Mode size converter for a planar waveguide
View Patent ↗A process for forming a mode size converter with an out-of-plane taper formed during deposition with a shadow mask is disclosed. Mode-size converters according to the present invention can have any number of configurations. Measured coupling efficiencies for waveguides with mode size converters according to the present invention show marked improvement.
1. A mode size converter, comprising:
a first layer of a dielectric material with a first refractive index deposited over a substrate;
a rare earth-doped aluminosilicate layer of a second refractive index deposited over the first layer,
wherein, the rare earth-doped aluminosilicate layer includes a vertical taper, and the vertical taper has an as-deposited average surface roughness of about 1.5 nm or less; wherein
the resulting average surface roughness is substantially as-deposited, and further having a rate of taper of about 0.14 parts per thousand.
2. The mode size converter of claim 1 , wherein the first refractive index is greater than the second refractive index.
3. The mode size converter of claim 2 , wherein for light traveling along the first layer into the rare earth-doped aluminosilicate layer, a mode size in the first layer is greater than a mode size in the rare earth-doped aluminosilicate layer.
4. The mode size converter of claim 1 , wherein the first layer is a core layer; and
the second layer is a core layer.
5. The mode size converter of claim 4 , wherein the first core layer is an active layer and the second core layer is a passive layer.
6. The mode size converter of claim 4 , wherein
the first core layer is a passive layer; and
the second core layer is an active layer.
7. The mode size converter of claim 1 , wherein
the first layer is an undercladding layer; and
the second layer is a core layer.
8. The mode size converter of claim 1 , further comprising:
a third layer deposited over the first layer, wherein
the third layer is one of a core layer or an undercladding layer.