Photonic Microsystems from LIGA Technology

Abstract

Due to its almost complete freedom in lateral structuring, to the large choice of materials, and to the cheap mass production feature, LIGA technology offers new possibilities to realise photonic microsystems, either integrated or microoptical. In particular, advantages can be expected with respect to systems combining optically nonlinear with linear materials and concerning flux and flux density of the optical energy flow. It is found that the optical Kerr coefficient n₂ of an interesting nonlinear material must exceed a lower limit, i.e., n₂ > (λΔø/2πI₀)α , in order to be useful for photonic microsystems. Herein, X is the wavelength, Δø/2π the phase shift caused by the nonlinear part of the microsystem, I₀ the energy flux density of the incident light, and a the absorption coefficient of the nonlinear material. Bubeck and coworkers have given relationships between a and n₂ for a variety of organic materials. In case of a recently described phthalocyaninatoruthenium complex the optical Kerr coefficient and the 3^rd order susceptibility should satisfy n₂ > 4·10⁻¹⁴ m²/W and x⁽³⁾ > 4·10⁻⁸ esu, respectively, at λ = 680 nm, Δø/2π = 0.01, and I₀ = 100 MW/cm² . This material comes close to these requirements.