We demonstrate an optical arbitrary waveform measurement (OAWM) system that exploits a bank of silicon photonic (SiP) frequency-tunable coupled-resonator optical waveguide (CROW) filters for gapless spectral slicing of broadband optical signals. The spectral slices are coherently detected using a frequency comb as a multi-wavelength local oscillator (LO) and stitched together by digital signal processing (DSP). For high-quality signal reconstruction, we have implemented a maximum-ratio combining (MRC) technique based on precise calibration of the complex-valued opto-electronic transfer functions of all detection paths. In a proof-of-concept experiment, we demonstrate the viability of the scheme by implementing a four-channel system that offers an overall detection bandwidth of 140 GHz. Exploiting a femtosecond laser with precisely known pulse shape for calibration along with dynamic amplitude and phase estimation, we reconstruct 100 GBd QPSK, 16QAM and 64QAM optical data signals. The reconstructed signals show improved quality compared to that obtained with a single high-speed intradyne receiver, while the electronic bandwidth requirements of the individual coherent receivers are greatly reduced.

References

Dengyang Fang, Andrea Zazzi, Juliana Müller, Daniel Drayss, Christoph Füllner, Pablo Marin-Palomo, Alireza Tabatabaei Mashayekh, Arka Dipta Das, Maxim Weizel, Sergiy Gudyriev, Wolfgang Freude, Sebastian Randel, J. Christoph Scheytt, Jeremy Witzens, and Christian Koos, "Optical Arbitrary Waveform Measurement (OAWM) Using Silicon Photonic Slicing Filters," J. Lightwave Technol. 40, 1705-1717 (2022)

D. Fang, A. Zazzi, J. Müller, D. Drayß, C. Füllner, P. Marin-Palomo, A. T. Mashayekh, A. D. Das, M. Weizel, S. Gudyriev, W. Freude, S. Randel, J. C. Scheytt, J. Witzens, and C. Koos, "Optical Arbitrary Waveform Measurement (OAWM) on the Silicon Photonic Platform," in Optical Fiber Communication Conference (OFC) 2021, P. Dong, J. Kani, C. Xie, R. Casellas, C. Cole, and M. Li, eds., OSA Technical Digest (Optica Publishing Group, 2021), paper F2E.6.