Optoelectronic device

1. An optoelectronic device, including:

a rib waveguide, the rib waveguide including:

a ridge portion, which includes a temperature-sensitive optically active region, and

a slab portion, positioned adjacent to the ridge portion;

wherein the optoelectronic device further comprises:

a heater, for heating the temperature-sensitive optically active region;

a bottom cladding layer, disposed adjacent to the slab portion; and

a thermal isolation cavity, located on an opposing side of the bottom cladding layer to the slab portion, and

wherein a part of the heater closest to the ridge portion is at least 2 μm away from the ridge portion.

2. The optoelectronic device of claim 1 , further including:

a buried oxide layer, disposed adjacent to a lower surface of the bottom cladding layer, wherein the thermal isolation cavity is located on an opposing side of the buried oxide layer and is adjacent to a silicon substrate.

3. The optoelectronic device of claim 1 , wherein the thermal isolation cavity has a width which is larger than a width of the slab portion.

4. The optoelectronic device of claim 1 , further including a thermal isolation trench, wherein the thermal isolation trench is positioned adjacent to the bottom cladding layer.

5. The optoelectronic device of claim 4 , wherein the heater is disposed on top of the slab portion.

6. The optoelectronic device of claim 5 , wherein a width of a first region of the heater tapers from a first width to a second width in a direction substantially parallel to a guiding direction of the rib waveguide.

7. The optoelectronic device of claim 6 , wherein the width of a second region of the heater increases from the second width to the first width along the direction substantially parallel to the guiding direction of the rib waveguide.

8. The optoelectronic device of claim 5 , wherein the heater comprises plural metal strips, connected at one end to an adjacent metal strip so as to form a serpentine form.

9. The optoelectronic device of claim 5 , further including a first and second electrode for the heater, which are electrically connected to the heater on the same side.

10. The optoelectronic device of claim 8 , wherein the heater is formed from any one of Ti, TiN, TiW, NiCr, or W.

11. The optoelectronic device of claim 4 , wherein the heater is disposed above an electrical contact for the slab portion and separated therefrom by an insulator.

12. The optoelectronic device of claim 4 , further including an upper cladding layer disposed on the heater.

13. The optoelectronic device of claim 4 , wherein the heater is a first heater, the optoelectronic device further including a second heater, substantially identical to the first heater and disposed on an opposing side of the ridge portion.

14. An optoelectronic device, including:

a rib waveguide, the rib waveguide including:

a ridge portion, which includes a temperature-sensitive optically active region, and

a slab portion, positioned adjacent to the ridge portion;

wherein the optoelectronic device further comprises:

a heater, for heating the temperature-sensitive optically active region;

a bottom cladding layer, disposed adjacent to the slab portion;

a thermal isolation cavity, located on an opposing side of the bottom cladding layer to the slab portion; and

an electrode, electrically connected to either the ridge portion or the slab portion, wherein the electrode includes at least one thermal isolation cavity.

15. The optoelectronic device of claim 14 , wherein the electrode comprises plural thermal isolation cavities in an array, wherein the array extends in a direction substantially parallel to the guiding direction of the rib waveguide.

16. The optoelectronic device of claim 15 , wherein the or each cavity in the electrode is filled with air or SiO2.

17. An optoelectronic device, including:

a rib waveguide, the rib waveguide including:

a ridge portion, which includes a temperature-sensitive optically active region, and

a slab portion, positioned adjacent to the ridge portion;

wherein the optoelectronic device further comprises:

a heater, for heating the temperature-sensitive optically active region;

a bottom cladding layer, disposed adjacent to the slab portion; and

a thermal isolation cavity, located on an opposing side of the bottom cladding layer to the slab portion, and

wherein the heater is disposed in the bottom cladding layer.

18. The optoelectronic device of claim 17 , wherein the bottom cladding layer is an epitaxial crystalline cladding layer.

19. The optoelectronic device of claim 18 , wherein the heater comprises a doped region of the epitaxial crystalline cladding layer.

20. The optoelectronic device of claim 19 , wherein the doped region of the epitaxial crystalline cladding layer extends in a direction substantially parallel to the guiding direction of the rib waveguide.

21. The optoelectronic device of claim 19 , further including an undoped region of the epitaxial crystalline cladding layer, the undoped region being located between the doped region and the slab portion.