Microtechnological Production of Integrated Optical Gratings Using Laser Beam Lithography for Atomic Interferometers

Inhalt:
High-precision matter wave interferometers offer advantages over classical interferometers in terms of measurement precision, reproducibility and obsolete calibration effort and maintenance. Due to the still stationary construction and the high complexity, the use for commercial purposes is difficult to realise. This requires further miniaturisation and integration of the overall system. A possible approach to further reduce the mass and volume can be the use of a grating MOT: For the previous MOT, four laser beams were needed in the experiments, which had to be adjusted and controlled accordingly. By integrating a micro-engineered grating on the atomic chip surface, the number of required lasers can be reduced to one, which hits the atom chip surface orthogonally. Due to the grating dimensions (<1 µm), the structuring was carried out in the past at IMPT using electron beam-based processes. In order to avoid high process times, the structuring in this paper is carried out by means of laser lithography. This method places new, increased demands on the process technology. For monochromatic exposure, an additional anti-reflective coating is required to avoid standing waves and to achieve resolutions <1 µm. For this purpose, a process plan for structuring and transferring submicrometre structures into the substrate material using suitable etching processes was successfully developed.