A Variable Optical Beam Splitter Utilizing a Tapered Velocity Coupler

Masahiro GESHIRO  Masashi HOTTA  

IEICE TRANSACTIONS on Electronics   Vol.E77-C   No.11   pp.1731-1734
Publication Date: 1994/11/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Electromagnetic Theory)
variable optical beam splitter,  tapered velocity coupler,  electro-optic effect,  LiNbO3,  finite difference method,  

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A new type of variable beam splitter at optical frequencies is proposed. The basic structure of the device utilizes a tapered velocity coupler which is composed of a center slab waveguide of constant-thickness, constant-index type and two identical outer slab waveguides of constant-thickness, variable-index type. The coupler is assumed to be fabricated on a LiNbO3 substrate, whith an external electric field applied in parallel with the optical axis. The numerical results obtained with the finite difference method show that a wide range of splitting ratios can be obtained with moderate drive voltages and that the splitting characteristics are stable over a wide range of frequencies.