Planar optical waveguide, modulator, variable coupler and switch

A passive planar three dimensional optical waveguide that has a planar structure comprising,

• a semiconductor substrate of one conductivity type of refractive index n.sub.1,
• an epitaxial layer of the same conductivity type on said substrate and of refractive index n.sub.2,
• said epitaxial layer having at least two spaced doped stripes of opposite conductivity type and of refractive index n.sub.3, in but not entirely through said layer,
• a medium in contact with the surface of said epitaxial layer whose refraction is n.sub.4,
• the magnitude of the refraction indices being n.sub.2 >n.sub.1 ;
• n.sub.2 >n.sub.3 ;
• n.sub.1, n.sub.2, and n.sub.3, each >n.sub.4,
• the n.sub.2 region of said layer between said spaced stripes forming said optical waveguide,
• said medium being an air medium,
• and said substrate and epitaxial layer are n-type GaAs, and said stripes in said epitaxial layer are p-type GaAs.

A passive three dimensional optical waveguide that has a planar structure comprising:

• a first doped semiconductor substrate of n-type conductivity of refractive index n.sub.1,
• an epitaxial layer of a second semiconductor of the n-type conductivity on said substrate and of refractive index n.sub.2, the carrier concentration of said epitaxial layer being less than that of the substrate,
• at least two spaced stripes of a third doped semiconductor of p-type conductivity and of refractive index n.sub.3 in but not entirely through said epitaxial layer, the carrier concentration of said third semiconductor being greater than the carrier concentration of said epitaxial layer,
• a medium in contact with the surface of said epitaxial layer and stripes whose refraction index is n.sub.4,
• the magnitude of the refraction indices being n.sub.2 >n.sub.1 ;
• n.sub.2 >n.sub.3 ;
• n.sub.1, n.sub.2, and n.sub.3, each >n.sub.4,
• the n.sub.2 region of said layer between said spaced stripes forming said optical waveguide.

A passive three dimensional optical waveguide switch that has a planar structure comprising:

• a plurality of optically connected said switches, each switch comprising a semiconductor substrate of one conductivity type and of refractive index n.sub.1,
• an epitaxial layer of the same conductivity type on said substrate and of refractive index n.sub.2,
• said epitaxial layer having three spaced doped stripes of opposite conductivity type and of refractive index n.sub.3 in but not entirely through said layer, to form two spaced optical guides in said n.sub.2 epitaxial layer between said stripes,
• the surface of said layer and stripes being in contact with a medium of refraction index n.sub.4,
• the magnitude of said refractive indices being related to each other by the relationships n.sub.2 >n.sub.1 ;
• n.sub.2 >n.sub.3 ;
• n.sub.1, n.sub.2, and n.sub.3, each >n.sub.4,
• means for making electrical contact to the bottom of said substrate,
• an electrode film extending along and on at least one outside stripe of said stripes,
• means for making electrical contact to at least one of the outside stripes,
• the length of said stripes being such as to couple at least a portion of the optical energy from one guide into the other guide in the absence of a reverse bias voltage across one stripe, and
• means for applying a reverse bias voltage across at least one of said outside stripes to change the index of refraction under said stripe and in the adjacent guide to change the amount of energy coupled to the other guide,
• each switch being on the same substrate and epitaxial layer and having their optical guides aligned with each other,
• the stripes of each switch being separated from the stripes of the adjacent switch.

A passive three dimensional optical waveguide switch that has a planar structure comprising:

• a doped semiconductor substrate of refractive index n.sub.1,
• an epitaxial layer of the same semiconductor and of the same conductivity type on said substrate and of refractive index n.sub.2
• said epitaxial layer having three spaced doped stripes of said semiconductor of opposite conductivity type and of refractive index n.sub.3 in but not entirely through said layer to form two spaced optical guides in said epitaxial layer between said stripes in said n.sub.2 region of the epitaxial layer,
• the surface of said layer and stripes being in contact with a medium of refraction index n.sub.4,
• the magnitude of said refractive indices being related to each other by the relationships n.sub.2 >n.sub.1 ;
• n.sub.2 >n.sub.3 ;
• n.sub.1, n.sub.2, and n.sub.3, each >n.sub.4 ;
• means for making electrical contact to the bottom of said substrate,
• an electrode film extending along and on at least one outside stripe of said stripes,
• means for making electrical contact to the film on at least one of the outside stripes,
• the length of said stripes being of such length to couple substantially all the optical energy from one guide into the other guide at zero bias,
• means for applying a reverse bias voltage across the junction of one of said outside stripes to change the index of refraction under said stripe and in the adjacent guide to change the amount of energy coupled to the other guide.

A passive three dimensional optical waveguide switch that has a planar structure comprising:

• a substrate of a first doped semiconductor of one conductivity type of refractive index n.sub.1,
• an epitaxial layer of a second semiconductor of the same one conductivity type on said substrate and of refractive index n.sub.2,
• three spaced doped stripes of a third semiconductor of opposite conductivity type and of refractive index n.sub.3 in but not entirely through said epitaxial layer, to form two spaced optical guides in said n.sub.2 epitaxial layer between said stripes,
• the surface of said layer and stripes being in contact with a medium of refraction index n.sub.4,
• the magnitude of said refractive indices being related to each other by the relationships n.sub.2 >n.sub.1 ;
• n.sub.2 >n.sub.3 ;
• n.sub.1, n.sub.2, and n.sub.3, each >n.sub.4 ;
• means for making electrical contact to the bottom of said substrate,
• an electrode film extending along and on at least one outside stripe of said stripes;
• means for making electrical contact to at least one of said outside stripes,
• the length of said stripes being of such length to couple substantially all the optical energy from one guide into the other guide at zero bias,
• means for applying a reversed bias voltage across the junction of one of said outside stripes to change the index of refraction under said stripe and in the adjacent guide to change the amount of energy coupled to the other guide.