Substrate-type optical waveguide and substrate-type optical modulator

Patent metadata

Field	Value
Publication number	US-10267995-B2
Application number	US-201715689121-A
Country	US
Kind code	B2
Filing date	Aug 29, 2017
Priority date	Aug 30, 2016
Publication date	Apr 23, 2019
Grant date	Apr 23, 2019

Abstract

In order to reduce a high frequency loss of a substrate-type optical waveguide without facilitating, in a low frequency domain, a reflection by an entrance end of a traveling-wave electrode, the substrate-type optical waveguide includes a coplanar line, provided on an upper surface of an upper cladding, which includes (i) a traveling-wave electrode connected to a P-type semiconductor region and (ii) an earth conductor connected to an N-type semiconductor region. The traveling-wave electrode and the earth conductor are provided so that a distance D therebetween decreases as a distance from an entrance end of the traveling-wave electrode increases.

First claim

The invention claimed is:

1. A substrate-type optical waveguide, comprising:
a lower cladding;
a core, provided on an upper surface of the lower cladding, which has a P-type semiconductor region and an N-type semiconductor region;
an upper cladding which is laminated on the lower cladding so that the core is buried in the upper cladding; and
a coplanar line, provided on an upper surface of the upper cladding, which includes (i) a traveling-wave electrode connected to one of the P-type semiconductor region and the N-type semiconductor region and (ii) an earth conductor connected to the other of the P-type semiconductor region and the N-type semiconductor region,
the traveling-wave electrode and the earth conductor being provided so that a distance therebetween decreases as a distance from an entrance end of the traveling-wave electrode increases, across an entire region which is present, relative to a portion at which (i) one of the P-type semiconductor region and the N-type semiconductor region and (ii) the traveling-wave electrode are connected to each other, in a direction orthogonal to a direction in which light propagating through the core travels.

2. The substrate-type optical waveguide as set forth in claim 1 , wherein:
the distance continuously decreases as the distance from the entrance end of the traveling-wave electrode increases.

3. The substrate-type optical waveguide as set forth in claim 1 , wherein:
the distance decreases in stages as the distance from the entrance end of the traveling-wave electrode increases.

4. The substrate-type optical waveguide as set forth in claim 1 , wherein:
a terminal resistor is connected to an exit end of the traveling-wave electrode; and
a resistance of the terminal resistor matches a characteristic impedance of the substrate-type optical waveguide.

5. The substrate-type optical waveguide as set forth in claim 1 , wherein:
the core is of a rib-slab type; and
a boundary surface between the P-type semiconductor region and the N-type semiconductor region is located within a rib of the core.

6. A substrate-type optical modulator employing, as a phase modulating section, a substrate-type optical waveguide recited in claim 1 .

Assignees

• Fujikura Ltd

Inventors

• Sakamoto Shinichi
• Goi Kazuhiro
• Ishikura Norihiro

Classifications

• G02B6/126

  using polarisation effects {(G02B6/1226 takes precedence)} · CPC title

• G02B6/29325 Primary

  of the slab or planar or plate like form, i.e. confinement in a single transverse dimension only (integrated circuit planar waveguide arrangements G02B6/12007; specially adapted for lighting G02B6/0011) · CPC title

• G02B6/10

  of the optical waveguide type (G02B6/02, G02B6/24 take precedence; devices or arrangements for the control of light by electric, magnetic, electro-magnetic or acoustic means G02F1/00; transferring the modulation of modulated light G02F2/00; optical logic elements G02F3/00; optical analogue/digital converters G02F7/00) · CPC title

• G02B6/125

  Bends, branchings or intersections · CPC title

• G02F1/035 Primary

  in an optical waveguide structure · CPC title