M. Hermatschweiler

Thin-film polarizer based on a one-dimensional–three-dimensional–one-dimensional photonic crystal heterostructure

The recent experimental demonstration of polarization stop bands in three-dimensional dielectric circular-spiral photonic crystals is extended in two ways. First, the combination with a one-dimensional set of lamellae on one side allows for “poor-man’s optical isolators” or for thin-film polarizers—depending on from which side light impinges onto the device. Second, a chiral three-dimensional photonic crystal sandwiched between two one-dimensional sets of lamellae acts as a thin-film polarizer from both sides. Corresponding polymeric heterostructures are fabricated by means of direct laser writing. Their performance is compared with theory.

Three-Dimensional Photonic Crystals

We review our work on two complementary and compatible techniques, namely direct laser writing and holographic lithography which are suitable for fabricating three-dimensional Photonic Crystal templates for the visible and near-infrared. The structures are characterized by electron micrographs and by optical spectroscopy, revealing their high optical quality.

Three-Dimensional Lithography of Photonic Crystals

We present our work on the fabrication of three-dimensional Photonic Crystal templates by holographic lithography and direct laser writing. Both optical methods are highly qualified for the production of top-quality polymeric three-dimensional Photonic Crystals and allow in combination the controlled incorporation of defects and waveguides in large-area structures. Scanning electron micrographs and optical spectra of different Photonic Crystals are presented and compared with numerical simulations. Our roadmap to infiltrate the polymeric templates with high refractive-index materials is outlined.

Three-dimensional photonic band gap structures made by direct laser writing and silicon single-inversion

We realize a variety of silicon photonic crystal structures. Direct laser writing of polymeric templates (square/circular spirals and slanted pore structures) combined with a silicon single-inversion procedure leads to band gaps in the near infrared.

Fabrication of Silicon Inverse Woodpile Photonic Crystals

We fabricate silicon inverse woodpile structures for the first time. Direct laser writing of polymeric templates and a novel silicon-single-inversion procedure lead to structures with gap/midgap ratios of 14.2 % centered at 2.5 mum wavelength.

Three‐dimensional Photonic Quasicrystals: Fabrication and Characterization

Quasicrystals are neither crystalline nor amorphous solids. They are aesthetically highly appealing and posses intriguing physical properties. Recently, three‐dimensional photonic quasicrystals have become available for the near‐infrared spectral region through nanofabrication. This opens the way for photonic transport measurements to understand the influence of symmetry onto transport properties. In this article we describe the fabrication via direct laser writing and silicon single inversion and the optical characterization via Laue‐diffraction experiments.

Recent progress in silicon double inversion of three-dimensional polymer templates

We present recent progress in converting polymer templates into three-dimensional silicon photonic crystals by using a silicon-double-inversion procedure. This has led to woodpiles with both improved structural and optical quality.

Three-Dimensional Silicon Photonic Crystals from Polymer Templates: Single versus Double Inversion

We present recent progress in converting polymer templates into three-dimensional silicon photonic crystals by using double (single) inversion. This has led to woodpiles (inverse woodpiles) with improved structural and optical quality.

3D photonic bandgap templating using holography and direct laser writing

We review our work on fabricating templates for photonic band gap materials at telecommunication wavelengths via holography and direct laser writing. Measured optical spectra are compared with theory, revealing the excellent quality of these structures.