Photonic crystal lens for coupling of two planar waveguides
V.V. Kotlyar, Ya.R. Triandofilov, A.A. Kovalev, M.I. Kotlyar, A.V. Volkov, B.O. Volodkin, V.A. Soifer, L. O’Faolain, Т. Krauss

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.

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.


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