Single mode laser with large optical mode size

Abstract

A laser including a grating configured to reduce lasing threshold for a selected vertically confined mode as compared to other vertically confined modes.

1 . A laser comprising:
 a waveguide layer configured to support a fundamental vertical optical mode and at least a first higher order vertical optical mode;   a first active region at a first position with respect to the waveguide layer;   a second active region at a second position with respect to the waveguide layer;   a tunnel junction between the first and the second positions; and   a grating at a third position with respect to the waveguide layer;   wherein the first and the second positions of the first and the second active regions, and the third position of the grating are configured to make a first lasing threshold for the fundamental vertical optical mode smaller than a second lasing threshold for the first higher order vertical optical mode.   
     
     
         2 . (canceled) 
     
     
         3 . The laser of  claim 1 , wherein the grating overlaps with a peak of the fundamental vertical optical mode. 
     
     
         4 . The laser of  claim 1 , wherein the grating overlaps with a null of the first higher order optical mode. 
     
     
         5 . The laser of  claim 1 , wherein the waveguide layer is configured to support a second higher order optical mode, and the grating overlaps with a null of the first or the second higher order optical mode. 
     
     
         6 . (canceled) 
     
     
         7 . The laser of  claim 1 , wherein a first product of an overlap of the fundamental vertical optical mode with the grating and an overlap of the fundamental vertical optical mode with the first and the second active regions is greater than a second product of an overlap of the first higher order vertical optical mode with the grating and an overlap of the first higher order vertical optical mode with the first and the second active regions. 
     
     
         8 . The laser of  claim 5 , wherein a first product of an overlap of the fundamental vertical optical mode with the grating and an overlap of the fundamental vertical optical mode with the first and the second active regions is greater than a second product of an overlap of the second higher order vertical optical mode with the grating and an overlap of the second higher order vertical optical mode with the first and the second active regions. 
     
     
         9 . The laser of  claim 1 , wherein the first lasing threshold for the fundamental vertical optical mode comprises a first threshold injection current and the second lasing threshold for the first higher order vertical optical mode comprises a second threshold injection current larger than the first threshold injection current, wherein an injection current larger than the first threshold current provided to the laser generates an optical output beam, and wherein a contribution of the first higher order vertical optical modes in the output optical beam being suppressed with respect to a contribution of the fundamental vertical optical mode by at least 10 dB. 
     
     
         10 . The laser of  claim 5 , wherein the first and the second positions of the first and the second active regions, and the third position of the grating are further configured to make the first lasing threshold for the fundamental vertical optical mode smaller than a third lasing threshold for the second higher order vertical optical mode. 
     
     
         11 . The laser of  claim 10 , wherein the first lasing threshold for the fundamental vertical optical mode comprises a first threshold injection current, the second lasing threshold for the first higher order vertical optical mode comprises a second threshold injection current, the third lasing threshold for the second higher order vertical optical mode comprises a third threshold injection current, wherein the third threshold current is larger than the second threshold injection current and the second threshold current is larger than the first threshold injection current. 
     
     
         12 . The laser of  claim 11 , wherein an injection current larger than the first threshold current is provided to the laser generates an optical output beam, and wherein contributions of the first and the second higher order vertical optical modes in the output optical beam are suppressed with respect to a contribution of the fundamental vertical optical mode by at least 10 dB. 
     
     
         13 . (canceled) 
     
     
         14 . The laser of  claim 1 , wherein an optical power of light outputted from the laser is between about 10 mW and about 50 W. 
     
     
         15 . (canceled) 
     
     
         16 . The laser of  claim 1 , wherein the waveguide layer comprises a first plurality of layers comprising a first material having a first refractive index and a second plurality of layers comprising a second material having a second refractive index. 
     
     
         17 . (canceled) 
     
     
         18 . The laser of  claim 1 , wherein at least one of the first and the second active regions is within the waveguide layer. 
     
     
         19 . The laser of  claim 1 , wherein the grating is within the waveguide layer. 
     
     
         20 . The laser of  claim 1 , wherein the waveguide layer is between and vertically confined by a first region and a second region, the first region comprising a first material having a first refractive index, the second region comprising a second material having a second refractive index, the waveguide layer comprising a third material having a third refractive index, the first refractive index less than the third refractive index, and the second refractive index less than the third refractive index. 
     
     
         21 . (canceled) 
     
     
         22 . (canceled) 
     
     
         23 . (canceled) 
     
     
         24 . (canceled) 
     
     
         25 . (canceled) 
     
     
         26 . (canceled) 
     
     
         27 . The laser of  claim 1 , wherein the third position is above the second position and below the first position. 
     
     
         28 . (canceled) 
     
     
         29 . The laser of  claim 1 , wherein the third position overlaps with the tunnel junction. 
     
     
         30 . A method for designing a laser comprising a waveguide layer, at least two active regions, and a grating, the method comprising:
 providing a first position of a first active region, a second position of a second active region, a third position of the grating;   calculating at least a first vertical optical mode and at least one second vertical optical mode supported by the waveguide layer for the first and the second positions of the first and second active regions and the third position of the grating;   adjusting the positions of the active regions and the grating such that a first product of an overlap of the first vertical optical mode with the grating and an overlap of the first vertical optical mode with the first and the second active regions is greater than a second product of an overlap of the at least one second vertical optical mode with the grating and an overlap of the at least one second vertical optical mode with the first and the second active regions;   re-calculating at least the first vertical optical mode and the at least one second vertical optical mode and determining perturbations of at least the first vertical optical mode and the at least one second vertical optical mode resulting from the adjusted positions of the first and the second active regions and the grating;   calculating a difference between the first product and the second product;   adjusting, if the difference is less than a threshold value, the positions of the first and the second active regions and the grating such that the first product is larger than the second product.   
     
     
         31 . (canceled) 
     
     
         32 . (canceled) 
     
     
         33 . (canceled) 
     
     
         34 . The method of  claim 30 , further comprising providing a fourth position of a tunnel junction between the first and the second positions. 
     
     
         35 . The method of  claim 34 , calculating the first vertical optical mode and the second vertical optical mode comprises, calculating the first vertical optical mode and the second vertical optical mode for the fourth position of the tunnel junction. 
     
     
         36 . (canceled) 
     
     
         37 . (canceled) 
     
     
         38 . (canceled) 
     
     
         39 . (canceled) 
     
     
         40 . (canceled) 
     
     
         41 . A laser comprising:
 a waveguide layer configured to support a first vertical optical mode and at least a second vertical optical mode;   a first active region at a first position with respect to the waveguide layer;   a second active region at a second position with respect to the waveguide layer;   a third active region at a third position with respect to the waveguide layer;   a first tunnel junction below the first position and above the second position; a second tunnel junction below the second position and above the third position; and   a grating at a fourth position with respect to the waveguide layer;   wherein a first product of an overlap of the first vertical optical mode with the grating and an overlap of the first vertical optical mode with the first, second, and the third active regions is greater than a second product of an overlap of the second vertical optical mode with the grating and an overlap of the second vertical optical mode with the first, second, and the third active regions.   
     
     
         42 - 51 . (canceled)