A monolithic bipolar CMOS electronic–plasmonic high-speed transmitter


To address the challenge of increasing data rates, next-generation optical communication networks will require the co-integration of electronics and photonics. Heterogeneous integration of these technologies has shown promise, but will eventually become bandwidth-limited. Faster monolithic approaches will therefore be needed, but monolithic approaches using complementary metal–oxide–semiconductor (CMOS) electronics and silicon photonics are typically limited by their underlying electronic or photonic technologies. Here, we report a monolithically integrated electro-optical transmitter that can achieve symbol rates beyond 100 GBd. Our approach combines advanced bipolar CMOS with silicon plasmonics, and addresses key challenges in monolithic integration through co-design of the electronic and plasmonic layers, including thermal design, packaging and a nonlinear organic electro-optic material. To illustrate the potential of our technology, we develop two modulator concepts—an ultra-compact plasmonic modulator and a silicon-plasmonic modulator with photonic routing—both directly processed onto the bipolar CMOS electronics.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Monolithic electronic–plasmonic high-speed transmitter.
Fig. 2: Electronic 4:1 PMUX performance.
Fig. 3: Monolithic integrated plasmonic MZMs.
Fig. 4: Magnified views of the monolithic transmitter assembly.
Fig. 5: Data modulation experiment with the monolithic transmitter.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.


  1. 1.

    Thraskias, C. A. et al. Survey of photonic and plasmonic interconnect technologies for intra-datacenter and high-performance computing communications. IEEE Commun. Surveys Tutorials 20, 2758–2783 (2018).

    Article  Google Scholar 

  2. 2.

    Winzer, P. J. & Neilson, D. T. From scaling disparities to integrated parallelism: a decathlon for a decade. J. Lightwave Technol. 35, 1099–1115 (2017).

    Article  Google Scholar 

  3. 3.

    Alexoudi, T. et al. Optics in computing: from photonic network-on-chip to chip-to-chip interconnects and disintegrated architectures. J. Lightwave Technol. 37, 363–379 (2019).

    Article  Google Scholar 

  4. 4.

    Kanakis, G. et al. High-speed VCSEL-based transceiver for 200 GbE short-reach intra-datacenter optical interconnects. Appl. Sci. 9, 2488 (2019).

    Article  Google Scholar 

  5. 5.

    Szilagyi, L., Khafaji, M., Pliva, J., Henker, R. & Ellinger, F. 40 Gbit/s 850 nm VCSEL-based full-CMOS optical link with power-data rate adaptivity. IEEE Photon. Technol. Lett. 30, 611–613 (2018).

    Article  Google Scholar 

  6. 6.

    Hu, S. et al. A 50 Gb/s PAM-4 retimer-CDR plus VCSEL driver with asymmetric pulsed pre-emphasis integrated into a single CMOS die. In Proc. 2019 Optical Fiber Communication Conference and Exhibition Tu3A.2 (Optical Society of America, 2019).

  7. 7.

    Ledentsov, N. et al. Energy efficient 850 nm VCSEL based optical transmitter and receiver link capable of 56 Gbit/s NRZ operation. In Proc. Vertical-Cavity Surface-Emitting Lasers XXIII 10938-18 (SPIE, 2019).

  8. 8.

    Wang, C. et al. Integrated lithium niobate electro-optic modulators operating at CMOS-compatible voltages. Nature 562, 101–104 (2018).

    Article  Google Scholar 

  9. 9.

    He, M. B. et al. High-performance hybrid silicon and lithium niobate Mach–Zehnder modulators for 100 Gbit s−1 and beyond. Nat. Photon. 13, 359–364 (2019).

    Article  Google Scholar 

  10. 10.

    Nagarajan, R. et al. InP photonic integrated circuits. IEEE J. Sel. Top. Quantum Electron. 16, 1113–1125 (2010).

    Article  Google Scholar 

  11. 11.

    Katopodis, V. et al. Serial 100 Gb/s connectivity based on polymer photonics and InP-DHBT electronics. Opt. Express 20, 28538–28543 (2012).

    Article  Google Scholar 

  12. 12.

    Ogiso, Y. et al. Over 67 GHz bandwidth and 1.5 V Vπ InP-based optical IQ modulator with n-i-p-n heterostructure. J. Lightwave Technol. 35, 1450–1455 (2016).

    Article  Google Scholar 

  13. 13.

    Ozolins, O. et al. 100 Gbaud 4PAM link for high speed optical interconnects. In Proc. 43rd European Conference on Optical Communication P2.SC5.6 (IEEE, 2017).

  14. 14.

    Going, R. et al. Multi-channel InP-based coherent PICs with hybrid integrated SiGe electronics operating up to 100 GBd, 32QAM. In Proc. 43rd European Conference on Optical Communication Th.PDP.C.3 (IEEE, 2017).

  15. 15.

    Lange, S. et al. 100 GBd intensity modulation and direct detection with an InP-based monolithic DFB laser Mach–Zehnder modulator. J. Lightwave Technol. 36, 97–102 (2018).

    Article  Google Scholar 

  16. 16.

    Estaran, J. M. et al. 140/180/204 Gbaud OOK transceiver for inter- and intra-data center connectivity. J. Lightwave Technol. 37, 178–187 (2019).

    Article  Google Scholar 

  17. 17.

    Nakamura, M. et al. 192 Gbaud signal generation using ultra-broadband optical frontend module integrated with bandwidth multiplexing function. In Optical Fiber Communication Conference Postdeadline Papers 2019 Th4B.4 (Optical Society of America, 2019).

  18. 18.

    Zhang, J. et al. Demonstration of 260 Gb/s single-lane EML-based PS-PAM-8 IM/DD for datacenter interconnects. In Proc. 2019 Optical Fiber Communication Conference (OFC) W4I.4 (Optical Society of America, 2019).

  19. 19.

    Leuthold, J. et al. Silicon-organic hybrid electro-optical devices. IEEE J. Sel. Top. Quantum Electron. 19, 3401413 (2013).

    Article  Google Scholar 

  20. 20.

    Rakowski, M. et al. Low-power, low-penalty, flip-chip integrated, 10 Gb/s ring-based 1 V CMOS photonics transmitter. In Proc. 2013 Optical Fiber Communication Conference and the National Fiber Optic Engineers Conference (OFC/NFOEC) OM2H.5 (Optical Society of America, 2013).

  21. 21.

    Yashiki, K. et al. 25 Gbps error-free operation of chip-scale Si-photonics optical transmitter over 70 °C with integrated quantum dot laser. In Proc. 2016 Optical Fiber Communication Conference (OFC) Th1F.7 (Optical Society of America, 2016).

  22. 22.

    Verbist, J. et al. Real-time 100 Gb/s NRZ and EDB transmission with a GeSi electroabsorption modulator for short-reach optical interconnects. J. Lightwave Technol. 36, 90–96 (2017).

    Article  Google Scholar 

  23. 23.

    Wolf, S. et al. Coherent modulation up to 100 GBd 16QAM using silicon-organic hybrid (SOH) devices. Opt. Express 26, 220–232 (2018).

    Article  Google Scholar 

  24. 24.

    Sun, J. et al. A 128 Gb/s PAM4 silicon microring modulator with integrated thermo-optic resonance tuning. J. Lightwave Technol. 37, 110–115 (2018).

    Article  Google Scholar 

  25. 25.

    Li, H. et al. A 112 Gb/s PAM4 transmitter with silicon photonics microring modulator and CMOS driver. In 2019 Optical Fiber Communication Conference Postdeadline Papers Th4A.4 (Optical Society of America, 2019).

  26. 26.

    Emboras, A. et al. Electrically controlled plasmonic switches and modulators. IEEE J. Sel. Top. Quantum Electron. 21, 276–283 (2015).

    Article  Google Scholar 

  27. 27.

    Hoessbacher, C. et al. Plasmonic modulator with >170 GHz bandwidth demonstrated at 100 GBd NRZ. Opt. Express 25, 1762–1768 (2017).

    Article  Google Scholar 

  28. 28.

    Messner, A. et al. Plasmonic ferroelectric modulators. J. Lightwave Technol. 37, 281–290 (2018).

    Article  Google Scholar 

  29. 29.

    Heni, W. et al. Ultra-high-speed 2:1 digital selector and plasmonic modulator IM/DD transmitter operating at 222 GBaud for intra-datacenter applications. J. Lightwave Technol. 38, 2734–2739 (2020).

    Article  Google Scholar 

  30. 30.

    Settaluri, K. T. et al. Demonstration of an optical chip-to-chip link in a 3D integrated electronic–photonic platform. In Proc. 41st European Solid-State Circuits Conference 156–159 (IEEE, 2015).

  31. 31.

    Vlasov, Y. A. Silicon CMOS-integrated nano-photonics for computer and data communications beyond 100G. IEEE Commun. Mag. 50, S67–S72 (2012).

    Article  Google Scholar 

  32. 32.

    Gill, D. M. et al. Demonstration of error-free 32 Gb/s operation from monolithic CMOS nanophotonic transmitters. IEEE Photon. Technol. Lett. 28, 1410–1413 (2016).

    Article  Google Scholar 

  33. 33.

    Atabaki, A. H. et al. Integrating photonics with silicon nanoelectronics for the next generation of systems on a chip. Nature 556, 349–354 (2018).

    Article  Google Scholar 

  34. 34.

    Stojanovic, V. et al. Monolithic silicon-photonic platforms in state-of-the-art CMOS SOI processes. Opt. Express 26, 13106–13121 (2018).

    Article  Google Scholar 

  35. 35.

    Weeber, J. C. et al. Characterization of CMOS metal based dielectric loaded surface plasmon waveguides at telecom wavelengths. Opt. Express 25, 394–408 (2017).

    Article  Google Scholar 

  36. 36.

    Burla, M. et al. 500 GHz plasmonic Mach–Zehnder modulator enabling sub-THz microwave photonics. APL Photonics 4, 056106 (2019).

    Article  Google Scholar 

  37. 37.

    Ayata, M. et al. High-speed plasmonic modulator in a single metal layer. Science 358, 630–632 (2017).

    Article  Google Scholar 

  38. 38.

    Koch, U. et al. Monolithic high-speed transmitter enabled by BiCMOS-plasmonic platform. In Proc. 2019 European Conference on Optical Communication (ECOC) PD.1.4 (IEEE, 2019).

  39. 39.

    Möller, M. et al. SiGe retiming high-gain power MUX for directly driving an EAM up to 50 Gbit/s. Electron. Lett. 34, 1782–1784 (1998).

    Article  Google Scholar 

  40. 40.

    Koch, U. et al. Ultra-compact terabit plasmonic modulator array. J. Lightwave Technol. 37, 1484–1491 (2019).

    Article  Google Scholar 

  41. 41.

    Heni, W. et al. Plasmonic IQ modulators with attojoule per bit electrical energy consumption. Nat. Commun. 10, 1694 (2019).

    Article  Google Scholar 

  42. 42.

    Baeuerle, B. et al. 120 GBd plasmonic Mach–Zehnder modulator with a novel differential electrode design operated at a peak-to-peak drive voltage of 178 mV. Opt. Express 27, 16823–16832 (2019).

    Article  Google Scholar 

  43. 43.

    Heni, W. et al. 108 Gbit/s plasmonic Mach-Zehnder modulator with >70 GHz electrical bandwidth. J. Lightwave Technol. 34, 393–400 (2016).

    Article  Google Scholar 

  44. 44.

    Heni, W. et al. Nonlinearities of organic electro-optic materials in nanoscale slots and implications for the optimum modulator design. Opt. Express 25, 2627–2653 (2017).

    Article  Google Scholar 

  45. 45.

    Xu, H. et al. Ultrahigh electro-optic coefficients, high index of refraction, and long-term stability from Diels–Alder cross-linkable binary molecular glasses. Chem. Mater. 32, 1408–1421 (2020).

    Article  Google Scholar 

  46. 46.

    Uhl, C., Hettrich, H. & Möller, M. A 100 Gbit/s 2 Vpp power multiplexer in SiGe BiCMOS technology for directly driving a monolithically integrated plasmonic MZM in a silicon photonics transmitter. In Proc. 2017 IEEE Bipolar/BiCMOS Circuits and Technology Meeting (BCTM) 106–109 (IEEE, 2017).

  47. 47.

    Uhl, C., Hettrich, H. & Möller, M. Design considerations for a 100 Gbit/s SiGe-BiCMOS power multiplexer with 2 Vpp differential voltage swing. IEEE J. Solid-State Circuits 53, 2479–2487 (2018).

    Article  Google Scholar 

  48. 48.

    Uhl, C., Hettrich, H. & Möller, M. 180 Gbit/s 4:1 power multiplexer for NRZ-OOK signals with high output voltage swing in SiGe BiCMOS technology. Electron. Lett. 56, 69–71 (2019).

    Article  Google Scholar 

  49. 49.

    Möller, M. Challenges in the cell-based design of very-high-speed SiGe-bipolar ICs at 100 Gb/s. IEEE J. Solid-State Circuits 43, 1877–1888 (2008).

    Article  Google Scholar 

  50. 50.

    Melikyan, A. et al. High-speed plasmonic phase modulators. Nat. Photon. 8, 229–233 (2014).

    Article  Google Scholar 

  51. 51.

    Essiambre, R. J., Kramer, G., Winzer, P. J., Foschini, G. J. & Goebel, B. Capacity limits of optical fiber networks. J. Lightwave Technol. 28, 662–701 (2010).

    Article  Google Scholar 

  52. 52.

    Schuh, K. et al. Single carrier 1.2 Tbit/s transmission over 300 km with PM-64 QAM at 100 GBaud. In 2017 Optical Fiber Communication Conference Postdeadline Papers Th5B.5 (Optical Society of America, 2017).

  53. 53.

    Carroll, L. et al. Photonic packaging: transforming silicon photonic integrated circuits into photonic devices. Appl. Sci 6, 426 (2016).

    Article  Google Scholar 

  54. 54.

    El-Fiky, E. et al. First demonstration of a 400 Gb/s 4λ CWDM TOSA for datacenter optical interconnects. Opt. Express 26, 19742–19749 (2018).

    Article  Google Scholar 

  55. 55.

    ITU-T Recommendation G.975.1 (International Telecommunications Union, 2004).

Download references


This work was funded in part by EU projects PLASMOfab (688166) and plaCMOS (980997) and the Air Force Office of Scientific Research (FA9550-19-1-0069). This work was carried out in part at the Binnig and Rohrer Nanotechnology Center.

Author information




U.K., C.H. and J.L. designed the plasmonic platform. C.U., H.H. and M.M. designed the BiCMOS electronic platform. U.K., C.U., H.H. and Y.F. developed the monolithic integration process. C.H., W.H. and M.A. contributed to the design and testing of the monolithic modulator. W.H., B.B., B.I.B. and A.J. contributed to the data modulation experiment. H.X., D.L.E. and L.R.D developed the temperature-stable organic material. E.M. and P.B. contributed to the design process. L.Z., S.L. and A.K. coordinated the wafer fabrication process. D.T., N.P., M.M. and J.L. designed and coordinated the project. All authors contributed to drafting of the manuscript.

Corresponding authors

Correspondence to Ueli Koch or Juerg Leuthold.

Ethics declarations

Competing interests

C.H., W.H., B.B. are involved in activities toward commercializing high-speed plasmonic modulators at Polariton Technologies Ltd. The other authors declare no competing interests.

Additional information

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

Extended data

Extended Data Fig. 1 Simplified interface between electronic output stage and plasmonic Mach–Zehnder modulator (MZM).

Typically, both output stage and modulator are terminated by 50 Ω. In our case, the plasmonic MZM can be modelled as electrically lumped, which allows for single end termination. Hence, the driving voltage is doubled without increase in energy consumption. Additionally, such an approach allows tuning of the output impedance to specific needs.

Extended Data Fig. 2 Active area and power consumption per circuit part.

The operation-critical functions (2:1 SEL and clock distribution) are separated from the optional parts for advanced functionalities and for measurement purposes.

Extended Data Fig. 3 Temperature map of monolithic transmitter.

Thermal simulations of the electronic circuit revealed the temperatures listed in the table inset, which have been compared to measurements with on-chip temperature diodes. Ideal and reduced thermal conduction to the substrate match well with measurements on a raw electronic chip and a post-processed transmitter chip, respectively.

Extended Data Fig. 4 Temperature stability of the nonlinear organic electro-optic material.

Stable operation until about 140 °C was measured with a drastic degradation when reaching the glass temperature of 150 °C. The small dip at 120 °C is due to thermally induced set-up fluctuations. The trend line (dashed) serves to guide the eye.

Extended Data Fig. 5 Data modulation experiment for externally driven monolithic plasmonic modulator.

An amplified external source applies the electrical signal to the modulator. 100 GBd NRZ-OOK has been modulated and transmitted to the receiver for direct detection. The insets show the received optical eye after equalization.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Koch, U., Uhl, C., Hettrich, H. et al. A monolithic bipolar CMOS electronic–plasmonic high-speed transmitter. Nat Electron 3, 338–345 (2020). https://doi.org/10.1038/s41928-020-0417-9

Download citation

Further reading


Quick links

Sign up for the Nature Briefing newsletter for a daily update on COVID-19 science.
Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing