PARALLEL FABRICATION OF PHOTONIC CRYSTALS USING INTERFERENCE LITHOGRAPHY
Photonic band gap property of photonic crystal structures has opened up many possibilities in the field of optical communications. The ability of photonic crystals to guide light through waveguide bends with feature sizes comparable to the wavelength of light has possible applications in fields like photonic integrated circuits. E-beam lithography is predominantly used for the fabrication of photonic crystals in semiconductors but its serial method of writing patterns limits its use in large area fabrication. This work presents interference lithography as a parallel method of fabrication of photonic crystals. Lloyds mirror interference lithography system was set up and used for photonic crystal fabrication in this thesis. Two dimensional square photonic crystal structures were fabricated on silicon and silicon-on-insulator (SOI) wafers by first recording a multiple exposure interference pattern of interference lithography on a photoresist and then transferring the pattern to the substrate underneath by Reactive ion etching (RIE). Period of the photonic crystal structures fabricated was measured using Scanning electron microscopy (SEM), Atomic force microscopy (AFM) and diffraction based measurement method to get a realistic picture of actual fabricated period. The fabricated structure was simulated using specialized simulator tools like FDTD Solutions to obtain the photonic band gap data of the fabricated structure. Reflectance properties were also analyzed by coupling light from a lensed fiber into the photonic crystal patterned top silicon layer of a SOI wafer and measuring reflected power in the available 90nm laser emission window. Measured data was presented in units similar to simulation data and a reasonable agreement on spectral reflectance properties was observed between the two.
School:University of Cincinnati
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:photonic crystals band gap lithography interference lloyds mirror shipley 1805 waveguides fabrication silicon soi lumerical translight
Date of Publication:01/01/2005