Oxide capacitor electro-optical phase shifter

Abstract

An electro-optical phase shifter to be located in an optical waveguide may include a rib of a semiconductor material extending along a length of the optical waveguide and a control structure configured to modify a concentration of carriers in the rib according to a control voltage present between first and second control terminals of the phase shifter. The control structure may include a conductive layer covering a portion of the rib and electrically connected to a first of the control terminals. An insulating layer may be configured to electrically isolate the conductive layer from the rib.

1 - 12 . (canceled) 
     
     
         13 . A method of making an electro-optical phase shifter associated with an optical waveguide, the method comprising:
 forming a control structure to modify a concentration of carriers in a rib according to a control voltage present between first and second control terminals, the rib comprising a semiconductor material along a length of the optical waveguide, forming the control structure comprising
 forming at least one conductive layer to cover at least a portion of the rib and be electrically coupled to the first control terminal, and 
 forming at least one insulating layer coupled to and between the rib and the at least one conductive layer to electrically isolate the at least one conductive layer from the rib, the at least one conductive layer and at least one insulating layer being coextensive. 
   
     
     
         14 . The method according to  claim 13 , wherein forming the control structure comprises forming at least one first wing comprising a semiconductor material having a homogeneous conductivity type adjacent a first face of the rib. 
     
     
         15 . The method according to  claim 14 , wherein the at least one insulating layer isolates the at least one first wing from the rib; the at least one conductive layer being defined by a region of the at least one first wing having a doping level greater than a doping level of the rib; and wherein the first control terminal is in electrical contact with a distal end of the at least one first wing. 
     
     
         16 . The method according to  claim 14 , wherein forming the control structure further comprises forming at least one second wing comprising a semiconductor material having a homogeneous conductivity type adjacent a second face of the rib opposite the first face. 
     
     
         17 . The method according to  claim 16 , wherein forming the at least one insulating layer comprises forming first and second insulating layers respectively to isolate at least one first and second wings from the rib; and wherein forming the at least one conductive layer comprises forming first and second conductive layers defined by respective first and second areas of the at least one first and second wings having a doping level greater than the doping level of the rib. 
     
     
         18 . The method according to  claim 13 , further comprising forming a plurality of wings comprising a semiconductor material of same conductivity type as the rib and extending outwardly from both sides of the rib. 
     
     
         19 . The method according to  claim 18 , wherein the at least one conductive layer is formed to cover at least a portion of the rib projecting from a plane of the plurality of wings. 
     
     
         20 . The method according to  claim 18 , wherein the at least one conductive layer comprises polysilicon; wherein forming the control structure comprises, on one of the plurality of wings, forming a polysilicon track coupling the at least one conductive layer to the first control terminal; wherein the first control terminal is located on a distal end of the one of the plurality of wings; and wherein the at least one insulating layer is formed to have an extension to isolate the first control terminal and the polysilicon track from the one of the plurality of wings. 
     
     
         21 . The method according to  claim 18 , wherein forming the control structure comprises:
 forming, on a second one of the plurality of wings, a configuration symmetrical to a first one of the plurality of wings;   forming, in a plane offset from that of the first and second one of the plurality of wings, third and fourth ones of the plurality wings comprising a semiconductor material of a same conductivity type as the rib and extending outwardly from both sides of the rib, wherein the at least one conductive layer is formed to cover at least a portion of the rib projecting from the plane of the third and fourth ones of the plurality of wings; and   forming at least one electrical contact on a distal end of each of the third and fourth ones of the plurality of wings.   
     
     
         22 . The method according to  claim 13  comprising forming the at least one conductive layer and at least one insulating layer to have a same height as the rib. 
     
     
         23 . A method of making an electro-optical phase shifter comprising:
 forming a control structure to modify a concentration of carriers in a rib according to a control voltage by at least
 forming at least one conductive layer to cover at least a portion of the rib, and 
 forming at least one insulating layer coupled to and between the rib and the at least one conductive layer to electrically isolate the at least one conductive layer from the rib, the at least one conductive layer and at least one insulating layer being coextensive. 
   
     
     
         24 . The method according to  claim 23 , wherein forming the control structure comprises forming at least one first wing comprising a semiconductor material having a homogeneous conductivity type adjacent a first face of the rib. 
     
     
         25 . The method according to  claim 24 , wherein the at least one insulating layer isolates the at least one first wing from the rib; the at least one conductive layer being defined by a region of the at least one first wing having a doping level greater than a doping level of the rib; and wherein a first control terminal is in electrical contact with a distal end of the at least one first wing. 
     
     
         26 . The method according to  claim 24 , wherein forming the control structure further comprises forming at least one second wing comprising a semiconductor material having a homogeneous conductivity type adjacent a second face of the rib opposite the first face. 
     
     
         27 . The method according to  claim 26 , wherein forming the at least one insulating layer comprises forming first and second insulating layers respectively to isolate at least one first and second wings from the rib; and wherein forming the at least one conductive layer comprises forming first and second conductive layers defined by respective first and second areas of the at least one first and second wings having a doping level greater than the doping level of the rib. 
     
     
         28 . The method according to  claim 23 , further comprising forming a plurality of wings comprising a semiconductor material of same conductivity type as the rib and extending outwardly from both sides of the rib. 
     
     
         29 . The method according to  claim 28 , wherein the at least one conductive layer is formed to cover at least a portion of the rib projecting from a plane of the plurality of wings. 
     
     
         30 . The method according to  claim 28 , wherein the at least one conductive layer comprises polysilicon; wherein forming the control structure comprises, on one of the plurality of wings, forming a polysilicon track coupling the at least one conductive layer to a first control terminal; wherein the first control terminal is located on a distal end of the one of the plurality of wings; and wherein the at least one insulating layer is formed to have an extension to isolate the first control terminal and the polysilicon track from the one of the plurality of wings. 
     
     
         31 . The method according to  claim 28 , wherein forming the control structure comprises:
 forming, on a second one of the plurality of wings, a configuration symmetrical to a first one of the plurality of wings;   forming, in a plane offset from that of the first and second one of the plurality of wings, third and fourth ones of the plurality wings comprising a semiconductor material of a same conductivity type as the rib and extending outwardly from both sides of the rib, wherein the at least one conductive layer is formed to cover at least a portion of the rib projecting from the plane of the third and fourth ones of the plurality of wings; and   forming at least one electrical contact on a distal end of each of the third and fourth ones of the plurality of wings.   
     
     
         32 . A method of making an electro-optical phase shifter comprising:
 forming a control structure to modify a concentration of carriers in a rib according to a control voltage by at least   forming at least one conductive layer to cover at least a portion of the rib, and   forming at least one insulating layer coupled to and between the rib and the at least one conductive layer to electrically isolate the at least one conductive layer from the rib, the at least one conductive layer and at least one insulating layer having a same height as the rib.   
     
     
         33 . The method according to  claim 32 , wherein forming the control structure comprises forming at least one first wing comprising a semiconductor material having a homogeneous conductivity type adjacent a first face of the rib. 
     
     
         34 . The method according to  claim 33 , wherein the at least one insulating layer isolates the at least one first wing from the rib; the at least one conductive layer being defined by a region of the at least one first wing having a doping level greater than a doping level of the rib; and wherein a first control terminal is in electrical contact with a distal end of the at least one first wing. 
     
     
         35 . The method according to  claim 33 , wherein forming the control structure further comprises forming at least one second wing comprising a semiconductor material having a homogeneous conductivity type adjacent a second face of the rib opposite the first face.