Applied Physics

Making Modulators from the Outside In

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Science  11 Oct 2002:
Vol. 298, Issue 5592, pp. 325
DOI: 10.1126/science.298.5592.325c

In communications, electro-optic fiber modulators are used to imprint electrical data onto the optical carrier or to change the output signal from phase to amplitude modulation. Such devices usually work as interferometers: A beam of light is split between two paths, and a change in the refractive index of one path is induced by an electrical bias, which introduces a phase difference between the two beams that results in constructive or destructive interference. This type of device requires the electrodes to run inside the length of the fiber, and current methods for inserting these electrodes are costly. Fokine et al. describe a simplified method for electrode insertion in which one end of a glass fiber with a twin-core and twin-hole design is placed in molten metal within a pressurized chamber. The melt is injected into the fiber holes and then allowed to solidify. For electrodes made of a Bi/Sn alloy, the bias required to induce a phase difference of p radians was ∼1.3 kilovolts. This approach may ultimately lead to lower cost electro-optic devices. — ISO

Opt. Lett.27, 1643 (2002).

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