Abstract
Integrated optical true time delay lines attract lots of attention for optically controlled mm-wave beam steering due to its low-loss/broadband performance and stable/compact system architecture. However, for remotely-controlled networks, the techniques that require local-site actively-tuned elements would make the network control more complicated. A passive design using wavelength-tuning is regarded as a promising candidate. In this paper, an integrated wavelength-tuned optical mm-wave beamformer with doubled delay resolution is proposed and demonstrated in a generic InP platform. A bidirectional looped-back arrayed waveguide grating (AWG) module acts as the stepwise tunable delay unit. By introducing an extra AWG router for delay mode (positive/negative) selection and a bidirectional optical interface, a pure λ-tuned, resolution-doubled optical delay network is realized without using any active component (e.g. heaters, current injection) at the local site. This photonic passive design is more beneficial to the remotely-controlled mm-wave beam steering system. Furthermore, the AWG router potentially allows multi-port wavelength switching to support the scaling-up of the network. The fabrication-caused delay error of <1.1 ps is experimentally verified on-chip. A further proof-of-concept 38-GHz fiber-wireless beam steering system with a 186° angular steering is experimentally demonstrated using QAM-4 modulation. Accurate mm-wave phase shifts originated from the proposed optical beamformer are obtained, which proves the effectiveness of the tunable integrated beamformer.
Original language | English |
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Article number | 8985297 |
Pages (from-to) | 2353-2359 |
Number of pages | 7 |
Journal | Journal of Lightwave Technology |
Volume | 38 |
Issue number | 8 |
DOIs | |
Publication status | Published - 15 Apr 2020 |
Funding
Manuscript received December 2, 2019; revised January 23, 2020; accepted February 2, 2020. Date of publication February 6, 2020; date of current version April 15, 2020. This work is supported by ERC Proof-of-Concept project BROWSE+; NWO Zwaartekracht program on Integrated Nanophotonics; National Natural Science Foundation of China (NSFC) under Grant 61575186 and Grant 61635001; and the Open Fund of the State Key Laboratory of Optoelectronic Materials and Technologies (Sun Yat-sen University). The involved integrated photonic circuit is fabricated in HHI through the JEPPIX platform (www.jeppix.eu), supported by ERC Project “PARADIGM.” (Corresponding author: Zizheng Cao.) The authors are with the Institute for Photonic Integration (IPI), Eindhoven University of Technology, NL 5600 MB Eindhoven, The Netherlands (e-mail: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]). The authors would like to thank Phoenix Software and Bright Photonics for providing the design kit, AWG module, and design support, and also thank Dr. X. Leijtens, Dr. K. Williams, and Dr. E. Smalbrugge from TU/e, and Dr. F. M. Soares from HHI for necessary measurement support. The involved integrated photonic circuit is fabricated in HHI through JEPPIX platform (www.jeppix.eu), supported by ERC Project ‘PARADIGM’
Keywords
- Indoor fiber-wireless communications
- integrated photonics
- looped-back AWG
- optical mm-wave beamformer
- wavelength-tuned