Terahertz waveform detection device and terahertz waveform detection method

Abstract

To accurately detect a waveform of a terahertz pulse wave.SOLUTION: A terahertz waveform detection device 1 includes: a carrier wave generation section 10 for generating a carrier wave where a frequency is changed in response to a time; a modulation section 20 for generating a modulation component by writing a terahertz pulse wave in the carrier wave; a phase correction section 30 for correcting a phase of the modulation component so as to generate a phase-corrected modulation component where a frequency is changed in response to a time by an opposite inclination of the inclination of the carrier wave in a plane space to be expressed by the frequency and a temporal axis; and a waveform detection section 50 for detecting the waveform of the terahertz pulse wave based on the phase-corrected modulation component and a chirp pulse wave corresponding to the carrier wave.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a terahertz waveform detection device and a terahertz waveform detection method. [Background technology]

[0002] A known spectroscopy method for waveforms in the terahertz region is terahertz time-domain spectroscopy (THz-TDS), in which a terahertz pulse wave (THz pulse wave) is incident on a sample, the waveform of the terahertz pulse wave after passing through the sample is measured in a time-resolved manner, and the waveform is then Fourier transformed to detect the amplitude and phase for each frequency.

[0003] The pump-and-probe method is also known as a method for measuring the waveform of terahertz pulse waves. In this method, laser light emitted from a laser generator is split into pump light for the terahertz pulse wave generation system and probe light for the detection system. The pump light is then guided to a terahertz pulse wave generator to generate terahertz pulse waves, and the probe light has its optical path length changed by a time delay device before being guided to a detection element to detect the terahertz pulse waves.

[0004] In this way, by delaying the probe light, the timing at which the probe light reaches the detecting element is changed, and the waveform of the repeatedly arriving terahertz pulse wave with the same waveform is sampled. Because the detecting element for the terahertz pulse wave only operates when irradiated with the probe light, the detector measures only the signal from the terahertz pulse wave that arrives at the same time as the probe light. The amplitude and phase for each frequency are obtained by Fourier transforming the time waveform of the measured terahertz pulse wave.

[0005] In measuring the waveform of terahertz pulse waves using the pump-probe method, the time waveform and spectrum of the terahertz pulse wave are obtained by sweeping the time using a repetitive phenomenon, so it is not suitable for measuring phenomena that behave differently each time, such as phase transitions and destructive phenomena, constantly changing phenomena, moving objects, or phenomena that require long periods of time to measure.

[0006] Therefore, it has been proposed to use chirped pulses to map time information to wavelength and then detect it using a spectrometer and a two-dimensional detector, but the detection speed is limited by the detection speed of the two-dimensional detector.In addition to the problem of detection speed, there are problems such as distortion of the observed waveform because the time domain signal does not correspond one-to-one to the spectral domain, and the spectrum is detected as a digital signal, making it difficult to perform calculations such as waveform multiplication (mixing).

[0007] To solve these problems, Patent Document 1 discloses detecting the waveform of a one-shot (single-shot) terahertz wave in measuring the waveform of a terahertz wave by a pump-probe method. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-142594 Summary of the Invention [Problem to be solved by the invention]

[0009] However, in the waveform detection of Patent Document 1, there is room for further improvement in terms of the problem of distortion of the observed waveform.

[0010] An object of the present invention is to detect the waveform of a terahertz pulse wave with higher accuracy. [Means for solving the problem]

[0011] The invention disclosed in this application to solve the above problems has various aspects, and representative aspects thereof are outlined below.

[0012] (1) A terahertz waveform detection device having: a carrier wave generation unit that generates a carrier wave whose frequency changes over time; a modulation unit that generates a modulated component by writing a terahertz pulse wave onto the carrier wave; a phase correction unit that corrects the phase of the modulated component to generate a phase-corrected modulated component whose frequency changes over time with a gradient opposite to that of the carrier wave in a plane space represented by the frequency and time axes; and a waveform detection unit that detects the waveform of the terahertz pulse wave based on the phase-corrected modulated component and a chirp pulse wave corresponding to the carrier wave.

[0013] (2) In (1), the terahertz waveform detection device, wherein the carrier wave and the chirp pulse wave are common.

[0014] (3) In (1), the carrier wave generating unit includes a pulsed laser that outputs pulsed laser light and an element that changes the frequency of the pulsed laser light over time, and both the carrier wave and the chirp pulse wave are waves generated based on the pulsed laser and the element.

[0015] (4) In the terahertz waveform detection device according to (3), the phase correction unit corrects the phase of the modulated component by using the element.

[0016] (5) In any one of (1) to (4), a terahertz waveform detection device, wherein a component generated by superimposing a high-frequency component of the phase-corrected modulated component with a component of the chirp pulse wave generated at the same timing as the high-frequency component has approximately the same frequency as a component generated by superimposing a low-frequency component of the phase-corrected modulated component with a component of the chirp pulse wave generated at the same timing as the low-frequency component.

[0017] (6) In any one of (1) to (5), the waveform detection unit detects the waveform of the terahertz pulse wave as a spectrum of light generated based on the sum frequency or difference frequency of the phase-corrected modulation component and the waveform detection chirp pulse wave.

[0018] (7) A terahertz waveform detection method including: a step of generating a carrier wave whose frequency changes over time; a step of generating a modulated component by writing a terahertz pulse wave onto the carrier wave; a step of correcting the phase of the modulated component to generate a phase-corrected modulated component whose frequency changes over time with a gradient opposite to that of the carrier wave in a plane space represented by the frequency and time axes; and a step of detecting the waveform of the terahertz pulse wave based on the phase-corrected modulated component and a chirp pulse wave corresponding to the carrier wave. [Effects of the Invention]

[0019] According to the above aspects (1) to (7) of the present invention, the waveform of a terahertz pulse wave can be detected with higher accuracy. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a diagram showing an outline of the overall configuration of a terahertz waveform detection device according to an embodiment of the present invention. [Figure 2] FIG. 10 is a diagram showing a state in which a carrier wave (chirp pulse) and modulated components are observed in a plane space represented by the frequency and time axes in this embodiment. [Figure 3] FIG. 10 is a diagram showing how a phase-corrected carrier wave and a phase-corrected modulated component are observed in a plane space represented by the frequency and time axes in this embodiment. [Figure 4] FIG. 10 is a diagram showing the state in which a chirp pulse wave for waveform detection, which is common to a carrier wave, is observed in a plane space represented by the frequency and time axes in this embodiment. [Figure 5] FIG. 10 is a diagram showing a state in which sum frequency light is observed in a plane space represented by a frequency axis and a time axis in this embodiment. [Figure 6] 4 is a flowchart showing a method for detecting a terahertz waveform in the present embodiment. [Figure 7] 1 is a diagram illustrating a first configuration example of a terahertz waveform detection device according to an embodiment of the present invention. [Figure 8] FIG. 2 is a diagram illustrating a second configuration example of a terahertz waveform detection device according to the present embodiment. [Figure 9] FIG. 10 is a diagram showing an outline of the overall configuration of a terahertz waveform detection device according to a modified example of the present embodiment. [Figure 10] FIG. 10 is a diagram showing a modulation component and a chirp pulse wave in a plane space represented by the frequency and time axes in a conventional example. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, an embodiment of the present invention (hereinafter referred to as the present embodiment) will be described in detail with reference to the drawings.

[0022] In this embodiment, terahertz pulse waves are observed using terahertz time-domain spectroscopy (THz-TDS). Terahertz time-domain spectroscopy (THz-TDS) is a method in which a terahertz pulse wave is incident on a sample, the electric field waveform of the terahertz pulse wave after passing through the sample is measured in a time-resolved manner, and the amplitude and phase for each frequency are measured by Fourier transforming the electric field waveform.

[0023] The terahertz pulse wave is an electromagnetic wave or signal in a frequency range called the terahertz region, which is approximately 0.1 to 100 THz (3.3 to 3333 cm −1 in wave numbers).

[0024] In conventional single-shot terahertz time-domain spectroscopy using chirped pulses, pulsed laser light is first split into pump light and probe light. The pump light generates a terahertz pulse wave. The terahertz pulse wave can be generated, for example, by irradiating a nonlinear optical crystal with a femtosecond optical pulse. The probe light is used to sample the time waveform of the terahertz pulse wave, and is passed through a delay time element and a dispersive element to adjust the timing and generate a chirped pulse wave. Note that a chirped pulse is a pulse whose frequency changes over time.

[0025] Detection of a terahertz electric field waveform using a chirp pulse in a conventional example will be described with reference to Fig. 10. Fig. 10 is a diagram showing modulated components and a chirp pulse wave in a plane space represented by the frequency and time axes in a conventional example.

[0026] FIG. 10 shows a carrier wave (chirp pulse) and a modulated component generated by writing a terahertz pulse wave. In the conventional example, the high-frequency component of the modulated component and the carrier wave component having the same frequency as the high-frequency component appear with a time difference, causing them to interfere with each other. Similarly, the low-frequency component of the modulated component and the chirp pulse wave component having the same frequency as the difference frequency component appear with a time difference, causing them to interfere with each other. This causes distortion in the waveform of the terahertz pulse wave read out as a spectrum. As a result, accurate information about the terahertz pulse wave may not be obtained.

[0027] It is also possible to detect the waveform of a terahertz pulse wave by writing a terahertz pulse wave into a continuous wave laser beam. However, in such a configuration, the power available for waveform detection may be insufficient, making it difficult to obtain information about the terahertz pulse wave.

[0028] Therefore, in this embodiment, a configuration is adopted in which a modulated component is generated by writing a terahertz wave onto a carrier wave, which is a chirp pulse wave whose frequency changes over time, a phase-corrected modulated component is generated by correcting the phase of the modulated component, and the electric field waveform of the terahertz pulse wave is read out based on the phase-corrected modulated component and the chirp pulse wave, which is common to the carrier wave.

[0029] FIG. 1 is a diagram showing an outline of the overall configuration of a terahertz waveform detection device according to this embodiment. FIG. 2 is a diagram showing how a carrier wave (chirp pulse) and modulated components are observed in a plane space represented by the frequency and time axes in this embodiment. FIG. 3 is a diagram showing how a phase-corrected carrier wave and a phase-corrected modulated component are observed in a plane space represented by the frequency and time axes in this embodiment. FIG. 4 is a diagram showing how a chirp pulse wave for waveform detection, which is common to the carrier wave, is observed in a plane space represented by the frequency and time axes in this embodiment. FIG. 5 is a diagram showing how sum frequency light generated by a sum frequency generation unit is observed in a plane space represented by the frequency and time axes in this embodiment.

[0030] As shown in FIG. 1, the terahertz waveform detecting device 1 includes a carrier wave generating section 10, a modulating section 20, a phase correcting section 30, a sum frequency generating section 40, an electric field waveform detecting section (waveform detecting section) 50, and an oscilloscope 60.

[0031] The carrier wave generating unit 10 preferably includes a pulsed laser that generates pulsed laser light. The pulsed laser generates laser light having a pulse width of about femtoseconds to picoseconds, and may be, for example, a fiber laser or a titanium sapphire laser.

[0032] The carrier wave generating unit 10 may also include a chirped fiber Bragg grating (hereinafter simply referred to as CFBG), which is a dispersive element that changes the frequency over time. A CFBG is a fiber Bragg grating in which the grating period changes so that the low-frequency and high-frequency components in the pulse are reflected at different positions. A fiber Bragg grating is a fiber-type device that forms a diffraction grating in the core of an optical fiber and functions as an optical filter.

[0033] The carrier wave generating unit 10 generates a carrier wave based on a pulse laser and a CFBG. In this embodiment, the carrier wave is a chirped pulse wave whose frequency varies over time, as shown in FIG. 2. In this embodiment, the chirp amount of the generated carrier wave can be adjusted by adjusting the design of the CFBG and the position and distance of an additional prism pair. The chirp amount is an amount equivalent to the gradient in a plane space represented by the frequency and time axes. In other words, the chirp amount is the gradient of the frequency that varies over time. The gradient increases as the absolute value of the chirp amount increases. The chirp amount is equivalent to the value obtained by differentiating the phase of light twice with respect to the frequency. In this embodiment, the chirp amount of the carrier wave generated by the carrier wave generating unit 10 is arbitrary.

[0034] The modulator 20 receives a carrier wave (chirp pulse) and the terahertz pulse wave generated by the terahertz pulse generator 2, and writes the terahertz pulse wave into the carrier wave to generate the modulated component shown in Fig. 2. The terahertz pulse generator 2 may generate the terahertz pulse wave based on pump light branched from the pulsed laser light from the carrier wave generator 10, or may generate the terahertz pulse wave independently.

[0035] The modulation unit 20 preferably includes an electro-optic crystal (EO crystal). When a carrier wave is incident on this electro-optic crystal, a terahertz pulse wave is written into the carrier wave, and a modulated component is generated. Note that, for example, ZnTe crystal, GaP, LiNbO3, etc. may be used as the electro-optic crystal.

[0036] The phase corrector 30 generates a phase-corrected carrier wave and a phase-corrected modulated component. Specifically, the phase corrector 30 accelerates the high-frequency components of the modulated component and slows the low-frequency components by passing the modulated component through an element such as a fiber. As a result, a phase-corrected modulated component is generated whose frequency changes over time with a slope opposite to that of the carrier wave in a plane represented by the frequency and time axes, as shown in FIG. 3. Note that when the phase of the modulated component is corrected by the phase corrector 30, the unmodulated component of the carrier wave is observed as a vertically elongated component in a plane represented by the frequency and time axes, as shown in FIG. 3.

[0037] It is preferable that the terahertz waveform detecting device 1 includes a control circuit (not shown) that controls each unit. For example, the control circuit may measure the waveform (slope) of the carrier wave and adjust the amount of phase correction by the phase corrector 30 based on the measured value.

[0038] The sum frequency generating unit 40 generates a sum frequency of the light composed of the phase-corrected carrier wave and the phase-corrected modulation component generated by the phase corrector 30 and the chirp pulse wave for waveform detection. In this embodiment, the chirp pulse wave for waveform detection is generated by the carrier wave generating unit 10 and may be the same as the carrier wave (chirp pulse) on which the terahertz pulse wave is written. As a result, as shown in FIG. 5, sum frequency light whose frequency does not change over time is observed. This is because the sum frequency component generated by superimposing the phase-corrected high-frequency component of the phase-corrected modulation component with the component of the chirp pulse wave for waveform detection that exists at the same timing as the modulation component has approximately the same frequency as the sum frequency component generated by superimposing the low-frequency component of the phase-corrected modulation component with the component of the chirp pulse wave for waveform detection that exists at the same timing as the modulation component.

[0039] The sum frequency generating unit 40 preferably includes a nonlinear optical crystal such as BBO (beta barium borate) or periodically poled LiNbO3, and generates sum frequency light by introducing a chirp pulse wave for waveform detection, and light consisting of a phase-corrected carrier wave and a phase-corrected modulation component into the nonlinear optical crystal (NLO: Non-Linear Optical).

[0040] In this embodiment, the chirp pulse wave serving as the carrier wave shown in FIG. 2 and the chirp pulse wave for waveform detection shown in FIG. 4 are shared. That is, a common device generates the carrier wave and a common device generates the chirp pulse wave for waveform detection. Therefore, the terahertz waveform detection device 1 does not need separate devices for generating the carrier wave and the chirp pulse wave for waveform detection, simplifying the configuration. However, this is not limiting, and separate devices for generating the carrier wave and the chirp pulse wave for waveform detection may be provided. In this case, the chirp pulse wave for waveform detection may correspond to the carrier wave. Specifically, the chirp amount of the chirp pulse wave for waveform detection should be the same as that of the carrier wave. That is, in a plane space represented by the frequency and time axes, the slope of the carrier wave and the slope of the chirp pulse wave for waveform detection should be equal. However, some error may be allowed between the chirp amount of the carrier wave and the chirp amount of the chirp pulse wave for waveform detection. Note that the chirp amounts of the phase-corrected modulation component and the chirp pulse for waveform detection must be approximately the same.

[0041] The electric field waveform detection unit 50 detects the spectrum of the sum frequency light generated by the sum frequency generation unit 40. The spectrum observed thereby corresponds to the electric field waveform of the terahertz pulse wave. By displaying this spectrum on an oscilloscope 60, the user can visually grasp the electric field waveform of the terahertz pulse wave. As a spectrum detection method, it is recommended to use a spectrum detection method using a CFBG and a high-speed photodiode or a wideband oscilloscope, or a high-speed spectrometer using a diffraction grating and a linear detector.

[0042] Next, a method for detecting a terahertz waveform in this embodiment will be described with reference to Fig. 6. Fig. 6 is a flowchart showing a method for detecting a terahertz waveform in this embodiment.

[0043] First, the carrier wave generating unit 10 generates a carrier wave (chirp pulse) whose frequency changes over time (step S1). Next, the modulating unit 20 writes a terahertz pulse wave into the carrier wave to generate a modulated component (step S2). Next, the phase correcting unit 30 corrects the phase of the carrier wave and the modulated component (step S3). Next, the sum frequency generating unit 40 calculates the sum frequency of the modulated and phase-corrected carrier wave and a chirp pulse wave that is common to the carrier wave and is used for waveform detection, thereby generating sum frequency light whose frequency does not change over time (step S4). Then, the electric field waveform detecting unit 50 detects the electric field waveform of the terahertz pulse wave based on the sum frequency light (step S5).

[0044] Next, specific configuration examples of the terahertz waveform detection device according to this embodiment will be described with reference to Figures 7 and 8. Figure 7 is a diagram showing a first configuration example of the terahertz waveform detection device according to this embodiment. Figure 8 is a diagram showing a second configuration example of the terahertz waveform detection device according to this embodiment.

[0045] 7, the carrier wave generating unit 10 may be configured, for example, with a pulsed fiber laser and a CFBG. A pulsed fiber laser is a device capable of generating pulses with a short pulse width.

[0046] The phase corrector 30 may be configured to include optical elements that perform waveform shaping, such as a polarizer (analyzer), an amplifier, and a compensator.

[0047] Furthermore, as shown in FIG. 8, the phase corrector 30 may correct the phase of the modulated component using a CFBG included in the carrier generator 10. In this case, compared to when a CFBG is used in the carrier generator 10, it is preferable to use a CFBG such that the reflected positions of the high-frequency component and the low-frequency component are reversed by inputting a modulated carrier wave from an input port on the opposite side of the CFBG. This allows the modulated component introduced into the phase corrector 30 to have an inverse slope to the slope of the chirp pulse used for waveform readout in a plane represented by the frequency and time axes. By adopting the second configuration example shown in FIG. 8, phase control can be achieved with a single CFBG, making the device configuration simpler than the first configuration example shown in FIG. 7.

[0048] The electric field waveform detection unit 50 may include, for example, a high-speed spectrometer, which may be used to wavelength-resolve the terahertz pulse wave into which the chirp pulse wave has been written, and detect the electric field waveform.

[0049] Next, a modified example of this embodiment will be described with reference to Fig. 9. In the above-described embodiment, an example in which sum frequency light is generated by sum frequency generating unit 40 has been described, but in this modified example, a terahertz waveform detecting device 1 having a difference frequency generating unit 140 that generates difference frequency light will be described. Note that components having the same functions as in the above-described embodiment will be assigned the same reference numerals, and detailed description thereof will be omitted.

[0050] As shown in FIG. 9 , the terahertz waveform detection device 1 according to the modified example may include a second harmonic generating unit 15. The second harmonic generating unit 15 includes a nonlinear optical crystal or the like, and generates a carrier wave (chirp pulse) of frequency 2ω in addition to a chirp pulse wave of frequency ω when a carrier wave of frequency ω generated by the carrier wave generating unit 10 is introduced thereto. The terahertz pulse wave is written onto the carrier wave (chirp pulse) of frequency 2ω, and the resulting modulated component is phase-corrected to generate a modulated component and a carrier wave with a predetermined chirp amount. This phase-corrected modulated component and a chirp pulse wave of frequency ω with the same chirp amount are introduced into the difference frequency generating unit 140. The difference frequency generating unit 140 calculates the difference frequency between the phase-corrected modulated component and the chirp pulse wave of frequency ω, generating difference frequency light of frequency ω whose frequency does not change over time. The electric field waveform detecting unit 50 then measures the spectrum of the difference frequency light to detect the electric field waveform of the terahertz pulse wave.

[0051] 9 illustrates an example in which a chirp pulse wave with a frequency ω generated by the second harmonic generating unit 15 is used for waveform detection, but this is not limiting. For example, a chirp pulse wave with a frequency ω generated by the carrier generating unit 10 that does not pass through the second harmonic generating unit 15 may be used for waveform detection. In this case, however, the frequency of the difference frequency component must be sufficiently high to enable spectrum detection. It is advisable to select the wavelengths of the carrier wave (chirp pulse) and the chirp pulse for waveform readout within this range.

[0052] In the terahertz waveform detecting device 1 according to the present embodiment and the modified examples described above, waveform distortion due to interference is suppressed, and the electric field waveform of the terahertz pulse wave can be detected with high accuracy.

[0053] Furthermore, in the terahertz waveform detecting device 1 according to this embodiment and its modifications, the power available for waveform detection is greater than that of a configuration in which a terahertz pulse wave is written into a continuous wave laser beam, making it easier to obtain information about the terahertz pulse wave. If the output of the continuous wave light source that generates the continuous wave laser beam is I [W] and the window width to be measured is w [s], the power available for waveform detection is Iw [J]. On the other hand, in this embodiment and its modifications, if the output of the pulse laser included in the carrier wave generating unit 10 is I [W] and the repetition frequency of the pulse laser is f rep When the value is set to [Hz], the power available for waveform detection is I / f rep [J]. This is because in this embodiment and its modified examples, all of the energy of one pulse can be used for waveform detection. Therefore, in this embodiment and its modified examples, the power available for waveform detection is 1 / wf rep (=(I / f rep )÷Iw) times larger. For example, in a typical example, the window width to be measured is w=100[ps], and the repetition frequency f rep = 100 [kHz], 10 5 (=1÷((100×10 -12 )×(100×10 3 )) times more power can be used for waveform detection.

[0054] Furthermore, by employing the terahertz waveform detection device 1 according to this embodiment and its modifications, it is possible to obtain ultrafast responses of materials and terahertz waveforms using a single optical pulse. This may open up applications such as the realization of a wideband terahertz oscilloscope for evaluating ultrafast devices, simultaneous acquisition of phase and amplitude in terahertz and infrared imaging, increased speed, and elucidation of the dynamics of irreversible phenomena. Furthermore, it is possible to provide high sensitivity and tunable window widths, which could lead to applications in high-resolution time-domain lidar for terahertz waves and infrastructure inspection. Furthermore, detecting the ultrafast responses of semiconductors with high sensitivity and high speed is expected to be useful for evaluating impurities in semiconductors.

[0055] In this embodiment and the modified example, an example of detecting a terahertz electric field waveform has been described, but this is not limited to this, and the object to be detected may be a wave or phenomenon that changes over time in the terahertz frequency domain (picosecond time domain), such as a terahertz wave magnetic field waveform or light intensity waveform.

[0056] Although the embodiments and modifications of the present invention have been described above, the specific configurations of the embodiments and modifications are shown by way of example only and are not intended to limit the technical scope of the present invention. Those skilled in the art may modify the disclosed embodiments and modifications as appropriate, and it should be understood that the technical scope of the invention disclosed in this specification also includes such modifications. [Explanation of symbols]

[0057] 1 Terahertz waveform detection device, 2 Terahertz pulse wave generation unit, 10 Carrier wave generation unit, 15 Double wave generation unit, 20 Modulation unit, 30 Phase correction unit, 40 Sum frequency generation unit, 140 Difference frequency generation unit, 50 Electric field waveform detection unit, 60 Oscilloscope.

Claims

1. a carrier wave generating unit that generates a carrier wave whose frequency changes over time; a modulation unit that generates a modulated component by writing a terahertz pulse wave into the carrier wave; a phase correction unit that corrects the phase of the modulated component to generate a phase-corrected modulated component whose frequency changes over time with a slope opposite to that of the carrier wave in a plane space represented by a frequency and time axis; a waveform detection unit that detects a waveform of the terahertz pulse wave based on the phase-corrected modulation component and a chirp pulse wave corresponding to the carrier wave; A terahertz waveform detection device having:

2. The carrier wave and the chirp pulse wave are common. The terahertz waveform detection device according to claim 1 .

3. the carrier wave generating unit includes a pulse laser that outputs pulse laser light and an element that temporally changes the frequency of the pulse laser light, The carrier wave and the chirped pulse wave are both waves generated based on the pulse laser and the element. The terahertz waveform detection device according to claim 1 .

4. the phase correction unit corrects the phase of the modulated component by using the element; The terahertz waveform detection device according to claim 3 .

5. a component generated by superimposing a high-frequency component of the phase-corrected modulation component and a component of the chirp pulse wave generated at the same timing as the high-frequency component has approximately the same frequency as a component generated by superimposing a low-frequency component of the phase-corrected modulation component and a component of the chirp pulse wave generated at the same timing as the low-frequency component; The terahertz waveform detection device according to any one of claims 1 to 4.

6. the waveform detection unit detects the waveform of the terahertz pulse wave as a spectrum of light generated based on a sum frequency or a difference frequency of the phase-corrected modulation component and the chirp pulse wave. The terahertz waveform detection device according to any one of claims 1 to 5.

7. generating a carrier wave whose frequency varies with time; generating a modulated component by writing a terahertz pulse wave onto the carrier wave; a step of correcting the phase of the modulated component to generate a phase-corrected modulated component whose frequency changes over time with a slope opposite to that of the carrier wave in a plane space represented by a frequency and time axis; detecting a waveform of the terahertz pulse wave based on the phase-corrected modulation component and a chirp pulse wave corresponding to the carrier wave; A terahertz waveform detection method comprising:

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