Ultrafast Nonlinear Optical Signal Processing

Nonlinear Optical Thresholding

Thresholders are the heart of analog-to-digital converters, comparators and operational amplifiers.  Moreover, an all-optical thresholder even beats the limits of electronics and are thus useful in photonic applications such as neuromorphic photonics and optical code division multiple access (OCDMA). A thresholder can effectively boost the signal to noise ratio (SNR) of optical signals and improve the system performance in a variety of scenarios including telecommunications, fiber sensing and quantum communications. We are particularly interested in its use in enhancing contrast in weakly modulated optical signals.


Our approach exploits the nonlinear silicon photonic processes to carry out the signal processing. We have successfully demonstrated an all-optical programmable nonlinear thresholder on a silicon integrated circuit. Our device structure is based on Mach-Zehnder interferometer loaded with microrings. It can accommodate optical signals of different power levels and wavelengths. We have achieved a significant power contrast enhancement with our current device and are currently exploring novel device architectures to enhance the device bandwidth and reduce the power costs.

nonlinear optical thresholding

Fig Microscope image of all-optical thresholder on silicon chip

nonlinear optical thresholding

Fig: Contrast enhancement using our nonlinear optical thresholder



Book Chapters

B. J. Shastri*, J. Chang*, A. N. Tait, M. P. Chang, B. Wu, M. A. Nahmias, and P. R. Prucnal, “Ultrafast Optical Techniques for Communication Networks and Signal Processing,” in All-Optical Signal Processing for Data Communication and Storage Applications, Springer Berlin Heidelberg, 2014, ch. 11, 20 pages (in press). [*equal contribution]. 

Journal Papers

  1. A Jha, C Huang, PR Prucnal, "Reconfigurable all-optical nonlinear activation functions for neuromorphic photonics", Optics Letters 45 (17), 4819-4822, (2020)
  2. [Invited] C Huang, A Jha, TF de Lima, A Tait, BJ Shastri, P Prucnal, "On-Chip Programmable Nonlinear Optical Signal Processor and Its Applications", IEEE Journal of Selected Topics in Quantum Electronics, (2020).
  3. A Jha, C Huang, TF de Lima, PR Prucnal, "High-speed all-optical thresholding via carrier lifetime tunability", Optics Letters 45 (8), 2287-2290, (2020).
  4. C Huang, TF De Lima, A Jha, S Abbaslou, AN Tait, BJ Shastri, PR Prucnal, "Programmable silicon photonic optical thresholder", IEEE Photonics Technology Letters 31 (22), 1834-1837, (2019).
  5. A. N. Tait, B. J. Shastri, M. A. Nahmias, M. P. Fok, and P. R. Prucnal, “The DREAM: an integrated photonic thresholder,” IEEE/OSA Journal of Lightwave Technology, vol. 31, no. 8, pp. 1263–1272, Apr. 2013.


Conference Papers

  1. A Jha, C Huang, PR Prucnal, "Reconfigurable all-optical nonlinear activation functions", IEEE Photonics Conference (2020).
  2. A Jha, C Huang, PR Prucnal, "Fast programmable all-optical thresholder", CLEO (2020).
  3. C Huang, TF De Lima, A Jha, S Abbaslou, BJ Shastri, PR Prucnal, "Giant enhancement in signal contrast using integrated all-optical nonlinear thresholder", 2019 Optical Fiber Communications Conference and Exhibition (OFC), 1-3


Group Members: 

  • Paul Prucnal, Professor of Electrical Engineering
  • Chaoran Huang, Posdoctoral Research Associate
  • Aashu Jha, Graduate Student