KR101144301B1 - Microwave photonic variable filter system using fixed-wavelength sources and method thereof - Google Patents

Microwave photonic variable filter system using fixed-wavelength sources and method thereof Download PDF

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KR101144301B1
KR101144301B1 KR1020110050556A KR20110050556A KR101144301B1 KR 101144301 B1 KR101144301 B1 KR 101144301B1 KR 1020110050556 A KR1020110050556 A KR 1020110050556A KR 20110050556 A KR20110050556 A KR 20110050556A KR 101144301 B1 KR101144301 B1 KR 101144301B1
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South Korea
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optical
signal
light source
modulated
fixed light
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KR1020110050556A
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Korean (ko)
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정병민
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삼성탈레스 주식회사
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/25—Arrangements specific to fibre transmission
    • H04B10/2507—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0201—Add-and-drop multiplexing
    • H04J14/0202—Arrangements therefor
    • H04J14/0205—Select and combine arrangements, e.g. with an optical combiner at the output after adding or dropping
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0201—Add-and-drop multiplexing
    • H04J14/0202—Arrangements therefor
    • H04J14/0209—Multi-stage arrangements, e.g. by cascading multiplexers or demultiplexers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B2210/00—Indexing scheme relating to optical transmission systems
    • H04B2210/25—Distortion or dispersion compensation

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optical Communication System (AREA)
  • Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)

Abstract

PURPOSE: A microwave photonic variable filter system and a method thereof which uses wavelength fixing light source is provided to reduce a processing time by using a wavelength fixing light source. CONSTITUTION: An optical amplifying unit(600) amplifies an optical modulation RF(Radio Frequency) signal combined with an optical coupling unit. A microwave photonic filter(11) performs RF signal process of the optical modulation RF signal. An optical detecting unit(1000) detects the optical modulation RF signal. The optical detecting unit converts the detected optical modulation RF signal into an RF signal. An RF signal processing unit(1100) outputs the converted RF signal.

Description

MICROWAVE PHOTONIC VARIABLE FILTER SYSTEM USING FIXED-WAVELENGTH SOURCES AND METHOD THEREOF}

The present invention relates to a microwave photonic variable filter system and a method thereof, and more particularly, to a microwave photonic variable filter system and a method using a wavelength fixed light source.

Hereinafter, a problem according to the prior art will be described with reference to FIG. 1.

1 is a block diagram of a microwave photonic variable filter system according to the prior art.

The conventional microwave photonic variable filter system according to FIG. 1 performs a function of a band pass filter or a notch filter according to a coefficient of a signal input to an RF filter. For example, if the coefficient of the RF signal of the filter consisting of eight array elements is (+1, +1, +1, +1, +1, +1, +1, +1), the transmission spectrum in the form of band pass is And (+1, -1, +1, -1, +1, -1, +1, -1), a transmission spectrum in the form of a notch filter is formed.

Referring to the operation of FIG. 1, the optical signals output from a plurality of variable wavelength light sources are used. In the conventional case, the overall variable processing time becomes very long due to the time required for wavelength conversion.

In addition, since a very precise and stable wavelength conversion operation is required, the unit cost of such a tunable light source is very expensive. In addition, since the number is also required a lot, the overall price of the microwave photonic variable filter system has a disadvantage that is raised by several orders of magnitude.

On the other hand, conventionally, since there is only one optical modulator, the optical modulator may only operate as one of the band pass filter or the notch filter according to the coefficient of the RF signal.

An object of the present invention is to provide a microwave photonic variable filter system using a wavelength fixed light source.

Another object of the present invention is to provide a microwave photonic variable filtering method using a wavelength fixed light source.

The microwave photonic variable filter system using the wavelength fixed light source according to the object of the present invention described above comprises a first wavelength fixed light source for outputting a plurality of optical signals having different fixed wavelengths, and a plurality of fixed wavelengths having different fixed wavelengths. Multiplexing a second wavelength fixed light source for outputting an optical signal, a first optical multiplexer for multiplexing a plurality of optical signals output from the first wavelength fixed light source, and a plurality of optical signals output from the second wavelength fixed light source A second optical multiplexer, a first optical modulator for converting an RF received signal into an optically modulated RF signal by using the optical signal multiplexed by the first optical multiplexer, and an optical signal multiplexed by the second optical multiplexer A second optical modulator for converting an RF received signal into an optically modulated RF signal, an optical modulated RF signal converted by the first optical modulator, and an optical modulated RF signal converted by the second optical modulator An optical coupling unit for combining and outputting an arc, an optical amplifying unit for amplifying the optically modulated RF signal output from the optical coupling unit, and a microwave photonic for RF signal processing the optically modulating RF signal output from the optical amplifying unit It may be configured to include a filter, an optical detector for converting the RF signal-processed light modulated RF signal into an RF signal, and an RF signal output unit. Here, further comprising a first bias voltage source for supplying a DC bias voltage to the first optical modulation unit, and a second bias voltage source for supplying a DC bias voltage to the second optical modulation unit, wherein the microwave photonic filter is band The first bias voltage source and the second bias voltage source supply the same DC bias voltage to each other for pass filtering, and the first bias voltage source and the second bias to cause the microwave photonic filter to perform notch filtering. The power supply may be configured to supply different DC bias voltages. In this case, the first wavelength fixed light source and the second wavelength fixed light source may be configured to output a plurality of optical signals having wavelengths that alternately increase. The microwave photonic filter may generate time delay differences in order according to wavelengths of optical signals of the first wavelength fixed light source and the second wavelength fixed light source through an optical fiber delay line matrix, thereby performing band pass filtering or notch filtering. It may be configured to convert the center frequency. In this case, the microwave photonic filter may be configured to expand the bandwidth of band pass filtering or notch filtering by variably attenuating the magnitude of the optical signal.

In the microwave photonic variable filtering method using a wavelength fixed light source according to another object of the present invention, the first optical multiplexer multiplexes a plurality of optical signals having different fixed wavelengths output from the first wavelength fixed light source, A second optical multiplexer multiplexing a plurality of optical signals having different wavelengths output from a second wavelength fixed light source, and a first optical modulator using an optical signal multiplexed by the first optical multiplexer using an RF received signal Converting the signal into an optically modulated RF signal, and converting an RF received signal into an optically modulated RF signal by using a second optical modulator by using the optical signal multiplexed by the second optical multiplexer; Combining and outputting the optically modulated RF signal converted by the second unit and the optically modulated RF signal converted by the second optical modulator; Amplifying and outputting an RF signal, RF signal processing of an optical modulated RF signal output from the optical coupling unit by a microwave photonic filter, and an optical detection unit converting the optical modulated RF signal processed by the RF signal into an RF signal And a RF signal output unit. Here, the first optical modulator converts the RF received signal into an optically modulated RF signal by using the optical signal multiplexed by the first optical multiplexer, and the second optical modulator uses the optical multiplexed by the second optical multiplexer. The converting of the RF received signal into an optically modulated RF signal by using a signal may include the first and second optical modulators having the same bias voltage so that the microwave photonic filter performs band pass filtering. The first light modulator and the second light modulator may be configured to receive different bias voltages so that the microwave photonic filter is notched filtered. In this case, the first optical multiplexer multiplexes a plurality of optical signals having different fixed wavelengths output from the first wavelength fixed light source, and the second optical multiplexer has a plurality of wavelengths having different wavelengths output from the second wavelength fixed light source. The multiplexing of the optical signal may be configured to output a plurality of optical signals having wavelengths that are alternately increased in the first wavelength fixed light source and the second wavelength fixed light source. The microwave photonic filter may perform RF signal processing on an optically modulated RF signal output from the optical coupling unit, wherein the microwave photonic filter comprises the first wavelength-fixed light source and the second wavelength through an optical fiber delay line matrix. It can be configured to convert the center frequency of band pass filtering or notch filtering by generating a time delay difference in sequence depending on the wavelength of the optical signal of the wavelength fixed light source. The microwave photonic filter may perform RF signal processing on an optically modulated RF signal output from the optical coupling unit, and the microwave photonic filter variably attenuates the magnitude of the optical signal, thereby performing band pass filtering or notching. It can be configured to extend the bandwidth of the filtering.

According to the microwave photonic variable filter system and the method using the plurality of wavelength fixed light sources as described above, by using a wavelength fixed light source instead of a conventional wavelength variable light source, it is possible to drastically reduce processing time and perform stable operation. There is. In addition, there is an advantage that the overall system price is reduced due to the wavelength fixed light source having a very low unit cost compared to the variable wavelength light source of excessive manufacturing cost. In addition, since the bias voltage source and the optical modulator are increased to two, the band pass filter and the notch filter can be simultaneously implemented in parallel.

1 is a block diagram of a microwave photonic variable filter system according to the prior art.
2 is a schematic block diagram of a microwave photonic variable filter system using a wavelength fixed light source according to an embodiment of the present invention.
Figure 3 is a detailed block diagram of a microwave photonic variable filter system using a wavelength fixed light source according to an embodiment of the present invention.
4 is a graph illustrating a transmission function characteristic according to a DC bias voltage of an optical modulator according to an exemplary embodiment of the present invention.
5 is an experimental schematic diagram of a microwave photonic variable filter system operating in two bits according to an embodiment of the present invention.
6 (a) and 6 (b) are graphs of simulation calculated values and measured values of the transmission spectrum when the time delay is 50 ps in the experimental configuration of FIG. 5.
7 is a graph of the output signal with the same DC bias voltage and 50 ps time delay in the experimental configuration of FIG. 5.
8 (a) and 8 (b) are graphs of simulation calculations and measured values for the transmission spectrum when the time delay is 150 ps in the experimental configuration of FIG. 5.
FIG. 9 is a graph of the detected RF signal when the same DC bias voltage and time delay is 150 ps in the experimental configuration of FIG. 5.
10 is a flowchart of a microwave photonic variable filtering method using a wavelength-fixed light source according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. Like reference numerals are used for like elements in describing each drawing.

The terms first, second, A, B, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Hereinafter, preferred embodiments according to the present invention will be described with reference to the accompanying drawings.

2 is a schematic block diagram of a microwave photonic variable filter system using a wavelength-fixed light source according to an embodiment of the present invention, and FIG. 3 is a detailed block diagram.

2 and 3, the microwave photonic variable filter system 10 (hereinafter referred to as a 'microwave photonic variable filter system') using a wavelength-fixed light source according to an embodiment of the present invention may be a first embodiment. The wavelength fixed light source 101, the second wavelength fixed light source 102, the first light multiplexer 201, the second light multiplexer 202, the first light modulator 301, and the second light modulator 302. ), RF signal input unit 400, the first bias voltage source 401, the second bias voltage source 402, the optical coupling unit 500, the optical amplifier 600, the microwave photonic filter 11, the optical detector 1000 and the RF signal output unit 1100. Here, the microwave photonic filter 11 may be configured to include an optical demultiplexer 701, an optical fiber delay line matrix 800, a variable light attenuator 900, and an optical multiplexer 702.

Unlike the conventional microwave photonic filter, the microwave photonic variable filter system 10 uses the wavelength-fixed light sources 101 and 102 to reduce manufacturing costs and improve operation speed and stability. In addition, by using the transmission function characteristics of the optical modulators 301 and 302 that adjust the phase of the RF signal by 180 degrees, it is easy to convert a function between band pass filtering and notch filtering. Hereinafter, the detailed structure is demonstrated.

The first wavelength fixed light source 101 is configured in plural to output a plurality of optical signals having different fixed wavelengths, and the second wavelength fixed light source 102 is configured to output a plurality of optical signals having different fixed wavelengths. Consists of dogs. Here, different fixed wavelengths of the first wavelength fixed light source 101 are λ 1 , λ 3 , λ 5,..., Λ 2m-1 , and the different fixed wavelengths of the second wavelength fixed light source 102 are λ 2 , λ 4 , λ 6 ,..., λ 2m can be configured to be assigned to the increasing wavelength alternately with each other. In this case, the first optical modulator 301 and the second optical modulator 302 each have the same +1 coefficient of the RF signal or +1 and -1, which are coefficients of different RF signals, alternately appear. Because it can.

The first optical multiplexer 201 multiplexes a plurality of optical signals output from the first wavelength fixed light source 101 and inputs the multiplexed optical signals to the optical ports of the first optical modulator 301. The second optical multiplexer 202 multiplexes a plurality of optical signals output from the second wavelength fixed light source 102 and inputs the multiplexed optical signals to the optical ports of the second optical modulator 302.

The first optical modulator 301 converts an RF received signal into an optically modulated RF signal by using the optical signal multiplexed by the first optical multiplexer 201, and the second optical modulator 302 uses the second optical multiplexer. The unit 201 converts the RF received signal into an optically modulated RF signal using the multiplexed optical signal. Here, the RF received signal is received from the RF signal input unit 400.

Meanwhile, the first bias voltage source 401 supplies a DC bias voltage to the first optical modulator 301, and the second bias voltage source 402 supplies a DC bias voltage to the second optical modulator 302. In this case, the first bias voltage source 401 may be configured to supply a fixed DC bias voltage and the second bias voltage source 402 may supply a variable DC bias voltage. The phase of the signal may be changed 180 degrees according to the difference of the DC bias voltage. The first bias voltage source 401 and the second bias voltage source 402 supply the same DC bias voltage to each other so that the microwave photonic filter 11 performs band pass filtering, and the microwave photonic filter 11 It is configured to supply different DC bias voltages for notch filtering.

The optical combiner 500 combines and outputs the optical modulated RF signal converted by the first optical modulator 301 and the optical modulated RF signal converted by the second optical modulator 302.

The optical amplifier 600 amplifies the light modulated RF signal output from the optical coupler 500.

The microwave photonic filter 11 RF-processes the amplified light modulated RF signal. Here, the microwave photonic filter 11 sequentially changes the time delay difference according to the wavelengths of the optical signals of the first wavelength fixed light source 101 and the second wavelength fixed light source 102 through the optical fiber delay line matrix 800. By generating a center frequency of band pass filtering or notch filtering.

In the microwave photonic filter 11, the optical fiber delay line matrix 800 is composed of an optical fiber delay line matrix composed of 2 × 2 optical switches connected to an optical fiber delay line at a cross port as shown in FIG. 3. The 2 × 2 optical switch matrix is configured to obtain a time delay by operating one column at the same time in a bar or cross state. When all the optical switches are in the bar state, the time delays of the signals output from λ 1 , λ 2 , ..., λ 2m-1 and λ 2m are the same. The length of the optical fiber delay line connected to the cross port of the optical switch column is the time delay corresponding to 2 0 Δτ for each increment of the row number in the case of the first optical switch column. Each time the number of rows increases by one, in the case of the second optical switch column, the time delay increases by the optical fiber length corresponding to 2 1 Δτ. In the case of the n-th optical switch column, each time the number of rows increases by one, the time delay increases by the optical fiber length corresponding to 2 (n-1) Δτ.

For example, when all the optical switches are in the bar state, the signal delay difference of each signal output from λ 1 , λ 2 , ..., λ 2m-1 , λ 2m is 0, and the first column ( When only the optical switch in column) is in the cross state, the time delay difference of each signal output in the rows of λ 1 , λ 2 ,..., λ 2m-1 , λ 2m is Δτ. As such, a time delay difference corresponding to 2Δτ may be obtained when only the optical switch of the second column is in the cross state, and 3Δτ when the first and second cross states are in the cross state.

Each signal time-delayed by the optical fiber delay line matrix 800 is adjusted in the variable optical attenuator 900. In order to increase the bandwidth, a uniform feed series is used and a main to secondary sidelobe ratio (MSSR) is used. In order to increase the size, the signal size corresponding to the Taylor series is adjusted to be light multiplexed by the light multiplexer 702, and then converted into an RF signal through the light detector 1000.

The variable light attenuator 900 may be configured to expand the bandwidth of band pass filtering or notch filtering by variably attenuating the size of the optical signal. The signal magnitude difference between the main lobe and the side lobe may be increased.

The light detector 1000 detects an RF signal processed light modulated RF signal and converts the detected light modulated RF signal into an RF signal.

The RF signal output unit 1100 outputs an RF signal.

4 is a graph illustrating a transmission function characteristic according to a DC bias voltage of an optical modulator according to an exemplary embodiment of the present invention.

Referring to FIG. 4, it can be seen that when the DC bias voltage is a [V] and b [V], the slope of the transmission function characteristic curve is different. That is, when a [V], the slope represents a positive slope, and when b [V], the slope represents a negative slope.

Therefore, when the band pass filter is to be implemented, the first light modulator 301 and the second light modulator 302 are supplied with the same voltage of a [V], and when the notch filter is implemented, the first light modulator ( 301 is supplied with a voltage of a [V] and a second light modulator 302 is supplied with a voltage of b [V].

5 is an experimental schematic diagram of a microwave photonic variable filter system operating in two bits according to an embodiment of the present invention.

Referring to FIG. 5, the experimental configuration of the microwave photonic variable filter system uses four wavelength fixed light sources. The microwave photonic filter includes a 1 × 4 optical demultiplexer and a 1 × 4 optical multiplexer in pairs, and is composed of a 2-bit optical fiber delay line matrix composed of optical switches having optical fiber delay lines connected to a cross port. Here, the length of the optical fiber delay line connected to the cross port of the optical switch column has a time delay of 2 0 Δτ each time the number of rows increases by one for the first 2X2 optical switch column. In the case of the second 2X2 optical switch column, each time the number of rows increases by one, the time delay increases by the fiber length corresponding to 2 1 Δτ.

For example, when all the optical switches are in a bar state, the time delay difference of each of the signals of λ 1 , λ 2 , λ 3 , and λ 4 is 0, and only the optical switches of the first column are crossed. ), The time delay difference between the signals of λ 1 , λ 2 , λ 3 , and λ 4 is Δτ. When only the 2X2 optical switch of the second column is in a cross state, a time delay difference corresponding to 3Δτ can be obtained when the first and second cross states are crossed.

In the experimental configuration of FIG. 5, Δτ is set to 50 ps, and when the time delay difference of each signal of λ 1 , λ 2 , λ 3 , and λ 4 is Δτ and 50 ps, free spectral range (1 / time delay) In the case of 100 ps at 20 GHz and 2Δτ, the FSR is 6.67 GHz at 10 GHz and 150 ps as 3Δτ. When the time delay is obtained by the optical fiber delay line matrix, the optically modulated RF signals of λ 1 , λ 2 , λ 3 , and λ 4 are optically multiplexed, converted into RF signals through an optical detector, and then input into a network analyzer and the micro The transmission spectrum of the wave photonic filter was measured. Since the influence of the variable light attenuator is easily implemented, it is not considered in the experimental configuration of FIG. 5, and in this case, the transmission spectral characteristics due to uniform feeding of the same signal magnitude input to the microwave photonic filter can be obtained.

FIG. 6 is a graph of simulation calculation values and measurement values for the transmission spectrum in the experimental configuration of FIG. 5.

6 (a) shows the DC bias voltages inputted to the optical modulator 1 and the optical modulator 2 to be the same, and the time delay difference of the optical fiber delay line matrix.

Figure 112011039801524-pat00001
Is a transmission spectrum according to the RF frequency signal when 50 ps. Since the DC bias voltages input to the optical modulator 1 and the optical modulator 2 are the same, the FSR is 20 GHz (the center frequency is 10 GHz) because the transmission spectrum of the band pass filter is shown and the time delay difference of the optical fiber delay line matrix is 50 ps. You can see that. Here, the solid line is a calculated value using simulation, and the dots are measured values by the experiment of FIG. 5. The simulation is a transmission spectrum from 0 GHz to 20 GHz, and in the experiment, the transmission spectrum from 4 GHz to 16 GHz was measured.

In FIG. 6B, when the DC bias is input so that the phases of the RF signals output from the optical modulator 1 and the optical modulator 2 are 180 degrees apart, and the time delay difference Δτ of the optical fiber delay line matrix is 50 ps. The transmission spectrum according to the RF frequency signal is shown. Here, since the phases of the RF signals output from the optical modulator 1 and the optical modulator 2 differ by 180 degrees, the transmission spectrum of the notch filter appears and the time delay difference of the optical fiber delay line matrix is 50 ps, so the FSR is 20 GHz. (The center frequency is 10 GHz). In FIG. 6B, the solid line is a calculated value using simulation, and the holes are measured values by the experiment of FIG. 5. The simulation calculated the transmission spectrum from 0 GHz to 20 GHz and the experiment measured the transmission spectrum from 4 GHz to 16 GHz.

7 is a graph of the output signal with the same DC bias voltage and 50 ps time delay in the experimental configuration of FIG. 5.

In FIG. 7, in order to examine whether the optical fiber delay line matrix is properly implemented in the experimental configuration of FIG. 5, the DC bias voltages input to the optical modulator 1 and the optical modulator 2 are the same and the time delay due to the optical fiber delay line matrix is 50. ps indicates the result of measuring the output signal of the photodetector on a digital oscilloscope. It can be seen that the time delay difference between adjacent wavelength signals is 50 ps. Thus, it can be seen that the experimental configuration of FIG. 5 and the experimental result of FIG. 6 are valid.

FIG. 8 is a graph of simulation calculations and experimental measurement values for the transmission spectrum when the time delay is 150 ps in the experimental configuration of FIG. 5.

In FIG. 8, when the time delay due to the optical fiber delay line matrix is 3Δτ (150 ps), simulation calculations for the transmission spectrum according to the RF frequency signal are compared with experimental measurements.

In FIG. 7A, the transmission spectrum according to the RF frequency signal when the DC bias voltages input to the optical modulator 1 and the optical modulator 2 are the same and the time delay difference of the optical fiber delay line matrix is 3Δτ (150 ps) is shown. Indicates. Since the DC bias voltages input to the optical modulator 1 and the optical modulator 2 are the same, the transmission spectrum of the band pass filter is shown, and the time delay difference of the optical fiber delay line matrix is 150 ps, so the FSR is 6.67 GHz (center frequency is 3.34 GHz). Able to know. In this case, the solid line is a calculated value using simulation, and the dots are measured values by experiment. The simulation is for the transmission spectrum from 0 GHz to 20 GHz, and the experiment measured the transmission spectrum from 4 GHz to 16 GHz.

In FIG. 7B, the DC bias is input so that the phases of the RF signals output from the optical modulator 1 and the optical modulator 2 are 180 degrees apart, and the time delay difference of the optical fiber delay line matrix is 3Δτ (150 ps). Shows the transmission spectrum according to the RF frequency signal. Since the phases of the RF signals output from the optical modulator 1 and the optical modulator 2 are 180 degrees out of phase, the transmission spectrum of the notch filter is shown and the time delay difference of the optical fiber delay line matrix is 150 ps, so the FSR is 6.67 GHz ( 3.34 GHz). The solid line is a calculated value using simulation, and the holes are measured values by the experiment of FIG. 5. The simulation calculated the transmission spectrum from 0 GHz to 20 GHz and the experiment measured the transmission spectrum from 4 GHz to 16 GHz.

FIG. 9 is a graph of the detected RF signal when the same DC bias voltage and time delay is 150 ps in the experimental configuration of FIG. 5.

9 illustrates a digital oscilloscope output signal of the optical detector when the DC bias voltages input to the optical modulator 1 and the optical modulator 2 are the same and the time delay of the optical fiber delay line matrix is 150 ps. It is the result measured on the phase. It can be seen that the time delay difference between signals of adjacent wavelengths is 150 ps. Thus, the experimental configuration of FIG. 5 and the experimental result of FIG. 8 are valid.

10 is a flowchart of a microwave photonic variable filtering method using a wavelength-fixed light source according to an embodiment of the present invention.

Referring to FIG. 10, the first optical multiplexer 201 multiplexes a plurality of optical signals having different fixed wavelengths output from the first wavelength fixed light source 101, and the second optical multiplexer 202 is configured to perform multiplexing. A plurality of optical signals having different wavelengths output from the two wavelength fixed light source 102 are multiplexed (S110). In this case, the first wavelength fixed light source and the second wavelength fixed light source may be configured to output a plurality of optical signals having wavelengths that alternately increase.

Next, the first optical modulator 301 converts the RF received signal into an optically modulated RF signal by using the optical signal multiplexed by the first optical multiplexer 201, and the second optical modulator 302 performs the second optical modulator 302. 2, the optical multiplexer 202 converts the RF received signal into an optically modulated RF signal using the multiplexed optical signal (S120). In this case, in order for the microwave photonic filter 11 to perform band pass filtering, the first optical modulator 301 and the second optical modulator 302 are supplied with the same bias voltage, and the microwave photonic filter ( In order to perform notch filtering 11, the first light modulator 301 and the second light modulator 302 may be configured to receive different bias voltages.

The optical combiner 500 combines and outputs the optical modulated RF signal converted by the first optical modulator 301 and the optical modulated RF signal converted by the second optical modulator 302 (S130).

The optical amplifier 600 amplifies the light modulated RF signal output from the optical coupler 500 (S140).

Next, the microwave photonic filter 11 RF-processes the optically modulated RF signal output from the optical amplifier 600 (S150). Here, the microwave photonic filter 11 sequentially varies the time delay difference according to the wavelengths of the optical signals of the first wavelength fixed light source 101 and the second wavelength fixed light source 102 through the optical fiber delay line matrix 800. By generating a center frequency of band pass filtering or notch filtering. The microwave photonic filter 11 may be configured to expand the bandwidth of band pass filtering or notch filtering by variably attenuating the magnitude of the optical signal.

Then, the light detector 1000 detects the RF modulated light modulated RF signal and converts the detected light modulated RF signal into an RF signal (S160).

The RF signal output unit 1100 outputs the converted RF signal (S170).

Although described with reference to the embodiments above, those skilled in the art will understand that the present invention can be variously modified and changed without departing from the spirit and scope of the invention as set forth in the claims below. Could be.

Claims (10)

A first wavelength fixed light source for outputting a plurality of optical signals having different fixed wavelengths;
A second wavelength fixed light source for outputting a plurality of optical signals having different fixed wavelengths;
A first optical multiplexer which multiplexes a plurality of optical signals output from the first wavelength fixed light source;
A second optical multiplexer which multiplexes a plurality of optical signals output from the second wavelength fixed light source;
A first optical modulator for converting an RF received signal into an optically modulated RF signal by using the optical signal multiplexed by the first optical multiplexer;
A second optical modulator for converting an RF received signal into an optically modulated RF signal using the optical signal multiplexed by the second optical multiplexer;
An optical combiner for combining and outputting the optical modulated RF signal converted by the first optical modulator and the optical modulated RF signal converted by the second optical modulator;
An optical amplifier for amplifying the optical modulated RF signal coupled by the optical coupler;
A microwave photonic filter for RF signal processing the optically modulated RF signal amplified by the optical amplifier;
An optical detector for detecting the RF modulated RF signal and converting the detected optical modulated RF signal into an RF signal;
Microwave photonic variable filter system using a wavelength fixed light source including an RF signal output unit for outputting the converted RF signal. The method of claim 1,
A first bias voltage source for supplying a DC bias voltage to the first optical modulator;
A second bias voltage source for supplying a DC bias voltage to the second optical modulator;
The first bias voltage source and the second bias voltage source supply the same DC bias voltage to each other so that the microwave photonic filter performs band pass filtering, and the microwave photonic filter to notch filter the same. A microwave photonic variable filter system using a wavelength fixed light source, wherein the first bias voltage source and the second bias power supply supply different DC bias voltages. The method of claim 2, wherein the first wavelength fixed light source and the second wavelength fixed light source,
A microwave photonic variable filter system using a wavelength fixed light source, characterized in that it is configured to output a plurality of optical signals having alternately increasing wavelengths. The method of claim 3, wherein the microwave photonic filter,
It is characterized by converting the center frequency of the band pass filtering or notch filtering by generating a time delay difference in accordance with the wavelength of the optical signal of the first wavelength fixed light source and the second wavelength fixed light source through an optical fiber delay line matrix. Microwave photonic variable filter system using wavelength fixed light source. The method of claim 4, wherein the microwave photonic filter,
And variably attenuating the magnitude of the optical signal, thereby extending the bandwidth of band pass filtering or notch filtering. The first optical multiplexer multiplexes a plurality of optical signals having different fixed wavelengths output from the first wavelength fixed light source, and the second optical multiplexer outputs a plurality of optical signals having different wavelengths output from the second wavelength fixed light source. Multiplexing;
A first optical modulator converts an RF received signal into an optically modulated RF signal using an optical signal multiplexed by the first optical multiplexer, and a second optical modulator uses an optical signal multiplexed by the second optical multiplexer Converting the RF received signal into a light modulated RF signal;
Combining and outputting an optical modulated RF signal converted by the first optical modulator and an optical modulated RF signal converted by the second optical modulator by an optical combiner;
Amplifying an optical modulated RF signal coupled by the optical amplifier by the optical amplifier;
A microwave photonic filter performing RF signal processing on the optically modulated RF signal amplified by the optical amplifier;
An optical detector detecting the RF modulated RF signal and converting the detected optical modulated RF signal into an RF signal;
And a microwave signal output unit outputting the converted RF signal. 7. The apparatus of claim 6, wherein the first optical modulator converts an RF received signal into an optically modulated RF signal using an optical signal multiplexed by the first optical multiplexer, and a second optical modulator is used by the second optical multiplexer. Converting the RF received signal into a light modulated RF signal by using the multiplexed optical signal,
The first light modulator and the second light modulator are supplied with the same bias voltage to allow the microwave photonic filter to perform band pass filtering, and the microwave photonic filter is notched to filter the notch. 1. A microwave photonic variable filtering method using a wavelength fixed light source, wherein the first light modulator and the second light modulator are supplied with different bias voltages. The method of claim 7, wherein the first optical multiplexer multiplexes a plurality of optical signals having different fixed wavelengths output from the first wavelength fixed light source, and the second optical multiplexer outputs different wavelengths from the second wavelength fixed light source. Multiplexing a plurality of optical signals having a,
And a plurality of optical signals having wavelengths alternately increased in the first wavelength fixed light source and the second wavelength fixed light source. The method of claim 8, wherein the microwave photonic filter RF signal processing the light modulated RF signal output from the optical coupling unit,
The microwave photonic filter sequentially generates a time delay difference according to the wavelengths of the optical signals of the first wavelength fixed light source and the second wavelength fixed light source through an optical fiber delay line matrix, thereby generating a center frequency of band pass filtering or notch filtering. Microwave photonic variable filtering method using a wavelength fixed light source, characterized in that for converting. The method of claim 9, wherein the microwave photonic filter RF signal processing the light modulated RF signal output from the optical coupling unit,
And the microwave photonic filter variably attenuates the magnitude of the optical signal, thereby extending the bandwidth of band pass filtering or notch filtering.
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