Tunable laser device and method for manufacturing the same

1. A tunable laser device comprising:

a lower clad layer;

first to third quantum well patterns disposed on the lower clad layer and arranged in a first direction parallel to a top surface of the lower clad layer;

an upper clad layer disposed on the first quantum well pattern; and

first grating patterns disposed between the third quantum well pattern and the lower clad layer,

wherein the first to third quantum well patterns are arranged in the first direction parallel to the top surface of the lower clad layer,

the upper clad layer comprises a p-type conductive clad layer,

the lower clad layer comprises an n-type conductive clad layer,

the third quantum well pattern is electrically intrinsic, and

when a reverse bias is applied to the upper clad layer, the third quantum well pattern, and the lower clad layer, the third quantum well pattern is changed in refractive index.

2. The tunable laser device of claim 1 , further comprising:

a first passive optical waveguide pattern disposed between the first and second quantum well patterns and optically coupled to the first and second quantum well patterns; and

a second passive optical waveguide pattern disposed between the second and third quantum well patterns and optically coupled to the second and third quantum well patterns,

wherein each of the first passive optical waveguide pattern and the second passive optical waveguide pattern has a refractive index different from that of the lower clad layer.

3. The tunable laser device of claim 1 , further comprising an airgap provided between the first grating patterns and the lower clad layer,

wherein the first grating patterns are exposed by the airgap.

4. The tunable laser device of claim 1 , further comprising an insulation layer disposed between the first quantum well pattern and the lower clad layer,

wherein the first grating patterns are disposed within the insulation layer.

5. The tunable laser device of claim 1 , further comprising a reflection layer disposed on a side surface of the third quantum well pattern to extend along the side surface of the third quantum well pattern.

6. The tunable laser device of claim 1 , further comprising:

a fourth quantum well pattern spaced apart from the third quantum well pattern in the first direction;

a third passive optical waveguide pattern disposed between the third and fourth quantum well patterns and optically coupled to the third and fourth quantum well patterns; and

second grating patterns disposed between the fourth quantum well pattern and the lower clad layer,

wherein the fourth quantum well pattern is electrically intrinsic, and

when the reverse bias is applied to the upper clad layer, the fourth quantum well pattern, and the lower clad layer, the fourth quantum well pattern is changed in refractive index.

7. The tunable laser device of claim 6 , wherein each of the first and second grating patterns comprises a distributed bragg reflector (DBR) or a sampled-grating DBR.

8. The tunable laser device of claim 1 , further comprising a spacer disposed between the first to third quantum well patterns and the first grating patterns,

wherein the spacer comprises substantially the same material as the lower clad layer.

9. The tunable laser device of claim 1 , further comprising:

a fifth quantum well pattern disposed at an opposite side of the second quantum well pattern with the third quantum well pattern between the second and fifth quantum well patterns; and

a sixth quantum well pattern disposed at an opposite side of the third quantum well pattern with the fifth quantum well pattern between the third and sixth quantum well patterns,

wherein the fifth and sixth quantum well patterns are disposed on the lower clad layer.

10. The tunable laser device of claim 1 , further comprising a passive optical waveguide layer disposed between the first to third quantum well patterns and the first grating patterns to extend in the first direction.

11. A method for manufacturing a tunable laser device, the method comprising:

preparing a lower clad layer;

forming a first quantum well pattern, a second quantum well pattern, and a third quantum well pattern on the lower clad layer laterally;

forming a first passive optical waveguide pattern between the first and second quantum well patterns and a second passive optical waveguide pattern between the second and third quantum well patterns; and

forming an upper clad layer on the first to third quantum well patterns,

wherein the first quantum well pattern, the first passive optical waveguide pattern, the second quantum well pattern, the second passive optical waveguide pattern, and the third quantum well pattern are arranged in a first direction parallel to a top surface of the lower clad layer.

12. The method of claim 11 , further comprising:

forming grating patterns on the lower clad layer before the forming of the first to third quantum well patterns; and

forming a spacer layer on the lower clad layer to cover the grating patterns,

wherein the spacer layer extends in the first direction.

13. The method of claim 12 , wherein the forming of the first quantum well pattern comprises:

forming a first preliminary quantum well layer, which extends in the first direction, on the spacer layer; and

patterning the first preliminary quantum well layer.

14. The method of claim 13 , wherein the forming of the second and third quantum well patterns comprises:

forming a second preliminary quantum well layer, which extends in the first direction, on the spacer layer; and

patterning the second preliminary quantum well layer.

15. The method of claim 14 , wherein the forming of the first passive optical waveguide pattern and the second passive optical waveguide pattern comprises:

forming a preliminary optical waveguide layer on the first to third quantum well patterns and the spacer layer; and

removing the preliminary optical waveguide layer formed on the first to third quantum well patterns to expose top surfaces of the third to third quantum well patterns.