Faculté des sciences

Continuous-relief fan-out elements with optimized fabrication tolerances

Ehbets, Peter ; Rossi, Markus ; Herzig, Hans-Peter

In: Optical Engineering, 1995, vol. 34, no. 12, p. 3456-3464

The design of kinoform fan-out elements with high efficiency and reduced sensitivity to vertical profile scaling errors is presented. We start from a high-efficiency continuous-phase fan-out solution and optimize the position of the 0-2π transitions in the phase function, in order to achieve a high fabrication-error tolerance. The sensitivity of Fourier-transform and focusing fan-out elements to... Plus

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    Summary
    The design of kinoform fan-out elements with high efficiency and reduced sensitivity to vertical profile scaling errors is presented. We start from a high-efficiency continuous-phase fan-out solution and optimize the position of the 0-2π transitions in the phase function, in order to achieve a high fabrication-error tolerance. The sensitivity of Fourier-transform and focusing fan-out elements to vertical etch-depth errors is analyzed. The limitations for the fabrication of such structures by laser-beam writing are discussed. In particular, the influence of the finite writing-spot diameter on the fan-out performance is investigated. Design rules for fan-out elements, which consider fabrication constraints, are derived. Experimental results are presented for cylindrical focusing fan-out elements with small uniformity error (2) and weak profile scaling dependence.