NEO-PGA—Nonvolatile Electro-Optically Programmable Gate Array

Reconfiguration of silicon photonic integrated circuits relying on the weak, volatile thermo-optic or electro-optic effect of silicon usually suffers from large footprint and energy consumption. Non-volatile phase change materials, such as Ge2Sb2Te5 (GST) provide an attractive solution to solve this problem. I will talk about our effort on integrating GST with silicon photonics to demonstrate an energy-efficient, compact, non-volatile, reprogrammable platform. By adjusting the energy and number of free-space laser pulses applied to the GST, we characterized the strong broadband attenuation and optical phase modulation effects of the platform, and perform quasi-continuous tuning enabled by the thermo-optically induced phase changes. As a result, a non-volatile optical switch with high extinction ratio as large as 33 dB is demonstrated [1]. We also solved the problem of large absorptive loss in GST by designing a new type of directional coupler, and demonstrated an optical switch with less than 1dB insertion loss, even though the material itself has very high loss [2]. Using silicon p-i-n heater, we demonstrated electrical actuation of the phase transition to create a prototype of electrically controlled reconfigurable switch with ultra-low power consumption [3,4]. Finally, I will discuss new phase change materials[5], and device engineering to create next generation low-loss reconfigurable optical switch and phase-shifters.<br/><br/><b>References</b><br/>[1] J. Zheng, A. Khanolkar, P. Xu, S. Colburn, S. Deshmukh, J. Myers, J. Frantz, E. Pop, J. Hendrickson, J. Doylend, N. Boechler, and A. Majumdar, "GST-on-silicon hybrid nanophotonic integrated circuits: a non-volatile quasi-continuously reprogrammable platform," <i>Optical Materials Express, </i>vol. 8, pp. 1551-1561, 2018/06/01 2018.<br/>[2] P. Xu, J. Zheng, J. K. Doylend, and A. Majumdar, "Low-Loss and Broadband Nonvolatile Phase-Change Directional Coupler Switches," <i>ACS Photonics, </i>vol. 6, pp. 553-557, 2019/02/20 2019.<br/>[3] J. Zheng, Z. Fang, C. Wu, S. Zhu, P. Xu, J. K. Doylend, S. Deshmukh, E. Pop, S. Dunham, M. Li, and A. Majumdar, "Nonvolatile Electrically Reconfigurable Integrated Photonic Switch Enabled by a Silicon PIN Diode Heater," <i>Advanced Materials, </i>vol. 32, p. 2001218, 2020/08/01 2020.<br/>[4] J. Zheng, S. Zhu, P. Xu, S. Dunham, and A. Majumdar, "Modeling Electrical Switching of Nonvolatile Phase-Change Integrated Nanophotonic Structures with Graphene Heaters," <i>ACS Applied Materials & Interfaces, </i>vol. 12, pp. 21827-21836, 2020/05/13 2020.<br/>[5] Z. Fang, J. Zheng, A. Saxena, J. Whitehead, Y. Chen, and A. Majumdar, "Non-Volatile Reconfigurable Integrated Photonics Enabled by Broadband Low-Loss Phase Change Material," <i>Advanced Optical Materials, </i>vol. 9, p. 2002049, 2021/05/01 2021.<br/>&lt;!--![endif]----&gt;