Dünnschichtfilter in der Telekommunikation

Abstract

Market forces are pushing the performance of optics to their limits. Optical components must be developed to provide the best possible combination of manufacturability, performance and price. One vital step to success in creating WDM optics lies in a discipline that is often overlooked or misunderstood – coating engineering. A key technology for controlling light in WDM systems is the optical filter, which performs functions from simple filtering in multiplexers and demultiplexers, to more sophisticated functions in optical amplifiers, modulators and test equipment. The basic tool of multiplexing and demultiplexing devices, thin film filters offer accurate center wavelength, broad flattop passband and high isolation from adjacent and nonadjacent channels. Thin film filters are widely used for gain flattening, band splitting, C and L band separation and combining amplifier-pump beams. Choosing the right thin-film-deposition process is essential for the efficiency and productivity of vacuum coating systems. LEYBOLD OPTICS has developed and optimized a comprehensive range of vacuum coating processes and process tools. LEYBOLD OPTICS has been proven the ability of producing shift-free coatings on large substrate areas by means of PIAD (Plasma Ion Assisted Deposition) in many applications over the past ten years. The low loss and stress values achieved, especially with silica and tantala films, allows besides the production of narrow band pass filters (DWDM, CWDM) also the production of gain flattening filters (GFF). PIAD is considerably improving the properties of evaporated thin films by high energy ion bombardment during the growing of the film. PIAD allows to produce dense shift free thin films with high refractive index, good adhesion and extremely low absorption. With the Advanced Plasma Source (APS) LEYBOLD OPTICS has developed a high power plasma source for PIAD. The APS provides high ion current densities over a large surface area in a neutral plasma to produce high quality layers at a high productivity.