Browse Prior Art Database

Multilayer Magneto Optic Structure

IP.com Disclosure Number: IPCOM000078081D
Original Publication Date: 1972-Nov-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Wieder, H: AUTHOR

Abstract

For read/write applications in beam addressable file systems, it is desirable to have a configuration which minimizes the energy needed to write information without adversely affecting the signal/noise of the readout. The structure shown achieves this, by allowing the incoming light to make two passes through the magneto-optic film. Since the effective volume of the heated area is halved, the Curie point within the volume can be reached with a pulse of energy considerably smaller than is required in a conventional single-pass system. Furthermore, since the readout signal (i.e. the Faraday rotation) is cumulative regardless of which direction the light is traveling, a double pass through the film provides twice the readout signal achieved in a single pass.

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Multilayer Magneto Optic Structure

For read/write applications in beam addressable file systems, it is desirable to have a configuration which minimizes the energy needed to write information without adversely affecting the signal/noise of the readout. The structure shown achieves this, by allowing the incoming light to make two passes through the magneto-optic film. Since the effective volume of the heated area is halved, the Curie point within the volume can be reached with a pulse of energy considerably smaller than is required in a conventional single-pass system. Furthermore, since the readout signal (i.e. the Faraday rotation) is cumulative regardless of which direction the light is traveling, a double pass through the film provides twice the readout signal achieved in a single pass.

One embodiment, shown in Fig. 1a, consists of a nonmagnetic substrate 1 having a highly reflecting layer 2 thereon. The reflectance of the layer is a function of and is chosen in accordance with the wavelength of the incoming light. An antireflectance layer 5 is upon the highly reflecting layer. Then, magneto-optic layer 3 and top antireflectance layer 4 are upon the previous layers. This configuration avoids reflections from the interfaces of the magneto- optic material, and thus eliminates both undesirable sources of noise and any component of signal introduced by the Kerr effect.

The highly reflecting layer 2 is preferably chosen to be of a dieiectric material to act as an i...