OPTICAL MODULATOR

• US 20170269454A1
• Filed: 04/20/2017
• Published: 09/21/2017
• Est. Priority Date: 04/15/2015
• Status: Abandoned Application

• Current Assignee: Chen-Kuo Sun
• Original Assignee: Chen-Kuo Sun
• Inventors: Sun, Chen-Kuo, Chen, Dingbo
• Application Number:
  US15/492,262
• Publication Number:
  US 20170269454A1
• Time in Patent Office: Days
• CPC Class Codes: G02B 2006/12142 Modulator
• CPC Class Codes: G02B 6/00 Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
• CPC Class Codes: G02B 6/136 by etching
• CPC Class Codes: G02B 6/138 by using polymerisation
• CPC Class Codes: G02F 1/065 in an optical waveguide structure
• CPC Class Codes: G02F 1/3132 of directional coupler type
• CPC Class Codes: G02F 1/3133 the optical waveguides being made of semiconducting materials
• CPC Class Codes: G02F 1/3135 Vertical structure
• CPC Class Codes: G02F 2201/06 integrated waveguide
• CPC Class Codes: G02F 2201/12 electrode
• CPC Class Codes: H01P 11/003 Manufacturing lines with conductors on a substrate, e.g. strip lines, slot lines

Abstract

An optical modulator for switching an optical signal of wavelength λ from one waveguide-electrode to another requires that both waveguide-electrodes be made of an electrically conducting material. Also, a non-conducting cross-coupling material fills a slot along a length L between the waveguide-electrodes. Importantly, cross-coupling material in the slot provides a separation distance x_c between the waveguide-electrodes that is less than 0.35 microns. When a switching voltage V_π is selectively applied to the waveguide-electrodes, a strong uniform electric field E is created within the cross-coupling material. Thus, E modulates the cross-coupling length of the optical signal by an increment ±Δ each time it passes back and forth through the cross-coupling material along the length L. Thus, after an N number of cross-coupling length cycles along the length L, when NΔ equals one cross-coupling length, the optical signal is switched from one waveguide-electrode to the other.

Claims

1. An optical modulator for switching an optical signal of wavelength λ

between two waveguides, which comprises;

a first waveguide-electrode made of an electrically conductive material and having an input port and an output port with a length L therebetween;

a second waveguide-electrode made of an electrically conductive material and having an input port and an output port, wherein the first waveguide-electrode and the second waveguide-electrode are oriented in a side-by-side alignment along the length L;

a non-conducting cross-coupling material positioned between the first waveguide-electrode and the second waveguide-electrode along the length L to establish a slot having a separation distance x_c therebetween, wherein x_c is less than 0.35 microns to establish a cross-coupling length L_c for the optical signal during transit through the cross-coupling material from one waveguide-electrode to the other, wherein L_c approaches the wavelength λ

; and

a voltage source electrically connected to the first waveguide-electrode and to the second waveguide-electrode to selectively apply a switching voltage V_π

therebetween for creating a strong, uniform electric field E confined within the cross-coupling material along the length L, to modulate the cross-coupling length L_c by an increment Δ

, to establish a modulated cross-coupling length L_c′

(L′

=L_c±

Δ

) for switching the optical signal from one waveguide-electrode to the other, wherein switching occurs after an N number of cross-coupling length cycles of the optical signal along the length L in the waveguide-electrodes, when L_c′

=NΔ

, and L=NL_c=(N±

1)L_c′

.

2. The optical modulator recited in claim 1 wherein L is in a range between 0.5 mm and 5 mm.

3. The optical modulator recited in claim 1 wherein L is in a range between 0.5 μ

m and 5 μ

m.

4. The optical modulator recited in claim 1 wherein no switching occurs when the voltage source applies a voltage V_base, and causes switching when an applied voltage from the voltage source equals V_base+V_π

.

5. The optical modulator recited in claim 4 wherein V_base=0.

6. The optical modulator recited in claim 1 wherein the first waveguide-electrode and the second waveguide-electrode are made of a conducting semiconductor material.

7. The optical modulator recited in claim 1 wherein the non-conducting cross-coupling material is a polymer and has an index of refraction n, wherein n is a function of an electro-optical index modulation coefficient r modulated by V_π

, with r greater than 20 pm/V.

8. The optical modulator recited in claim 1 wherein the cross-coupling material in the slot establishes an optical slot confinement factor Γ

, wherein the confinement factor Γ

is greater than 0.15 when x_c is less than 0.35 μ

m, to create a modulated cross-coupling length L_c′

less than 2λ

under the influence of V_π

(Γ

>

0.15, when x_c<

0.35 μ

m, to achieve L_c′

<

2λ

).

9. The optical modulator recited in claim 1 wherein the length L of the slot is determined relative to the modulation increment Δ

created by the switching voltage V_π

to establish a relationship wherein L=NL_c=(N±

1)L_c′

.

10. A method for manufacturing an optical modulator for switching an optical signal between two waveguides, wherein the optical signal has a wavelength λ

and follows a wave path through the optical modulator, the method comprising the steps of;

providing a non-conducting cross-coupling material, a first waveguide-electrode and a second waveguide-electrode, wherein each waveguide-electrode is made of an electrically conductive material and has an input port and an output port with a length L therebetween;

orienting the first waveguide-electrode to the second waveguide-electrode in a side-by-side alignment to create a slot therebetween along the length L, wherein the slot has a separation distance x_c between the first and second waveguide-electrodes, and x_c is less than 0.35 microns; and

filling the slot between the first waveguide-electrode and the second waveguide-electrode with the non-conducting cross-coupling material along the length L to establish an optical slot confinement factor Γ

in the slot wherein, when a switching voltage V_π

is applied between the first and second waveguide-electrodes, the confinement factor Γ

is greater than 0.15 to create a cross-coupling length L_c less than 2λ

for the optical signal during transit through the cross-coupling material from one waveguide-electrode to the other (Γ

>

0.15, when x_c<

0.35 μ

m, to achieve L_c′

<

2λ

).

11. The method recited in claim 10 further comprising the step of connecting a voltage source to the first waveguide-electrode and to the second waveguide-electrode to selectively apply the switching voltage V_π

therebetween for creating a strong, uniform electric field E confined within the cross-coupling material along the length L, to modulate the cross-coupling length L_c of the optical signal by an increment Δ and

establish a modulated cross-coupling length L_c′

(L_c′

=L_c±

Δ

), wherein after an N number of cross-coupling length cycles of the optical signal along the length L in the waveguide-electrodes, when L=NL_c=NL_c′

±

NΔ and

L_c′

=NΔ

, the optical signal is switched from one waveguide-electrode to the other.

12. The method recited in claim 11 wherein the length L of the slot is determined relative to the modulation increment Δ

created by the switching voltage V_π

to establish a relationship wherein L=NL_c=(N±

1)L_c′

.

13. The method recited in claim 12 wherein L_c is in a range between 0.5 μ

m and 5 μ

m.

14. The method recited in claim 12 wherein L is in a range between 0.5 mm and 5 mm.

15. A method for manufacturing an optical modulator for switching an optical signal between two waveguides, wherein the optical signal has a wavelength λ

and follows a wave path through the optical modulator, the method comprising the steps of;

providing a non-conducting cross-coupling material, a first waveguide-electrode and a second waveguide-electrode, wherein each waveguide-electrode is made of an electrically conductive material and has an input port and an output port with a length L therebetween;

orienting the first waveguide-electrode parallel to the second waveguide-electrode in a side-by-side alignment to create a slot therebetween along the length L, wherein the slot has a separation distance x_c between the first and second waveguide-electrodes, and x_c is less than 0.35 microns; and

filling the slot between the first waveguide-electrode and the second waveguide-electrode with the non-conducting cross-coupling material along the length L, wherein the length L is established for a requirement that the wave path of the optical signal be changed by a length less than 2λ

during transit of the optical signal along the length L.

16. The method recited in claim 15 wherein the orienting step establishes an optical slot confinement factor Γ

in the slot wherein, when a switching voltage V_π

is applied between the first and second waveguide-electrodes, the confinement factor Γ

is greater than 0.15 to create a cross-coupling length L_c less than 2λ

for the optical signal during transit through the cross-coupling material from one waveguide-electrode to the other (Γ

>

0.15, when x_c<

0.35 μ

m, to achieve L_c′

<

2λ

).

17. The method recited in claim 15 further comprising the step of connecting a voltage source to the first waveguide-electrode and to the second waveguide-electrode to selectively apply the switching voltage V_π

therebetween for creating a strong, uniform electric field E confined within the cross-coupling material along the length L, to modulate the unmodulated cross-coupling length L_c of the optical signal by an increment Δ and

establish a modulated cross-coupling length L_c′

(L_c′

=L_c±

Δ

), wherein after an N number of cross-coupling length π

cycles of the optical signal along the length L in the waveguide-electrodes, when L=NL_c=NL_c′

±

NΔ and

L_c′

=NΔ

, the optical signal is switched from one waveguide-electrode to the other.

18. The method recited in claim 15 wherein L_c is in a range between 0.5 μ

m and 5 μ

m.

19. The method recited in claim 15 wherein L is in a range between 0.5 mm and 5 mm.

20. The method recited in claim 15 wherein the first and second waveguides are made of a conducting semiconductor material.