishibashi, T. & Ito, H. Uni-traveling-carrier photodiodes. J. Appl. Phys. 127, 031101 (2020).

  12. Ishibashi, T. & Ito, H. Uni-traveling carrier photodiodes: development and prospects.IEEE J. Sel. Topics Quantum Electron. 28, 3803006 (2022).

    Article  Google Scholar 

  13. Ishibashi, T. et al. InP/InGaAs uni-traveling-carrier photodiodes. IEICE Electron. Express 83, 938–949 (2000).

    Google Scholar 

  14. Wun, J.-M., Wang, Y.-W. & Shi, J.-W. Ultrafast uni-traveling carrier photodiodes with GaAs0.5Sb0.5/In0.53Ga0.47As type-II hybrid absorbers for high-power operation at THz frequencies. IEEE J. Sel. Topics Quantum Electron. 24, 8500207 (2018).

    Article  Google Scholar 

  15. Ito, H., Furuta, T., Kodama, S. & Ishibashi, T. InP/InGaAs uni-travelling-carrier photodiode with 310 GHz bandwidth. Electron. Lett. 36, 1 (2000).

    Article  Google Scholar 

  16. Huang, Y.-C., Chen, N.-W., Wu, Y.-K., Naseem & Shi, J.-W. Improvements in the maximum THz output power and responsivity in near-ballistic uni-traveling-carrier photodiodes with an undercut collector. J. Lightwave Technol. 42, 2362–2370 (2024).

    Article  ADS  Google Scholar 

  17. Wei, C. et al. 150 GHz high-power photodiode by flip-chip bonding. J. Lightwave Technol. 41, 7238–7244 (2023).

    Article  ADS  Google Scholar 

  18. Tian, Y. et al. Ultrafast MUTC photodiodes over 200 GHz with high saturation power. Opt. Express 31, 23790–23800 (2023).

    Article  ADS  Google Scholar 

  19. Li, Q. et al. High-power evanescently coupled waveguide MUTC photodiode with >105-GHz bandwidth. J. Lightwave Technol. 35, 4752–4757 (2017).

    Article  ADS  Google Scholar 

  20. Rouvalis, E. et al. 170 GHz uni-traveling carrier photodiodes for InP-based photonic integrated circuits. Opt. Express 20, 20090–20095 (2012).

    Article  ADS  Google Scholar 

  21. Li, L. et al. Ultra-fast waveguide MUTC photodiodes over 220 GHz. J. Lightwave Technol. 42, 7451–7457 (2024).

    Article  ADS  Google Scholar 

  22. Rouvalis, E., Renaud, C. C., Moodie, D. G., Robertson, M. J. & Seeds, A. J. Continuous wave terahertz generation from ultra-fast InP-based photodiodes. IEEE Trans. Microw. Theory Techn. 60, 509–517 (2012).

    Article  ADS  Google Scholar 

  23. Grzeslo, M. et al. High saturation photocurrent THz waveguide-type MUTC-photodiodes reaching mW output power within the WR3.4 band. Opt. Express 31, 6484–6498 (2023).

    Article  ADS  Google Scholar 

  24. Kato, K. et al. 110-GHz, 50%-efficiency mushroom-mesa waveguide pin photodiode for a 1.55-μm wavelength. IEEE Photon. Technol. Lett. 6, 719–721 (1994).

    Article  ADS  Google Scholar 

  25. Runge, P. et al. Broadband 145 GHz photodetector module targeting 200 GBaud applications. In Optical Fiber Communication Conference (OFC) M2A.1 (Optica Publishing Group, 2020).

  26. Demiguel, S. et al. Very high-responsivity evanescently coupled photodiodes integrating a short planar multimode waveguide for high-speed applications. IEEE Photon. Technol. Lett. 15, 1761–1763 (2003).

    Article  ADS  Google Scholar 

  27. Li, Z., Pan, H., Chen, H., Beling, A. & Campbell, J. C. High-saturation-current modified uni-traveling-carrier photodiode with cliff layer. IEEE J. Quantum Electron. 46, 626–632 (2010).

    Article  ADS  Google Scholar 

  28. Maloney, T. J. & Frey, J. Transient and steady-state electron transport properties of GaAs and InP. J. Appl. Phys. 48, 781–787 (1977).

    Article  ADS  Google Scholar 

  29. Li, Q. et al. High-power flip-chip bonded photodiode with 110 GHz bandwidth. J. Lightwave Technol. 34, 2139–2144 (2016).

    Article  ADS  Google Scholar 

  30. Gardes, C. et al. Numerical simulations with energy balance model for unitraveling-carrier photodiode. In IEEE International Conference on Nanotechnology (NANO) 350–353 (IEEE, 2015).

  31. Morgan, J. S. et al. Bias-insensitive GaAsSb/InP CC-MUTC photodiodes for mmWave generation up to 325 GHz. J. Lightwave Technol. 41, 7092–7097 (2023).

    Article  ADS  Google Scholar 

  32. Chao, E. et al. D-band MUTC photodiodes with flat frequency response. IEEE J. Sel. Topics Quantum Electron. 28, 3802208 (2022).

    Article  Google Scholar 

  33. Guen, A., Sayah, C., Bouazza, B. S. & Sari, N. Steady-state and transient electron transport within bulk InAs, InP and GaAs: an updated semiclassical three-valley Monte Carlo simulation analysis. J. Mod. Phys. 4, 616–621 (2013).

    Article  Google Scholar 

  34. Latzel, P. et al. Generation of mW level in the 300-GHz band using resonant-cavity-enhanced unitraveling carrier photodiodes. IEEE Trans. THz Sci. Technol. 7, 800–807 (2017).

    Article  Google Scholar 

  35. Ito, H., Ito, T., Muramoto, Y., Furuta, T. & Ishibashi, T. Rectangular waveguide output unitraveling-carrier photodiode module for high-power photonic millimeter-wave generation in the F-band. J. Lightwave Technol. 21, 3456 (2003).

    Article  ADS  Google Scholar 

  36. Furuta, T. et al. D-band rectangular-waveguide-output uni-travelling-carrier photodiode module. Electron. Lett. 41, 1 (2005).

    Article  Google Scholar 

  37. Ito, H., Furuta, T., Muramoto, Y., Ito, T. & Ishibashi, T. Photonic millimetre-and sub-millimetre-wave generation using J-band rectangular-waveguide-output uni-travelling-carrier photodiode module. Electron. Lett. 42, 1424–1425 (2006).

    Article  ADS  Google Scholar 

  38. Kurokawa, T., Ishibashi, T., Shimizu, M., Kato, K. & Nagatsuma, T. Over 300 GHz bandwidth UTC-PD module with 600 GHz band rectangular-waveguide output. Electron. Lett. 54, 705–706 (2018).

    Article  ADS  Google Scholar 

  39. Zhou, W. et al. 135-GHz D-band 60-Gbps PAM-8 wireless transmission employing a joint DNN equalizer with BP and CMMA. J. Lightwave Technol. 38, 3592–3601 (2020).

    Article  ADS  Google Scholar 

  40. Dat, P. T. et al. 60-Gb/s D-band wireless signal generation and transmission using photonic technology. In RIVF International Conference on Computing and Communication Technologies (RIVF) 1–5 (IEEE, 2022).

  41. Wang, K. et al. Complex-valued 2D-CNN equalization for OFDM signals in a photonics-aided MMW communication system at the D-band. J. Lightwave Technol. 40, 2791–2798 (2022).

    Article  ADS  Google Scholar 

  42. Zhao, L., Wang, K. & Zhou, W. Transmission of 4,096-QAM OFDM at D-band. Opt. Express 31, 2270–2281 (2023).

    Article  ADS  Google Scholar 

  43. Chen, Q. et al. Photonics-aided D-band 64-QAM MMW transmission utilizing modified multi-symbol output neural network equalization. Opt. Fiber Technol. 87, 103925 (2024).

    Article  Google Scholar 

  44. Tian, Y. X. et al. Photonics-assisted THz wireless communication enabled by wide-bandwidth packaged back-illuminated modified uni-traveling-carrier photodiode. Opto-Electron Sci. 3, 230051 (2024).

    Article  Google Scholar 

  45. Tian, Y. et al. High-power MUTC photodiode module for photonics-assisted beyond 100 Gb/S wireless sub-THZ communications in the F-band. J. Lightwave Technol. 42, 5616–5623 (2024).

    Article  ADS  Google Scholar 

  46. Xiong, B. et al. Ultra-wide bandwidth and high saturation power uni-traveling carrier photodiodes. In Optical Fiber Communication Conference (OFC) Tu3D.4 (Optica Publishing Group, 2024).

  47. Beling, A. & Campbell, J. C. High-speed photodiodes. IEEE J. Sel. Topics Quantum Electron. 20, 3804507 (2014).

  48. Umezawa, T. et al. d.c.–226 GHz well-impedance-matched high-speed photoreceiver for multi-band signal detection. In Optical Fiber Communication Conference (OFC) Tu3D.2 (Optica Publishing Group, 2024).

  49. Bach, H.-G. et al. InP-based waveguide-integrated photodetector with 100-GHz bandwidth. IEEE J. Sel. Topics Quantum Electron. 10, 668–672 (2004).

    Article  ADS  Google Scholar 

  50. Beling, A., Bach, H.-G., Mekonnen, G., Kunkel, R. & Schmidt, D. Miniaturized waveguide-integrated p-i-n photodetector with 120-GHz bandwidth and high responsivity. IEEE Photon. Technol. Lett. 17, 2152–2154 (2005).

    Article  ADS  Google Scholar 

  51. Runge, P. et al. Waveguide integrated InP-based photodetector for 100Gbaud applications operating at wavelengths of 1310 nm and 1550 nm. In Proc. European Conference on Optical Communication (ECOC) 1–3 (IEEE, 2015).

  52. Sun, M. et al. Ultrafast evanescently coupled waveguide MUTC-PDs with high responsivity. Opt. Express 32, 16455–16466 (2024).

    Article  ADS  Google Scholar 

  53. Lischke, S. et al. Ultra-fast germanium photodiode with 3-dB bandwidth of 265 GHz. Nat. Photon. 15, 925–931 (2021).

    Article  ADS  Google Scholar 

  54. Li, L. et al. Supporting data for article over-200 GHz bandwidth MUTC photodiodes with 0.81 A/W external responsivity. Figshare https://doi.org/10.6084/m9.figshare.28659041 (2025).

Download references

Acknowledgements

B.C. acknowledges support from the National Key Research and Development Program of China (grant number 2018YFB2201000) and the National Natural Science Foundation of China (grant number 61975121). J.Y. acknowledges support from the National Natural Science Foundation of China (grant numbers 62127802, 62331004, 62305067, U24B20142, U24B20168 and 62427815). The PD chips were fabricated with support from the ShanghaiTech Material and Device Lab (SMDL).

Author information

Author notes

  1. These authors contributed equally: Linze Li, Tianyu Long, Xiongwei Yang.

Authors and Affiliations

  1. School of Information Science and Technology, ShanghaiTech University, Shanghai, China

    Linze Li, Tianyu Long, Zhouze Zhang, Luyu Wang, Jingyi Wang, Juanjuan Lu & Baile Chen

  2. Fastphide Photonics, Shanghai, China

    Linze Li, Tianyu Long, Luyu Wang & Jingyi Wang

  3. China State Key Laboratory of ASIC and System, Fudan University, Shanghai, China

    Xiongwei Yang, Mingxu Wang & Jianjun Yu

  4. School of Information Science and Technology, Fudan University, Shanghai, China

    Xiongwei Yang, Mingxu Wang & Jianjun Yu

  5. Key Laboratory for Information Science of Electromagnetic Waves, Fudan University, Shanghai, China

    Xiongwei Yang, Mingxu Wang & Jianjun Yu

  6. Purple Mountain Laboratories, Nanjing, China

    Jianjun Yu

Authors
  1. Linze Li
    View author publications

    Search author on:PubMed Google Scholar

  2. Tianyu Long
    View author publications

    Search author on:PubMed Google Scholar

  3. Xiongwei Yang
    View author publications

    Search author on:PubMed Google Scholar

  4. Zhouze Zhang
    View author publications

    Search author on:PubMed Google Scholar

  5. Luyu Wang
    View author publications

    Search author on:PubMed Google Scholar

  6. Jingyi Wang
    View author publications

    Search author on:PubMed Google Scholar

  7. Mingxu Wang
    View author publications

    Search author on:PubMed Google Scholar

  8. Juanjuan Lu
    View author publications

    Search author on:PubMed Google Scholar

  9. Jianjun Yu
    View author publications

    Search author on:PubMed Google Scholar

  10. Baile Chen
    View author publications

    Search author on:PubMed Google Scholar

Contributions

B.C. conceived the idea. L.L., Z.Z. and B.C. designed the device epilayer structure. L.L., T.L., L.W., Z.Z. and J.W. jointly fabricated the devices and participated in the testing process. T.L. designed and packaged the WR-5.1 module and tested its performance. X.Y., T.L., Z.Z. and M.W. conducted the THz communication experiment supervised by J.Y. L.L., T.L., X.Y., Z.Z., L.W., J.W., M.W., J.L. and B.C. primarily wrote the manuscript. B.C. initiated the collaboration and supervised the project.

Corresponding authors

Correspondence to Jianjun Yu or Baile Chen.

Ethics declarations

Competing interests

The authors declare no competing interests.

Peer review

Peer review information

Nature Photonics thanks Emilien Peytavit and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Source data

Source Data Fig. 1 (download XLSX )

Statistical source data for Fig. 1.

Source Data Fig. 2 (download XLSX )

Statistical source data for Fig. 2.

Source Data Fig. 3 (download XLSX )

Statistical source data for Fig. 3.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Li, L., Long, T., Yang, X. et al. Modified uni-travelling-carrier photodiodes with 206 GHz bandwidth and 0.81 A W−1 external responsivity. Nat. Photon. 19, 1301–1308 (2025). https://doi.org/10.1038/s41566-025-01784-0

Download citation

  • Received:

  • Accepted:

  • Published:

  • Version of record:

  • Issue date:

  • DOI: https://doi.org/10.1038/s41566-025-01784-0

This article is cited by

Search

Advanced search

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