LOVE AND RIESEN:SINGLE-,FEW-,AND MULTIMODE Y-JUNCTIONS 309 RefeREnceS 0.9 [1]J.D.Love,R.W.C.Vance,and A.Joblin,"Asymmetric,adiabatic 0.8 Output Arm A multipronged planar splitters,"Opt.Ouantum Electron.,vol.28,no.4, Mode Sorting: 0.7 ·-Output Arm B Pp.353-369,1996. [2]H.Sasaki and I.Anderson,"Theoretical and experimental studies Power Splitting: Fundamental Mode on active Y-junctions in optical-waveguides,"IEEE J.Quantum 0.5 Second Mode Electron.,vol.14,no.11,pp.883-892,Nov.1978. 0.4 [3]A.G.Medoks,"Theory of symmetric waveguide Y-junction,"Radio Eng.Electron.P,vol.13,no.1,p.106,1968. 0.3 [4]M.Izutsu,Y.Nakai,and T.Sueta,"Operation mechanism of the 0.2 single-mode optical-waveguide-Y junction,"Opt.Lett.,vol.7,no.3, 0.1 I51 w.K.Bumns and A.F.Milton."Mode conversion in planar-diele 0 0.5 2.5 4.5 6.5 8.5 10.5 12.5 separating waveguides,"IEEE J.Quantum Electron.,vol.QE-11,no. Taper Angle(Degrees) L,pp.32-39,Jan.1975 [6]W.Y.Hung,H.P.Chan,and P.S.Chung,"Novel design of wide-angle single-mode symmetric Y-junctions,"Electron.Lett.,vol.24,no.18. Fig.14.Power outputs from the two arms of the asymmetric two-mode Y-junc- pp.1184-1185,1988. tion as a function of taper angle,with the FM excited in the stem (blue curves) [7]W.M.Henry andJ.D.Love,"Asymmetric multimode Y-junctionsplit- and the power in the first-even and first-odd supermodes of a symmetric two- ters,"Opt.Quantum Electron.,vol.29,no.3,pp.379-392,1997. mode Y-junction resulting from independent excitations of the first and second [8]N.Goto and G.L.Yip,"A TE-TM mode splitter in LINBO by proton- modes in the stem,respectively (red curves). exchange and TI diffusion,"J.Lightw.Technol.,vol.7,no.10,pp. 1567-1574,0ct1989. [9]J.Vandertol and J.H.Laarhuis,"A polarization splitter on LINBOa using only titanium diffusion,"J.Lighne.Technol.,vol.9,no.7,pp angle increases,the output of arm A decreases and that from 879-886.Jul.1991. arm B increases due to mode conversion at the junction,but as [10]J.D.Love and A.Ankiewicz,"Purely geometrical coarse wave- length multiplexer/demultiplexer,"Electron.Lett.,vol.39,no.19,pp. radiation loss begins to dominate with further increasing taper 1385-1386.2003. angle,the power in both arms eventually decreases. [11]K.Shirafuji and S.Kurazono,"Transmission characteristics of optical Similarly,the combined power in the first two supermodes of asymmetric-Y junction with a gap region,"J.Lighnw.Technol.,vol.9, the symmetric two-mode Y-junction output arms also decreases n0.4,Pp.426-429,Apr.1991. [12]N.Riesen and J.D.Love,"Dispersion equalisation in few-mode fi- at larger angles because of radiation loss as shown in Fig.14 bres,"Opt.Quantum Electron.,vol.42,no.9,pp.577-585,2011. (e.g.,red Power Splitting curves). [13]J.E.Baran and D.A.Smith,"Adiabatic 2 x 2 polarization splitter on LINBOa,"Photon.Technol.Lett.,vol.4,no.1,pp.39-40,1992. [14]J.D.Love and A.Ankiewicz,"Photonic devices based on mode con- version,"in Proc.Australian Conf.Opt.Fibre Technol,Sydney,Aus- tralia,2001,pp.80-81. V.CONCLUSION John D.Love was born in the U.K.in 1942.He received the M.A.and M.Maths degrees in mathematics from the University of Cambridge,Cambridge,U.K. In this paper,the conceptual framework for understanding and the M.A.,D.Phil.,and D.Sc.degrees in mathematics from the University of propagation through symmetric and asymmetric single-mode, Oxford.Oxford.U.K. few-mode,and multimode weakly guiding Y-junctions has Since 1973,he has been with The Australian National University,Can- berra,A.C.T.,Australia,researching theoretical aspects of fiber optics,planar been presented,with the functionality of these devices being waveguides,and associated light processing devices.He co-authored Optical confirmed using BPM simulations.The paper also demon- Waveguide Theory (Berlin,Germany:Springer,1983)and Silica-based Buried strates the properties of asymmetric Y-junctions that make Channel Waveguides and Devices (London,U.K.:Chapman Hall,1996). His research activities encompass both academic and industrial problems.In them suitable for low-loss wavelength-and phase-independent teaching,he is the Convenor for the Master of Photonics degree and teaches mode sorting.Foreseeable applications for asymmetric Y-junc- several undergraduate and masters courses in photonics. tions include mode-division multiplexing/demultiplexing for Dr.Love is an honorary Life Member of the Australian Optical Society. high-capacity data transmission or high-resolution distributed sensing Nicolas Riesen was born in Canberra,A.C.T.,Australia,in 1987.He received the B.Sc.degree majoring in physics and the B.Eng.degree (first class Hons.) in systems engineering from The Australian National University,Canberra,in ACKNOWLEDGMENT 2011,where he is currently working toward the Ph.D.degree at the Research School of Physics and Engineering (in collaboration with the Commonwealth Scientific and Industrial Research Organization). The authors would like to thank Dr.S.Madden and the Laser His main research interests include mode-division multiplexing and dis- Physics Centre,The Australian National University for the use tributed fiber sensing. Mr.Riesen received the University Medal from The Australian National Uni- of their software. versity.He is the recipient of an ANU research scholarship.LOVE AND RIESEN: SINGLE-, FEW-, AND MULTIMODE Y-JUNCTIONS 309 Fig. 14. Power outputs from the two arms of the asymmetric two-mode Y-junc￾tion as a function of taper angle, with the FM excited in the stem (blue curves) and the power in the first-even and first-odd supermodes of a symmetric two￾mode Y-junction resulting from independent excitations of the first and second modes in the stem, respectively (red curves). angle increases, the output of arm A decreases and that from arm B increases due to mode conversion at the junction, but as radiation loss begins to dominate with further increasing taper angle, the power in both arms eventually decreases. Similarly, the combined power in the first two supermodes of the symmetric two-mode Y-junction output arms also decreases at larger angles because of radiation loss as shown in Fig. 14 (e.g., red Power Splitting curves). V. CONCLUSION In this paper, the conceptual framework for understanding propagation through symmetric and asymmetric single-mode, few-mode, and multimode weakly guiding Y-junctions has been presented, with the functionality of these devices being confirmed using BPM simulations. The paper also demon￾strates the properties of asymmetric Y-junctions that make them suitable for low-loss wavelength- and phase-independent mode sorting. Foreseeable applications for asymmetric Y-junc￾tions include mode-division multiplexing/demultiplexing for high-capacity data transmission or high-resolution distributed sensing. ACKNOWLEDGMENT The authors would like to thank Dr. S. Madden and the Laser Physics Centre, The Australian National University for the use of their software. REFERENCES [1] J. D. Love, R. W. C. Vance, and A. Joblin, “Asymmetric, adiabatic multipronged planar splitters,” Opt. Quantum Electron., vol. 28, no. 4, pp. 353–369, 1996. [2] H. Sasaki and I. Anderson, “Theoretical and experimental studies on active Y-junctions in optical-waveguides,” IEEE J. Quantum Electron., vol. 14, no. 11, pp. 883–892, Nov. 1978. [3] A. G. Medoks, “Theory of symmetric waveguide Y-junction,” Radio Eng. Electron. P, vol. 13, no. 1, p. 106, 1968. [4] M. Izutsu, Y. Nakai, and T. Sueta, “Operation mechanism of the single-mode optical-waveguide-Y junction,” Opt. Lett., vol. 7, no. 3, pp. 136–138, 1982. [5] W. K. Burns and A. F. Milton, “Mode conversion in planar-dielectric separating waveguides,” IEEE J. Quantum Electron., vol. QE-11, no. 1, pp. 32–39, Jan. 1975. [6] W. Y. Hung, H. P. Chan, and P. S. Chung, “Novel design of wide-angle single-mode symmetric Y-junctions,” Electron. Lett., vol. 24, no. 18, pp. 1184–1185, 1988. [7] W. M. Henry and J. D. Love, “Asymmetric multimode Y-junction split￾ters,” Opt. Quantum Electron., vol. 29, no. 3, pp. 379–392, 1997. [8] N. Goto and G. L. Yip, “A TE-TM mode splitter in LINBO by proton￾exchange and TI diffusion,” J. Lightw. Technol., vol. 7, no. 10, pp. 1567–1574, Oct. 1989. [9] J. Vandertol and J. H. Laarhuis, “A polarization splitter on LINBO using only titanium diffusion,” J. Lightw. Technol., vol. 9, no. 7, pp. 879–886, Jul. 1991. [10] J. D. Love and A. Ankiewicz, “Purely geometrical coarse wave￾length multiplexer/demultiplexer,” Electron. Lett., vol. 39, no. 19, pp. 1385–1386, 2003. [11] K. Shirafuji and S. Kurazono, “Transmission characteristics of optical asymmetric-Y junction with a gap region,” J. Lightw. Technol., vol. 9, no. 4, pp. 426–429, Apr. 1991. [12] N. Riesen and J. D. Love, “Dispersion equalisation in few-mode fi- bres,” Opt. Quantum Electron., vol. 42, no. 9, pp. 577–585, 2011. [13] J. E. Baran and D. A. Smith, “Adiabatic 2 2 polarization splitter on LINBO ,” Photon. Technol. Lett., vol. 4, no. 1, pp. 39–40, 1992. [14] J. D. Love and A. Ankiewicz, “Photonic devices based on mode con￾version,” in Proc. Australian Conf. Opt. Fibre Technol., Sydney, Aus￾tralia, 2001, pp. 80–81. John D. Love was born in the U.K. in 1942. He received the M.A. and M.Maths. degrees in mathematics from the University of Cambridge, Cambridge, U.K., and the M.A., D.Phil., and D.Sc. degrees in mathematics from the University of Oxford, Oxford, U.K. Since 1973, he has been with The Australian National University, Can￾berra, A.C.T., Australia, researching theoretical aspects of fiber optics, planar waveguides, and associated light processing devices. He co-authored Optical Waveguide Theory (Berlin, Germany: Springer, 1983) and Silica-based Buried Channel Waveguides and Devices (London, U.K.: Chapman & Hall, 1996). His research activities encompass both academic and industrial problems. In teaching, he is the Convenor for the Master of Photonics degree and teaches several undergraduate and masters courses in photonics. Dr. Love is an honorary Life Member of the Australian Optical Society. Nicolas Riesen was born in Canberra, A.C.T., Australia, in 1987. He received the B.Sc. degree majoring in physics and the B.Eng. degree (first class Hons.) in systems engineering from The Australian National University, Canberra, in 2011, where he is currently working toward the Ph.D. degree at the Research School of Physics and Engineering (in collaboration with the Commonwealth Scientific and Industrial Research Organization). His main research interests include mode-division multiplexing and dis￾tributed fiber sensing. Mr. Riesen received the University Medal from The Australian National Uni￾versity. He is the recipient of an ANU research scholarship