17 February 1995 Integrated optical detection circuit for magneto-optical drive
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An integrated optical circuit (IOC) combining all the detection functions of a standard magneto-optical reading head (MO reading, focus and tracking control) is presented. The reading function is achieved by means of a patented interferometric circuit. For tracking control, the well-known push-pull method has been applied and adapted to integrated optics. In this case, the role of the IOC is just to separate the beam reflected back from the disc in two halves in order to compare their intensity. For focus control, several principles have been tested: standard ones adapted to integrated optics (`wax-wane' method or Foucault knife-edge) and an original method based on multimode interferences, taking benefits of integrated optics specificity. The implemented technology is based on a silicon substrate with a silicon nitride core between two silica cladding layers (Si/SiO2/Si3N4/SiO2). This technology is a low cost technology well adapted for mass production. The optical components of the circuits are made by standard contact photolithography and reactive ion etching. Several wafers with about 50 devices each, have been processed and characterized. In particular, the detection signals have been compared with the detection signals delivered simultaneously by a Philips-IBM 128 MB MO drive. This experiment demonstrates the feasibility of an integrated detection device for MO drive.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Patrick Louis Mottier, V. Lapras, C. Chabrol, "Integrated optical detection circuit for magneto-optical drive", Proc. SPIE 2451, Advanced Image and Video Communications and Storage Technologies, (17 February 1995); doi: 10.1117/12.201221; https://doi.org/10.1117/12.201221


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