Coherent microwave photonics radar detection method and system based on injection locking frequency multiplication

Patent metadata

Field	Value
Publication number	US-12411208-B2
Application number	US-202218088743-A
Country	US
Kind code	B2
Filing date	Dec 26, 2022
Priority date	Jul 7, 2021
Publication date	Sep 9, 2025
Grant date	Sep 9, 2025

Abstract

Discloses a coherent microwave photonics radar detection method and system based on injection locking frequency multiplication. The method uses a baseband signal to modulate an optical carrier to generate a modulated optical signal including a plurality of high-order sidebands; the modulated optical signal is divided into two paths which are respectively injected into two slave lasers for high-order sideband injection locking to obtain two locked sideband optical signals; Based on combining and splitting two locked sideband optical signals, the radar transmitting signal and receiving optical signal can be obtained through photo-detection and electro-optic modulation. After coherent detection of receiving optical signal, obtaining the intermediate frequency signal, and detection target information can be extracted from intermediate frequency signal by radar algorithm.

First claim

What is claimed is:

1. A coherent microwave photonics radar detection method based on injection locking frequency multiplication, comprising the following steps of:
modulating an optical carrier fc output by a master laser through an electro-optic modulator by using a baseband linear frequency modulation (LFM) signal with a frequency of f LFM to obtain a modulated optical signal containing a high-order modulation sideband f C ±nf LFM , where n is a positive integer;
dividing the modulated optical signal into two paths to be injected into two slave lasers respectively for high-order sideband injection locking, and outputting, by the two slave lasers, respectively, a first amplified locked sideband f C −Mf LFM optical signal and a second amplified locked sideband f C +Nf LFM optical signal, where M and N are positive integers;
selecting one locked sideband optical signal to be divided into two paths, wherein one path is combined with the other amplified locked sideband optical signal to form a radar detection optical signal, and the other path serves as a receiving optical signal to receive a radar echo signal to obtain a radar receiving optical signal;
dividing the radar detection optical signal into two paths, wherein one path is subjected to photoelectric conversion to obtain a frequency multiplication radar transmitting signal (M+N)f LFM , and setting the frequency multiplication radar transmitting signal being reflected from target as the radar echo signal, and the other path serves as a reference optical signal to achieve coherent receiving of the radar echo signal together with the radar receiving optical signal, so as to obtain a complex intermediate frequency signal carrying target information; and
processing the complex intermediate frequency signal to extract detection target information.

2. The method according to claim 1 , wherein the slave laser is a distributed feedback laser, and a free working frequency f SL1 of a first slave laser whose frequency is close to the sideband f C −Mf LFM is required to satisfy:

-

f

d
⁢
1

⁢

I
11

I
01

⁢

(

1
+

α
1

2

)

<

f

C
-

⁢

Mf

LFM
-

⁢

f
SLI

<

f

d
⁢
1

⁢

I
11

I
01

where f d1 is a mode interval of the first slave laser, I 11 is an optical injection power of the first slave laser, I 01 is an output power of the first slave laser, and α 1 is a linewidth enhancement factor related to the first slave laser; a free working frequency f SL2 of a second slave laser whose frequency is close to the sideband f C +Nf LFM is required to satisfy:

-

f

d
⁢
2

⁢

I
12

I
02

⁢

(

1
+

α
2

2

)

<

f
C

+

Nf

LFM
-

⁢

f

SL
⁢
2

<

f

d
⁢
2

⁢

I
12

I
02

where f d2 is a mode interval of the second slave laser, I 12 is an optical injection power of the second slave laser, I 02 is an output power of the second slave laser, and α 2 is a linewidth enhancement factor related to the second slave laser.

3. The method according to claim 1 , wherein different sidebands of the modulated optical signal are selectively locked and amplified by controlling free working wavelengths, optical injection powers and output powers of the two slave lasers, so as to realize a different frequency multiplication factor M+N of the radar transmitting signal relative to a baseband LFM signal.

4. A coherent microwave photonics radar detection system based on injection locking frequency multiplication, comprising:
a master laser configured to generate an optical carrier signal fc;
a signal source configured to generate a baseband linear frequency modulation (LFM) signal with a frequency of f LFM ,
a first electro-optic modulator configured to modulate a baseband LFM signal to the optical carrier signal to obtain a modulated optical signal containing a high-order modulation sideband f C ±nf LFM , where n is a positive integer;
a first optical coupler configured to divide the modulated optical signal into two paths;
two slave lasers configured to respectively receive the two paths of the modulated optical signal output

Assignees

• Zhejiang Lab

Inventors

• Guo Qingshui
• Yin Kun
• Ji Chen
• Wang Jihou
• Ying Xiaojun

Classifications

• G01S13/34

  using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal · CPC title

• G01S13/0209

  Systems with very large relative bandwidth, i.e. larger than 10 %, e.g. baseband, pulse, carrier-free, ultrawideband · CPC title

• G01S7/352

  Receivers · CPC title

• H04B10/615

  Arrangements affecting the optical part of the receiver · CPC title

• G01S7/48

  of systems according to group G01S17/00 · CPC title