CN103532604B - Based on the Wave-packet shaping network able to programme of light WDM technology - Google Patents

Abstract

A programmable beamforming network with ultra-wideband and large dynamic range based on optical wavelength division multiplexing technology. Its structure includes: wavelength division multiplexer, photoelectric modulator, 1×2 optical switch, 2×2 optical switch, optical amplifier, Circulators, Faraday rotators, and fiber optic real-time delay lines. The invention can generate coherent microwave carrier signals with different phase delays, thereby replacing the function of the electric phase shifter in the traditional electronically controlled phased array radar, greatly eliminating the aperture effect in the traditional phased array radar, and having ultra-wideband, Large dynamic range, programmable control and other advantages.

Description

Programmable Beamforming Network Based on Optical Wavelength Division Multiplexing Technology

technical field

The invention relates to a device in the field of microwave photonics, in particular to a programmable beamforming network with ultra-wideband and large dynamic range based on optical wavelength division multiplexing technology.

Background technique

Phased array antenna systems are widely used in fields such as radar and communication systems, and one of the essential components is the phase-delayed beamforming network. In the traditional electronically controlled phased array antenna, an electric phase shifter is set on each antenna unit to change the phase relationship of the signals between the antenna units, so as to provide coherent microwaves with different phase differences for the phased array radar. Signal. However, the traditional electronically controlled phased array radar is limited by the "aperture effect" of the phased array antenna (see Zhang Guangyi, Zhao Yujie, Phased Array Radar Technology. Beijing: Electronic Industry Press, 2006.12:390-392), that is, the signal The frequency change will cause the beam pointing to shift, thus limiting the bandwidth of the radar, which can only be scanned in a relatively narrow signal bandwidth, which limits the performance of its wide bandwidth angle scanning, thus restricting the phased array antenna in complex Environmental and high performance field applications. This is a huge drawback for radars, radar imaging and spread spectrum signal radars where high-resolution measurements are to be made.

With the development of microwave photonics technology and its wide application in the field of radar, optically controlled phased array antennas can effectively offset the limitation of aperture transit time by using real-time delay line technology (see I.Frigyes and A.Seeds, "Optically generated true- time delay in phased-array antennas," Microwave Theory and Techniques, IEEE Transactions on, vol. 43, pp. 2378-2386, 1995.). The beam forming and scanning of the optically controlled phased array antenna realized by using the optically controlled beamforming network has a series of advantages such as large instantaneous bandwidth, no beam squint effect, low loss, small size, anti-electromagnetic interference, and long detection distance. An important direction for the development of phased array radar.

The core part of optically controlled phased array radar is the beamforming network structure that can generate real-time delay. At this stage, the real-time delay schemes of mainstream optically controlled phased array antennas at home and abroad include dispersion structure and optical fiber real-time delay line structure. Among them, there are many ways to form the dispersion structure, such as: fiber gratings (see C.Fan, S.Huang, X.Gao, J.Zhou, W.Gu, and H.Zhang, "Compact high frequency true-time-delay beam former using bidirectional reflection of the fiber gratings, "Optical Fiber Technology, vol.19, pp.60-65, 2013.), high dispersion optical fiber (see M.Y. Chen,"Hybridphotonictrue-timedelaymodulesforquasi-continuoussteeringof2-Dphased-arrayantennas,"JournalofLightwaveTechnology, vol.31, pp.910-917, 2013 .) etc.; the composition of the optical fiber real-time delay line structure includes two directions: the structure of simply changing the length of the optical fiber real-time delay line by switching the optical switch (see B.-M.Jung, D.-H.Kim, I.-P.Jeon, S.-J.Shin, and H.-J.Kim, "Opticaltruetime-delaybeamformerbasedonmicrowavephotonicsforphasedarrayradar,"in20113rdInternationalAsia-PacificConferenceonSyntheticApertureRadar,APSAR2011,September26,2011-September30,201pp1,Seoul,1Korea,2011 .824-827.) and the structure of the combination of wavelength division multiplexer and optical fiber real-time delay line (see O.Raz, S.Barzilay, R.Rotman, and M.Tur,"Submicrosecondscan-angleswitchingphotonicbeamformerwithflatRFResponseintheCandXbands,"JournalofLightwaveTechnology, vol.26 , pp.2774-2781, 2008.). The use of multiple wavelength division multiplexing optical delay technology can greatly simplify the structure of the system, making the system compact.

Contents of the invention

The purpose of the present invention is to provide a multi-wavelength beam forming network device, so as to generate an ultra-wideband, large dynamic range and programmable optical delay network.

Technical solution of the present invention is as follows:

A programmable beamforming network with ultra-wideband and large dynamic range based on optical wavelength division multiplexing technology, characterized in that its composition includes: a first wavelength division multiplexer, a second wavelength division multiplexer, an optoelectronic modulator, a first 1 The ×2 optical switch, the second 1×2 optical switch, the multi-stage delay unit, and the connection component between the delay units, the connection component is a four-port connection component.

The delay unit includes a circulator, a component, a wavelength division multiplexer, an optical fiber real-time delay line and a Faraday rotating mirror; 2 ports of the circulator are connected to the wavelength division multiplexer through the component After light wave demultiplexing is realized, different channels pass through optical fiber real-time delay lines with different delays, and the end of each channel optical fiber real-time delay line is connected with the Faraday rotating mirror; multiple optical signals of different wavelengths are obtained by the After the first wavelength division multiplexer is multiplexed, it enters the optical input end of the photoelectric modulator, and the optical output end of the photoelectric modulator is connected to the port 2 of the first 1×2 optical switch; Port 3 of the first 1×2 optical switch is connected to port 1 of the connection component between the first-stage delay unit and the second-stage delay unit, and port 1 of the first 1×2 optical switch is connected to the first-stage delay unit. The 1 port of the circulator of the unit is connected, the 3 port of the circulator is connected to the 2 port of the connection component between the first stage delay unit and the second stage delay unit, and the 3 port of the connection component is connected to the ring circuit of the second stage delay unit Port 1 of the circulator of the last stage delay unit is connected to port 3 of the second 1×2 optical switch, and port 1 of the second 1×2 optical switch is connected to the previous stage connection component 4 ports, and 2 ports of the second 1×2 optical switch are connected to the second wavelength division multiplexer.

If the component of the delay unit is an optical fiber jumper, the connection component is a dual-input and dual-output connection module composed of an optical switch and an optical amplifier.

If the components of the delay unit are optical amplifiers, the connecting components are 2×2 optical switches.

The wavelength division multiplexer is a dense wavelength division multiplexer (DWDM) or an arrayed waveguide grating type wavelength division multiplexer/demultiplexer (AWG).

The 1×2 optical switch and the 2×2 optical switch are MEMS optical switches, electro-optic switches or magneto-optical switches.

The photoelectric modulator is an optical intensity modulator or an optical phase modulator, and the optical intensity modulator is a lithium niobate MZ structured optical intensity modulator/or a polymer MZ structured optical intensity modulator or an electroabsorption modulator. The optical phase modulator is a lithium niobate phase modulator or a polymer phase modulator.

The optical fiber real-time delay line is a single-mode optical fiber with the following specified lengths:

The optical fiber real-time delay line connected to the back end of the wavelength division multiplexer in the first-stage delay unit has a channel interval of Δτ, and the optical fiber real-time delay line connected to the rear end of the wavelength division multiplexer in the second-stage delay unit has a channel of 2Δτ interval, and so on, the optical fiber real-time delay line connected to the back end of the wavelength division multiplexer in the K-th stage delay unit has a channel interval of 2 ^K-1 Δτ.

The optical amplifier is an erbium-doped optical fiber amplifier or a semiconductor optical amplifier, which is used to amplify the optical signal, effectively suppress the insertion loss of the microwave signal, and reduce the noise figure of the system.

The Faraday rotating mirror is a light wave reflection device, which is used to reduce the length of the optical fiber real-time delay line by half.

The circulator is a low-loss optical passive device for realizing directional transmission of light waves.

The present invention has the following advantages:

1. The optical fiber real-time delay line in the present invention is made on-line by a high-precision cutting method, and the manufacturing accuracy can be continuously improved by improving the measurement method, thereby reducing the interval of the optical fiber real-time delay line between different channels and realizing smaller delay stepping.

2. The present invention is a programmable beamforming network with ultra-bandwidth and wide dynamic range based on optical wavelength division multiplexing technology, using wavelength division multiplexers, photoelectric modulators, optical switches, optical amplifiers, circulators and Faraday rotating mirrors, Combined with different lengths of optical fiber real-time delay lines, different delay steps can be achieved, thereby improving the scanning accuracy of multi-wavelength beamforming.

3. In the present invention, microwave signals are modulated on optical signals of different wavelengths by photoelectric modulators, and real-time optical fiber delay lines are used to realize different delays in the all-optical system, thereby realizing different phase delays of microwave signals. The optical fiber real-time delay line is used in the whole system to realize the real-time delay of the optical signal, so the function of optical phase shifting can be realized for microwave signals of any band, which greatly improves the working bandwidth of the system, that is, the present invention has super characteristics of broadband.

4. In the present invention, optical amplification is performed on each stage of the multi-wavelength delay unit, which effectively suppresses the insertion loss of microwave signals and reduces the noise figure of the system. Therefore, through the topology of the multi-wavelength delay unit, increasing the number of stages of the wavelength division multiplexer can realize a wide range of adjustable delay, that is, the present invention has the characteristics of a large dynamic range.

5. The present invention can perform programmable control on the 1×2 and 2×2 optical switches in the system. Through the combination of "ON" and "OFF" in different modes of the optical switch, different delay channels are selected to realize different delay amounts, that is, the present invention has the feature of programmable.

Description of drawings

FIG. 1 is a schematic structural diagram of an embodiment of an ultra-wideband and large dynamic range programmable beamforming network based on optical wavelength division multiplexing technology in the present invention.

FIG. 2 is a schematic diagram of a topological structure of a programmable beamforming network with ultra-wideband and large dynamic range based on optical wavelength division multiplexing technology according to the present invention.

Figure 3(a) is the port description of 1×2 optical switch, and Figure 2(b) is the port description of 2×2 optical switch.

FIG. 4 is a schematic illustration of a dual-input and dual-output connection module composed of two 1×2 optical switches and optical amplifiers.

Figure 5 shows the ports of the circulator. In the circulator, light waves can only pass from port 1 to port 2, and from port 2 to port 3, and vice versa.

Fig. 6 is an experimental test result of phase delay and frequency generated by a certain channel of optical wavelength division multiplexing under different delay states during the specific implementation of the present invention.

detailed description

A specific embodiment of the present invention is given below in conjunction with the accompanying drawings. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and processes are given, but the protection scope of the present invention should not be limited to the following embodiments.

FIG. 1 is a schematic structural diagram of an embodiment of an ultra-wideband and large dynamic range programmable beamforming network based on optical wavelength division multiplexing technology in the present invention. As can be seen from the figure, this embodiment is based on the optical wavelength division multiplexing technology ultra-wideband large dynamic range programmable beamforming network, which consists of: a first wavelength division multiplexer 1, a second wavelength division multiplexer 19, an optical modulation 2, the first 1×2 optical switch 3, the second 1×2 optical switch 18, the first 2×2 optical switch 8, the second 2×2 optical switch 13, and the three-stage delay unit 23. The first-stage delay unit is composed of a wavelength division multiplexer 5, an optical amplifier 20, a circulator 4, an optical fiber real-time delay line 6, and a Faraday rotating mirror 7; the second-stage delay unit is composed of a wavelength division multiplexer 10 and an optical amplifier 21 , circulator 9, optical fiber real-time delay line 11, Faraday rotating mirror 12; the third stage delay unit is composed of wavelength division multiplexer 15, optical amplifier 22, circulator 14, optical fiber real-time delay line 16, Faraday rotating mirror 17 constitute.

The connection relationship of the above components is as follows:

The optical signals of different wavelengths are multiplexed by the wavelength division multiplexer 1 and enter the optical input end of the photoelectric modulator 2, and the optical output end of the photoelectric modulator 2 is connected to port 2 of the 1×2 optical switch 3, Port 1 of the 1×2 optical switch 3 is connected to port 1 of the circulator 4, and port 3 of the 1×2 optical switch 3 is connected to a port in the direction of the input end of the 2×2 optical switch 8; The light waves are multiplexed by the wavelength division multiplexer 1, and the interfaces of different channels passed through and the microwave input port of the photoelectric modulator are used as the input end of the device;

The 2 ports of the circulator 4 are connected with the optical amplifier 20, and then connected with the wavelength division multiplexer 5 to realize the optical wave demultiplexing, different channels pass through the optical fiber real-time delay lines 6 with different delays, and then each channel The ends are all connected to the Faraday rotating mirror 7; the 3 ports of the circulator 4 are connected to the other port in the direction of the input end of the 2×2 optical switch 8;

One port in the direction of the output end of the 2*2 optical switch 8 is connected to port 1 of the circulator 9, and the other port is connected to a port in the direction of the input end of the 2*2 optical switch 13; The port is connected to an optical amplifier 21, and then connected to a wavelength division multiplexer 10 to realize optical wave demultiplexing. Different channels pass through optical fiber real-time delay lines 11 with different delays, and then the end of each channel is connected to a Faraday rotating mirror 12. ; Port 3 of the circulator 9 is connected to another port in the direction of the input end of the 2×2 optical switch 13;

One port in the output direction of the 2×2 optical switch 13 is connected to the 1 port of the circulator 14, and the other port is connected to the 1 port of the 1×2 optical switch 18; the 2 ports of the circulator 14 are connected to the optical amplifier After 22 is connected, after being connected with wavelength division multiplexer 15 to realize light wave demultiplexing, different channels pass through optical fiber real-time delay lines 16 with different delays, and then each channel end is connected with Faraday rotating mirror 17; circulator 14 The 3 ports of the 1×2 optical switch 18 are connected to each other;

Port 2 of the 1×2 optical switch 18 is connected to a wavelength division multiplexer 19, and different channels after demultiplexing of light waves are realized as output ends of the device.

The wavelength division multiplexers 1, 5, 10, 15, and 19 are dense wavelength division multiplexers (DWDM). The 1×2 optical switches 3, 18 and 2×2 optical switches 8, 13 are MEMS optical switches, wherein the 1×2 optical switches are replaced by 2×2 optical switches. The photoelectric modulator 2 is a lithium niobate MZ structured light intensity modulator. The optical amplifier is a semiconductor optical amplifier (SOA). The optical fiber real-time delay lines 6, 11, and 16 are single-mode optical fibers with a specified length after precision cutting, and the optical fiber real-time delay lines 6 connected to the rear end of the wavelength division multiplexer 5 have a channel interval of Δτ, and the wavelength division The optical fiber real-time delay line 11 connected to the back end of the multiplexer 10 has a channel spacing of 2Δτ, and the optical fiber real-time delay line connected to the rear end of the wavelength division multiplexer 15 has a channel spacing of 4Δτ.

Table 1 shows the test data of four channel intervals in the specific implementation process of the present invention.

Table 1.

The working principle of the present invention is as follows:

Firstly, lasers with multiple wavelengths are multiplexed by DWDM1 and used as carrier signals. Microwave signals are modulated onto carrier signals through the RF input port of photoelectric modulator 2, and then are delayed by DWDM, circulators, optical amplifiers, optical switches, and optical fibers in real time. The programmable optical fiber real-time delay network composed of wires and Faraday rotating mirrors is demultiplexed by DWDM19, thus forming multi-channel coherent modulated carrier signals, which can be sent to the back-end photodetectors and antenna arrays, thereby Complete beam scanning of space.

Among them, the core part of the entire multi-wavelength beamforming network device is the optical fiber real-time delay network. The number of DWDM channels in the basic unit of the delay network is equal to the number of antenna subarrays that need phase shift control. Each channel of DWDM adopts a reflection delay line, and a Faraday rotating mirror is used as a reflection mirror at the end of the channel delay line. The fiber length between DWDM channels is distributed according to the arithmetic sequence. In order to achieve a greater delay, the delay units are cascaded, and an optical switch is introduced for control.

In the delay units of different stages, the inter-wavelength delays of the wavelength division multiplexing are distributed by stages. For example, the first-level DWDM inter-channel (inter-wavelength) delay is distributed according to an arithmetic sequence, and the length difference between channels is set to ΔL. The delay between different channels of the second-level DWDM is still distributed according to an arithmetic sequence, but the inter-channel delay is set to 2×ΔL, the inter-wavelength delay of the third-level DWDM is set to 4×ΔL, and the inter-wavelength delay of the K-level DWDM is set to 2 ^K-1 ×ΔL. For example, during the system implementation, we set the interval between the first-level DWDM5 channels to 5mm, the interval between the second-level DWDM10 channels to 10mm, and the interval between the third-level DWDM15 channels to 20mm for verification. Then we connect the basic units in series through circulators and optical switches to form a continuous, rapidly adjustable multi-wavelength beamforming delay network. Through the "ON" and "OFF" of the optical switch, different delay channels are selected, and finally the carrier signals of different wavelengths form different phase delays.

Claims (9)

1. A programmable beamforming network with ultra-wideband and large dynamic range based on optical wavelength division multiplexing technology, characterized in that its composition includes: a first wavelength division multiplexer, a second wavelength division multiplexer, an optoelectronic modulator, a A 1×2 optical switch, a second 1×2 optical switch, a multi-stage delay unit and a connection component between the delay unit, the connection component is a four-terminal connection component, and the delay unit includes a circulator, a component, A wavelength division multiplexer, an optical fiber real-time delay line and a Faraday rotating mirror; the 2 ports of the circulator are connected to the wavelength division multiplexer through the described components to realize optical wave demultiplexing, and different channels pass through a Optical fiber real-time delay lines with different delays, the end of the optical fiber real-time delay line of each channel is connected to the Faraday rotating mirror; multiple optical signals of different wavelengths are multiplexed by the first wavelength division multiplexer After use, enter the optical input end of the photoelectric modulator, the optical output end of the photoelectric modulator is connected to the 2 port of the first 1×2 optical switch, and the 3 port of the first 1×2 optical switch Connect to port 1 of the connecting component between the first-stage delay unit and the second-stage delay unit, port 1 of the first 1×2 optical switch is connected to port 1 of the circulator of the first-stage delay unit, and the circulator’s Port 3 is connected to port 2 of the connection component between the first-stage delay unit and the second-stage delay unit, port 3 of the connection component is connected to port 1 of the circulator of the second-stage delay unit, and the circulator of the last-stage delay unit Port 3 of the second 1×2 optical switch is connected to port 3 of the second 1×2 optical switch, port 1 of the second 1×2 optical switch is connected to port 4 of the previous stage connection component, and the second 1×2 optical switch The 2 ports are connected to the second wavelength division multiplexer. 2. The programmable beamforming network according to claim 1, wherein if the components of the delay unit are optical amplifiers, the connecting components are 2×2 optical switches. 3. The programmable beamforming network according to claim 1, wherein the wavelength division multiplexer is a dense wavelength division multiplexer (DWDM) or an arrayed waveguide grating type wavelength division multiplexer/demultiplexer (AWG). 4. The programmable beamforming network according to claim 1, characterized in that the 1×2 optical switch, the 2×2 optical switch is a MEMS optical switch, an electro-optical switch or a magneto-optical switch, 5. The programmable beamforming network according to claim 1, characterized in that the optoelectronic modulator is an optical intensity modulator or an optical phase modulator. 6. The programmable beamforming network according to claim 5, characterized in that the optical intensity modulator is a lithium niobate MZ structured optical intensity modulator/or a polymer MZ structured optical intensity modulator or an electroabsorption modulator . 7. The programmable beamforming network according to claim 5, wherein the optical phase modulator is a lithium niobate phase modulator or a polymer phase modulator. 8. The programmable beamforming network according to claim 1, characterized in that said optical fiber real-time delay line is a single-mode optical fiber with the following specified length: the wavelength division multiplexer rear end connection in the first-stage delay unit The optical fiber real-time delay line has a channel interval of Δτ, the optical fiber real-time delay line connected to the back end of the wavelength division multiplexer in the second-stage delay unit has a channel interval of 2Δτ, and so on, the WDM in the K-th-stage delay unit The fiber optic real-time delay line connected to the back end of the multiplexer has a channel spacing of 2 ^K-1 Δτ. 9. The programmable beamforming network according to claim 2, characterized in that said optical amplifier is an erbium-doped fiber amplifier or a semiconductor optical amplifier.