Improved usage of binary diffractive optical elements in ultrafast all-optical switching modules

In next generation large capacity photonic networks, the necessity of all-optical data processing is increased. Reviewing the author's previous experimental trial [R. Hainberger and T. Kamiya: Jpn. J. Appl. Phys. 39 (2000) 1533] of all-optical switching modules employing both compound semiconductor saturable absorbers and binary diffractive optical elements, it is clear that further improvement of zone plates should be pursued by introducing wave-theoretical design. The previous formulation by the author's group [Y. Orihara, W. Klaus, M. Fujino and K. Kodate: Appl. Opt. 40 (2001) 5877] was extended, applied to the analysis of the old design, and was used for a new design of all-optical switching modules. Through the evaluation of efficiency and spot-size, it was revealed that the minimum feature size of I micrometer in fabrication allows both small spot-size and high efficiency, suitably applicable to all-optical switching modules operating at a wavelength of 1.55 micrometers.