Semiconductor optical device
Provided herein is a semiconductor optical device, including a waveguide including lattices buried therein and having a buried hetero (BH) structure formed in an optical oscillation region in which single mode light is oscillated, a waveguide having a deep ridge structure formed in an optical modulation region, and a passive waveguide formed in a mode transition region interposed between the optical oscillation region and the optical modulation region, formed as a connecting structure of the waveguide having the BH structure extending from the optical oscillation region and the waveguide having the deep ridge structure extending from the optical modulation region, and inducing evanescent optical coupling, wherein a width of the waveguide having the BH structure in the mode transition region is smaller than a width of the waveguide having the deep ridge structure in the optical modulation region.
1. A semiconductor optical device, comprising:
a BH waveguide including lattices buried therein and having a buried hetero (BH) structure formed in an optical oscillation region in which single mode light is oscillated;
a deep ridge waveguide having a deep ridge structure formed in an optical modulation region; and
a passive waveguide formed in a mode transition region interposed between the optical oscillation region and the optical modulation region, formed as a connecting structure of the BH waveguide extending from the optical oscillation region and the deep ridge waveguide extending from the optical modulation region, and inducing evanescent optical coupling,
wherein a width of the BH waveguide in the mode transition region is smaller than a width of the deep ridge waveguide in the optical modulation region.
2. The semiconductor optical device of claim 1 , wherein in the mode transition region, the BH waveguide comprises:
a first portion extending from the optical oscillation region and having a uniform width;
a second portion extending from the first portion and having a width decreasing toward the optical modulation region; and
a third portion extending from the second portion so as to be connected to the deep ridge waveguide extending from the optical modulation region and having a width increasing toward the deep ridge waveguide.
3. The semiconductor optical device of claim 2 , wherein the single mode light passes through the second portion to have a smaller optical spot size, passes the third portion, and forms the evanescent optical coupling in the deep ridge waveguide.
4. The semiconductor optical device of claim 1 , wherein each of the BH waveguide and the deep ridge waveguide comprises:
a core pattern extending along the optical oscillation region, the mode transition region, and the optical modulation region;
a lower clad pattern formed under the core pattern; and
an upper clad pattern formed over the core pattern.
5. The semiconductor optical device of claim 4 , wherein the core pattern comprises:
a first core portion having a multiple quantum well structure arranged in the optical oscillation region;
a second core portion butt-coupled to the first core portion and having a bulk structure arranged in the mode transition region; and
a third core portion butt-coupled to the second core portion and having a multiple quantum well structure arranged in the optical modulation region.
6. The semiconductor optical device of claim 5 , wherein the second core portion includes a first taper structure decreasing in width toward the optical oscillation region, and
the upper clad pattern includes a second taper structure having a width decreasing toward the optical modulation region and arranged in the mode transition region so as to be closer to the optical oscillation region than the first taper structure.
7. The semiconductor optical device of claim 4 , wherein the core pattern includes InGaAsP.
8. The semiconductor optical device of claim 4 , further comprising a current interrupting structure surrounding a portion of the core pattern forming the BH waveguide.
9. The semiconductor optical device of claim 8 , wherein the current interrupting structure comprises:
the upper clad pattern;
a first current interrupting clad pattern arranged between the upper clad pattern and the lower clad pattern and formed along a shape of an upper surface of the lower clad pattern and a shape of a sidewall of the core pattern; and
a second current interrupting clad pattern arranged between the first current interrupting clad pattern and the upper clad pattern.
10. The semiconductor optical device of claim 9 , wherein the first current interrupting clad pattern, the second current interrupting clad pattern, and the upper clad pattern form the current interrupting structure having a PNP structure.
11. The semiconductor optical device of claim 1 , wherein the deep ridge waveguide is patterned to be horizontally inclined at an optical output.
12. The semiconductor optical device of claim 1 , wherein a distributed feedback laser diode is formed in the optical oscillation region, and
an electro-absorption modulator is formed in the optical modulation region.