Phase shift measuring device and phase shift measuring method

Patent metadata

Field	Value
Publication number	US-12320708-B2
Application number	US-202318316027-A
Country	US
Kind code	B2
Filing date	May 11, 2023
Priority date	May 13, 2022
Publication date	Jun 3, 2025
Grant date	Jun 3, 2025

Abstract

Disclosed is a phase shift measuring device, which includes a dual mode laser including a first beat light source generating a first beating signal and a second beat light source generating a second beating signal, and that outputs a dual mode signal including the first beating signal and the second beating signal, a first splitter that receives the dual mode signal to generate a first branch signal and a second branch signal, the first branch signal and the second branch signal being including the branched first beating signal and the branched second beating signal, respectively, a phase control unit that receives the first branch signal and to generate a combined signal, a transmitting end that receives the combined signal from the phase control unit and generates a transmission signal based on the combined signal, and a receiving end.

First claim

What is claimed is:

1. A phase shift measuring device comprising:
a dual mode laser including a first beat light source generating a first beating signal and a second beat light source generating a second beating signal, and configured to output a dual mode signal including the first beating signal and the second beating signal;
a first splitter configured to receive the dual mode signal to generate a first branch signal and a second branch signal, the first branch signal and the second branch signal being including the branched first beating signal and the branched second beating signal, respectively;
a phase control unit configured to receive the first branch signal to generate a combined signal;
a transmitting end configured to receive the combined signal from the phase control unit and to generate a transmission signal based on the combined signal; and
a receiving end configured to receive the second branch signal from the first splitter and to generate a reference signal based on the second branch signal, and
wherein the phase control unit includes:
a second splitter configured to branch the first branch signal to generate a third branch signal and a fourth branch signal;
a phase adjuster configured to adjust a phase of the third branch signal; and
a combiner configured to generate the combined signal by combining the third branch signal of which the phase is adjusted by the phase adjuster and the fourth branch signal, and
wherein the receiving end includes:
a reception antenna configured to receive the transmission signal; and
a phase analyzer configured to measure a phase shift based on the reference signal and the received transmission signal.

2. The phase shift measuring device of claim 1 , wherein the transmitting end includes:
a first photo mixer configured to generate the transmission signal by mixing a first beating signal and a second beating signal included in the combined signal received to the transmitting end; and
a transmission antenna configured to output the transmission signal to an outside of the transmission end.

3. The phase shift measuring device of claim 2 , wherein the receiving end includes a second photo mixer, and
wherein the second photo mixer is configured to generate the reference signal by mixing a first beating signal and a second beating signal included in the second branch signal received to the receiving end.

4. The phase shift measuring device of claim 3 , wherein the phase analyzer is configured to measure a measurement current by multiplying the transmission signal received by the reception antenna by the reference signal, and
wherein the phase analyzer is configured to measure a phase shift value by a sample by comparing the measurement current when the sample is provided with the measurement current when the sample is not provided.

5. The phase shift measuring device of claim 2 , wherein the first photo mixer includes:
a coupler configured to generate a mixed beating signal by mixing the first beating signal and the second beating signal included in the combined signal, and
an optical-to-electrical converter configured to modulate a photocurrent of a photodiode based on the mixed beating signal to generate the transmission signal.

6. The phase shift measuring device of claim 1 , wherein a strength of the transmission signal output from the transmitting end is expressed by Equation 1,
I T_THz =I 0 {cos(ω THz t+ϕ m1 )+cos(ω THz t−ϕ m1 )+2 cos(ω THz t )},  Equation 1:

in Equation 1, ϕ m1 is an adjustment phase value modulated by the phase adjuster,
ω THz is a difference frequency ω1−ω2 between a first frequency ω1 of the first beating signal and a second frequency ω2 of the second beating signal,
when the transmission signal is irradiated to the sample, a strength of the transmission signal received at the receiving end is expressed by Equation 2,
I m =4 I 0 I 1 cos(ϕ s )[1+cos(ϕ m1 )],  Equation 2:

in Equation 2, ϕ s is the phase shift value according to the sample.

7. The phase shift measuring device of claim 6 , wherein a strength of the reference signal generated at the receiving end is expressed by Equation 3,
I Ref_THz =4 I 1 cos(ω THz t ),  Equation 3:

in Equation 3, ω THz is a difference frequency ω1−ω2 between a first frequency ω1 of the first beating signal and a second frequency ω2 of the second beating signal.

8. The phase shift measuring device of claim 7 , wherein the phase analyzer is configured to obtain a measurement current expressed by Equation 4 by multiplying the strength of the received transmission signal by the strength of the reference signal,
  Equation 4: I m =4 I 0 I 1 cos(ϕ s )[1+cos(ϕ m1 )].

9. The phase shift measuring device of claim 1 , wherein the dual mode laser includes a first single mode laser and a second single mode laser, and
wherein the first single mode laser and the second single mode laser are a distributed feedback laser diode (DFB LD), a distributed Bragg reflector laser diode (DBR LD), a sampled grating distributed Bragg reflector (SGDBR) laser diode (SGDBR LD), or a wavelength tunable single mode laser diode.

10. A method of measuring a phase shift, the method comprising:
outputting a dual mode signal including a first beating signal and a second beating signal through a dual mode laser;
generating a first branch signal and a second branch signal by branching the dual mode laser, the first branch signal and the second branch signal being including the branched first beating signal and the branched second beating signal, respectively;
receiving the first branch signal to generate a combined signal;
receiving the combined signal to generate a transmission signal at a terahertz band;
generating a reference signal based on the second branch signal; and
receiving the transmission signal to measure a phase shift value based on the received transmission signal and the reference signal, and
wherein the generating of the combined signal includes:
branching the first branch signal to generate a third branch signal and a fourth branch signal;
adjusting a phase of the third branch signal; and
generating the combined signal by combining the third branch signal of which the phase is adjusted and the fourth branch signal.

11. The method of claim 10 , wherein the generating of the transmission signal includes generating the transmission signal by mixing a first beating signal and a second beating signal included in the combined signal.

12. The method of claim 11 , wherein the generating of the reference signal includes generating the reference signal by mixing a first beating signal and a second beating signal included in the second branch signal.

13. The method of claim 12 , wherein the measuring of the phase shift value includes:
measuring a measurement current by multiplying the received transmission signal by the reference signal; and
measuring the phase shift value by a sample by comparing the measurement current when the sample is provided with the measurement current when the sample is not provided.

14. The method of claim 10 , wherein a strength of the transmission signal is expressed by Equation 1,
I T_THz =I 0 {cos(ω THz t+ϕ m1 )+cos(ω THz t−ϕ m1 )+2 cos(ω THz t )},  Equation 1:

in Equation 1, ϕ m1 is an adjustment phase value modulated by a phase adjuster,
ω THz is a difference frequency ω1−ω2 between a first frequency ω1 of the first beating signal and a second frequency ω2 of the second beating signal,
when the transmission signal is irradiated to the sample, a strength of the received transmission s

Assignees

• Electronics & Telecommunications Res Inst

Inventors

• Lee Il Min
• Choi Da Hye
• Kim Mugeon
• Park Kyung Hyun
• Park Dong Woo
• Shin Jun-Hwan
• Lee Eui Su

Classifications

• H04B10/07

  Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems · CPC title

• G01J9/04 Primary

  by beating two waves of a same source but of different frequency and measuring the phase shift of the lower frequency obtained · CPC title

• H04B10/90

  Non-optical transmission systems, e.g. transmission systems employing non-photonic corpuscular radiation · CPC title

• H04B2210/006

  Devices for generating or processing an RF signal by optical means · CPC title

• H01S5/1092

  Multi-wavelength lasing · CPC title