Frequency shifting device and communication device

Abstract

Provided is a frequency transition device (1) comprising: an optical wavelength multiplexing unit (13) which executes wavelength multiplexing of pilot light with carrier light, the pilot light being different in wavelength from the carrier light; and an optical intensity modulation unit (14) which uses a signal which is a target of frequency transition to modulate the optical intensity of the carrier light after the multiplexing with the pilot light by the optical wavelength multiplexing unit (13) and outputs intensity-modulated light, which is the carrier light after the optical intensity modulation. Moreover, the frequency transition device (1) further comprises: an optical wavelength demultiplexing unit (15) which applies the intensity-modulated light output from the optical intensity modulation unit (14) to obtain a wavelength component of the carrier light and a wavelength component of the pilot light; an optical pulse compression unit (16) which compresses the wavelength component of the carrier light in the time direction and outputs time-compressed pulse light, which is a wavelength component of the carrier light after the compression; and a control unit (18) which controls, on the basis of the wavelength component of the pilot light, the optical intensity modulation by the optical intensity modulation unit (14).

Description

[Technical field]

[0001] The present disclosure relates to a frequency transition device and a communication device. [Background technology]

[0002] There is a frequency shifting device that shifts the frequency of a signal that is a frequency shift target. As such a frequency shift device, for example, Patent Document 1 discloses a device including an optical carrier generator, a modulator, a dispersion compensator, and an optical-electrical converter. The optical carrier generation unit generates an optical carrier. The modulator modulates the optical carrier generated by the optical carrier generation unit with a first electrical signal. The first electrical signal is a signal to be frequency-shifted. The dispersion compensator compresses the optical carrier modulated by the modulator in the time direction. The optical-to-electrical converter converts the optical carrier compressed by the dispersion compensator into a second electrical signal. The second electrical signal is a frequency-shifted signal having a higher frequency than the first electrical signal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 079710 Summary of the Invention [Problem to be solved by the invention]

[0004] In the device disclosed in Patent Document 1, for example, a temperature drift may occur in the modulator due to a change in the temperature around the modulator. In addition, a time drift may occur in the modulator over time. There is a problem that the signal level of the second electrical signal may deviate from the original signal level due to the temperature drift or time drift occurring in the modulator.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a frequency shift device that can return the signal level of a signal after a frequency shift to its original signal level even if the signal level of the signal after the frequency shift deviates from the original signal level. [Means for solving the problem]

[0006] The frequency shift device according to the present disclosure includes an optical wavelength multiplexing unit that wavelength-multiplexes pilot light having a different wavelength from the carrier light onto the carrier light, an optical intensity modulation unit that optically intensity-modulates the carrier light after the pilot light multiplexing by the optical wavelength multiplexing unit with a signal to be frequency shifted, and outputs intensity-modulated light which is the carrier light after the optical intensity modulation. The frequency shift device also includes an optical wavelength demultiplexing unit that demultiplexes the intensity-modulated light output from the optical intensity modulation unit into a wavelength component of the carrier light and a wavelength component of the pilot light, an optical pulse compression unit that compresses the wavelength component of the carrier light in the time direction, and outputs time-compressed pulse light which is the wavelength component of the compressed carrier light, and a control unit that controls the optical intensity modulation by the optical intensity modulation unit based on the wavelength component of the pilot light. Effect of the Invention

[0007] According to the present disclosure, even if the signal level of a frequency-shifted signal, which is an electrical signal converted from time-compressed pulsed light, deviates from the original signal level, the signal level of the frequency-shifted signal can be restored to the original signal level. [Brief description of the drawings]

[0008] [Figure 1] 1 is a configuration diagram showing a communication device including a frequency shift device 1 according to a first embodiment. [Diagram 2] 1 is a configuration diagram showing a frequency shift device 1 according to a first embodiment. [Diagram 3] 1 is an explanatory diagram showing a short pulse light PC and a carrier light PCAR. FIG. [Figure 4]Figure 4A is an explanatory diagram showing the time waveforms of the carrier light PCAR and the pilot light PPIL, Figure 4B is an explanatory diagram showing the carrier light PCAR+PIL in which the pilot light PPIL is wavelength multiplexed, and Figure 4C is an explanatory diagram showing the wavelengths of the carrier light PCAR and the pilot light PPIL. [Diagram 5] FIG. 2 is an explanatory diagram showing a time waveform of an RF signal (1). [Figure 6] 1 is an explanatory diagram showing a time waveform of intensity-modulated light PIM. [Figure 7] FIG. 7A is an explanatory diagram showing the time waveform of the wavelength component of the carrier light PCAR, and FIG. 7B is an explanatory diagram showing the time waveform of the wavelength component of the pilot light PPIL. [Figure 8] 1 is an explanatory diagram showing a time waveform of time-compressed pulsed light PTC. FIG. [Figure 9] FIG. 2 is an explanatory diagram showing a time waveform of an RF signal (2). [Figure 10] FIG. 11 is a configuration diagram showing a frequency shift device 1 according to a second embodiment. [Figure 11] Figure 11A is an explanatory diagram showing the time waveforms of the carrier light PCAR' and pilot light PPIL after waveform shaping, Figure 11B is an explanatory diagram showing the carrier light PCAR'+PIL after waveform shaping in which the pilot light PPIL is wavelength multiplexed, and Figure 11C is an explanatory diagram showing the wavelengths of the carrier light PCAR' and pilot light PPIL. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] In order to describe the present disclosure in more detail, embodiments of the present disclosure will be described below with reference to the accompanying drawings.

[0010] Embodiment 1 FIG. 1 is a configuration diagram showing a communication device including a frequency shift device 1 according to a first embodiment. The communication device shown in FIG. 1 includes a frequency shifting device 1, a communication circuit 2 and an antenna 3. The frequency shift device 1 shifts the frequency of an RF (Radio Frequency) signal (1) to be shifted. 1 , and other frequencies f 2 Then, the frequency f 2 The device outputs an RF signal (2). The frequency shift device 1 outputs the frequency-shifted RF signal (2) to the communication circuit 2. Frequency of RF signal (2) f 2 Examples of such frequencies include frequencies in the microwave band, millimeter wave band, and terahertz wave band. 1, the frequency shift device 1 is implemented in a communication device. However, this is merely an example, and the frequency shift device 1 may be implemented in a device other than a communication device.

[0011] The communication circuit 2 outputs the RF signal ( 2 ) output from the frequency shift device 1 to the antenna 3 . The communication circuit 2 performs general signal processing such as modulation processing on the RF signal (2) output from the frequency shift device 1, and the RF signal (2) output from the communication circuit 2 to the antenna 3 is a signal that has been subjected to modulation processing by the communication circuit 2. General signal processing such as modulation processing on the RF signal (2) is a known technique, and therefore a detailed description thereof will be omitted. The antenna 3 radiates radio waves based on the RF signal (2) output from the communication circuit 2 into space.

[0012] FIG. 2 is a configuration diagram showing the frequency shift device 1 according to the first embodiment. The frequency shift device 1 shown in Figure 2 includes a carrier light generation unit 11, a pilot light generation unit 12, an optical wavelength multiplexing unit 13, an optical intensity modulation unit 14, an optical wavelength demultiplexing unit 15, an optical pulse compression unit 16, an opto-electrical conversion unit 17, and a control unit 18. In the frequency shift device 1 shown in FIG. 2, the carrier light generation unit 11 and the optical wavelength multiplexing unit 13, the pilot light generation unit 12 and the optical wavelength multiplexing unit 13, the optical wavelength multiplexing unit 13 and the optical intensity modulation unit 14, the optical intensity modulation unit 14 and the optical wavelength demultiplexing unit 15, the optical wavelength demultiplexing unit 15 and the optical pulse compression unit 16, the optical pulse compression unit 16 and the photoelectric conversion unit 17, and the optical wavelength demultiplexing unit 15 and the control unit 18 are each connected, for example, by an optical fiber.

[0013] The carrier light generating section 11 includes a short pulse light source 11a and a light pulse extending section 11b. The carrier light generator 11 emits light having a wavelength λ C [nm] pulsed light (hereafter referred to as "short pulse light")P C By stretching the time domain, the carrier light P CAR The generated carrier light P CAR is output to the optical wavelength multiplexing unit 13.

[0014] The short pulse light source 11a is realized by, for example, a mode-locked fiber laser. The short pulse light source 11a has a wavelength of λ C [nm] short pulse light P C is repeatedly oscillated, and a short pulse of light P C is repeatedly output to the optical pulse stretching unit 11b. C The pulse width is W1, the short pulse P C The oscillation period is D.

[0015] The optical pulse stretcher 11b is realized, for example, by a passive optical component that uses a dispersive medium. The optical pulse stretching unit 11b stretches the short pulse light P output from the short pulse light source 11a. C The wavelength dispersion is then performed to extend the signal in the time direction. The optical pulse stretching unit 11b stretches the carrier light P CAR The carrier light P CAR The wavelength band of, for example, λ C -α to λ C It's in the range of +α.

[0016] The pilot light generating unit 12 includes a light source driving circuit 12a and a pilot light source 12b. The pilot light generator 12 generates the carrier light P CAR and a different wavelength λ P [nm] pilot light P PIL The generated pilot light P PIL is output to the optical wavelength multiplexing unit 13.

[0017] The light source driving circuit 12a is realized by, for example, an FPGA (Field Programmable Gate Array). Light source drive circuit 12a is a control circuit that drives pilot light source 12b so that continuous wave light (hereinafter referred to as "CW light") is output from pilot light source 12b.

[0018] The pilot light source 12b is realized by, for example, a semiconductor laser. The pilot light source 12b emits carrier light P CAR and a different wavelength λ P Pilot light P PIL The CW light is generated as a pilot light P PIL is output to the optical wavelength multiplexing unit 13.

[0019] The optical wavelength multiplexing unit 13 includes, for example, a wavelength division multiplexing coupler, an arrayed waveguide grating, and an optical multiplexer. The optical wavelength multiplexing unit 13 receives the carrier light P from the carrier light generation unit 11. CAR is given, and the pilot light P PIL is given. The optical wavelength multiplexing unit 13 outputs pilot light P PIL Carrier light P CAR The carrier light P CAR+PIL The carrier light P CAR+PIL is the carrier light after multiplexing with the pilot light. The optical wavelength multiplexing unit 13 receives the carrier light P CAR+PIL to the optical intensity modulation unit 14.

[0020] The optical intensity modulation section 14 is realized by, for example, a Mach-Zehnder type modulator, an electroabsorption modulator, or an acousto-optic modulator. The optical intensity modulation unit 14 receives an RF signal (1) that is a signal to be frequency-shifted from the outside, and receives a carrier light P CAR+PIL and a bias signal B is provided from the control unit 18. The optical intensity modulation unit 14 receives the carrier light P CAR+PIL The optical intensity modulation by the optical intensity modulation unit 14 is controlled by the bias signal B. The light intensity modulation unit 14 outputs the intensity-modulated light P IM is output to the optical wavelength demultiplexing unit 15.

[0021] The optical wavelength demultiplexing unit 15 includes, for example, a wavelength division multiplexing coupler, an arrayed waveguide grating, and an optical demultiplexer. The optical wavelength demultiplexing unit 15 receives the intensity-modulated light P IM is given. The optical wavelength division multiplexing unit 15 divides the intensity modulated light P IM , the carrier light P CAR and the pilot light P PIL The wavelength components are separated from each other. The optical wavelength demultiplexing unit 15 demultiplexes the carrier light P CAR The wavelength component of the pilot light P PIL The wavelength component is output to the control unit 18.

[0022] The optical pulse compressor 16 is realized, for example, by a passive optical component that uses a dispersive medium. The optical pulse compressor 16 receives the carrier light P CAR The wavelength components are given. The optical pulse compressor 16 outputs a carrier light P CAR The wavelength components are compressed in the time direction. The optical pulse compressor 16 outputs the compressed carrier light P CAR The wavelength component of the time-compressed pulsed light P TCis output to the photoelectric conversion unit 17.

[0023] The photoelectric conversion unit 17 is realized by, for example, a photodiode. The photoelectric conversion unit 17 receives the time-compressed pulsed light P from the optical pulse compression unit 16. TC is given. The photoelectric conversion unit 17 converts the time-compressed pulsed light P TC The frequency f of the RF signal (2) is converted to an electrical signal and output to the communication circuit 2 as a signal after frequency shift. 2 is the frequency f of the RF signal (1) 1 Higher than. 2, the photoelectric conversion unit 17 outputs the RF signal (2) to the communication circuit 2. However, this is merely an example, and the photoelectric conversion unit 17 may output the RF signal (2) to a device other than the communication circuit 2.

[0024] The control unit 8 includes a photoelectric conversion unit 18a and a bias control circuit 18b. The control unit 8 receives the pilot light P PIL The wavelength components are given. The control unit 8 controls the pilot light P PIL Based on the wavelength component, the light intensity modulation by the light intensity modulation unit 14 is controlled.

[0025] The photoelectric conversion unit 18a is realized by, for example, a photodiode. The photoelectric conversion unit 18a receives the pilot light P PIL The wavelength components are given. The photoelectric conversion unit 18a converts the pilot light P PIL The wavelength component is converted into an electrical signal E, and the electrical signal E is output to the bias control circuit 18b.

[0026] The bias control circuit 18b is realized by, for example, a bias controller. The bias control circuit 18b receives an electrical signal E from the photoelectric conversion unit 18a. The bias control circuit 18b controls the bias signal B provided to the light intensity modulation unit 14 based on the electrical signal E, thereby controlling the light intensity modulation by the light intensity modulation unit 14.

[0027] Next, the operation of the frequency shift device 1 shown in FIG. 2 will be described. As shown in FIG. 3, the short pulse light source 11a of the carrier light generation unit 11 emits light having a wavelength of λ C Short pulse light P C is repeatedly oscillated. The short pulse light source 11a emits short pulse light P C is repeatedly output to the optical pulse stretching unit 11b.

[0028] The optical pulse stretching unit 11b receives the short pulse light P from the short pulse light source 11a. C As shown in Figure 3, each time C The wavelength dispersion is then performed to extend the signal in the time direction. The optical pulse stretching unit 11b stretches the carrier light P CAR is output to the optical wavelength multiplexing unit 13.

[0029] Figure 3 shows the short pulse light P C and carrier light P CAR FIG. In FIG. 3, the horizontal axis indicates time, and the vertical axis indicates the short pulse light P C and carrier light P CAR The respective light intensities at W1 is the short pulse light P C is the pulse width of the short pulse light P from the short pulse light source 11a. C is the oscillation period. W2 is the carrier light P CAR is the pulse width. G is the time-adjacent carrier light P CAR This is the gap time. During the gap time G, the optical intensity modulation unit 14 CAR+PIL This is the time when the optical intensity of the carrier light P cannot be modulated by the RF signal (1). CARThe wider the pulse width W2 and the shorter the gap time G, the more the carrier light P CAR+PIL In other words, the time during which the carrier light P CAR+PIL The time during which the optical intensity can be modulated by the RF signal (1) is increased. For this reason, the optical pulse stretching unit 11b splits two adjacent carrier lights P CAR do not overlap each other (G≧0), the short pulse light P C It is desirable to extend the time direction as much as possible.

[0030] As shown in FIG. 4C, the pilot light source 12b of the pilot light generating unit 12 emits a carrier light P CAR and a different wavelength λ P Pilot light P PIL The pilot light P PIL The wavelength λ P [nm] is the carrier light P CAR The wavelengths do not overlap with the wavelength bands of In FIG. 4C, the pilot light P PIL The wavelength λ P But the carrier light P CAR However, this is only an example, and the pilot light P PIL The wavelength λ P But the carrier light P CAR The wavelength band may be shorter than that of the wavelength band of the optical fiber. The oscillation of the CW light by the pilot light source 12b is controlled by a light source drive circuit 12a. The pilot light source 12b emits pilot light P PIL is output to the optical wavelength multiplexing unit 13.

[0031] FIG. 4A shows the carrier light P CAR and pilot light P PIL 4A is an explanatory diagram showing the time waveforms of the carrier light P CAR and pilot light P PIL The respective light intensities at FIG. 4B shows the pilot light PPIL The carrier light P CAR+PIL 4B is an explanatory diagram showing the time, and the vertical axis shows the carrier light P CAR+PIL The light intensity is shown. FIG. 4C shows the carrier light P CAR and pilot light P PIL 4C is an explanatory diagram showing the wavelengths in the respective cases. In FIG. 4C, the horizontal axis shows the wavelength, and the vertical axis shows the carrier light P CAR and pilot light P PIL The respective light intensities at

[0032] In the example of FIG. 4A, the pilot light P PIL The light intensity of the carrier light P CAR However, this is only an example. PIL The light intensity of the carrier light P CAR However, the light intensity of the pilot light P output from the pilot light source 12b is not limited to being greater than that of the pilot light P PIL The light intensity is a constant light intensity. Pilot light P PIL The wavelength of the carrier light P CAR It is a wavelength that does not interfere with the wavelength of

[0033] The optical wavelength multiplexing unit 13 receives the carrier light P as shown in FIG. CAR 4A is generated from the pilot light generating unit 12. PIL is given. The optical wavelength multiplexing unit 13 outputs pilot light P PIL Carrier light P CAR The wavelengths are multiplexed into the carrier light P shown in Fig. 4B. CAR+PIL Generate. The optical wavelength multiplexing unit 13 receives the carrier light P CAR+PIL to the optical intensity modulation unit 14.

[0034] The optical intensity modulation unit 14 receives an RF signal (1) as shown in FIG. 5 from the outside, and receives the carrier light P CAR+PILand a bias signal B is provided from the control unit 18. FIG. 5 is an explanatory diagram showing the time waveform of the RF signal (1). In FIG. 5, the horizontal axis indicates time, and the vertical axis indicates the optical intensity of the RF signal (1). The optical intensity modulation unit 14 receives the carrier light P CAR+PIL The optical intensity is modulated by an RF signal (1). The light intensity modulation unit 14 outputs the intensity-modulated light P IM is output to the optical wavelength demultiplexing unit 15. The light intensity modulation by the light intensity modulation unit 14 is controlled by a bias signal B. IM As shown in FIG. 6, the light intensity changes according to the change in the RF signal (1) over time. Figure 6 shows the intensity modulated light P IM FIG. In FIG. 6, the horizontal axis indicates time, and the vertical axis indicates the intensity modulated light P IM The light intensity is shown.

[0035] The optical wavelength demultiplexing unit 15 receives the intensity-modulated light P IM is given. The optical wavelength division multiplexing unit 15 divides the intensity modulated light P IM , the carrier light P CAR and the pilot light P PIL The wavelength components of the intensity modulated light P IM Since the demultiplexing itself is a known technique, a detailed description thereof will be omitted. The optical wavelength demultiplexing unit 15 demultiplexes the carrier light P CAR The wavelength component of the pilot light P PIL The wavelength component is output to the control unit 18. FIG. 7A shows the carrier light P CAR FIG. 2 is an explanatory diagram showing the time waveform of the wavelength component of In FIG. 7A, the horizontal axis indicates time, and the vertical axis indicates the carrier light P CAR 4 shows the light intensity of the wavelength components. FIG. 7B shows the pilot light P PILFIG. 2 is an explanatory diagram showing the time waveform of the wavelength component of In FIG. 7B, the horizontal axis indicates time, and the vertical axis indicates the pilot light P PIL 4 shows the light intensity of the wavelength components.

[0036] The optical pulse compressor 16 receives the carrier light P CAR The wavelength components are given. As shown in FIG. 8, the optical pulse compressor 16 CAR The wavelength components are compressed in the time direction. The optical pulse compressor 16 outputs the compressed carrier light P CAR The wavelength component of the time-compressed pulsed light P TC is output to the photoelectric conversion unit 17. Figure 8 shows the time-compressed pulsed light P TC FIG. In FIG. 8, the horizontal axis indicates time, and the vertical axis indicates the time-compressed pulsed light P TC The light intensity is shown.

[0037] The photoelectric conversion unit 17 receives the time-compressed pulsed light P from the optical pulse compression unit 16. TC is given. The photoelectric conversion unit 17 converts the time-compressed pulsed light P TC The RF signal (2) is converted into an electrical signal and output to the communication circuit 2. The RF signal (2) is a carrier light P compressed in the time direction. CAR The wavelength component of the time-compressed pulsed light P TC Therefore, the frequency f of the RF signal (2) 2 is the frequency f of the RF signal (1) 1 Higher than. FIG. 9 is an explanatory diagram showing the time waveform of the RF signal (2). In FIG. 9, the horizontal axis indicates time, and the vertical axis indicates the optical intensity of the RF signal (2).

[0038] The signal level of the RF signal (2) output from the photoelectric conversion unit 17 to the communication circuit 2 may deviate from the original signal level due to temperature drift, time drift, or the like occurring in the optical intensity modulation unit 14. The frequency shifting device 1 shown in FIG. 2 includes the control unit 18, and is therefore capable of compensating for the deviation in signal level.

[0039] The photoelectric conversion unit 18a of the control unit 8 receives the pilot light P PIL The wavelength components are given. The photoelectric conversion unit 18a converts the pilot light P PIL The wavelength component is converted into an electrical signal E, and the electrical signal E is output to the bias control circuit 18b.

[0040] The bias control circuit 18b receives an electrical signal E from the photoelectric conversion unit 18a. The bias control circuit 18b controls the bias signal B provided to the light intensity modulation unit 14 based on the electrical signal E, thereby controlling the light intensity modulation by the light intensity modulation unit 14. Specifically, the bias control circuit 18b compares the electrical signal E with a threshold value Th. The threshold value Th indicates the value of the electric signal E output from the photoelectric conversion unit 18a when the light intensity modulation unit 14 does not experience temperature drift, time drift, or the like. The value of the electric signal E when the light intensity modulation unit 14 does not experience temperature drift, or the like, is determined by, for example, the characteristics of the light intensity modulation unit 14. The threshold value Th may be stored in an internal memory of the bias control circuit 18b, or may be provided from outside the frequency shifting device 1.

[0041] If the electrical signal E is greater than the threshold Th, the bias control circuit 18b controls the intensity modulated light P output from the light intensity modulation unit 14. IM The bias signal B to be supplied to the light intensity modulation section 14 is controlled so that the light intensity of the light beam is reduced. If the electrical signal E is smaller than the threshold Th, the bias control circuit 18b controls the intensity modulated light P output from the light intensity modulation unit 14. IM The bias signal B to be supplied to the light intensity modulation section 14 is controlled so that the light intensity of the light beam is increased. The bias control circuit 18b maintains the bias signal B provided to the light intensity modulation unit 14 if the electrical signal E is equal to the threshold value Th.

[0042] Here, if the electrical signal E is greater than the threshold Th, the bias control circuit 18b controls the intensity-modulated light P output from the light intensity modulation unit 14. IM However, this is merely an example. Even if the electric signal E is greater than the threshold value Th, the bias control circuit 18b controls the intensity-modulated light P output from the optical intensity modulation unit 14 only when the difference between the electric signal E and the threshold value Th is equal to or greater than a set value. IM The bias signal B to be provided to the light intensity modulation section 14 may be controlled so that the light intensity of the light beam is reduced. In addition, here, if the electrical signal E is smaller than the threshold value Th, the bias control circuit 18b controls the intensity modulated light P IM However, this is merely an example. Even if the electric signal E is smaller than the threshold value Th, the bias control circuit 18b controls the intensity-modulated light P output from the optical intensity modulation unit 14 only when the difference between the electric signal E and the threshold value Th is equal to or larger than the set value. IM The bias signal B to be provided to the light intensity modulation section 14 may be controlled so that the light intensity of the light beam is increased.

[0043] In the above-described first embodiment, the frequency shift device 1 is configured to include an optical wavelength multiplexing unit 13 that wavelength-multiplexes pilot light having a wavelength different from that of the carrier light into the carrier light, and an optical intensity modulation unit 14 that optically intensity-modulates the carrier light after the pilot light multiplexing by the optical wavelength multiplexing unit 13 with a signal to be frequency-shifted, and outputs the intensity-modulated carrier light after the optical intensity modulation. The frequency shift device 1 also includes an optical wavelength demultiplexing unit 15 that demultiplexes the intensity-modulated light output from the optical intensity modulation unit 14 into a wavelength component of the carrier light and a wavelength component of the pilot light, an optical pulse compression unit 16 that compresses the wavelength component of the carrier light in the time direction, and outputs a time-compressed pulse light that is the wavelength component of the compressed carrier light, and a control unit 18 that controls the optical intensity modulation by the optical intensity modulation unit 14 based on the wavelength component of the pilot light. Therefore, even if the signal level of the frequency-shifted signal, which is an electrical signal converted from the time-compressed pulse light, deviates from the original signal level, the frequency shift device 1 can restore the signal level of the frequency-shifted signal to the original signal level.

[0044] Embodiment 2 In the second embodiment, the carrier light P generated by the carrier light generating unit 11 CAR A frequency shifting device 1 including a spectrum shaping unit 19 that shapes the time waveform of the signal will be described.

[0045] Fig. 10 is a configuration diagram showing a frequency shift device 1 according to embodiment 2. In Fig. 10, the same reference numerals as in Fig. 2 indicate the same or corresponding parts, and detailed description thereof will be omitted. The frequency shift device 1 shown in Figure 10 includes a carrier light generating unit 11, a pilot light generating unit 12, an optical wavelength multiplexing unit 13, an optical intensity modulation unit 14, an optical wavelength demultiplexing unit 15, an optical pulse compression unit 16, an opto-electrical conversion unit 17, a control unit 18, and a spectrum shaping unit 19. In the frequency shift device 1 shown in FIG. 10, the carrier light generation unit 11 and the spectrum shaping unit 19, and the spectrum shaping unit 19 and the optical wavelength multiplexing unit 13 are connected by, for example, optical fibers.

[0046] The spectrum shaping unit 19 is realized by, for example, a wavelength selective switch. The spectrum shaping unit 19 receives the carrier light P CAR is given. The spectrum shaping unit 19 is a carrier light P CAR Shape the time waveform of. The spectrum shaping unit 19 converts the waveform-shaped carrier light P CAR ' is output to the optical wavelength multiplexing unit 13. 10, the spectrum shaping unit 19 is disposed between the optical pulse stretching unit 11b and the optical wavelength multiplexing unit 13. However, this is merely an example, and for example, the optical wavelength multiplexing unit 13 may have the function of the spectrum shaping unit 19.

[0047] Next, the operation of the frequency shift device 1 shown in Fig. 10 will be described. However, since the frequency shift device 1 is similar to the frequency shift device 1 shown in Fig. 2 except for the spectrum shaping unit 19, the operation of the spectrum shaping unit 19 will be mainly described here.

[0048] Carrier light P generated by the carrier light generation unit 11 CAR The light intensity of is expressed as the wavelength λ C The largest is at wavelength λ C The shorter the carrier light P CAR The light intensity of C The longer it is, the smaller it becomes. In other words, the carrier light P CAR The light intensity of the carrier light P CAR may cause distortion.

[0049] The spectrum shaping unit 19 receives the carrier light P CAR is given. The spectrum shaping unit 19 is a carrier light P CAR In order to eliminate the distortion of the carrier light P CAR Shape the time waveform of. The carrier light P shown in FIG. CARThe carrier light P after waveform shaping shown in FIG. CAR 'The distortion has been eliminated. Specifically, the spectrum shaping unit 19 divides the carrier light P CAR As shown in FIG. 11A, by adjusting the optical attenuation for each frequency slice in CAR Shape the time waveform of. The spectrum shaping unit 19 converts the waveform-shaped carrier light P CAR ' is output to the optical wavelength multiplexing unit 13.

[0050] FIG. 11A shows the carrier light P after waveform shaping. CAR ' and pilot light P PIL 11A is an explanatory diagram showing the time waveforms in the carrier light P after waveform shaping. CAR ' and pilot light P PIL The respective light intensities at FIG. 11B shows the pilot light P PIL The carrier light P after waveform shaping in which wavelengths are multiplexed CAR’+PIL In FIG. 11B, the horizontal axis indicates time, and the vertical axis indicates the carrier light P CAR’+PIL The light intensity is shown. FIG. 11C shows the carrier light P CAR ' and pilot light P PIL 11C is an explanatory diagram showing the wavelengths in the respective cases. In FIG. 11C, the horizontal axis shows the wavelength, and the vertical axis shows the carrier light P CAR ' and pilot light P PIL The respective light intensities at In FIG. 11C, the pilot light P PIL The wavelength λ P But the carrier light P CAR However, this is only an example, and the pilot light P PIL The wavelength λ P But the carrier light P CAR ' may be shorter than the wavelength range of

[0051] The spectrum shaping unit 19 converts the carrier light P CARBy shaping the time waveform of the frequency shift device 1 shown in FIG. C and wavelength λ P Even if you bring the pilot light P PIL The carrier light P does not interfere with the wavelength of CAR It is possible to generate the wavelength λ ′ shown in FIG. C and wavelength λ P The difference between the wavelength λ C and wavelength λ P is smaller than the difference between

[0052] The optical wavelength multiplexing unit 13 receives the waveform-shaped carrier light P as shown in FIG. 11A from the carrier light generation unit 11. CAR 11A. PIL is given. The optical wavelength multiplexing unit 13 outputs pilot light P PIL After waveform shaping, the carrier light P CAR ' are wavelength-multiplexed. As shown in FIG. 11B, the optical wavelength multiplexing unit 13 outputs a pilot light P PIL The carrier light P after waveform shaping in which the wavelengths are multiplexed CAR’+PIL to the optical intensity modulation unit 14.

[0053] The optical intensity modulation unit 14 receives an RF signal (1) from the outside and receives the carrier light P CAR’+PIL and a bias signal B is provided from the control unit 18. The optical intensity modulation unit 14 receives the carrier light P CAR’+PIL The optical intensity is modulated by an RF signal (1). The light intensity modulation unit 14 outputs the intensity-modulated light P IM is output to the optical wavelength demultiplexing unit 15.

[0054] In the above-described second embodiment, the frequency shift device 1 shown in Fig. 10 is configured to include a spectrum shaping unit 19 that shapes the time waveform of the carrier light generated by the carrier light generation unit 11 and outputs the waveform-shaped carrier light to the optical wavelength multiplexing unit 13. Therefore, the frequency shift device 1 shown in Fig. 10 can improve the accuracy of compensation for the deviation in the signal level compared to the frequency shift device 1 shown in Fig. 2.

[0055] In addition, the present disclosure allows free combination of the respective embodiments, modification of any of the components of each embodiment, or omission of any of the components of each embodiment. [Industrial Applicability]

[0056] The present disclosure is suitable for frequency shifting devices and communication devices. [Explanation of symbols]

[0057] 1 frequency shift device, 2 communication circuit, 3 antenna, 11 carrier light generation unit, 11a short pulse light source, 11b optical pulse stretching unit, 12 pilot light generation unit, 12a light source driving circuit, 12b pilot light source, 13 optical wavelength multiplexing unit, 14 optical intensity modulation unit, 15 optical wavelength demultiplexing unit, 16 optical pulse compression unit, 17 photoelectric conversion unit, 18 control unit, 18a photoelectric conversion unit, 18b bias control circuit, 19 spectrum shaping unit.

Claims

1. an optical wavelength multiplexing unit that wavelength-multiplexes pilot light having a wavelength different from that of a carrier light with the carrier light; an optical intensity modulation unit that optically intensity-modulates the carrier light obtained by the pilot light multiplexing by the optical wavelength multiplexing unit with a signal to be frequency-shifted, and outputs intensity-modulated light that is the carrier light obtained by the optical intensity modulation; an optical wavelength demultiplexing unit that demultiplexes the intensity-modulated light output from the optical intensity modulation unit into a wavelength component of the carrier light and a wavelength component of the pilot light; an optical pulse compression unit that compresses the wavelength component of the carrier light in a time direction and outputs a time-compressed pulse light that is the wavelength component of the compressed carrier light; a control unit that controls the light intensity of the intensity-modulated light output from the light intensity modulation unit based on the wavelength component of the pilot light; A frequency shifting device comprising:

2. The control unit is 2. The frequency shift device according to claim 1, further comprising: a first input terminal for inputting a first bias signal to said first optical fiber; a second input terminal for inputting a second bias signal to said first optical fiber;

3. a carrier light generating unit that generates carrier light by stretching pulse light in a time direction and outputs the generated carrier light to the optical wavelength multiplexing unit; a pilot light generating unit that generates pilot light having a wavelength different from that of the carrier light generated by the carrier light generating unit and outputs the generated pilot light to the optical wavelength multiplexing unit; 2. The frequency shifting device according to claim 1, further comprising:

4. 4. The frequency shift device according to claim 3, further comprising a spectrum shaping unit that shapes a time waveform of the carrier light generated by the carrier light generation unit and outputs the waveform-shaped carrier light to the optical wavelength multiplexing unit.

5. 2. The frequency shifting device according to claim 1, further comprising an opto-electrical conversion unit that converts the time-compressed pulsed light output from the optical pulse compression unit into an electrical signal and outputs the electrical signal as a frequency-shifted signal.

6. A frequency shifting device according to claim 5; a communication circuit that outputs an electrical signal output from the photoelectric conversion unit of the frequency shift device to an antenna; A communication device comprising:

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