Directional photonic coupler with independent tuning of coupling factor and phase difference

Patent metadata

Field	Value
Publication number	US-11579368-B2
Application number	US-201917290062-A
Country	US
Kind code	B2
Filing date	Oct 9, 2019
Priority date	Oct 31, 2018
Publication date	Feb 14, 2023
Grant date	Feb 14, 2023

Abstract

The present invention discloses a directional photonic coupler (1) with independent tuning of the coupling factor and phase difference. The coupler comprises: two waveguides (4, 5), with respective propagation constants “β1, β2”, on which phase shifters (6, 7) configured to modify the propagation coefficients are located. Both phase shifters are configured such that, by independent modification (differential or unique) of the propagation coefficients, the power coupling factor (K) between an input signal (2a or 2b) and the output signals (3b and 3a) is tuned, and by equal and simultaneous modification of the propagation coefficients, the common phase difference of the optical output signals (3 a, 3b) is tuned. A third phase shifter (15) can be used to retune the phase difference at the input/output of one of the waveguides. The coupler is of particular interest in PIC circuits, coupled resonators, Mach-Zehnder interferometers and mesh structures.

First claim

The invention claimed is:

1. A directional photonic coupler independent tuning of a coupling factor and a phase difference, the directional photonic coupler comprising:
a first waveguide with a propagation coefficient, denoted as β 1 , and a second waveguide with a propagation coefficient, denoted as β 2 ;
an input and an output of the first waveguide and an input and an output of the second waveguide;
a first phase shifter, located at a predetermined distance from the first waveguide, configured to modify the propagation coefficient, denoted as β 1 , of the first waveguide; and
a second phase shifter, located at a predetermined distance from the second waveguide, configured to modify the propagation coefficient, denoted as β 2 , of the second waveguide;
wherein the first phase shifter and the second phase shifter are configured such that, by independent modification of the propagation coefficient, denoted as β 1 , of the first waveguide and of the propagation coefficient, denoted as β 2 , of the second waveguide, respectively, a coupling factor, denoted as “K,” between an optical input signal of one of the first waveguide or the second waveguide and optical output signals of the first waveguide and the second waveguide, is tuned, and
wherein, by equal and simultaneous modification of the propagation coefficient, denoted as β 1 , of the first waveguide and of the propagation coefficient, denoted as β 1 , of the second waveguide, respectively, a common phase difference of the optical output signals of the first waveguide and the second waveguide is tuned.

2. The directional photonic coupler of claim 1 , further comprising a substrate and a cladding, wherein the cladding is located on the substrate, which comprises therein at least the first waveguide and the second waveguide, with the first phase shifter and the second phase shifter located on the cladding.

3. The directional photonic coupler of claim 2 further comprising a third phase shifter located in an input of one of the first waveguide or the second waveguide, wherein the third phase shifter is configured to introduce a phase difference before the phase difference introduced by the first phase shifter and the second phase shifter.

4. The directional photonic coupler of claim 3 , wherein the microprocessor is additionally connected to a plurality of optical power monitors at one or both outputs of the directional photonic coupler for reading and calculating the coupling factor, denoted as K.

5. The directional photonic coupler of claim 2 further comprising a third phase shifter located in an output of one of the first waveguide or the second waveguide, wherein the third phase shifter is configured to introduce a phase difference after the phase difference introduced by the first phase shifter and the second phase shifter.

6. The directional photonic coupler of claim 2 further comprising a microprocessor connected to the first phase shifter and to the second phase shifter for the activation thereof, wherein the microprocessor calculates the change in the propagation coefficient, denoted as β 1 , of the first waveguide to obtain the coupling factor, denoted as K, and wherein the microprocessor also calculates the simultaneous variation of the propagation coefficient, denoted as β 1 , of the first waveguide and the propagation coefficient, denoted as, β 2 , of the second waveguide to obtain the phase difference.

7. The directional photonic coupler of claim 1 further comprising a third phase shifter located in an input of one of the first waveguide or the second waveguide, wherein the third phase shifter is configured to introduce a phase difference before the phase difference introduced by the first phase shifter and the second phase shifter.

8. The directional photonic coupler of claim 7 further comprising a microprocessor connected to the first phase shifter and to the second phase shifter for the activation thereof, wherein the microprocessor calculates the change in the propagation coefficient, denoted as β 1 , of the first waveguide to obtain the coupling factor, denoted as K, and wherein the microprocessor also calculates the simultaneous variation of the propagation coefficient, denoted as β 1 , of the first waveguide and the propagation coefficient, denoted as, β 2 , of the second waveguide to obtain the phase difference.

9. The directional photonic coupler of claim 1 further comprising a third phase shifter located in an output of one of the first waveguide or the second waveguide, wherein the third phase shifter is configured to introduce a phase difference after the phase difference introduced by the first phase shifter and the second phase shifter.

10. The directional photonic coupler 9 further comprising a microprocessor connected to the first phase shifter and to the second phase shifter for the activation thereof, wherein the microprocessor calculates the change in the propagation coefficient, denoted as β 1 , of the first waveguide to obtain the coupling factor, denoted as K, and wherein the microprocessor also calculates the simultaneous variation of the propagation coefficient, denoted as β 1 , of the first waveguide the propagation coefficient, denoted as β 2 , of the second waveguide to obtain the phase difference.

11. The directional photonic coupler of claim 10 , wherein the microprocessor is additionally connected to the third phase shifter the activation thereof.

12. The directional photonic coupler of claim 10 , wherein the microprocessor is additionally connected to a plurality of optical power monitors at one or both outputs of the directional photonic coupler for reading and calculating the coupling factor, denoted as “K”.

13. A photonic integrated circuit “(PIC)” comprising the directional photonic coupler of claim 1 .

14. A coupled resonator comprising the directional photonic coupler of claim 1 .

15. The directional photonic coupler of claim 1 further comprising a microprocessor connected to the first phase shifter and to the second phase shifter for the activation thereof, wherein the microprocessor calculates the change in the propagation coefficient, denoted as β 1 , of the first waveguide to obtain the coupling factor, denoted as K, and wherein the microprocessor also calculates the simultaneous variation of the propagation coefficient, denoted as β 1 , of the first waveguide and the propagation coefficient, denoted as, β 2 , of the second waveguide to obtain the phase difference.

Assignees

• Univ Valencia Politecnica

Inventors

• Perez Lopez Daniel
• Capmany Francoy José
• Gasulla Mestre Ivana
• Sánchez Gomáriz Erica

Classifications

• G02B6/287

  Structuring of light guides to shape optical elements with heat application (G02B6/255 takes precedence) · CPC title

• G02B6/29355 Primary

  Cascade arrangement of interferometers · CPC title

• G02B6/29352 Primary

  in a light guide · CPC title

• G02B2006/12147

  Coupler · CPC title

• G02B6/29395

  configurable, e.g. tunable or reconfigurable (switching G02B6/35) · CPC title