Electro-optic modulator on rib waveguide

Abstract

An electro-optic modulator is formed on a silicon-on-insulator (SOI) rib waveguide. An optical field in the modulator is confined by using an electrically modulated microcavity. The microcavity has reflectors on each side. In one embodiment, a planar Fabry-Perot microcavity is used with deep Si/SiO 2 Bragg reflectors. Carriers may be laterally confined in the microcavity region by employing deep etched lateral trenches. The refractive index of the microcavity is varied by using the free-carrier dispersion effect produced by a p-i-n diode formed about the microcavity. In one embodiment, the modulator confines both optical field and charge carriers in a micron-size region.

1 . A method comprising:
 providing light to a silicon optical resonator;   modulating the light in the silicon optical resonator by changing the carrier concentration in the optical resonator to vary its refractive index.   
   
   
       2 . The method of the  claim 1  where the light is provided to the silicon optical resonator by an optically coupled waveguide. 
   
   
       3 . The method of  claim 1  wherein the optical resonator is a ring resonator. 
   
   
       4 . The method of  claim 1  wherein the optical resonator is a Fabry-Perot resonator. 
   
   
       5 . The method of  claim 1  wherein the optical resonator is an optical cavity. 
   
   
       6 . The method of  claim 1  and further comprising providing a p doped region and an n doped region adjacent to the optical resonator. 
   
   
       7 . The method of  claim 6  wherein the doped regions are heavily doped. 
   
   
       8 . The method of  claim 7  wherein the heavily doped regions form a p-i-n diode about the resonator. 
   
   
       9 . The method of  claim 8  wherein the heavily doped regions are positioned to selectively inject carriers into the optical resonator responsive to a forward bias voltage across the diode and to deplete carriers in the optical resonator responsive to a reverse bias voltage across the diode. 
   
   
       10 . A method comprising:
 providing light to a silicon optical resonator;   modulating the light in the silicon optical resonator by changing its refractive index.   
   
   
       11 . The method of  claim 10  wherein the refractive index is changed by varying the carrier concentration in the optical resonator. 
   
   
       12 . The method of the  claim 10  where the light is provided to the silicon optical resonator by an optically coupled waveguide. 
   
   
       13 . The method of  claim 10  wherein the optical resonator is a ring resonator. 
   
   
       14 . The method of  claim 10  wherein the optical resonator is a Fabry-Perot resonator. 
   
   
       15 . The method of  claim 10  wherein the optical resonator is an optical cavity. 
   
   
       16 . The method of  claim 10  and further comprising providing a p doped region and an n doped region adjacent to the optical resonator. 
   
   
       17 . The method of  claim 16  wherein the doped regions are heavily doped. 
   
   
       18 . The method of  claim 17  wherein the heavily doped regions form a p-i-n diode about the resonator. 
   
   
       19 . The method of  claim 18  wherein the heavily doped regions are positioned to selectively inject carriers into the optical resonator responsive to a forward bias voltage across the diode and to deplete carriers in the optical resonator responsive to a reverse bias voltage across the diode. 
   
   
       20 . A method comprising:
 providing light to a silicon waveguide;   modulating the light in the silicon waveguide by varying the refractive index of a silicon optical resonator coupled to the silicon waveguide.   
   
   
       21 . The method of  claim 20  wherein the refractive index is varied by changing the carrier concentration in the silicon optical resonator. 
   
   
       22 . The method of  claim 21  wherein varying the refractive index changes the coupling efficiency of the silicon optical waveguide to the silicon waveguide. 
   
   
       23 . A method comprising:
 providing light to a silicon waveguide; and   modulating the light in the silicon waveguide by varying the coupling efficiency of a silicon optical resonator to the silicon waveguide.