Challenges in micro-optics

H. P. Herzig
Institute of Microtechnology, University of Neuchâtel, Rue A.-L. Breguet 2, CH-2000 Neuchâtel, Switzerland

Today, a wide range of manufacturing technology is available to produce optical micro and nanostructures, such as diffractive optics, refractive microlens arrays, photonic crystals, resonant grating filters, and nanoparticles. The technology is strongly driven by the needs of microelectronics. Very fine structures with less than 100 nm feature sizes can be realized. This is fine enough for applications in the visible and infrared region. However, this high-end equipment is not really made for optics. For the special needs of optics (accuracy, overlay, material, substrate thickness) the equipment has to be adapted. This makes the fabrication expensive. Therefore, research effort is also focused on flexible and low cost technology. Binary or multilevel elements with feature sizes of 500 nm are commercially available. Electron-beam writing is used for laboratory demonstrators with fine structures. For larger structures laser-beam writing is more suitable (less expensive). Analog structures are still highly challenging. Standard are microlenses, which have spherical or cylindrical surface. Also aspheric shapes are feasible. However, more general structures are difficult to be realized with optical quality.

We will present different examples (diffractive optics, photonic crystal waveguides and optical MEMS) for application wavelengths ranging from the nanometer to micrometer. Challenges and limitations due the miniaturization will be discussed.

Keywords

micro-optics, diffractive optics, microlenses, photonic crystals, optical MEMS