Phase shifter employing electro-optic material sandwich
Electro-optical devices and methods for constructing electro-optical devices such as a switch or phase shifter. An electrode layer is deposited on a substrate layer, a waveguide structure is deposited on the electrode layer, a first cladding layer is deposited on the waveguide structure, and the first cladding layer is planarized and bonded to a wafer. The substrate layer is removed and the electrode layer is etched to split the electrode layer into a first electrode separated from a second electrode. A second cladding layer is deposited on the etched electrode layer. The first and second electrodes may be composed of a material with a large dielectric constant, or they may be composed of a material with a large electron mobility. The device may exhibit a sandwich waveguide architecture where an electro-optic layer is disposed between two strip waveguides.
1 . A device, comprising:
a first cladding layer comprising a single material;
a first electrode;
a second electrode, wherein at least one of the first electrode and the second electrode is composed of a high-κ material;
a second cladding layer;
a waveguide structure, comprising:
a first strip waveguide portion composed of a first material;
a second strip waveguide portion composed of a second material; and
an electro-optic layer composed of a barium titanate, wherein the electro-optic layer is disposed between the first and second cladding layers, wherein the electro-optic layer is disposed between the first strip waveguide portion and the second strip waveguide portion, wherein the electro-optic layer is coupled to the first electrode and the second electrode, wherein the electro-optic layer abuts the first strip waveguide portion, and wherein the second strip waveguide portion is embedded a distance within the first cladding layer and the second strip waveguide portion is separated from the electro-optic layer by the distance.
2 . The device of claim 1 ,
wherein the first material comprises silicon nitride, and
wherein the second material comprises silicon.
3 . The device of claim 1 ,
wherein the first strip waveguide portion is disposed between and abuts the first and second electrodes, and
wherein the first and second electrodes and the first strip waveguide portion have a first thickness.
4 . The device of claim 1 ,
wherein the first and second materials have a lower index of refraction than barium titanate.
5 . The device of claim 1 ,
wherein the first and second cladding layers are comprised of silicon dioxide or an oxide material.
6 . A device, comprising:
a first cladding layer comprising a single material;
a first electrode;
a second electrode, wherein at least one of the first electrode and the second electrode is composed of a high-κ material;
a waveguide structure comprising an electro-optic layer composed of a first material, a first strip waveguide portion composed of a second material, and a second strip waveguide portion composed of a third material, wherein the electro-optic layer is disposed between the first strip waveguide portion and the second strip waveguide portion, wherein the electro-optic layer abuts the first strip waveguide portion, and wherein the second strip waveguide portion is embedded a distance within the first cladding layer such that the second strip waveguide portion is separated from the electro-optic layer by the distance, and wherein the electro-optic layer is coupled to the first electrode and the second electrode; and
a second cladding layer.
7 . The device of claim 6 ,
wherein the first electrode and the second electrode abut the first strip waveguide portion, wherein the first electrode and the second electrode have a first thickness.
8 . The device of claim 6 ,
wherein the first and second strip waveguide portions are configured to concentrate an optical mode within the electro-optic layer.
9 . The device of claim 6 , further comprising:
a first lead coupled to the first electrode; and
a second lead coupled to the second electrode.
10 . The device of claim 6 ,
wherein the second and third materials comprise silicon nitride.
11 . The device of claim 6 ,
wherein the second material comprises silicon nitride, and
wherein the third material comprises silicon.
12 . The device of claim 6 ,
wherein the first and second electrodes are composed of one of:
gallium arsenide (GaAs);
an aluminum gallium arsenide (AlGaAs)/GaAs heterostructure;
an indium gallium arsenide (InGaAs)/GaAs heterostructure;
zinc oxide (ZnO);
zinc sulfide (ZnS);
indium oxide (InO);
doped silicon;
a two-dimensional electron gas; or
doped strontium oxide, and
wherein the doped strontium titanate is either:
niobium doped;
lanthanum doped; or
vacancy doped; and
wherein the first material comprises one of:
barium titanate;
barium strontium titanate;
lead zirconium titanate;
lead lanthanum zirconium titanate; or
strontium barium niobate.
13 . The device of claim 6 ,
wherein the first electrode and the second electrode are configured to generate an electric field along an x-direction in the waveguide structure, and
wherein the waveguide structure is characterized by an electro-optic coefficient having a nonzero value aligned along the x-direction.
14 . The device of claim 6 ,
wherein the first electrode and the second electrode comprise a second layer coplanar to the electro-optic layer and disposed adjacent to a first side of the electro-optic layer.
15 . The device of claim 6 ,
wherein the second material and the third material have a lower index of refraction than the first material.
16 . The device of claim 6 ,
wherein the first and second cladding layers are comprised of silicon dioxide or an oxide material.
17 . A method for constructing a device, the method comprising:
receiving a first wafer comprising a first layer stack, wherein the first layer stack comprises:
a substrate layer;
a seed layer disposed on the substrate layer;
an electro-optic layer disposed on the seed layer;
receiving a second wafer, the second wafer comprising a second strip waveguide structure disposed within a second cladding layer, wherein the second strip waveguide structure is embedded a distance within the second cladding layer, wherein the second cladding layer is comprised of a single material;
bonding the first layer stack to the second wafer such that the electro-optic layer is separated from the second strip waveguide structure by the distance;
removing the substrate layer;
etching the seed layer to form, in the seed layer, a first electrode separated from a second electrode, wherein at least one of the first electrode and the second electrode is composed of a high-κ material;
depositing a first strip waveguide structure between the first and second electrodes, wherein the first strip waveguide structure abuts the electro-optic layer; and
depositing a first cladding layer on the first and second electrodes and the first strip waveguide structure.
18 . The method of claim 17 , the method further comprising:
etching the first cladding layer to expose a first portion of the first electrode;
etching the first cladding layer to expose a second portion of the second electrode;
depositing a first lead onto the first electrode through the exposed first portion; and
depositing a second lead onto the second electrode through the exposed second portion.
19 . The method of claim 17 ,
wherein the electro-optic layer is composed of a first material,
wherein the first and second strip waveguide structures are composed of a second material, and
wherein the second material has a lower index of refraction than the first material.
20 . The method of claim 17 ,
wherein the first and second cladding layers are comprised of silicon dioxide or an oxide material.