JP5271580B2 - High frequency band noise generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-frequency band noise-producing device for producing noise in a microwave band, a millimeter wave band or a sub-terahertz band. <P>SOLUTION: This high-frequency band noise-producing device for producing noise in a high-frequency band of a microwave, a millimeter wave or a sub-terahertz, has a noise light source 100 for producing a light signal in some frequency band width, and a photoelectric converter 109 for converting a light signal produced in a wide band including at least a microwave, a millimeter wave and a sub-terahertz into an electric signal and outputting it as a noise signal. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a technology of a high frequency band noise generator that generates noise in a high frequency band of microwaves, millimeter waves, and sub-terahertz.

  Various noises exist not only in the past but also in the present natural world. Such noise is generated in a mathematically random process and can be handled with a statistical distribution. Generally defined by additive white Gaussian noise (AWGN), which acts linearly on an object, has a constant average energy over a wide band, and has a Gaussian amplitude distribution. can do. For example, thermal noise, shot noise, black body radiation, and the like are suitable examples. In order to evaluate the influence of such noise on the entire system including an electronic device composed of electrical / electronic devices, the above-described noise generating device that generates AWGN and its method have attracted attention.

  Noise sources used by conventional noise generators as noise sources are usually composed of devices that can handle microwaves and millimeter waves, and are generated by adjusting the noise figure, dynamic range, sensitivity, etc. The noise can be adjusted. Specifically, noise tubes, semiconductor diodes, black body radiation, and the like are used (see Non-Patent Documents 1 and 2). As the noise tube, a gas-filled tube to which a very high voltage is applied is used, and noise is generated by discharge in the noise tube. In addition, when a noise tube is used instead of the noise tube, although a noise of a frequency up to about 100 GHz is generated, a very high voltage is required. In the case of using a semiconductor diode, noise is generated by using a technique of dielectric breakdown using electron discharge by an internal electric field and carrier amplification based thereon. That is, since the carriers generated by dielectric breakdown behave randomly, random noise can be obtained with a low bias voltage. A noise generator using such a noise source is used to measure the spectral characteristics of materials in the research field of materials and life sciences.

At present, a noise generator that generates noise in a high frequency band from about 10 GHz to 1 THz has been attracting attention from the viewpoint of application in a large-capacity data communication system and radio astronomy.
FBLlewellyn, `` A Study of Noise in Vacuum Tubes and Attached Circuits '', Proceedings of the Institute of Radio Engineers, Volume 18, Number 2, February 1930, p.243-265 NJKeen, `` Avalanche Diode Noise Sources at Short Centimeter and Millimeter Wavelengths '', Microwave Theory and Techniques, IEEE Transactions, Volume 24, Number 3, March 1976, p.153-155

  However, for example, the frequency of noise generated using the aforementioned semiconductor diode or the like does not exceed about 150 GHz at the maximum. Also, there is radiation up to several terahertz as a part of black body radiation from all materials with mass exceeding 10K, but this thermal radiation is very weak and it is very difficult to use for evaluation of devices and parts. . Accordingly, there has been a problem that a device that handles a high frequency band from about 10 GHz to 1 THz cannot be evaluated.

  The present invention has been made in view of the above, and an object of the present invention is to provide a high-frequency band noise generator that generates noise in a high-frequency band of microwaves, millimeter waves, and sub-terahertz.

The present invention according to claim 1 is an optical fiber amplifier or a semiconductor optical amplifier that generates light having a certain frequency bandwidth as an optical signal that is a source of noise, and includes at least first optical signal generation means that is used as the light source itself , The gist of the invention is to have photoelectric conversion means for converting the optical signal into an electric signal in a wide band including microwaves, millimeter waves, and sub-terahertz, and outputting the electric signal as a noise signal.

In the present invention, the optical fiber amplifier or the semiconductor optical amplifier that generates light having a certain frequency bandwidth as an optical signal serving as a noise source, the first optical signal generating means used as the light source itself , and at least a microwave, Because it has photoelectric conversion means that converts optical signals generated in a wide band including millimeter waves and sub-terahertz into electrical signals and outputs them as noise signals, it generates noise in the high frequency band of microwaves, millimeter waves, and sub-terahertz It is possible to provide a high frequency band noise generator.

  The present invention described in claim 2 further includes light passing means for passing an optical signal having a desired frequency bandwidth from the optical signal generated by the first optical signal generating means, and the photoelectric conversion means comprises: The gist is to convert the optical signal that has passed through the light passage means into an electrical signal and output it as a noise signal.

  According to a third aspect of the present invention, there is provided an optical distribution unit that distributes the optical signal generated by the first optical signal generation unit to at least two optical signals, and at least a micro signal from the distributed one optical signal. First optical passage means for passing an optical signal having a frequency bandwidth included in a wave, millimeter wave, and sub-terahertz, and the frequency of the optical signal passing through the first optical passage means from the other distributed optical signals A second optical passage means for passing an optical signal having a frequency bandwidth different from the bandwidth and having a frequency bandwidth included in at least a microwave, a millimeter wave, and a sub-terahertz, and the first optical passage means An optical multiplexing unit that multiplexes the optical signal and the optical signal that has passed through the second optical passage unit, and the photoelectric conversion unit converts each of the combined optical signals into the optical signal. Frequency difference electrical signal Conversion, and summarized in that output as a noise signal.

According to a fourth aspect of the present invention, there is provided an optical passage means for allowing an optical signal having a frequency bandwidth included in at least microwave, millimeter wave, and sub-terahertz to pass from the optical signal generated by the first optical signal generation means. A second optical signal generating unit that generates an optical signal having a single frequency, an optical signal that combines the optical signal that has passed through the optical passing unit, and the optical signal that has been generated by the second optical signal generating unit. And a wave means, wherein the photoelectric conversion means converts each combined optical signal into an electric signal having a frequency difference between the optical signals and outputs the electric signal as a noise signal.
The gist of the present invention described in claim 5 is that the first optical signal generating means is an optical fiber amplifier or a semiconductor optical amplifier.

  ADVANTAGE OF THE INVENTION According to this invention, the high frequency band noise generator which generate | occur | produces noise in the high frequency band of a microwave, a millimeter wave, and a sub terahertz can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a block diagram showing a functional block configuration of a high frequency band noise generator according to the first embodiment. This high frequency band noise generator includes a noise light source 100 that generates an optical signal that is a source of noise, an optical filter 104 that passes only a predetermined optical signal, an optical amplifier 107 that amplifies the optical signal, and an optical signal. And a photoelectric converter 109 for converting into an electric signal.

  FIG. 2 is an explanatory diagram for explaining the processing of the high frequency band noise generator according to the first embodiment. In the figure, description of the optical filter 104 and the optical amplifier 107 is omitted. Hereinafter, processing of the high frequency band noise generator will be described with reference to FIGS. 1 and 2.

  First, the noise light source 100 generates light having a certain frequency bandwidth as an optical signal that is a source of noise. For example, as shown in FIG. 2, the noise light source 100 generates an optical signal having a bandwidth of 4 THz, which is 190 THz to 194 THz and the center frequency is 192 THz. As such a noise light source 100, an optical amplifier such as an optical fiber amplifier (EDFA) or a semiconductor optical amplifier (SOA) can be used.

  Next, the optical filter 104 passes an optical signal having a desired frequency bandwidth from the optical signal generated by the noise light source 100. For example, an optical signal having a bandwidth of 3 THz may be passed. Alternatively, a broadband optical filter 104 set in advance so as to pass an optical signal having the same 4 THz bandwidth as the frequency bandwidth generated by the noise light source 100 may be used. The optical filter 104 is used when the user wants to output noise in a certain specific frequency band from the high frequency band noise generating device. Therefore, when such a specific frequency band is not specified, the optical filter 104 is not necessarily used. There is no need to pass the optical signal through the optical filter 104, and a wider-band noise signal can be output from the photoelectric conversion means described later than when the optical filter 104 is used.

  The optical amplifier 107 amplifies the optical signal that has passed through the optical filter 104 to a desired magnitude. By using the optical amplifier 107, it is possible to control the magnitude of the noise signal output from the high frequency band noise generator.

  Finally, the photoelectric converter 109 receives the optical signal amplified by the optical amplifier 107, converts it into an electric signal in a wide band including at least microwaves, millimeter waves, and sub-terahertz, and outputs it as a noise signal. Specifically, as shown in FIG. 2, a broadband noise signal from 0 (DC (direct component)) to several terahertz is output. As the photoelectric converter 109, a square detector, a photodetector, a photoconductor, an optical mixer, a single traveling carrier photodiode (UTC-PD), or the like can be used.

  Therefore, according to the present embodiment, the noise light source 100 that generates an optical signal having a certain frequency bandwidth and the optical signal generated in a wide band including at least microwaves, millimeter waves, and sub-terahertz are converted into electrical signals, and noise is generated. Since it has the photoelectric converter 109 that outputs as a signal, it is possible to provide a high frequency band noise generator that generates noise in a high frequency band of microwave, millimeter wave, and sub-terahertz.

[Second Embodiment]
FIG. 3 is a block diagram showing a functional block configuration of the high frequency band noise generator according to the second embodiment. The high frequency band noise generator includes a noise light source 100 that generates an optical signal that is a source of noise, an optical coupler 103 that distributes the generated optical signal into a plurality, and an optical filter 104a that passes only a predetermined optical signal, 104b, an optical coupler 106 that multiplexes a plurality of optical signals, an optical amplifier 107 that amplifies the optical signals, an optical attenuator 108 that attenuates the optical signals, and a photoelectric converter 109 that converts the optical signals into electrical signals; It has.

  FIG. 4 is an explanatory diagram for explaining the processing of the high frequency band noise generator according to the second embodiment. In the figure, an optical waveguide (AWG) 201 having the functions of the optical coupler 103 and the optical filters 104a and 104b is shown, and descriptions of the optical amplifier 107 and the optical attenuator are omitted. Hereinafter, processing of the high frequency band noise generator will be described with reference to FIGS. 3 and 4.

  First, the noise light source 100 generates light having a certain frequency bandwidth as an optical signal that is a source of noise. For example, as shown in FIG. 4, the noise light source 100 generates an optical signal having a bandwidth of 4 THz, which is 190 THz to 194 THz and the center frequency is 192 THz. As such a noise light source 100, an optical amplifier such as an optical fiber amplifier (EDFA) or a semiconductor optical amplifier (SOA) can be used.

  The optical coupler 103 distributes the optical signal generated by the noise light source 100 into two optical signals.

  Next, the optical filter 104a passes an optical signal having a frequency bandwidth included in at least microwaves, millimeter waves, and sub-terahertz from one of the optical signals distributed by the optical coupler 103, and the optical filter 104b Light having a frequency bandwidth that is different from the frequency bandwidth of the optical signal that passes through the optical filter 104a from the other optical signal distributed in 103, and that is at least included in microwaves, millimeter waves, and sub-terahertz Let the signal pass. For example, as shown in FIG. 4, the optical waveguide 201 cuts out and outputs an optical signal having an intensity peak at 192.01 THz and an optical signal having an intensity peak at 192.02 THz. Of course, a center frequency or the like can be used instead of the intensity peak.

  Subsequently, the optical coupler 106 multiplexes the optical signal that has passed through the optical filter 104a and the optical signal that has passed through the optical filter 104b.

  The optical amplifier 107 amplifies each optical signal combined by the optical coupler 106 to a desired magnitude. By using the optical amplifier 107, it is possible to control the magnitude of the noise signal output from the high frequency band noise generator.

  Thereafter, the optical attenuator 108 attenuates the magnitude of each optical signal amplified by the optical amplifier 107. By adjusting the attenuation amount of the optical signal using the optical attenuator 108, it is possible to control the magnitude of the noise signal output from the high frequency band noise generator.

  Finally, the photoelectric converter 109 converts each optical signal combined by the optical coupler 106, amplified by the optical amplifier 107, and attenuated by the optical attenuator 108 into an electrical signal having a frequency difference between these optical signals, Output as a noise signal. That is, the photoelectric converter 109 converts two optical signals based on the formula (1), and as shown in FIG. 4, a noise signal of a DC component (DC component) corresponding to “1” in the formula (1). And a noise signal having a frequency difference corresponding to “2Δω” obtained by the difference between “−Δω” and “+ Δω”. Since this DC component has a frequency in the vicinity of 0 (zero), it is not used for evaluation of a device or the like that handles a high frequency band from about 10 GHz to 1 THz.

[Equation 1]
[{Sin (ω−Δω) t} + {Sin (ω + Δω) t}] ² = 1 + Cos2Δωt Equation (1)
In this equation, components such as ω and 2ω that are not responded by the photoelectric converter 109 are ignored. Further, in the above specific example, noise having an intensity peak at 10 GHz (= 192.02 THz−192.01 THz) is output from the photoelectric converter 109.

  Therefore, it is possible to provide a high frequency band noise generator that generates noise in the high frequency band of microwave, millimeter wave, and sub-terahertz.

  Note that, in the first embodiment, it is possible to output broadband noise than in the case described in the second embodiment, but the noise efficiency and power spectrum in a high frequency band are very small. Therefore, as described in the present embodiment, a noise signal having a power spectrum desired by the user can be output by narrowing a frequency band desired to be output as a noise signal using an optical filter.

  In addition, as an example of the optical filter described in the present embodiment, a wavelength tunable optical filter that can set the operating frequency bandwidth and the bandwidth to pass through the profile and can change the center wavelength may be used. .

[Third Embodiment]
FIG. 5 is a block diagram showing a functional block configuration of a high frequency band noise generator according to the third embodiment. This high frequency band noise generator includes a noise light source 100 that is a noise source and generates an optical signal having a predetermined frequency bandwidth, a laser light source 102 that generates an optical signal having a single frequency, and a predetermined optical signal only. An optical filter 104 that passes the optical signal, an optical coupler 106 that combines a plurality of optical signals, an optical amplifier 107 that amplifies the optical signal, an optical attenuator 108 that attenuates the optical signal, and converts the optical signal into an electrical signal. And a photoelectric converter 109.

  Next, processing of the high frequency band noise generation device according to the present embodiment will be described. First, the noise light source 100 generates light having a certain frequency bandwidth as an optical signal that is a source of noise. For example, the noise light source 100 generates an optical signal having a bandwidth of 4 THz with 190 THz to 194 THz and a center frequency of 192 THz. As such a noise light source 100, an optical amplifier such as an optical fiber amplifier (EDFA) or a semiconductor optical amplifier (SOA) can be used.

  On the other hand, the laser light source 102 generates single-frequency light as an optical signal that becomes a noise source. For example, the laser light source 102 generates an optical signal having a frequency of 192.02 THz.

  Next, the optical filter 104 passes an optical signal having a frequency bandwidth included in at least microwaves, millimeter waves, and sub-terahertz from the optical signal generated by the noise light source 100. For example, the optical filter 104 passes an optical signal having an intensity peak at 192.01 THz. Of course, a center frequency or the like can be used instead of the intensity peak.

  Subsequently, the optical coupler 106 multiplexes the optical signal that has passed through the optical filter 104 and the optical signal generated by the laser light source 102.

  The optical amplifier 107 amplifies each optical signal combined by the optical coupler 106 to a desired magnitude. By using the optical amplifier 107, it is possible to control the magnitude of the noise signal output from the high frequency band noise generator.

  Thereafter, the optical attenuator 108 attenuates the magnitude of each optical signal amplified by the optical amplifier 107. By adjusting the attenuation amount, it is possible to control the magnitude of noise in the microwave band, millimeter wave band, and sub-terahertz band output from the high frequency band noise generator.

  Finally, the photoelectric converter 109 converts each optical signal combined by the optical coupler 106, amplified by the optical amplifier 107, and attenuated by the optical attenuator 108 into an electrical signal having a frequency difference between these optical signals, Output as a noise signal. That is, the photoelectric converter 109 converts two optical signals based on the equation (1) described in the second embodiment, and a direct current component (DC component) corresponding to “1” in the equation (1). And a noise signal having a frequency difference corresponding to “2Δω” obtained by the difference between “−Δω” and “+ Δω”. Since this DC component has a frequency in the vicinity of 0 (zero), it is not used for evaluation of a device or the like that handles a high frequency band from about 10 GHz to 1 THz. Further, in the above specific example, noise having an intensity peak at 10 GHz (= 192.02 THz−192.01 THz) is output from the photoelectric converter 109.

  Therefore, it is possible to provide a high-frequency band noise generator that generates noise in the microwave band, millimeter wave band, and sub-terahertz band.

  Note that, in the first embodiment, it is possible to output broadband noise than in the case described in the second embodiment, but the noise efficiency and power spectrum in a high frequency band are very small. Therefore, as described in the present embodiment, a noise signal having a power spectrum desired by the user can be output by narrowing a frequency band desired to be output as a noise signal using an optical filter or a laser light source.

  In addition, as an example of the optical filter described in the present embodiment, a wavelength tunable optical filter that can set the operating frequency bandwidth and the bandwidth to pass through the profile and can change the center wavelength may be used. .

[Fourth Embodiment]
FIG. 6 is a block diagram showing a functional block configuration of a high frequency band noise generator according to the fourth embodiment. This high frequency band noise generator includes two high frequency band noise generators described in the second embodiment and the high frequency band noise generator described in the third embodiment. The above optical signals can be multiplexed. Note that each block constituting the high frequency band noise generator has the same function as that described in the second and third embodiments, and thus redundant description is omitted, and the optical coupler 106 and the photoelectric converter 109 are not described. The function will be described.

  The optical coupler 106 multiplexes the optical signal that has passed through the optical filters 104 a to 104 c and the optical signal generated by the laser light source 102. That is, for example, an optical signal having an intensity peak at 192.01 THz (A) that has passed through the optical filter 104a, an optical signal having an intensity peak at 192.02 THz (B) that has passed through the optical filter 104b, and an optical filter 104c. The optical signal having an intensity peak at 192.31 THz (C) and the optical signal having a frequency of 192.41 THz (D) generated by the laser light source 102 are combined.

  The photoelectric converter 109 converts the optical signal having the frequency difference between the optical signals combined by the optical coupler 106, amplified by the optical amplifier 107, and attenuated by the optical attenuator 108 into an electrical signal. Output as a noise signal. That is, 10 GHz (= BA), 300 GHz (= CA), 400 GHz (= DA), 290 GHz (= CB), 390 GHz (= DB), 100 GHz (= DC) Noise having an intensity peak is output from the photoelectric converter 109.

  As described in the second and third embodiments, it is of course possible to use a center frequency or the like instead of the intensity peak.

  Therefore, it is possible to provide a high-frequency band noise generator that generates noise in the microwave band, millimeter wave band, and sub-terahertz band. Needless to say, the same effect can be obtained even when three or more optical noise sources, four or more optical filters, or two or more laser light sources are used.

〔Example〕
FIG. 7 is a block diagram showing a practical implementation example based on the high frequency band noise generator described in the second embodiment. An optical fiber amplifier (EDFA) 200 is used as the noise light source 100 and the optical amplifier 107, an optical waveguide (AWG) 201 is used as the optical coupler 103 and the optical filters 104a and 104b, and a single traveling carrier photodiode ( The case where UTC-PD) 204 is used is described. By changing the center wavelength difference of the channel selected by the optical waveguide 201, it is possible to control the occupied band of noise in the output microwave band, millimeter wave band, and sub-terahertz band.

  FIG. 8 is a graph showing measurement results obtained by measuring the spectral intensity of noise output from the high frequency band generator when the center wavelength of the channel selected by the optical waveguide 201 in FIG. 7 is changed. As can be seen from FIG. 8, a noise signal having a noise spectrum intensity of about −130 dBm / Hz at 350 GHz is obtained. This noise spectrum intensity is 44 dB larger than the noise spectrum intensity of thermal noise (about −174 dBm / Hz), and is sufficiently large as the intensity of noise signals for various measurements. Therefore, it can be said that the high frequency band noise generator described in each embodiment is sufficiently applicable to a noise source in various measurements using noise.

It is a block diagram which shows the functional block structure of the high frequency band noise generator which concerns on 1st Embodiment. It is explanatory drawing explaining the process of the high frequency band noise generator which concerns on 1st Embodiment. It is a block diagram which shows the functional block structure of the high frequency band noise generator which concerns on 2nd Embodiment. It is explanatory drawing explaining the process of the high frequency band noise generator which concerns on 2nd Embodiment. It is a block diagram which shows the functional block structure of the high frequency band noise generator which concerns on 3rd Embodiment. It is a block diagram which shows the functional block structure of the high frequency band noise generator which concerns on 4th Embodiment. It is a block diagram which shows the practical mounting example based on the high frequency band noise generator demonstrated in 2nd Embodiment. FIG. 7 is a graph showing measurement results obtained by measuring the spectral intensity of noise output from the high frequency band generator when the center wavelength of the channel selected by the optical waveguide 201 is changed in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100,100a, 100b ... Noise light source 102 ... Laser light source 103 ... Optical coupler 104, 104a-104c ... Optical filter 106 ... Optical coupler 107 ... Optical amplifier 108 ... Optical attenuator 109 ... Photoelectric converter 200, 203 ... Optical fiber amplifier ( EDFA)
201: Optical waveguide (AWG)
204 ... Single traveling carrier photodiode (UTC-PD)

Claims (4)

An optical fiber amplifier or a semiconductor optical amplifier that generates light of a certain frequency bandwidth as an optical signal that is a source of noise , and a first optical signal generating means used as the light source itself ;
Photoelectric conversion means for converting the optical signal into an electric signal in a wide band including at least microwave, millimeter wave, and sub-terahertz, and outputting the signal as a noise signal;
A high frequency band noise generator characterized by comprising: The optical signal generated by the first optical signal generating means further includes a light passing means for passing an optical signal having a desired frequency bandwidth,
2. The high frequency band noise generator according to claim 1, wherein the photoelectric conversion means converts the optical signal that has passed through the light passage means into an electrical signal and outputs it as a noise signal. Optical distribution means for distributing the optical signal generated by the first optical signal generation means into at least two optical signals;
First light passing means for passing an optical signal having a frequency bandwidth included in at least microwaves, millimeter waves, and sub-terahertz from one of the distributed optical signals;
A frequency bandwidth that is different from the frequency bandwidth of the optical signal that passes through the first optical passage means from the other distributed optical signals, and that is included in at least microwaves, millimeter waves, and sub-terahertz Second light passing means for passing an optical signal having:
Optical multiplexing means for multiplexing the optical signal that has passed through the first light passing means and the optical signal that has passed through the second light passing means;
2. The high frequency band noise generating apparatus according to claim 1, wherein the photoelectric conversion unit converts each combined optical signal into an electric signal having a frequency difference between the optical signals and outputs the electric signal as a noise signal. Light passing means for passing an optical signal having a frequency bandwidth included in at least microwave, millimeter wave, and sub-terahertz from the optical signal generated by the first optical signal generating means;
Second optical signal generating means for generating a single frequency optical signal;
Optical multiplexing means for multiplexing the optical signal that has passed through the optical passing means and the optical signal generated by the second optical signal generating means;
The high-frequency band noise generation according to claim 1 or 3, wherein the photoelectric conversion means converts each combined optical signal into an electric signal having a frequency difference of the optical signal and outputs it as a noise signal. apparatus.

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