Die Entwicklung von Technologien für lithografische Prozesse zur Herstellung hochfrequenter diffraktiver Dünnschichtbauelemente direkt auf den Stirnflächen von Lichtleitfasern erfordert die Modifizierung der für die Prozessdurchführung auf Wafern optimierten lithografischen Verfahren. Dies umfasst die Schichtherstellung, einzustellende Prozessparameter und die Prozessführung.
Durch die Strukturierung metallischer Schichten werden faserbasierte Lithografiemasken für die Faser-zu-Faser-Belichtung zur effizienten und reproduzierbaren Fotolithografie auf Faserstirnflächen erzeugt.
Beschrieben wird zudem die hochfrequente DUV-Interferenzlithografie an einem für die Elektronenstrahllithografie spezifizierten Resist auf unterschiedlichen Substratmaterialien.
Die direkte Oberflächenstrukturierung von Hochfrequenzgittern in auf die Stirnflächen von Quarzglaslichtleitfasern aufgebrachten hochbrechenden Schichten aus As
In this thesis the development of technologies for lithographic processes for the fabrication of high-frequency diffractive thin film elements directly on the end-faces of optical fibres is described. For this purpose lithographic procedures, optimised for wafer processing lithographic procedures, have to be modified in a convenient way. This concerns the fabrication of the layers as well as the processing and the required process parameters. In dependence on used materials and structural dimensions different functionalities of the structured layers can be implemented.Two different systems are applied for exposure. Direct laser writing at 442 nm exposure wavelength is used for the fabrication of structures with grating periods larger than 3 µm. For the realisation of high-frequency gratings with periods smaller than 1 µm laser interference lithography utilizing an excimerlaser emitting at a wavelength of 248 nm is applied. At this specific wavelength is investigated the feasibility to structure a resist which is actually designed for electron-beam-lithography also by interference lithography. Due to its unique properties like small sensitivity to humidity, good long-term stability, good adhesion and simplified process management this resist is particularly well-suited for the development of technologies for the structuring of materials on fibre-end-faces. Suitable parameters for the realisation of high-frequency grating structures regarding exposure and general processing parameters for different substrate layers are determined.Structuring of metallic layers on fibre-end-faces results in fibre based lithographic masks which can be used for efficient and reproducible photolithography on fibre-end-faces by fibre-to-fibre exposure.Efficient fibre-coupled high-index-contrast gratings can be realised by direct excimerlaser interference lithography surface-structuring of high-frequency gratings in high-index layers of As35S65 at the end-face of fused-silica-fibres. Wavelength and polarising filters based on such gratings are designed, appropriate exposure conditions are determined and the properties of realised structures are compared to results of simulations.