I.Free-Space Optical Communications (FSO)

     Prof. Hai-Han Lu’s most significant contribution is his seminal work on high-speed and long-haul FSO communications. FSO communications, previously limited to moderate bandwidth of a few hundreds of MHz and a short-range of few meters, have been tremendously improved by Prof. Lu using a combination of innovative ideas, like: (i) employing two-stage injection locking technique to significantly enhance the laser-diode transmitter bandwidth, (ii) using multiple-input-multiple-output (MIMO) scheme to improve the free-space transmission capacity, and (iii) incorporating PAM4 modulation with wavelength-division-multiplexing (WDM)/polarization-multiplexing scheme to increase the transmission rate.
     Prof. Lu has been the first to develop high performance WDM FSO communication systems with laser diodes in the visible wavelength range, and also the first to develop high performance MIMO FSO with red-light VCSELs and spatial light modulators. For long-haul free-space transmission, he has introduced tracking and steering technologies to mitigate the laser beam misalignment by turbulence, thus providing a long-haul FSO transmission with high accessibility. The presently achieved performances of 448 Gb/s aggregate transmission capacity and 600-m free-space link are the world record making his approach a new viable technology in FSO communications.
     The impact of the Candidate’s work and relevance to the Nomination category is witnessed by the selected papers (*: Corresponding Author) mostly on OSA Journals, and by the technologies transfer commented below.

1. W. Y. Lin, C. Y. Chen, H. H. Lu*, C. H. Chang, Y. P. Lin, H. C. Lin, and H. W. Wu, “10m/500Mbps WDM visible light communication systems,” Opt. Express, vol. 20, no. 9, pp. 9919-9924, 2012. (Top Download Honor, May 2012). The paper has received 123 citations (Google Scholar) and has triggered the interest of Companies for technology transfers and industry-academia collaborations.​

2. C. H. Chang, C. Y. Li, H. H. Lu*, et al., “A 100-Gbps multiple-input-multiple-output visible laser light communication system,” IEEE/OSA J. Light. Technol., vol. 32, no. 24, pp. 4121-4127, 2014. The performance enhancement of FSO communication to 100 Gbps data rate has been the scientific base of the technology transfers reported below.

3. H. H. Lu*, Y. P. Lin, P. Y. Wu, C. Y. Chen, M. C. Chen, and T. W. Jhang, “A multiple-input-multiple-output visible light communication system based on VCSELs and spatial light modulators,” Opt. Express, vol. 22, no. 3, pp. 3468-3474, 2014 (69 citations). An influential paper reporting enhancement of the FSO communication up to 10 Gbps data rate.

4. H. H. Lu*, C. Y. Li, C. M. Ho, M. T. Cheng, X. Y. Lin, Z. Y. Yang, and H. W. Chen, “64 Gb/s PAM4 VCSEL-based FSO link,” Optics Express, vol. 25, no. 5, pp. 5749-5757, 2017. The paper presents the first 64-Gb/s FSO link implemented with PAM4 modulation and injection-locked VCSEL over a 100-m free-space transmission.

5. C. Y. Li, X. H. Huang, H. H. Lu*, Y. C. Huang, Q. P. Huang, and S. C. Tu, “A WDM PAM4 FSO-UWOC integrated system with a channel capacity of 100 Gb/s,” IEEE/OSA J. Light. Technol., vol. 38, no. 7, pp. 1766–1776, 2020. The milestone attaining 100 Gb/s transmission rate over 505-m distance is presented in this paper.

6. H. W. Wu, H. H. Lu*, W. S. Tsai, Y. C. Huang, J. Y. Xie, Q. P. Huang, and S. C. Tu, “A 448-Gb/s PAM4 FSO communication with polarization-multiplexing injection-locked VCSELs through 600 m free-space link,” IEEE Access, vol. 8, pp. 28859–28866, 2020. A 448-Gb/s FSO communication with multi-wavelength polarization-multiplexing and PAM4 modulation schemes through a 600-m free-space link is demonstrated, setting a world records for transmission capacity and distance

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     The MIMO high-speed FSO communication system introduced by Prof. Lu is an advancement in communication technology because it enhances the transmission capacity up to 100 Gbps making possible 5G and 6G connectivity through the fiber-FSO link (Ref. [b1]). The relevance of the advancement is witnessed by the industry-university technology transfer program entitled “A 100-Gbps Ultra-High-Speed FSO Communication” whose results have been successfully transferred to Hold Precision Technology Co., Ltd. of Taiwan, (Ref. [b2]). This Company is nowadays the first to fabricate and sell MIMO high-speed FSO communications.

 

     Another research result, the 25-Gps high-speed LiFi transmission system with two-stage injection locking (Ref. [b3]), overcomes the limitations of traditional WiFi transmission systems, and this system has been the subject of a technology transfer to Arno Electro-Optics Co., Ltd (Taiwan), see Ref. [b4].

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     In addition, the fiber-FSO-5G/6G convergent system has a significant impact for linking fiber-backhaul and optical/RF wireless feeders at comparatively high-speed and long-reach operations. It is an innovative convergence that became the subject of the technology transfer entitled “Fiber-FSO-5G/6G Convergent System”, productively transferred to TS RF Instruments Co., Ltd (Taiwan), see Ref. [b5]. Thanks to the Technology Transfer Programs, all the Companies mentioned above have substantially increased their portfolio of products as well as their revenues.

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     The commented list below [Ref. [b1] to [b5]] is exemplary of the impact of the Candidate’s effort on making the transition from research to innovative products by means of the Technology Transfer and the Industry-Academia Research programs, fitting perfectly the Category of Engineering, Application and Development.

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1. “A Real-Time PAM4 Fiber-5G and Fiber-6G Hybrid System (2019-2020)” and “A Hybrid 5G/6G Fiber-FSO Convergent System (2020-2021)” — Industry-Academia Research Collaborations – beneficiary: Qualcomm Technologies Inc. (USA). Prof. Lu has implemented the above two industry-academia collaboration programs and also followed with a Technology Transfer to Qualcomm in 2021 March.

2.  “A 100-Gbps Ultra-High-Speed FSO Communication” — Technology Transfer to Hold Precision Technology Co., Ltd., 2019. Hold Precision Technology Co., Ltd. utilizes this technology to become an ODM of FSO communication transceiver

3. (see http://artolink.com/page/products/free_space_optics_Artolink_30Gbps/).

4. H. H. Lu, C. Y. Li, C. A. Chu, et al., “10 m/25 Gbps LiFi transmission system based on a two-stage injection-locked 680 nm VCSEL transmitter,” Opt. Lett., vol. 40, no. 19, pp. 4563-4566, 2015. A milestone of Candidate’s demonstration of LiFi transmission system reaching 25 Gbps transmission rate.

5. “A 25-Gbps LiFi Transmission System Based on Spatial Light Modulator” — Technology Transfer to Arno Electro-Optics Co., Ltd., 2018. Arno Electro-Optics Co., Ltd. utilizes this technology to become an ODM of LiFi transceiver (see http://www.ecsystem.cz/en/products/free-space-optic-equipment/free-space-optics-10-gbps).

6. “Fiber-FSO-5G/6G Convergent System” — Technology Transfer to TS RF Instruments Co., Ltd., 2019. TS RF Instruments Co., Ltd. utilizes this technology to operate system integration for integrating optical fiber, FSO, and 5G/6G wireless systems (see http://www.ts-corp.com.tw/applications).

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II.Underwater Wireless Optical Communication (UWOC)

     Prof. Lu’s research on the high-speed and long-range UWOC systems (Ref. [c1] to [c8]) is the second most significant contribution. He has been able to enhance the UWOC state-of-the-art performance of some hundred MHz rates on a few meters distance to multi-Gb/s and several tens of meter underwater link in clear water. He has incorporated in his design several novelties, like light injection and optoelectronic feedback techniques (Ref. [c1]), optical beam reducer/expander (Ref. [c2]), and integration of PAM4 modulation with multi-wavelength polarization-multiplexing (Ref. [c3]). As a first example, the PAM4 UWOC system (Ref. [c1]) employs a light injection and optoelectronic feedback in a blue-light LD transmitter fo`r operation in piped underwater link and outperforms prior UWOC systems reaching 16-Gb/s.

     Second, the 25-Gbps UWOC system (Ref. [c4]) has a two-stage injection-locked VCSEL transmitter for operation in high-turbidity underwater link and is presently the world fastest UWOC link. For long-range free-space plus underwater links, the Candidate has developed systems employing low-cost optics, plastic optical fiber (POF), and optical beam reducer (Ref. [c5]) to attain a long-range free-space in series with the underwater link. The presently achieved performance of 500 Gb/s aggregate transmission rate over a 110 m free-space and 10-m underwater distance is the world record of UWOC systems, as described in his Invited Paper presented at OFC 2018 (Ref. [c3] and [c6]).

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     About product development, the high-speed PAM4 UWOC link (Ref. [c1]) has led to the technology transfer entitled “A 16-Gb/s High-Speed PAM4 UWOC Link” (Ref. [d1]), beneficiary the Agilelink Technology Co., Ltd. (Taiwan), who since then has been the first company to fabricate and sell a high-performance UWOC system. Agilelink Technology utilized this technology to manufacture LD-based mini submarine and became an ODM of LD-based mini submarine (see https://www.cool3c.com/article/106145).

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     The technology of light injection and optoelectronic feedback of the 25-Gb/s/10-m PAM4 UWOC system (Ref. [c4]) has also resulted in an industry-academia collaboration with Samwell Testing Co., Ltd. (Taiwan), entitled “A 25-Gb/s/10-m PAM4 UWOC System” (Ref. [d2]). Thanks to this program, the company is now manufacturing LD-based UWOC ship-and-diver links and has become an ODM supplier of UWOC (see https://www.youtube.com/watch?v=ynn9ORQewEE).

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     With the help of the Technology Transfer Program and Industry-Academia Collaboration, the Companies mentioned above have substantially increased their portfolio of products as well as their revenues.

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     The commented list below demonstrates the significant inventions of Prof. Lu as well as the impact on the advancement of optical communication science and technology and related products readied by Companies who have been helped by the Technology Transfers driven by the Candidate.

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1. C. Y. Li, H. H. Lu*, W. S. Tsai, M. T. Cheng, C. M. Ho, Y. C. Wang, Z. Y. Yang, and D. Y. Chen, “16 Gb/s PAM4 UWOC system based on 488-nm LD with light injection and optoelectronic feedback techniques,” Opt. Express, vol. 25, no. 10, pp. 11598-11605, 2017. In this paper, light injection and optoelectronic feedback techniques are adopted for the first time to enhance LD’s 3-dB bandwidth and provide a 16-Gb/s high-speed underwater link.

2. W. S. Tsai, H. H. Lu*, H. W. Wu, C. W. Su, and Y. C. Huang, “A 30 Gb/s PAM4 underwater wireless laser transmission system with optical beam reducer/expander,” Sci. Rep., vol. 9, 2019, paper 8605. A beam reducer/expander is demonstrated for the first time to improve the performance of UWOC systems

3. W. S. Tsai, H. H. Lu*, H. W. Wu, S. C. Tu, Y. C. J. Y. Xie, Q. P. Huang, and S. E. Tsai, “500 Gb/s PAM4 FSO-UWOC convergent system with a R/G/B five-wavelength polarization-multiplexing scheme,” IEEE Access, vol. 8, pp. 16913–16821, 2020. This paper describes an improved design to enhance the FSO-UWOC transmission capacity and distance into 500 Gb/s and 110 m, respectively.

4. C. Y. Li, H. H. Lu*, W. S. Tsai, Z. H. Wang, C. W. Hung, C. W. Su, and Y. F. Lu, “A 5 m/25 Gbps underwater wireless optical communication system,” IEEE Photonics J., vol. 10, no. 3, 2018, Art. no. 7904809. This paper describes an innovative UWOC system using two-stage injection-locked technique over high-turbidity underwater link.

5. C. Y. Li, H. H. Lu*, Y. C. Wang, Z. H. Wang, C. W. Su, Y. F. Lu, and W. S. Tsai, “An 82-m 9 Gb/s PAM4 FSO-POF-UWOC convergent system,” IEEE Photonics J., vol. 11, no. 1, 2019, paper 7900609. This paper is the first to report a long-haul FSO-POF-UWOC convergent system with an optical wireless link of 82-m.

6. J. C. Chang, Y. C. Wang, D. Y. Chen, C. Y. Li, H. H. Lu*, X. H. Huang, and W. S. Tsai, “Optical-based underwater communications (Invited),” Conference on Optical Fiber Communication, Tu2I.3, 2018. The candidate’s contributions to high-speed and long-range UWOC systems are summarized in this Invited Paper delivered to OFC 2018.

7. H. H. Lu*, C. Y. Li, H. H. Lin, W. S. Tsai, C. A. Chu, B. R. Chen, and C. J. Wu, “An 8 m/9.6 Gbps underwater wireless optical communication system,” IEEE Photonics J., vol. 8, no. 5, 2016, paper 7906107. This paper is the first to report a two-stage injection-locked technique in UWOC systems. (73 citations and 400 Downloads).

8. C. Y. Li, H. H. Lu*, Y. C. Huang, Q. P. Huang, J. Y. Xie, and S. E. Tsai, “50 Gb/s PAM4 underwater wireless optical communication systems across the water-air-water interface (Invited),” Chinese Opt. Lett., vol. 17, no. 10, 2019, paper 100004.

9. “A 16-Gb/s High-Speed PAM4 UWOC Link” — Technology Transfer (Agilelink Technology Co., Ltd, Taiwan) – 2017
   This technology transfer made by Prof. Lu and his group to Agilelink Technology Co., Ltd. features a record of 16 Gb/s transmission-rate.

10.  “A 25-Gb/s/10-m PAM4 UWOC System” — Industry-Academia Collaboration (Samwell Testing Co., Ltd., Taiwan) – 2018. This industry-academia collaboration to Samwell Testing Co., Ltd. features a record of 25 Gb/s transmission-rate with 10 m underwater link.