CN102324892A - High-frequency microwave signal full-gloss down conversion system - Google Patents

Abstract

The invention provides a high-frequency microwave signal full-gloss down conversion system which comprises a light source, a dual-parallel intensity modulator, a polarization controller and a low-frequency detector, wherein the light source is used for generating light carriers in any polarization state; the dual-parallel intensity modulator is in a two-way radio frequency input mode, comprises two radio frequency input ports and is used for inputting a high-frequency microwave signal and a local oscillation signal respectively through the two input ports, simultaneously loading the high-frequency microwave signal and the local oscillation signal to a light carrier as well as modulating and coupling the two paths of optical signals and then outputting the modulated and coupled optical signals through one port; the polarization controller is connected between the light source and the dual- parallel intensity modulator and is used for adjusting the polarization states of the light carriers output by the light source to be consistent with that of the main shaft of the dual-parallel intensity modulator; the low-frequency detector is connected with the dual parallel intensity modulator and is used for converting the optical signals output by the modulator into electric signals and shooting the high-frequency microwave signal difference to low-mid frequency (LMF) so as to realize the full-gloss down conversion of the microwave signal and simultaneously filter out high-frequency interference signals. The system provided by the invention has the advantages of low cost, simple structure, reliable performance and capability of realizing the direct down conversion of the high-frequency microwave signal.

Description

The full light down conversion system of high-frequency microwave signal

Technical field

The present invention relates to the microwave photon technical field, the full light down conversion system of particularly a kind of high-frequency microwave signal.

Background technology

Along with the development of following microwave communication technology, radio system will realize high frequencyization and broadband gradually, and this has all proposed challenge to follow-up analog-to-digital conversion and digital processing element.In order to break through the development bottleneck of electronic device, must introduce the microwave down-conversion technique, carry out analog-to-digital conversion and digital processing in the medium and low frequency section, this will greatly reduce the subsequent treatment difficulty and to the bandwidth requirement of electronic device.Traditional microwave down-conversion technique needs to adopt multi-stage transformation at present, and the component number of use is many, complex structure, and volume is big, and cost is high, and the conversion loss of system is bigger, and phase noise and nonlinear distortion are serious, have local-oscillator leakage.Than traditional microwave down-conversion technique; The microwave photon down conversion system has plurality of advantages owing to introduced powerful photon technology as auxiliary, such as; Simple in structure, bandwidth is high, volume is little, loss is low, anti-electromagnetic interference etc., can effectively overcome the drawback of conditional electronic device.Therefore, adopt the microwave photon technology to realize that the direct down conversion of frequency has very application prospects in the microwave telecommunication system in future.

The full light down-conversion chain of the high-frequency microwave signal line structure figure that is of the prior art based on the series connection intensity modulator as shown in Figure 1.Local oscillation signal is modulated on the light carrier through first intensity modulator 30 ', and the radiofrequency signal that antenna receives is loaded on the light carrier through second intensity modulator 40 ', obtains the intermediate-freuqncy signal after the down-conversion through detector 50 ' beat frequency at last.

Above-mentioned microwave photon down conversion is simple in structure, and the input port of radiofrequency signal and local oscillator separates, and has high isolation.Yet the cascade of modulator makes that the loss of link is bigger, and it is limited to gain, the intermediate-freuqncy signal after the down-conversion a little less than, reduced the performance of frequency conversion system.

Therefore, be necessary to design a kind of reliable and stable, simple and practical, cost is lower, and can realize the full light down conversion system of the directly efficient down-conversion of high-frequency microwave signal.

Summary of the invention

The technical problem that (one) will solve

The purpose of this invention is to provide a kind of low cost, the full light down conversion system of high-frequency microwave signal simple in structure, dependable performance, realize the directly efficient down-conversion of high-frequency microwave signal.

(2) technical scheme

In order to solve the problems of the technologies described above, the invention provides the full light down conversion system of a kind of high-frequency microwave signal based on two parallel intensity modulators, comprising:

Light source is used to produce the light carrier of random polarization state;

Two parallel intensity modulators; Be two-way radio frequency input pattern, comprise two rf inputs mouths, be used for high-frequency microwave signal and local oscillation signal are imported from said two rf inputs mouths respectively; Be loaded on the light carrier simultaneously, and two ways of optical signals modulation coupling back is exported from a port;

Polarization Controller is connected between said light source and the two parallel intensity modulators, is used for being adjusted into the polarization state of the light carrier of light source output consistent with the main shaft of pair parallel intensity modulators; And

The low-frequency acquisition device; Connect with said two parallel intensity modulators, be used for converting the light signal of modulator output to the signal of telecommunication, and required medium and low frequency section is arrived in the high-frequency microwave signal beat; Realize the full light down-conversion of microwave signal, filter out high-frequency interferencing signal simultaneously.

Preferably; Said two parallel intensity modulator comprises that also three direct current biasing ends regulate the gain and the linearity of said two ways of optical signals respectively through changing the first and second direct current biasing ends, and the coupled modes through changing the 3rd direct current biasing end control two ways of optical signals are also regulated gain.

Preferably, said light source is the continuous laser source.

(3) beneficial effect

1. the present invention is in order to realize the direct down-conversion design of high-frequency microwave signal single-stage, and core devices is two parallel intensity modulators, uses project organization of the present invention, can the microwave signal of any frequency range be direct down-conversion-to needed medium and low frequency section on the principle.The frequency range of the microwave signal of required down-conversion is limited by the operating frequency range of modulator, detector and other microwave device only.Therefore, the present invention can realize the direct down-conversion of single-stage of high-frequency microwave signal.

2. the bias point of modulator can be set arbitrarily according to system's needs, changes first, second direct current biasing, can regulate the gain and the linearity of the full light down conversion system of high-frequency microwave signal; Change the 3rd direct current biasing, can control the coupled modes of two paths of signals up and down, regulate the gain of the full light down conversion system of high-frequency microwave signal; Optimization of system performance; Greatly reduce the complexity of system, make simple to operately, be easy to realize.

3. use commercial two parallel intensity modulator to realize that high-frequency microwave signal is down-converted to the medium and low frequency section, this mixing system height is integrated, reliable and stable, the drawback of having avoided discrete intensity modulator scheme to bring.

4. the two parallel intensity modulator that uses is two-way radio frequency input pattern, and high-frequency microwave signal and local oscillation signal can be loaded on the light carrier through two rf inputs mouths, have realized high isolation.

Description of drawings

Fig. 1 is the full light down-conversion chain of the high-frequency microwave signal line structure figure based on separation series connection intensity modulator of the prior art;

Fig. 2 is the structure chart of integrated two parallel intensity modulator one embodiment of the present invention's employing;

Fig. 3 is the structure chart of full light down conversion system one embodiment of high-frequency microwave signal of the present invention.

Wherein, prior art: 10 ': light source; 20 ': Polarization Controller; 30 ', 40 ': Mach increases the Dare intensity modulator; 31 ', 41 ': the rf inputs mouth; 32 ', 42 ': the direct current biasing end; 50 ': detector; The present invention: 10: light source; 20: Polarization Controller; 30: two parallel intensity modulators; 31,32,35: the direct current biasing end; 33,34: the rf inputs mouth; 40: the low-frequency acquisition device.

Embodiment

Below in conjunction with accompanying drawing and embodiment, specific embodiments of the invention describes in further detail.Following examples are used to explain the present invention, but are not restriction scopes of the present invention.

Fig. 2 is the structure chart of integrated two parallel intensity modulator one embodiment that the present invention adopts, comprises two rf inputs mouths 33,34, three direct current biasing ends 31,32,35 and one road optical output ports.In the present embodiment; Use wherein one road rf input port input microwave signal, other one road rf input port input local oscillation signal can be through changing preceding two direct current biasings 31; 32 regulate the gain and the linearity of the full light down conversion system of high-frequency microwave signal; Through changing the 3rd the direct current biasing 35 controls coupled modes of two paths of signals up and down, regulate the gain of the full light down conversion system of high-frequency microwave signal, optimization of system performance.

Fig. 3 is the structure chart of full light down conversion system one embodiment of high-frequency microwave signal of the present invention, comprising: light source 10, be used to produce light carrier, and carry microwave signal, and this light carrier is random polarization state, light source 10 is the continuous wave laser source in the present embodiment; Two parallel intensity modulators 30 are used for high-frequency microwave input signal and local oscillation signal are imported from two rf inputs mouths 33,34 of modulator respectively; Be modulated on the light carrier simultaneously; Through changing the gain and the linearity that preceding two direct current biasing ends 31,32 are regulated two paths of signals, through changing the 3rd the direct current biasing end 35 controls coupled modes of two paths of signals up and down; Regulate the gain of the full light down conversion system of high-frequency microwave signal, optimization of system performance; Polarization Controller 20 is connected between said light source 10 and the two parallel intensity modulators 30, is used for being adjusted into the polarization state of the light carrier of light source 10 outputs consistent with the main shaft of pair parallel intensity modulators 30; And low-frequency acquisition device 40, connect with said two parallel intensity modulators 30, be used for converting the light signal of modulator output to the signal of telecommunication, and realize the high-frequency microwave signal beat to the medium and low frequency section, filtering simultaneously the interference signal of high frequency, realize filter function.

In the present embodiment, two parallel intensity modulators 30 are imported high-frequency microwave input signal and local oscillation signal respectively from two rf inputs mouths of modulator, be modulated on the light carrier simultaneously; Through changing preceding two direct current biasings; Regulate the gain and the linearity of the full light down conversion system of high-frequency microwave signal, through changing the 3rd direct current biasing, control is the coupled modes of two paths of signals up and down; Regulate the gain of the full light down conversion system of high-frequency microwave signal, optimization of system performance.The output field intensity of two way modulators is respectively shown in formula (1) and (2) about in two parallel intensity modulators:

$E_a=2E_{\mathrm{in}}\cos \left(\frac{\mathrm{\π}(V_{b1}+V_{\mathrm{RF}}\left(t\right))}{2V_{\mathrm{\π}1}}\right)e^{j\frac{\mathrm{\π}(V_{b1}+V_{\mathrm{RF}}\left(t\right))}{2V_{\mathrm{\π}1}}}---\left(1\right)$

$E_b=2E_{\mathrm{in}}\cos \left(\frac{\mathrm{\π}(V_{b2}+V_{\mathrm{LO}}\left(t\right))}{2V_{\mathrm{\π}2}}\right)e^{j\frac{\mathrm{\π}(V_{b3}+V_{\mathrm{LO}}\left(t\right))}{2V_{\mathrm{\π}2}}}{e}^{j\frac{\mathrm{\π}{V}_{b3}}{V_{\mathrm{\π}3}}}---\left(2\right)$

Wherein, E _InBe the input optical signal field intensity of two-way about the double-parallel modulator, V _B1And V _B2Be respectively the bias voltage of preceding two the direct current biasing ends 31 of modulator and 32, V _{π 1}And V _{π 2}Be respectively two parallel intensity modulators direct current half-wave voltage of two way modulators up and down, V _B3And V _{π 3}Be respectively the bias voltage and the direct current half-wave voltage of the 3rd offset side, V _RF(t) and V _LO(t) be respectively radiofrequency signal and the local oscillation signal that the upper and lower two branch road rf inputs of double-parallel modulator are imported.

In two parallel intensity modulators, the light signal of two branch roads after modulation is coupled at output up and down, obtains the power output of modulator, wherein comprises the corresponding afterwards intermediate-freuqncy signal item of high-frequency microwave signal down-conversion, shown in formula (3):

$P_{\mathrm{IF}}=2P_{\mathrm{in}}{\left(\frac{\mathrm{\π}}{V_{\mathrm{\π}}}\right)}^2\cos \left[\frac{\mathrm{\π}}{V_{\mathrm{\π}}}(V_{b1}-V_{b2}-V_{b3})\right]\cos ({\mathrm{\ω}}_{\mathrm{RF}}-{\mathrm{\ω}}_{\mathrm{LO}})t---\left(3\right)$

Because the direct current half-wave voltage of two three offset sides of parallel intensity modulator is generally identical, so, V is here arranged _{π 1}=V _{π 2}=V _{π 3}=V _π

The present invention directly is loaded into microwave input signal and local oscillation signal on two rf inputs mouths of two parallel intensity modulators, through the bias voltage of adjusting modulator, and the performance of optimization system, simple to operate, be easy to realize.

The above only is a preferred implementation of the present invention; Should be pointed out that for those skilled in the art, under the prerequisite that does not break away from know-why of the present invention; Can also make some improvement and replacement, these improvement and replacement also should be regarded as protection scope of the present invention.

Claims (3)

1. the full light down conversion system of high-frequency microwave signal is characterized in that, comprising:

Light source (10) is used to produce the light carrier of random polarization state;

Two parallel intensity modulators (30); Be two-way radio frequency input pattern, comprise two rf inputs mouths (33,34); Be used for high-frequency microwave signal and local oscillation signal respectively from said two rf inputs mouths (33; 34) input is loaded on the light carrier simultaneously, and two ways of optical signals modulation coupling back is exported from a port;

Polarization Controller (20) is connected between said light source (10) and the two parallel intensity modulators (30), is used for being adjusted into the polarization state of the light carrier of light source (10) output consistent with the main shaft of pair parallel intensity modulators (30); And

Low-frequency acquisition device (40); Connect with said two parallel intensity modulators (30), be used for converting the light signal of modulator output to the signal of telecommunication, and required medium and low frequency section is arrived in the high-frequency microwave signal beat; Realize the full light down-conversion of microwave signal, filter out high-frequency interferencing signal simultaneously.

2. the full light down conversion system of high-frequency microwave signal as claimed in claim 1; It is characterized in that; Said two parallel intensity modulator (30) comprises that also three direct current biasing ends (31,32,35) are through changing the first and second direct current biasing ends (31; 32) regulate the gain and the linearity of said two ways of optical signals respectively, the coupled modes through changing the 3rd direct current biasing end (35) control two ways of optical signals are also regulated gain.

3. the full light down conversion system of high-frequency microwave signal as claimed in claim 1 is characterized in that said light source (10) is the continuous laser source.

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