Image Processing Systems Institute of the Russian Academy of Sciences,
S.P. Korolyov Samara State Aerospace University,
School of Physics & Astronomy at University of St. Andrews

Full text of article: Russian language.

Abstract:
We report design, fabrication and characterization of a new nanophotonic device comprising a two-dimensional photonic crystal (PhC) lens of size 3×4 μm fabricated in a silicon film of fused silica. The PhC lens is put at the output of a planar waveguide of width 4.5 μm to couple light into a planar waveguide of width 1 μm, each waveguide being of length 5 mm. A 1 μm off-axis displacement of the smaller waveguide leads to an 8-fold reduction of output light intensity, which means that the focal spot size at output of the PhC lens in silicon is less than 1 μm. The simulation has shown that the PhC lens has the maximal transmittance at 1.55 μm, with the waveguides coupling efficiency being 73%. The transmission spectrum measured has four local minima in the range 1.50-1.60 μm. The difference between the calculated and measured transmission spectrum is 29%. The focal spot size of the lens in air calculated at the FWHM is 0.32λ (where λ is the wavelength), which is less than the diffraction limit of 0.44 λ, defined by the sinc-function.

Key words:
photonic crystal lens, planar waveguides, sharp focusing of light, coupling two different waveguides, e-beam lithography.

Citation: Kotlyar VV, Triandofilov YaR, Kovalev AA, Kotlyar MI, Volkov AV, Volodkin BOl, Soifer VA, O’Faolain L, Krauss T. Photonic crystal lens for coupling of two planar waveguides. Computer Optics 2008; 32(4): 326-37.

References:

1. Xu Y, Lee RK, Yariv A. Adiabatic coupling between conventional dielectric waveguides with discrete translational symmetry. Opt. Lett. 2000; 25(10): 755-757.
2. Mekis A, Joannopoulos JD. Tapered couplers for efficient interfacing between dielectric and photonic crystal waveguides. J. Light Techn. 2001; 19(6): 861-865.
3. Happ TD, Kamp M, Forchel A. Photonic crystal tapers for ultracompact mode conversion. Opt. Lett. 2001; 26(14): 1102-1104.
4. Talneau A. Low-reflection photonic crystal taper for efficient coupling between guide sections of arbitrary widths. Opt. Lett. 2002; 27(17): 1522-1524.
5. Almeida VR, Panepucci RR, Lipson M. Nanotaper for compact mode conversion. Opt. Lett. 2003; 28(15): 1302-1304.
6. Bienstman P. Taper structures for coupling into photonic crystal slab waveguides. J. Opt. Soc. Am. B 2003; 20(9): 1817-1821.
7. MacNab SJ, Moll N, Vlasov YA. Ultra-low loss photonic integrated circit with membrane-type photonic crystal waveguide. Opt. Express 2003; 11(22): 2927-2939.
8. Barclay PE, Srinivasan K, Painter O. Design of photonic crystal waveguide for evanescent coupling to optical fiber tapers and integration with high-Q cavities. J. Opt. Soc. Am. B 2003; 20(11): 2274-2284.
9. Orobtchouk R. High-efficiency light coupling in a submicrometric silicon-on-insulator waveguide. Appl. Opt. 2000; 39(31): 5773- 5777.
10. Lardenois S. Low-loss submicrometer silicon-on-insulator rib waveguides and corner mirrors. Opt. Lett. 2003; 28(13): 1150-1153.
11. Taillaert D. Grating couplers for couping between optical fiber and nanophotonic waveguides. Jap. J. Appl. Phys. 2006; 45(8): 6071- 6077.
12. Van Laere F. Compact and high efficient grating couplers between optical fiber and nanophotonic waveguides. J. Light. Techn. 2007; 25(1): 151-156.
13. Bachim BL, Ogunsola OO, Gaylord TK. Optical fiber-to-waveguide coupling using carbon-dioxide-laser-induced long-period fiber gratings. Opt. Lett. 2005; 30(16): 2080-2082.
14. Prather DW. High-efficiency coupling structure for a single-line-defct photonic crystal waveguide. Opt. Lett. 2002; 27(18): 1601-1603.
15. Kim H. High efficiency coupling technique for photonic crystal waveguides using a waveguide lens. OSA Techn. Digest: Frontiers in optics 2003; MT68.
16. Corbett JCW, Allington-Smith JR. Coupling starlight into single-mode photonic crystal fiber using a field lens. Opt. Express 2005; 13(17): 6527-6540.
17. Michaelis D. Micro-optical assisted high-index waveguide coupling. Appl. Opt. 2006; 45(8): 1831-1838.
18. Kong G. Lensed photonic crystal fiber obtained by use of an arc discharge. Opt. Lett. 2006; 31(7): 894-896.
19. Pokrovsky AL, Efros AL. Lens based on the use of left-handed materials. Appl. Opt. 2003; 42(28): 5701-5705.
20. Fabre N. Toward focusing using photonic crystal flat lens. Opto-electronics Review 2006; 14(3): 225-232.
21. Li C, Efros AL. Far-field imagimg by the Veselago lens made of a photonic crystal. J. Opt. Soc. Am. B 2006; 23(3): 490-497.
22. Matsumoto T, Eom K, Baba T. Focusing of light by negative refraction in a photonic crystal slab superlens on silicon-on-insulator substrate. Opt. Lett. 2006; 31(18): 2786-2788.
23. Li CY, Holt JM, Efros AL. Imaging by the Veselago lens based upon a twodimensional photonic crystal with a triangular lattice. J. Opt. Soc. Am. B 2006; 23(5); 963-968.
24. Geng T, Lin T, Zhuang S. All angle negative refraction with the effective phase index of -1. Chinese Opt. Lett. 2007; 5(6): 361-363.
25. Asatsume T, Baba T. Abberation reduction and unique light focusing in a photonic crystal negative refractive lens. Opt. Express 2008; 16(12): 8711-8718.
26. Fabre N. Measurement of a flat lens focusing in a 2D photonic crystal at optical wavelength. OSA Digest, CLEO/QELS 2008; CTuDD6, CA.
27. Yang S, Hong C, Yang H. Focusing concave lens photonic crystals with magnetic materials. J. Opt. Soc. Am. A 2006; 23(4): 956-959.
28. Luan P, Chang K. Photonic crystal lens coupler using negative refraction. Prog. In Electr. Res. 2007; 3(1): 91-95.
29. Haxha S, AbdelMalek F. A novel design of photonic crystal lens based on negative refractive index. Prog. In Electr. Res. 2008; 4(2): 296-300.
30. Lu Z. Three-dimensional photonic crystal flat lens by full 3D negative refraction. Opt. Express 2005; 13(15): 5592-5599.
31. Lu Z. Experimental demonstration of negative refraction imaging in both amplitude and phase. Opt. Express 2005; 13(6): 2007-2012.
32. Minin IV. Subwavelength diffractive photonic crystal lens. Prog. In Electr. Res. B 2008; 7: 257-264.
33. Pshenay-Severin E. Photonic crystal lens for photonic crystal waveguide coupling. OSA Techn. Digest:CLEO 2006; CThK3.
34. Hugonin JP. Coupling into clow-mode photonic crystal waveguide. Opt. Lett. 2007; 32(18): 2638-2640.
35. Triandafilov YR, Kotlyar VV. Photonic crystal Michaelian lens [In Russian]. Computer Optics 2007; 31(3): 27-31.
36. Triandafilov YR, Kotlyar VV. Photonic crystal Mikaelian lens. Opt. Mem. Neur. Net. 2008; 17(1): 1-7.
37. Michaelian AL. Application of medium properties for wave focusing [In Russian]. Doklady AN SSSR 1951; 81: 2406-2415.

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