Optical modulator

Abstract

Provided is an optical modulator which can suppress degradation of modulation characteristics such as a drift characteristic of a bias point of the optical modulator in the optical modulator in which a thin substrate having a thickness of 20 [mu]m or less is used, even in a case where it is necessary to increase a width of a control electrode due to widening of a gap between optical waveguides. An optical modulator comprises a substrate (4) having a thickness of 20 [mu]m or less and an electro-optic effect, a reinforcing substrate (6) holding the substrate (4) thereon, and a resin layer (5) disposed between the substrate and the reinforcing substrate, in which the substrate (4) includes optical waveguides (1, 2) and control electrodes (3, 31) which control light waves propagating through the optical waveguides (1, 2), in which the optical waveguides include at least two optical waveguides (1) separated from each other, and in which the control electrodes (31) disposed between the two optical waveguides are configured to include two electrodes (31) disposed along each optical waveguide, and a thin line (8) conducting the two electrodes (31) at a same potential.

Description

technical field [0001] The present invention relates to an optical modulator, in particular to an optical modulator comprising: a substrate having an electro-optical effect with a thickness of 20 μm or less; a reinforcing substrate holding the substrate; and a resin arranged between the substrate and the reinforcing substrate Floor. Background technique [0002] In the technical fields of optical communication and optical measurement, electro-optical crystals such as lithium niobate (LN) are used for optical modulation, and optical waveguides with a Mach-Zehnder (MZ) structure formed on the crystal substrate are widely used. Traveling wave modulator. [0003] When reducing the thickness of the substrate constituting the optical modulator to about 20 μm, it is not necessary to form a substrate made of SiO between the substrate forming the optical waveguide and the control electrode. 2 The buffer layer is formed to match the speed of the light wave propagating in the optical...

AI Technical Summary

Problems solved by technology

When the applied DC bias voltage is increased to control the offset point of the modulation curve, the electric field will further penetrate into the resin layer 5, and as a result, the deterioration of the characteristics of the optical modulator will be further accelerated.

[0010] On the other hand, it is also possible to change the shape of the branched waveguide 1 and form the control electrode 30 by narrowing the space between the branched waveguides. However, in this case, a conversion part for changing the waveguide spacing is required, resulting in an increase in the length of the element.

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