Hybrid EO polymer modulator with silicon photonics

Patent metadata

Field	Value
Publication number	US-11435604-B2
Application number	US-202017121118-A
Country	US
Kind code	B2
Filing date	Dec 14, 2020
Priority date	Dec 14, 2020
Publication date	Sep 6, 2022
Grant date	Sep 6, 2022

Abstract

An EO polymer modulator including a substrate with a cladding layer formed on a surface and a passive waveguide core, having a cross-sectional area, formed in the cladding layer and including an elongated tapered active section. An elongated trench in the cladding layer, the elongated tapered active section of the waveguide core positioned in the elongated trench, electrodes positioned on a surface of the cladding layer on opposite sides of the elongated trench, and an elongated strip of EO polymer overlying the elongated tapered active section of the waveguide core. The elongated strip of EO polymer positioned between and parallel with the electrodes and coplanar with the electrodes.

First claim

Having fully described the invention in such clear and concise terms as to enable those skilled in the art to understand and practice the same, the invention claimed is:

1. An EO polymer modulator comprising:
a substrate with a cladding layer formed on a surface;
a passive waveguide core, having a cross-sectional area, formed in the cladding layer and including an elongated tapered active section;
an elongated trench in the cladding layer, the elongated tapered active section of the waveguide core positioned in the elongated trench;
electrodes positioned on a surface of the cladding layer on opposite sides of the elongated trench; and
an elongated strip of EO polymer overlying the elongated tapered active section of the waveguide core, the elongated strip of EO polymer positioned between and parallel with the electrodes and coplanar with the electrodes.

2. The EO polymer modulator as claimed in claim 1 wherein the elongated tapered active section of the waveguide core includes a portion that tapers from the cross-sectional area to zero and a spaced apart portion that expands from zero to the cross-sectional area.

3. The EO polymer modulator as claimed in claim 2 wherein the portion of the elongated trench where the waveguide core tapers to zero is filled with a portion of the elongated strip of EO polymer.

4. The EO polymer modulator as claimed in claim 1 wherein the elongated tapered active section of the waveguide core includes a portion that tapers from the cross-sectional area to a smaller dimension and a spaced apart portion that expands from the smaller dimension to the cross-sectional area.

5. The EO polymer modulator as claimed in claim 1 wherein the electrodes include a pair of spaced apart RF electrodes.

6. The EO polymer modulator as claimed in claim 5 wherein the RF electrodes are high bandwidth electrodes and extend into the surface of the cladding layer and/or above the surface of the elongated strip of EO polymer.

7. The EO polymer modulator as claimed in claim 5 wherein the electrodes include a pair of spaced apart poling electrodes, the poling electrodes being positioned between the RF electrodes and adjacent opposite sides of the elongated trench.

8. The EO polymer modulator as claimed in claim 1 wherein elongated strips of low refractive index material are positioned between the electrodes and adjacent opposite sides of the elongated strip of EO polymer, the low refractive index material having a refractive index lower than a refractive index of the EO polymer material.

9. The EO polymer modulator as claimed in claim 1 further including an encapsulation layer covering at least the electrodes positioned on a surface of the cladding layer and the elongated strip of EO polymer.

10. The EO polymer modulator as claimed in claim 1 wherein the elongated strips of low refractive index material include SiO 2 .

11. The EO polymer modulator as claimed in claim 1 wherein the modulator is a Mach-Zehnder modulator and the passive waveguide core includes a pair of spaced apart legs with each leg having a cross-sectional area, and each leg including an elongated tapered active section.

12. An EO polymer Mach-Zehnder modulator comprising:
a substrate with a cladding layer formed on the surface;
a passive waveguide core including an input waveguide, and an output waveguide connected at opposite ends to spaced apart parallel legs, each of the legs having a common cross-sectional area, the passive waveguide core formed in the cladding layer and each leg including an elongated tapered active section;
elongated strips of EO polymer, the elongated strips of EO polymer positioned between and parallel with the electrodes and coplanar with the electrodes;
elongated spaced apart, parallel trenches in the cladding layer and/or in an upper surface of the elongated strips of EO polymer, the elongated tapered active sections of the waveguide core positioned in the elongated trenches;
electrodes positioned on a surface of the cladding layer on opposite sides of each of the elongated trenches; and
the elongated strips of EO polymer overlying each of the elongated tapered active sections of the waveguide core.

13. The EO polymer Mach-Zehnder modulator as claimed in claim 12 wherein the elongated tapered active section of the waveguide core includes a portion that tapers from the cross-sectional area to zero and a spaced apart portion that expands from zero to the cross-sectional area.

14. The EO polymer Mach-Zehnder modulator as claimed in claim 13 wherein the portion of the elongated trench where the waveguide core tapers to zero is filled with a portion of the elongated strip of EO polymer.

15. The EO polymer Mach-Zehnder modulator as claimed in claim 12 wherein the elongated tapered active section of the waveguide core includes a portion that tapers from the cross-sectional area to a smaller dimension and a spaced apart portion that expands from the smaller dimension to the cross-sectional area.

16. The EO polymer Mach-Zehnder modulator as claimed in claim 12 wherein the electrodes include a pair of spaced apart RF electrodes.

17. A method of fabricating an EO polymer modulator comprising the steps of:
providing a substrate with a cladding layer formed on the surface;
forming an elongated trench in the cladding layer;
providing a passive waveguide core, having a cross-sectional area, in the cladding layer and including an elongated tapered active section, the elongated tapered active section of the waveguide core positioned in the elongated trench;
depositing elongated strips of auxiliary metal on the surface of the cladding layer on opposite sides of the elongated trench, parallel with and spaced from the elongated trench;
depositing elongated strips of electrically conductive material on the surface of the cladding layer adjacent to and parallel with outer surfaces of the auxiliary metal elongated strips;
depositing a layer of EO polymer material over the elongated trench, the elongated strips of auxiliary metal, and the elongated strips of electrically conductive material, the elongated strips of EO polymer positioned between and parallel with the electrodes and coplanar with the electrodes;
applying an electric field across the elongated strips of auxiliary metal while simultaneous heating the structure to a critical temperature to align permanent dipole chromophore molecules in the EO layer;
removing a portion of the EO polymer layer overlying the elongated strips of auxiliary metal to expose an upper surface of the elongated strips of auxiliary metal;
removing the exposed elongated strips of auxiliary metal to form trenches between the elongated strips of electrically conductive material and the EO polymer material;
depositing a layer of low refractive index material, with a refractive index lower than a refractive index of the EO polymer material, over the elongated strips of electrically conductive material and the EO polymer layer.

18. The method as claimed in claim 17 including a step of depositing encapsulation material over the layer of low refractive index material.

19. The method as claimed in claim 18 wherein the step of depositing encapsulation material includes depositing aluminum oxide (AlxOy) using ALD (atomic layer deposition).

20. The method as claimed in claim 17 wherein the step of providing a passive waveguide core includes providing the elongated tapered active section of the waveguide core with a portion that tapers from the cross-sectional area to zero and a spaced apar

Assignees

• Lightwave Logic Inc

Inventors

• Lebby Michael
• Liu Zhiming
• Chen Baoquan

Classifications

• G02F1/0356 Primary

  controlled by a high-frequency electromagnetic wave component in an electric waveguide structure · CPC title

• G02F2201/06

  integrated waveguide · CPC title

• G02F1/065 Primary

  in an optical waveguide structure · CPC title

• G02F2202/022

  polymeric · CPC title