Stefan Sinzinger

Planar-integrated optical vector-matrix multiplier

We present the design of a planar-integrated optoelectronic vector-matrix multiplier. The inherent parallel-processing potential is fully exploited by optical implementation of multiplications and summations. Planar integration makes the free-space optical system compatible with electronic VLSI technologies. It is composed of phase-only diffractive optical elements, which implement lens and multiple-beam-splitter functions. A demonstrator version of the optical system for a matrix of size 10 x 10 was fabricated on quartz glass by means of multimask lithography and reactive ion etching. It shows low cross talk and good uniformity of the signals.

Iterative optimization of phase-only diffractive optical elements based on a lenslet array

We describe the design of Fourier-type phase-only array generators. The numerical optimization employs the Fienup algorithm, where the parageometric design of the phase retardation profile, with the form of a lenslet array, is used as the initial guess of the optimization process. This approach provides designs with high performance that can be obtained with comparatively low computing effort. This is particularly true for elements generating large spot arrays. For symmetric reconstruction fields, the optimized phase profile typically has the same symmetry as that for the reconstruction field and can be easily unwrapped.

Compact planar-integrated optical correlator for spatially incoherent signals

A new, to our knowledge, approach for the planar integration of optical correlators is demonstrated. A VanderLugt-type architecture was used to allow the processing of the spatially incoherent signals of active optoelectronic smart-pixel-device arrays. In a folded optical system all passive components were implemented as a single multiple-phase-level element. The relations among the spatial resolution, the light efficiency, and the system design parameters are derived. High signal quality and low noise levels were achieved experimentally.

Compact discrete correlators with improved design

Abstract Optical correlators are of interest for a variety of signal processing tasks. In a recent paper [Appl. Opt. 39 (2000) 759–765], we described an approach to build discrete correlators for spatially incoherent signals using planar-integrated free-space optics. In that paper, input and output array were spatially interlaced in the same area. Here, we present an improved design with separated input and output.

Evaluation of microlens properties in the presence of high spherical aberration

Microlenses can be generated with various fabrication technologies. Some of these technologies cause large spherical aberrations in the resulting microlenses. We describe an algorithm based on Rayleighs quarter-wave criterion, which allows the evaluation of lens parameters for those microlenses. Specifically, we investigate numerical aperture, focal length, and space-bandwidth product with respect to applications in optical microsystems. We apply our algorithm to different types of microlenses, three gradient-index lenses, and one surface-relief lens. The experimental results demonstrate that our algorithm provides a helpful characterization method for microlenses with large aberrations.

A communication network composed of fiber- and planar-integrated free-space optical components

We propose a communication network composed of commercially available MT-connected multifiber ribbons and custom-designed planar-integrated free-space optical components for a high-bandwidth, low-latency optoelectronic bus architecture.