Vertical electro-optically coupled switch

Abstract

An electro-optically coupled switch includes first and second waveguides which are aligned in parallel to each other, with a thin, flat layer of cross-coupling material sandwiched therebetween. A voltage source is provided to establish a strong uniform electric field that is oriented perpendicular across the entire layer of cross-coupling material between the waveguides. Incorporated with the voltage source is a switch for changing the electric field, to thereby alter the refractive index of the cross-coupling material for transferring the transmission of an optical signal from one waveguide to the other.

What is claimed is: 
     
         1 . A method for manufacturing an electro-optic coupler switch for switching and modulating an optical signal of wavelength λ, which comprises the steps of:
 positioning a thin, flat layer of cross-coupling material between a first conductive waveguide and a second conductive waveguide to create a waveguide stack, wherein the first and second waveguides each has a length L and a width W, and wherein the layer of cross-coupling material has a depth d; 
 adding a first electrode to the waveguide stack with the first waveguide on one side of the layer of cross-coupling material and adding a second electrode with the second waveguide opposite the cross-coupling material from the first electrode; 
 orienting the first waveguide, the second waveguide, the layer of cross-coupling material, the first electrode and the second electrode in a colinear alignment; and 
 connecting a voltage source to the first and second electrodes to selectively establish an electric field E through the cross-coupling material between the first waveguide and the second waveguide, wherein E is uniform and is oriented perpendicular across the layer of cross-coupling material in the waveguide stack, and wherein the voltage source imposes a switching voltage V π  on the cross-coupling material to change a refractive index of the cross-coupling material to selectively transfer an optical signal λ between the first and second waveguides. 
 
     
     
         2 . The method recited in  claim 1  wherein the cross-coupling material is made of a polymer and the first and second waveguides are made of a conducting semiconductor material. 
     
     
         3 . The method recited in  claim 1  wherein the first waveguide is made of a P doped conductive material, and the second waveguide is made of an N doped conductive material, and the cross-coupling material is made of a multiple-quantum-well semiconductor. 
     
     
         4 . The method recited in  claim 3  wherein the first electrode is a P +  doped layer positioned in electrical contact between the P doped waveguide and the voltage source, and the second electrode is an N +  doped layer positioned in electrical contact between the N doped waveguide and the voltage source. 
     
     
         5 . The method recited in  claim 1  wherein the first waveguide and the second waveguide each have an upstream end and a downstream end, and the method further comprises the steps of:
 establishing a first input port at the upstream end of the first waveguide, and a first output port at the downstream end of the first waveguide; and 
 establishing a second output port at the downstream end of the second waveguide, wherein an incoming optical signal λ is received at the first input port and is selectively routed to the second output port by the switching voltage V π . 
 
     
     
         6 . The method recited in  claim 1  wherein the first waveguide has a refractive index n 1  and the second waveguide has a refractive index n 2  resembling n 1  (n 1 ≈n 2 ). 
     
     
         7 . A method for manufacturing an electric-optic coupler switch with electrical components in a colinear alignment which comprises the steps of:
 orienting electrical components of the switch in a colinear aligned sequence, wherein the electrical components include,
 i) a first electrode, 
 ii) a first conductive waveguide having a refractive index n 1 , 
 iii) a layer of cross-coupling material having a refractive index n c  and a depth d, 
 iv) a second conductive waveguide having a refractive index n 2 , wherein n 1 ≈n 2 , and 
 v) a second electrode: and 
   connecting a voltage source to the first and second electrodes to selectively establish an electric field E through the cross-coupling material between the first waveguide and the second waveguide, wherein E is uniform and is oriented perpendicular across the layer of cross-coupling material in the waveguide stack and parallel to the alignment of the electrical components, and wherein the voltage source imposes a switching voltage V π  on the cross-coupling material to change the refractive index n c  for selectively transferring an optical signal λ between the first and second waveguides,   
     
     
         8 . The method recited in  claim 7  wherein the cross-coupling material is made of a polymer and the first and second waveguides are made of a conductive semiconductor material. 
     
     
         9 . The method recited in  claim 7  wherein the cross-coupling material is a polymer, the first waveguide and the second waveguide are N doped and the first electrode is an N +  doped layer positioned in electrical contact between the first N doped waveguide and the voltage source, and the second electrode is an N +  doped layer positioned in electrical contact between the second N doped waveguide and the voltage source. 
     
     
         10 . The method recited in  claim 7  wherein the cross-coupling material is a multiple-quantum-well. 
     
     
         11 . The method recited in  claim 10  wherein the first waveguide is P doped and the second waveguide is N doped and the first electrode is a P +  doped layer positioned in electrical contact between the P doped waveguide and the voltage source, and the second electrode is an N +  doped layer positioned in electrical contact between the N doped waveguide and the voltage source.