Vertical cavity surface emitting laser, vertical cavity surface emitting laser device, optical transmission device, and information processing apparatus

Abstract

A vertical cavity surface emitting laser that includes: a substrate; a first semiconductor multilayer reflector; an active region; a second semiconductor multilayer reflector; a columnar structure formed from the second semiconductor multilayer reflector to the first semiconductor multilayer reflector; a current narrowing layer formed inside of the columnar structure and having a conductive region surrounded by an oxidization region; a first electrode formed at a top of the columnar structure, electrically connected to the second semiconductor multilayer reflector and defining a beam window; a first insulating film comprised of a material with a first refractive index and formed on the first electrode to cover the beam window; and a second insulating film comprised of a material with a second refractive index and formed on the first insulating film, of which a radius is smaller than a radius of the conductive region.

1 . A vertical cavity surface emitting laser comprising:
 a substrate;   a first semiconductor multilayer reflector of a first conductive type formed on the substrate;   an active region formed on the first semiconductor multilayer reflector;   a second semiconductor multilayer reflector of a second conductive type formed on the active region;   a columnar structure that is formed from the second semiconductor multilayer reflector to the first semiconductor multilayer reflector on the substrate;   a current narrowing layer that is formed inside of the columnar structure, and has a conductive region surrounded by an oxidization region selectively oxidized;   a first electrode that is annular, is formed at a top of the columnar structure, is electrically connected to the second semiconductor multilayer reflector, and defines a beam window;   a first insulating film that is comprised of a material which has a first refractive index capable of transmitting an oscillation wavelength, and formed on the first electrode to cover the beam window; and   a second insulating film that is circular, is comprised of a material which has a second refractive index that is able to transmit an oscillation wavelength and greater than the first refractive index, and is formed on the first insulating film, and of which a radius is smaller than a radius of the conductive region.   
     
     
         2 . The vertical cavity surface emitting laser according to  claim 1 , wherein a third refractive index to an oscillation wavelength of a semiconductor layer which composes the second semiconductor multilayer reflector is greater than the second refractive index. 
     
     
         3 . The vertical cavity surface emitting laser according to  claim 1 , further comprising a third insulating layer that covers a sidewall and a part of a top of the columnar structure, wherein an opening to connect to the first electrode is formed between the third insulating film and the first insulating film. 
     
     
         4 . The vertical cavity surface emitting laser according to  claim 3 , wherein the third insulating film is comprised of a same material as that of the second insulating film. 
     
     
         5 . The vertical cavity surface emitting laser according to  claim 1 , wherein the radius of the conductive region is at least 5 μm. 
     
     
         6 . A fabrication method of a vertical cavity surface emitting laser having a columnar structure on a substrate, the fabrication method comprising:
 stacking a semiconductor layer including a first semiconductor multilayer reflector of a first conductive type, an active region, a current narrowing layer which is conductive, a second semiconductor multilayer reflector of a second conductive type on the substrate;   forming a first electrode which is annular and defines a beam window on the second semiconductor multilayer reflector;   forming a first insulating film that is comprised of a material having a first refractive index to an oscillation wavelength on the first electrode to cover a beam window of the first electrode;   forming the columnar structure including the first electrode and the first insulating film at a top on the substrate by etching the semiconductor layer from the second semiconductor multilayer reflector to the first semiconductor multilayer reflector;   forming an oxidization region and a conductive region surrounded by the oxidization region inside of a current narrowing layer by oxidizing the current narrowing layer inside of the columnar structure selectively;   forming a second insulating film that is comprised of a material having a second refractive index that is greater than the first refractive index on whole area of the substrate including the columnar structure; and   forming a pattern of the second insulating film that corresponds to a center of the conductive region and is smaller than a radius of the conductive region, and an opening that exposes the first electrode on the first insulating film by removing the second insulating film at the top of the columnar structure selectively.   
     
     
         7 . The fabrication method according to  claim 7  wherein a third refractive index to an oscillation wavelength of a semiconductor layer composing the second semiconductor multilayer reflector is greater than the second refractive index. 
     
     
         8 . A vertical cavity surface emitting laser device comprising:
 a vertical cavity surface emitting laser including:
 a substrate; 
 a first semiconductor multilayer reflector of a first conductive type formed on the substrate; 
 an active region formed on the first semiconductor multilayer reflector; 
 a second semiconductor multilayer reflector of a second conductive type formed on the active region; 
 a columnar structure that is formed from the second semiconductor multilayer reflector to the first semiconductor multilayer reflector on the substrate; 
 a current narrowing layer that is formed inside of the columnar structure, and has a conductive region surrounded by an oxidization region selectively oxidized; 
 a first electrode that is annular, is formed at a top of the columnar structure, is electrically connected to the second semiconductor multilayer reflector, and defines a beam window; 
 a first insulating film that is comprised of a material which has a first refractive index capable of transmitting an oscillation wavelength, and formed on the first electrode to cover the beam window; and 
 a second insulating film that is circular, is comprised of a material which has a second refractive index that is able to transmit an oscillation wavelength and greater than the first refractive index, and is formed on the first insulating film, and of which a radius is smaller than a radius of the conductive region; and 
   an optical member that receives a beam from the vertical cavity surface emitting laser.   
     
     
         9 . An optical transmission device comprising:
 a vertical cavity surface emitting laser device that comprises:
 a vertical cavity surface emitting laser that includes:
 a substrate; 
 a first semiconductor multilayer reflector of a first conductive type formed on the substrate; 
 an active region formed on the first semiconductor multilayer reflector; 
 a second semiconductor multilayer reflector of a second conductive type formed on the active region; 
 a columnar structure that is formed from the second semiconductor multilayer reflector to the first semiconductor multilayer reflector on the substrate; 
 a current narrowing layer that is formed inside of the columnar structure, and has a conductive region surrounded by an oxidization region selectively oxidized; 
 a first electrode that is annular, is formed at a top of the columnar structure, is electrically connected to the second semiconductor multilayer reflector, and defines a beam window; 
 a first insulating film that is comprised of a material which has a first refractive index capable of transmitting an oscillation wavelength, and formed on the first electrode to cover the beam window; and 
 a second insulating film that is circular, is comprised of a material which has a second refractive index that is able to transmit an oscillation wavelength and greater than the first refractive index, and is formed on the first insulating film, and of which a radius is smaller than a radius of the conductive region; and 
 
 an optical member that receives a beam from the vertical cavity surface emitting laser; and 
   a transmission unit that transmits a laser beam emitted from the vertical cavity surface emitting laser device through an optical medium.   
     
     
         10 . An information processing apparatus comprising:
 a vertical cavity surface emitting laser that includes:
 a substrate; 
 a first semiconductor multilayer reflector of a first conductive type formed on the substrate; 
 an active region formed on the first semiconductor multilayer reflector; 
 a second semiconductor multilayer reflector of a second conductive type formed on the active region; 
 a columnar structure that is formed from the second semiconductor multilayer reflector to the first semiconductor multilayer reflector on the substrate; 
 a current narrowing layer that is formed inside of the columnar structure, and has a conductive region surrounded by an oxidization region selectively oxidized; 
 a first electrode that is annular, is formed at a top of the columnar structure, is electrically connected to the second semiconductor multilayer reflector, and defines a beam window; 
 a first insulating film that is comprised of a material which has a first refractive index capable of transmitting an oscillation wavelength, and formed on the first electrode to cover the beam window; and 
 a second insulating film that is circular, is comprised of a material which has a second refractive index that is able to transmit an oscillation wavelength and greater than the first refractive index, and is formed on the first insulating film, and of which a radius is smaller than a radius of the conductive region; 
   a focusing unit that focuses a laser beam emitted from the vertical cavity surface emitting laser onto a record medium; and   a structure which scans the laser beam focused by the focusing unit on the record medium.