An Analysis of Isolation Properties of Mono-Sectional Optical Isolators Consisting of Magnetooptic Guide Layers and Substrates

Yasumitsu MIYAZAKI  Kazunari TAKI  

IEICE TRANSACTIONS (1976-1990)   Vol.E73   No.5   pp.695-704
Publication Date: 1990/05/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: PAPER
Category: Electro-Optics

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Isolation properties of mono-sectional optical isolators consisting of magnetooptic guide layers and substrates have been theoretically investigated by using hybrid modes. The magnetization of its mode converter uniformly tilts by an elevation angle θ from the film plane in the plane transverse to the light propagation direction. The guide layer thickness is chosen to be near the cut-off so that the longitudinal electric field should be large and the mode conversions through the first and second order magnetooptic effects should be the same each other. Since these mode conversions cancel and add up each other in the forward and backward directions, respectively, the unidirectional mode conversion can be realized. By using the substrate which has the opposite first order magnetooptic effect to that of the guide layer, the propagation length of the mode converter can be reduced. When the refractive index, optical birefringence, the first and the second order magnetooptic effects of the guide layer are 2.18, 2.510-3, -2.7910-3 and -5.5810-4, and those of the substrate are 2.137, 2.510-3, 3.8510-4 and -7.7010-5 at the wavelength of 1.152µm, the isolation ratio of 30 dB can be achieved at the propagation length of 4.68 mm and the film thickness of W=0.975µm by tilting the magnetization by the elevation angle of θ=79.5 for the refractive index of the top layer of 1.50.