Bloch mirror resonator and distributed feedback laser using same
View Patent ↗A resonator is provided having a waveguide with a first boundary, a second boundary parallel to the first boundary, a first end, a second end, and a waveguide cavity at least partly between the first boundary and the second boundary. A first grating, having a period of distance a, is at the first boundary of the waveguide, and a second grating, having a period of distance a, is at the second boundary of the waveguide. The first and second boundaries are separated by a constant distance d. The first boundary may have a periodic profile aligned with a periodic profile of the second boundary. The periodic profile of the first boundary and the second boundary may be a sinusoidal profile, a square profile, or profile of another shape. The resonator may be suitable for use in a distributed feedback laser.
1. A resonator, comprising:
a waveguide having a first boundary, a second boundary parallel to the first boundary, a first end, a second end, and a waveguide cavity at least partly between the first boundary and the second boundary;
a first grating at the first boundary of the waveguide, the first grating having a period of distance a;
a second grating at the second boundary of the waveguide, the second grating having a period of distance a;
wherein a distance d between the first boundary and the second boundary is equal to
a
2
p
2
-
m
2
,
wherein p and m are mode indices in the waveguide and p>m.
2. The resonator of claim 1 , wherein a periodic profile of the first boundary is aligned with a periodic profile of the second boundary along the waveguide.
3. The resonator of claim 1 , wherein the waveguide mode indices are p=2 and m=1, and the distance d between the first boundary and the second boundary is equal to a√{square root over (3)}/2.
4. The resonator of claim 1 , wherein a first phase of the first grating is substantially aligned with a second phase of the second grating.
5. The resonator of claim 1 , wherein the waveguide cavity is an optical waveguide.
6. The resonator of claim 5 , wherein the optical waveguide comprises a dielectric material having a high refractive index.
7. The resonator of claim 6 , wherein the dielectric material is GaN.
8. The resonator of claim 1 , wherein the first grating and second grating have a sinusoidal profile.
9. The resonator of claim 1 , wherein the first grating and second grating have a profile with a thickness between 10% and 30% (inclusive) of the distance d.
10. The resonator of claim 1 , wherein the first grating and the second grating are formed using one or more transducers.
11. The resonator of claim 10 , wherein one or more transducers are acousto-optic transducers.
12. The resonator of claim 10 , wherein one or more transducers are electro-optic transducers.
13. The resonator of claim 10 , wherein one or more transducers are piezoelectric transducers.
14. The resonator of claim 10 , wherein the first grating and the second grating are acoustic waves.
15. The resonator of claim 1 , further comprising an active layer for light generation.
16. A distributed feedback laser, comprising a resonator according to claim 1 .