Metamaterial-inspired Photonic Crystal Fiber Exhibits High Birefringence

Significance 

The Terahertz frequency range of the electromagnetic spectrum has attracted much research attention as a result of their impactful applications in sensing, imaging, security and communication. Despite recent technological advances, a majority of the commercial THz systems are still based on free space propagation. These systems suffer from drawbacks such as absorption losses, difficulties in integration with other devices, and high sensitivity to the surrounding environment. Alternative THz waveguides have thus been proposed, however, they are all based on metallic wires and subwavelength dielectric fibers. On the other hand, photonic crystal fibers have been successfully deployed in the optical regime due to their performance advantages. For effective photonic crystal fiber practical applications, characteristics such as loss, bandwidth, dispersion and birefringence must be considered. In particular, high birefringence is desired. Unfortunately, the polarization maintaining ability of birefringent photonic crystal fibers remains affected by polarization cross talk and polarization mode dispersion.

To this effect, University of Technology Sydney scientists from the Global Big Data Technologies Centre: Tianyu Yang (PhD candidate), Dr. Can Ding, Professor Richard W. Ziolkowski and Professor Y. Jay Guo have developed a novel photonic crystal fiber design that would yield very high birefringence. Specifically, high index contrast between the propagating X- and Y-polarized modes was attained without breaking the symmetry of the overall geometrical structure, but with breaking the material symmetry by loading only certain of its circular air holes with materials having different refractive indexes. Their work is currently published in the research journal, Optics Express.

In brief, the research method employed commenced with the introduction and thorough study of two complementary photonic crystal fiber configurations and their design parameters. Next, the researchers selected one model based on its performance characteristics and optimized it for the THz regime. The optimized THz photonic crystal fiber model was then scaled to the optical regime. They then recalculated the performance characteristics of both the THz and optical photonic crystal fibers with realistic epsilon-near-zero (ENZ) materials. Lastly, potential methods to realize the reported epsilon-near-zero -based THz and optical photonic crystal fiber designs were evaluated.

The authors observed a birefringence above 0.1 and a loss below 0.01 cm−1 over a wide band of frequencies. These properties were achieved based on extensive simulation results of the symmetric geometry and asymmetric material distribution in the lower THz range. Additionally, they noted that the optimized THz photonic crystal fiber exhibited near zero dispersion at 0.75 THz for both the X- and Y-polarization modes and a birefringence equal to 0.28. These results were obtained with ideal ENZ materials. With currently available ENZ materials this THz photonic crystal fiber design still exhibits a high birefringence, but with slightly larger losses. Anticipated future developments of ENZ materials with lower loss properties will mitigate this practical issue.

In summary, the study by the University of Technology Sydney researchers presented a photonic crystal fiber design that was able to achieve very high birefringence, low loss, and near zero dispersion characteristics in both the THz and optical regimes. While its configuration was essentially a simple circular hole, triangular lattice, the enhanced performance characteristics were seen to be facilitated by the introduction of localized asymmetries in its material distributions. Altogether, significantly enhanced birefringence was achieved in a novel photonic crystal fiber by filling selected air holes in its cladding with an epsilon-near-zero material. Its development presents potential for future applications.

Metamaterial-inspired Photonic Crystal Fiber Exhibits High Birefringence - Advances in Engineering
Configuration of the ENZ-based PCF and its X- and Y-polarized mode field intensity distributions

About the author

Can Ding was born in Anhui Province, China, in 1989. He received a Bachelor degree in Micro-electronics from Xidian University, Xi’an, China, in 2009; and a PHD degreed from Macquarie University, Sydney, Australia, in 2015. From 2012 to 2015, he is under the cotutelle agreement between Macquarie University, Australia and Xidian University, China. During this period, he is also with Commonwealth Scientific and Industrial Research Organisation (CSIRO) DPaS Flagship, Marsfield, Australia.

From 2015 to 2017, he was a postdoctoral Research Fellow in University of Technology Sydney (UTS), Sydney, Australia. He is currently a lecturer with Global Big Data Technologies Centre (GBDTC), University of Technology Sydney (UTS), Sydney, Australia. His research interest is in the area of antennas and THz fibres.

About the author

Y. Jay Guo (Fellow’ 2014) received a Bachelor Degree and a Master Degree from Xidian University in 1982 and 1984, respectively, and a PhD Degree from Xian Jiaotong University in 1987, all in China. He is a Fellow of the Australian Academy of Engineering and Technology, a Fellow of IEEE and a Fellow of IET, and a member of the College of Experts of Australian Research Council (ARC). He has won a number of prestigious Australian national awards, and was named one of the most influential engineers in Australia in 2014 and 2015. His research interest includes reconfigurable antennas, conformal and wideband arrays, meta-material, mm-wave and THz communications and sensing systems.

Currently, Jay is a Distinguished Professor and the Director of Global Big Data Technologies Centre at the University of Technology Sydney (UTS), Australia. Prior to this appointment in 2014, he served as a Research Director in CSIRO for over nine years, managing a number of ICT research portfolios. Before joining CSIRO, Jay held various senior leadership positions in Fujitsu, Siemens and NEC in the U.K.

Jay has chaired numerous international conferences. He is the International Advisory Committee Chair of IEEE VTC2017, General Chair of ISAP2015, iWAT2014 and WPMC’2014, and TPC Chair of 2010 IEEE WCNC, and 2012 and 2007 IEEE ISCIT.

He serves as Guest Editor of special issues on “Antennas for Satellite Communications” and “Antennas and Propagation Aspects of 60-90GHz Wireless Communications,” both in IEEE Transactions on Antennas and Propagation, Special Issue on “Communications Challenges and Dynamics for Unmanned Autonomous Vehicles,” IEEE Journal on Selected Areas in Communications (JSAC), and Special Issue on “5G for Mission Critical Machine Communications”, IEEE Network Magazine.

About the author

Tianyu Yang was born in Anhui Province, China, in 1990. He received a Bachelor degree and Master degree in Measurement and Control Technology from Hefei University of Technology, Hefei, China, in 2012 and 2016 respectively. He is currently working toward the Ph.D. degree in Engineering at University of Technology Sydney (UTS), Sydney, Australia. His current research interests include THz and optical photonic crystal fibers.

About the author

Richard W. Ziolkowski received the Sc. B. (magna cum laude) degree (Hons.) in physics from Brown University, Providence, RI, USA, in 1974; the M.S. and Ph.D. degrees in physics from the University of Illinois at Urbana-Champaign, Urbana, IL, USA, in 1975 and 1980, respectively; and an Honorary Doctorate degree from the Technical University of Denmark, Kongens Lyngby, Denmark in 2012.

Prof. Ziolkowski is the recipient of the 2019 IEEE Electromagnetics Award (IEEE Field Award). He is a Fellow of the Optical Society of America (OSA, 2006) and the American Physical Society (APS, 2016). He served as the President of the IEEE Antennas and Propagation Society in 2005. He is also actively involved with the URSI, OSA and SPIE professional societies. He was the Australian DSTO Fulbright Distinguished Chair in Advanced Science and Technology from 2014-2015. He was a 2014 Thomas-Reuters Highly Cited Researcher.

He is a Distinguished Professor in the Global Big Data Technologies Centre in the Faculty of Engineering and Information Technologies (FEIT) at the University of Technology Sydney, Ultimo NSW, Australia.

He became a Professor Emeritus at the University of Arizona in 2018, where he was a Litton Industries John M. Leonis Distinguished Professor in the Department of Electrical and Computer Engineering in the College of Engineering and was also a Professor in the College of Optical Sciences. He was the Computational Electronics and Electromagnetics Thrust Area Leader with the Engineering Research Division of the Lawrence Livermore National Laboratory before joining The University of Arizona, Tucson, AZ, USA, in 1990.

His current research interests include the application of new mathematical and numerical methods to linear and nonlinear problems dealing with the interaction of electromagnetic and acoustic waves with complex linear and nonlinear media, as well as metamaterials, metamaterial-inspired structures, nano-structures, and other classical and quantum applications-specific configurations.

Reference

Tianyu Yang, Can Ding, Richard W. Ziolkowski, Y. Jay Guo. Circular hole ENZ photonic crystal fibers exhibit high birefringence. Volume 26, Number 13 | 2018 | Optics Express 17264

Go To Optics Express

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