Transmission type high-absorption optical modulator and method of manufacturing the same

Abstract

Provided are a transmission type high-absorption optical modulator and a method of manufacturing the transmission type high-absorption optical modulator. The optical modulator includes: a substrate; a lower distributed Bragg reflector (DBR) layer on the substrate; a lower clad layer on the lower DBR layer; an active layer that is formed on the lower clad layer and includes a quantum well layer and a quantum barrier layer; an upper clad layer on the active layer; an upper DBR layer on the upper clad layer; and a doping layer that supplies carriers to the quantum well layer. In the optical modulator, the doping layer may be included in the quantum barrier layer or in at least one of the upper and lower clad layers.

What is claimed is: 
     
         1 . A transmission type high-absorption optical modulator, comprising:
 a substrate;   a lower distributed Bragg reflector (DBR) layer disposed on the substrate;   a lower clad layer disposed on the lower DBR layer;   an active layer disposed on the lower clad layer, wherein the active layer comprises a quantum well layer and a quantum barrier layer;   an upper clad layer disposed on the active layer;   an upper DBR layer disposed on the upper clad layer; and   a doping layer that supplies carriers to the quantum well layer,   wherein the doping layer is disposed at an outside of the active layer.   
     
     
         2 . The transmission type high-absorption optical modulator of  claim 1 , wherein at least one of the upper clad layer and the lower clad layer comprises the doping layer. 
     
     
         3 . The transmission type high-absorption optical modulator of  claim 1 , wherein the active layer is a multi-quantum well layer comprising a plurality of quantum well layers and a plurality of quantum barrier layers and comprising one of a rectangular quantum well, a 3-asymmetric-coupled quantum well, and a 3-coupled quantum well;
 wherein the 3-coupled quantum well is a quantum well in which an energy level between sub-quantum barriers is equal to an energy level between a quantum barrier and the sub-quantum barriers and the 3-asymmetric-coupled quantum well is a quantum well in which the energy level between the sub-quantum barriers is lower than the energy level between the quantum barrier and the sub-quantum barriers.   
     
     
         4 . The transmission type high-absorption optical modulator of  claim 1 , wherein the doping layer has a thickness (t) in a range of 0<t<1.8 nm and does not contact the quantum well layer. 
     
     
         5 . The transmission type high-absorption optical modulator of  claim 1 , wherein a doping density of the doping layer is from about 5×10 15 /cm 3  to about 1×10 20 /cm 3 . 
     
     
         6 . The transmission type high-absorption optical modulator of  claim 1 , wherein the doping layer is doped with a p-type dopant. 
     
     
         7 . The transmission type high-absorption optical modulator of  claim 1 , wherein the doping layer is doped with an n-type dopant. 
     
     
         8 . A method of manufacturing a transmission type high-absorption optical modulator, the method comprising:
 forming a lower distributed Bragg reflector (DBR) layer on a substrate;   forming a lower clad layer on the lower DBR layer;   forming, on the lower clad layer, an active layer comprising a quantum well layer and a quantum barrier layer;   forming an upper clad layer on the active layer;   forming an upper DBR layer on the upper clad layer; and   forming a doping layer that supplies carriers to the quantum well layer, wherein the doping layer is disposed at an outside of the active layer.   
     
     
         9 . The method of  claim 8 , wherein at least one of the forming the lower clad layer and the forming the upper clad layer comprises forming the doping layer therein. 
     
     
         10 . The method of  claim 8 , wherein the doping layer is a layer doped with a P-type dopant. 
     
     
         11 . The method of  claim 8 , wherein the doping layer is a layer doped with an N-type dopant. 
     
     
         12 . The method of  claim 8 , wherein the active layer is a multi-quantum well layer including a plurality of quantum well layers and a plurality of quantum barrier layers and comprising one of a rectangular quantum well, a 3-asymmetric-coupled quantum well, and a 3-coupled quantum well. 
     
     
         13 . The method of  claim 8 , wherein the doping layer has a thickness (t) in a range of 0<t<1.8 nm and does not contact the quantum well layer. 
     
     
         14 . The method of  claim 8 , wherein a doping density of the doping layer is from about 5×10 15 /cm 3  to about 1×10 20 /cm 3 .