A brief survey of the electrical and optical properties of poled polymer electrets for sensors and photonic applications is given Semicrystalline ferroelectric polymers are highly suitable for piezo‐ and pyroelectric applications, while amorphous polymers containing molecular dipoles with acceptor and donor groups linked by delocalized π electrons (A‐π‐D) are interesting for photonic applications The large variety of poling techniques, such as electrode, corona, electron‐beam, and photothermal poling, is discussed in detail together with specifically developed poling techniques for ferroelectric or amorphous polymers Methods for the experimental investigation of the polar order are based on the piezo‐, and pyroelectric effect, birefringence, the electro‐optical effect and second‐harmonic generation Newly developed thermal analysis techniques and dipole relaxation spectroscopies complement traditional techniques, such as thermally stimulated depolarization and broadband linear and nonlinear dielectric relaxation spectroscopy The compatibility of polymers with semiconductor technology is illustrated with selected applications in hybrid integrated thermal and acoustical imaging devices, electro‐optical modulators and second‐harmonic generators

Poled polymers for sensors and photonic applications

Polymeric Electro‐Optic Modulators: Matereials synthesis and processing

UV-moulded microlens arrays with high replication quality were fabricated using a parametric design method. It is important to maximize replication quality because one can obtain replicated micro-optical components with desired properties by accurate control of the shape. In this study, nickel mould inserts for microlens arrays with lenses having diameters between 3 and 230??m were fabricated by an electroforming process. The reflow method was used to make the master for the metallic mould insert. A UV-moulding system was designed and constructed, and the effects of compression pressure and UV-curing dose on the replication quality of UV-moulded microlens arrays with a diameter of 14??m were examined experimentally. Finally, geometrical and optical properties of the replicated microlens arrays were measured and analysed.

Replication qualities and optical properties of UV-moulded microlens arrays

An algorithm is proposed to reconstruct two-dimensional wave-front from phase differences measured by lateral shearing interferometer. Two one-dimensional phase profiles of object wave-front are computed using Fourier transform from phase differences, and then the two-dimensional wave-front distribution is retrieved by use of least-square fitting. The algorithm allows large shear amount and works fast based on fast Fourier transform. Investigations into reconstruction accuracy and reliability are carried out by numerical experiments, in which effects of different shear amounts and noises on reconstruction accuracy are evaluated. Optical measurement is made in a lateral shearing interferometer based on double-grating.

Two-dimensional wave-front reconstruction from lateral shearing interferograms.

The invention concerns the combination of optical elements with active optoelectronic to monolithic optoelectronic systems. An optoelectronic wafer (1) comprising active optical components (2) is provided with (micro-) optical structures. The optical structures (12, 13) are allocated to the active optical components (2), i.e. they are configured to influence light impinging on the active optical components (2) and/or originating from them in a desired manner. To this end they are either aligned to the optical components or otherwise adjusted to serve this purpose. The combined active optical components/optical structures are separated for example by dicing the semiconductor wafer with the optical structures into parts containing at least one active optical component (2) and at least one optical structure (12, 13).

Micro-optics on optoelectronics

Wave aberrations of refractive photoresist microlenses and silicon microlenses were measured with a lateral shearing interferometer. Because of the silicon elements, a near-infrared working wavelength (λ = 1.32 μm) was used. The wave front was evaluated by a phase step technique with four steps. Integration of the phase distributions was performed with a computationally efficient Fourier transformation algorithm. The influence of the detector vidicon nonlinearity on the measured wave front was calculated. The defocusing behavior of the interferometer was investigated by fitting the measured wave fronts with the help of Zernike circle polynomials. It is shown that the reproducibility can be kept below λ/100 rms. Examples for the measured wave fronts of plano–convex silicon microlenses are discussed in detail.

Testing of refractive silicon microlenses by use of a lateral shearing interferometer in transmission.

A replication technique allowing for the wafer scale integration of microoptical elements is presented and illustrated by various examples. The technique is based on polymer UV reaction moulding using a modified contact mask aligned where mask and wafer are replaced by the replication tool and an arbitrary substrate, respectively. The technology takes advantage of the high precision and adjustment accuracy of photolithography equipment. The replication masters are nickel shims, etched Silicon wafers or uv-transparent fused silica tools. The latter ones allow for replication on opaque substrates. Additionally, polymer elements with unique properties can be obtained by the combination of replication and resist technology using partially transparent replication tools. Wafer scale hybrid integration of microoptical subsystems is accomplished by replication of polymer elements like lenses, lens arrays, micro prisms etc. onto semiconductor wafers containing detectors or VCSELs, or by combining microoptical elements on both sides of a glass wafer. The use of thin layers of uv cured polymers on inorganic substrates results in good thermal and mechanical stability compare to all-polymer devices.

Wafer scale integration of micro-optic and optoelectronic elements by polymer UV reaction molding

A. Brauer, 1. Gase, L. Erdmann, P. Dannberg, W. KartheFraunhofer-Institution for Applied Optics and Precision Mechanics,07745 Jena, Federal Republic of GermanyABSTRACTPolymer multilayer waveguide technology was used to fabricate a polarization-indepen-dent phasemodulator. Refractive indices and electro-optic coefficient of the materialsused (Co. SANDOZ) were determined by waveguide methods.1. INTRODUCTION

Polarization-independent integrated electro-optic phase modulator in polymers

A solution is described for replication of polymer microoptical elements on arbitrary substrates. The replication is done on wafer scale level and includes the adjustment step between the optical elements and the substrate. Demonstrators are various microlens arrays, structures for the efficient coupling between monomode waveguides or multimode fibers and photodiodes, and between multimode waveguides and LED's. Out of the many different replication techniques, UV-reaction molding is chosen for this application. This technique has advantages against hot embossing and injection molding. Network polymers which are stable against temperature changes can be used. The replication is made in thin layers on a solid substrate resulting in high mechanical stability and very good flatness of the samples. The process introduces mechanical stress nor thermal load on the substrate which can be a fully processed semiconductor wafer containing elements like diodes or LEDs.

High-precision micro-optic elements by wafer-scale replication on arbitrary substrates

Electro-optic waveguide elements are fabricated in the polymer-on-silicon technology. Measured field distributions of the inverted rib waveguides show excellent agreement with vectorial FEM calculations. This method is also used for electro-optic phasemodulator design. The dynamics of electrode poling is studied by reflectrometry. An integrated waveguide interferometer with lateral electrodes allows the determination of the r 33 /r 31 equals 3.5.

Lars Erdmann

Papers

Testing of refractive silicon microlenses by use of a lateral shearing interferometer in transmission.

Wafer scale integration of micro-optic and optoelectronic elements by polymer UV reaction molding

Polarization-independent integrated electro-optic phase modulator in polymers

High-precision micro-optic elements by wafer-scale replication on arbitrary substrates

Electro-optic effects in polymer waveguide devices for optical communication