CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2019-163416, filed on Sep. 6, 2019, the entire contents of which are incorporated herein by reference.

FIELD

The embodiments discussed herein are related to an optical modulation device and a method for manufacturing an optical modulation device.

BACKGROUND

In recent years, with a rapid increase in transmission capacity of an optical communication network for transmitting, for example, internet protocol (IP) data, communication devices that deal with the increased transmission capacity is being actively developed. An optical modulator, for example, is an important factor to achieve high-speed data transmission. There is demand for speed as high as about 400 gigabit (Gbit)/sec (64 Gbaud/sec at a symbol rate).

Recently, an optical modulator including an electro-optic organic material (polymer material) which has a higher electro-optic effect and a wider bandwidth than lithium niobate (LiNbO3) is expected as an optical modulator that enables ultra-high-speed optical communication. In particular, there is proposed an EO polymer modulator including a slot waveguide where an electro-optic polymer material (hereinafter referred to as “EO polymer”) is applied and filled between two adjacent conductive electrodes. Since EO polymer modulators have an advantage of reducing a drive voltage, they are highly anticipated as compact, low-power, ultra-high-speed optical modulators. EO polymers have significantly improved in heat resistance which is one of reliability problems, and practical use of EO polymers is being studied.[Patent Document 1] Japanese Laid-open Patent Publication No. 2005-17648[Patent Document 2] Japanese Laid-open Patent Publication No. 2015-75598[Patent Document 3] U.S. Patent Application Publication No. 2009/0022445[Patent Document 4] International Publication Pamphlet No. 2017/159815[Patent Document 5] Japanese Laid-open Patent Publication No. 2014-130196[Non-Patent Document 1] D. Rezzonico et al., “Photostabililty studies of pi-conjugated chromophores with resonant and nonresonant light excitation for long-life polymeric telecommunication devices”, J. Opt. Soc. Am. B., vol. 24, no. 9, pp. 2199-2207, 2007

However, when strong light having an optical wavelength band of, for example, 1550 nm (nanometer) passes through an EO polymer in the air (that is, when an EO polymer is in contact with oxygen), the EO polymer deteriorates (such a phenomenon is called as “photooxidation”), which may lead to the degradation of an EO polymer modulator in modulation characteristics and optical characteristics.

As a measure against this problem, it is considered to mount an EO polymer modulator on a hermetically sealed package so that the EO polymer does not come into contact with oxygen. However, in general, mounting an optical integrated device in a hermetically sealed package brings down a cost increase. In other words, an EO polymer modulator in a hermetically sealed package is connected to the outside of the hermetically sealed package by, for example, an optical fiber in which a portion penetrating the hermetically sealed package is metalized. The hermetically sealed package itself and components such as the metalized optical fiber generates additional costs. Furthermore, when an EO polymer modulator is sealed in a hermetically sealed package, an opening of the hermetically sealed package is sealed by, for example, seam welding under an atmosphere in which nitrogen is substituted. Accordingly, equipment for such additional steps is desired, which makes it difficult to reduce costs.

SUMMARY

According to an aspect of an embodiment, an optical modulation device includes a substrate, a slot waveguide formed by arranging a pair of electrodes in a groove formed on one side of the substrate and by filling the groove with an electro-optical material, a dielectric film that covers a surface of the electro-optic material filled in the slot waveguide, and a plate member that covers the slot waveguide and is bonded to the dielectric film with an adhesive resin.

The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed.

