Optical switch devices using the magnetic fluid thin films

Two optical switch designs are proposed, with the transmitted intensity of a He-Ne Laser light measured to demonstrate the feasibility of both designs. It was found that the transmitted polarized-light intensity of the magnetic fluid film subjected to a parallel magnetic field is proportional to field strength and tends to saturate at high field. On the other hand, when an unpolarized He-Ne laser light passes through a magnetic fluid film subjected to a perpendicular magnetic field, the magnetic field tends to reduce the transmitted intensity. In both methods, the curves of the intensity versus field strength possess two types of behaviors; one is independent of sweep rate and the other one is sweep rate dependent. This suggests that the structure formation in the magnetic film may play a decisive role in determining the transmittance of light. (C) 1999 Elsevier Science B.V. All rights reserved.