Optical switching element

• US 7,403,678 B2
• Filed: 11/29/2006
• Issued: 07/22/2008
• Est. Priority Date: 05/12/2006
• Status: Expired due to Fees

• Current Assignee: Fuji Xerox Company Limited (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Xerox Company Limited (Fujifilm Holdings Corporation)
• Inventors: Kikuchi, Takashi, Thapliya, Roshan, Nakamura, Shigetoshi
• Primary Examiner(s): PENG, CHARLIE YU
• Application Number:
  US11/605,348
• Publication Number:
  US 20070263953A1
• Time in Patent Office: 601 Days
• Field of Search: 385 16- 23, 385/4, 385/8, 385/9, 385/15, 385 39- 42, 385129-132
• US Class Current: 385/20
• CPC Class Codes: G02F 1/217 Multimode interference type
• CPC Class Codes: G02F 1/3132 of directional coupler type
• CPC Class Codes: G02F 1/3136 of interferometric switch type
• CPC Class Codes: G02F 2202/07 poled

Abstract

An optical switching element comprising: a multimode waveguide having an electro-optical effect; one or a plurality of first single mode waveguides; a plurality of second single mode waveguides; a first electrode arranged in the vicinity of one edge on one side of the multimode waveguide; a second electrode arranged in the vicinity of the other edge on the same side of the multimode waveguide; and a third electrode arranged on the other side of the multimode waveguide, over the first electrode and the second electrode being arranged so as to be positioned on bright spots formed by multimode interference in an optical mode field generated by the light propagating through the multimode waveguide, and an optical path being switched between the first single mode waveguide and the second single mode waveguide by applying voltage between the first electrode and the third electrode and between the second electrode and the third electrode, is provided.

Claims

1. An optical switching element comprising:

a substrate;

a lower cladding layer formed on the substrate;

an upper cladding layer positioned above the lower cladding layer;

a dielectric layer formed on the surface of the upper cladding layer and having a dielectric constant greater than the upper cladding layer,

a multimode waveguide for propagating multimode light and having an electro-optical effect;

one or a plurality of first single mode waveguides connected to one end of the multimode waveguide;

a plurality of second single mode waveguides connected to the other end of the multimode waveguide;

a first electrode arranged in the vicinity of one edge on one side of the multimode waveguide;

a second electrode arranged in the vicinity of the other edge on the same side of the multimode waveguide;

a third electrode arranged on the other side of the multimode waveguide; and

a core layer sandwiched between the lower cladding layer and the upper cladding layer and formed with the multimode wave guide, the first single mode waveguide and the second single mode waveguide,

wherein;

the core layer has a refractive index greater than both of the upper cladding layer and the lower cladding layer,

the first electrode and the second electrode the first electrode and the second electrode are formed on the surface of the dielectric layer, and

the third electrode is formed between the substrate and the lower cladding layer,

the first electrode and the second electrode are arranged to be positioned respectively on at least two of a plurality of luminescent spots formed by multimode interference apart from each other in an optical mode field generated by the light propagating through the multimode waveguide, and

an optical path is switched between the first single mode waveguide and the second single mode waveguide by applying voltage between the first electrode and the third electrode and between the second electrode and the third electrode.

2. The optical switching element of claim 1, wherein a portion between the first electrode and the third electrode and a portion between the second electrode and the third electrode in the multimode waveguide are both subjected to a polarization orientation process by electric fields with the same direction to provide the electro-optical effect.

3. The optical switching element of claim 1, wherein a portion between the first electrode and the third electrode and a portion between the second electrode and the third electrode in the multimode waveguide are subjected to a polarization orientation process by electric fields with opposite directions to provide the electro-optical effect.

4. The optical switching element of claim 1, wherein the ratio W₂/W₁ of the width of the multimode waveguide with respect to the first single mode waveguide and the second single mode waveguide is 1<

W₂/W₁<

100 where W₁ is the width of the first single mode waveguide and the width of the second single mode waveguide, and W₂ is the width of the multimode waveguide.

5. The optical switching element of claim 1, wherein the multimode waveguide is a waveguide of rib structure in which the core layer projects in a rib form towards the upper cladding layer.

6. The optical switching element of claim 1, wherein the multimode waveguide is a waveguide of inverse rib structure in which the core layer projects in a rib form towards the lower cladding layer.

7. The optical switching element of claim 1, wherein a seed electrode is formed above the upper cladding layer after forming the third electrode, the lower cladding layer, the core layer and the upper cladding layer on the substrate;

and

the core layer is subjected to a polarization orientation process by applying an electric field in the thickness direction between the seed electrode and the third electrode.

8. The optical switching element of claim 1, wherein the core layer is subjected to a polarization orientation process in advance, and the upper cladding layer and the lower cladding layer are formed on both surfaces of the core layer that has been subjected to the polarization orientation process.