All-photonic Boolean logic device based on phase change straight waveguide and full binary logic implementation method thereof

Patent metadata

Field	Value
Publication number	US-11906876-B2
Application number	US-202117910835-A
Country	US
Kind code	B2
Filing date	Jul 22, 2021
Priority date	Jul 12, 2021
Publication date	Feb 20, 2024
Grant date	Feb 20, 2024

Abstract

The disclosure provides a straight waveguide phase change all-photonic Boolean logic device and a full binary logic implementation method thereof, including a ridge- shape straight waveguide structure, two phase change functional units near the two ends and a Bragg grating between two phase change functional units. The phase change functional units and Bragg grating are situated on the ridge of the waveguide. The write and read optic pulses have different wavelengths. The Bragg grating are designed to reflect the write optical pulse and transmit the read pulse, so that write pulses input from the two ends only act on the phase change functional unit closest to that end, and read pulse can go through the whole device from input end to output end. In terms of the logic implementation method, with three-step write operation, 16 full Boolean logic functions can be implemented in this device.

First claim

What is claimed is:

1. A straight waveguide phase change all-photonic Boolean logic device, comprising: a straight waveguide, two phase change functional units, and a Bragg grating, wherein
on the upper surface of the straight waveguide there is a ridge, the two phase change functional units and the Bragg grating are all disposed on the ridge; the Bragg grating is located between the two phase change functional units and is in a straight line with the two phase change functional units;
based on an evanescent wave coupling effect, an optical pulse signal with a relatively large power is input into the straight waveguide from any one of the two ends, the phase change functional unit near the end absorbs a part of the relatively large power and generates a crystalline or amorphous phase change to implement a write operation; when the two phase change functional units have different state combinations, transmittance of a detection optical signal would be different accordingly, which is used to implement a reading operation; when the write operation is performed on one phase change functional unit, the optical pulse signal transmitted from one side of the Bragg grating does not act on the other phase change functional unit of the two phase change functional units on other side;
through the writing write operation and the reading operation on the two phase change functional units, the straight waveguide phase change all-photonic Boolean logic device implements functions of all 16 types of binary Boolean logic operations.

2. The straight waveguide phase change all-photonic Boolean logic device according to claim 1 , wherein a material of each of the two phase change functional units is a chalcogenide compound that generates a crystalline or amorphous reversible phase change under an action of different optical pulses.

3. The straight waveguide phase change all-photonic Boolean logic device according to claim 1 , wherein a real part of a complex refractive index of the two phase change functional units is larger than a real part of a complex refractive index of the straight waveguide, so that a part of light propagating in the straight waveguide enters the phase change functional units for propagation;
an imaginary part of the complex refractive index of the phase change functional units is not 0, so that the phase change functional units absorb the light propagated therein.

4. The straight waveguide phase change all-photonic Boolean logic device according to claim 3 , wherein the complex refractive indexes mentioned in the real part of the complex refractive index of each of the two phase change functional units being larger than the real part of the complex refractive index of the straight waveguide and the imaginary part of the complex refractive index of each of the two phase change functional units being not 0 refers to the complex refractive indexes of the two phase change functional units and the straight waveguide under two wavelengths of a pump optical pulse signal and a detection signal.

5. The straight waveguide phase change all-photonic Boolean logic device according to claim 1 , wherein the 16 types of binary Boolean logic operations comprise logic true, logic false, P, Q, not P, not Q, P and Q, P and not Q, P or Q, P or not Q, P implies Q, P implies not Q, P inverse implies Q, P inverse implies not Q, P exclusive OR Q, and P exclusive NOR Q logic operations.

6. The straight waveguide phase change all-photonic Boolean logic device according to claim 1 , wherein the optical pulse signal is input into a side of the straight waveguide where the first phase change functional unit is located, the first phase change functional unit heats up by absorbing the optical power thereby to induce the crystalline or amorphous phase change, so that the first phase change functional unit is finally in the crystalline state or in the amorphous state, so as to perform the write operation on the first phase change functional unit;
through setting parameters of the Bragg grating, after the optical pulse signal incident from one end of the straight waveguide passes through the Bragg grating, the transmitted optical pulse signal does not act on the second phase change functional unit on the other side of the straight waveguide.

7. The straight waveguide phase change all-photonic Boolean logic device according to claim 1 , wherein a detection signal is input into one end of the straight waveguide, an intensity of an optical signal output from the other end of the straight waveguide is detected and compared with an intensity of the input detection signal to determine transmittance of the two phase change functional units, so as to perform the reading operation on the two phase change functional units, the detection signal is an optical pulse or a continuous light with a relatively low power that does not change states of the two phase change functional units; through setting parameters of the Bragg grating, the detection signal is not affected by the Bragg grating.

8. The straight waveguide phase change all-photonic Boolean logic device according to claim 1 , wherein each of the two phase change functional units comprises a phase change functional unit layer and a protective layer from bottom to top; the protective layer is used to prevent the two phase change functional units from being oxidized.

9. The straight waveguide phase change all-photonic Boolean logic device according to claim 1 , wherein a material of the Bragg grating is same as a material of the straight waveguide.

10. A full binary logic implementation method of a straight waveguide phase change all-photonic Boolean logic device according to claim 1 , comprising:
presetting a detection signal to detect that the two phase change functional units are both in the amorphous state, wherein a logic value output by the detection signal after reading the two phase change functional units is 1, and logic values output in other cases are all 0;
presetting a three-step operation to respectively input the corresponding logic values into the two phase change functional units; presetting operation manners of 16 types of binary Boolean logic operations to respectively input the logic values into the two phase change functional units with the three-step operation, and then input the detection signal into one side of the straight waveguide to read states of the two phase change functional units through detecting an intensity of a signal output from the other side of the straight waveguide, and comparing with an intensity of the input detection signal to obtain a result after the Boolean logic operation, so as to implement a full binary Boolean logic operation, wherein inputting the logic values into the two phase change functional units refers to inputting corresponding write optical pulse signals into the two phase change functional units using the three-step operation,
wherein the three-step operation comprises:
when logic 0 is input into the first phase change functional unit, in a first operation step a first optical pulse signal is input into the straight waveguide from an end where the first phase change functional unit locates, in the second operation step a second optical pulse signal is input into the straight waveguide from the end where the first phase change functional unit locates, in the third operation step the first optical pulse signal is input into the straight waveguide from the end where the first phase change functional unit locates;
when logic 1 is input into the first phase change functional unit, in the first operation step the second optical pulse signal is input into the straight waveguide from the end where the first phase change functional unit locates, and the optical

Assignees

• Univ Huazhong Science Tech

Inventors

• Cheng Xiaomin
• He Zhuli
• Zhu Yunlai
• Li Han
• Miao Xiangshui

Classifications

• G02F3/00 Primary

  Optical logic elements; Optical bistable devices · CPC title

• G02F2201/307

  Reflective grating, i.e. Bragg grating · CPC title

• G02F2203/11

  involving infrared radiation · CPC title

• G02F2203/50

  Phase-only modulation · CPC title

• G02F1/0147

  based on thermo-optic effects (G02F1/132 takes precedence) · CPC title