Sumitomo Osaka Cement Co., Ltd.

Yasuyuki Miyama

Hirotoshi Nagata

Toshihiro Sakamoto

Takashi Shinriki

Tohru Sugamata

Ryo Shimizu

Yoshihiro Hashimoto

Futoshi Yamamoto

Tetsuya Fujino

A first film () is formed between a substrate () and a signal electrode (); ground electrodes () and () which constitute an optical waveguide device (), and a second film () is formed between the substrate () and a signal electrode (); ground electrodes () and (). An optical phase modulator (A) is composed of the substrate (), an optical waveguide (), the signal electrode (), the ground electrodes () and (), and the first film (). An optical intensity modulator (B) is composed of the substrate (), the optical waveguide (), the signal electrode (), the ground electrodes () and (), and the second film (). The optical waveguide device () is composed of the optical phase modulator (A) and the optical intensity modulator (B), which are integrated monolithically.

Optical waveguide device

There is provided a high performance optical waveguide type optical modulator with excellent long term reliability, in which contamination of the buffer layer in a forming process of a signal field adjustment region on the buffer layer by a lift-off method or an etching method, is prevented and DC drift thus suppressed. The optical waveguide type optical modulatorcomprises a substratehaving an electro-optic effect, optical waveguidesformed on the surface of this substratea traveling-wave type signal electrodeand ground electrodeswhich are provided on the substrateand control a lightwave, and a buffer layerprovided between the electrodesand the optical waveguidesand furthermore, a dielectric layeris provided on the entire surface of the buffer layeron the side of the electrodesand a signal field adjustment regionwhich has a wider width than that of the traveling-wave type signal electrodeand is made of a material with a higher refractive index than that of the dielectric layeris formed between the dielectric layerand the traveling-wave type signal electrode

Optical waveguide type optical modulator and production method therefor

An optical waveguide is formed on a substrate made of a material with an electro-optic effect. Then, an intermediate layer is fabricated, on the main surface of the substrate, by a dielectric material selected from the group consisting of AOx, B Oy, COz (A: divalent element, B: trivalent element, C: quadrivalent element, 0<x<1, 0<y<3, 0<z<2, O: oxygen). Then, a metal-cladding type optical polarizer is fabricated on the intermediate layer and the optical waveguide. A buffer layer is formed and partially removed by non-reactive dry-etching to form a first opening. Subsequently, a metal-cladding type optical polarizer is fabricated inside the first opening, and a signal electrode and a ground electrode, constituting a modulation electrode, are fabricated on the buffer layer.

Optical waveguide device and method for forming optical waveguide device

An electro-optic element comprising a ferroelectric substrate comprising a single crystal having an electro-optic effect, in which an optical waveguide is formed by thermal diffusion of titanium in a main face, and in which an axis in which said electro-optic effect is induced is parallel to said main face; a heat treated buffer layer provided on said ferroelectric substrate on a side in which said optical waveguides are formed; electrodes provided on a part of the buffer layer; and a protective film for preventing contamination of the buffer layer provided on at least the region of the buffer layer on which the electrodes are not formed.

Electro-optical element having protective film on top and side surfaces of buffer layer

An optical waveguide modulator has a substrate made of a material with an electrooptic effect, an optical waveguide to guide a lightwave a travelling wave-type signal electrode and the ground electrodes to control the lightwave. Moreover, it has a buffer layer at least a part thereof being embedded in the superficial layer of the substrate having a larger width &ldquo;W&rdquo; than a width &ldquo;&ohgr;&rdquo; of the travelling wave-type signal electrode only under the signal electrode and its nearby part.

Light modulator of waveguide type

An optical modulator including a substrate made of lithium niobate having an electrooptical effect, first and second optical waveguides formed in the substrate by effecting a thermal diffusion of titanium into a surface of the substrate, a buffer layer formed on the surface of the substrate, a hot electrode provided on the buffer layer and having a width W.sub.e not larger than a width W.sub.f of the optical waveguide, first and second ground electrodes provided on the buffer layer such that these ground electrodes are symmetrical with respect to the hot electrode, and an electric field adjusting region having a width not smaller than that of the hot electrode is provided between the buffer layer and the hot electrode. First and second ground side electric field adjusting main- and sub-regions may be provided between the buffer layer and the first and second ground electrodes, respectively. An interaction between an electric field generated by applied microwave and lightwave propagating along the optical waveguides can be enhanced, and thus a driving voltage can be decreased.

Growing community of inventors

Funabashi, Japan

Yasuyuki Miyama