WO2024147248A1 - Temporal waveform measuring method and temporal waveform measuring device - Google Patents

Temporal waveform measuring method and temporal waveform measuring device Download PDF

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WO2024147248A1
WO2024147248A1 PCT/JP2023/042686 JP2023042686W WO2024147248A1 WO 2024147248 A1 WO2024147248 A1 WO 2024147248A1 JP 2023042686 W JP2023042686 W JP 2023042686W WO 2024147248 A1 WO2024147248 A1 WO 2024147248A1
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time
spectrum
varying
frequency
time waveform
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PCT/JP2023/042686
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French (fr)
Japanese (ja)
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毅 小西
将之 牧野
知樹 辻
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国立大学法人大阪大学
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J11/00—Measuring the characteristics of individual optical pulses or of optical pulse trains

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  • This disclosure relates to a time waveform measurement method and a time waveform measurement device.
  • the present disclosure provides a time waveform measurement method or device that can measure the time waveform of a signal to be measured without using a wideband oscilloscope.
  • a time waveform measurement method discretizes the spectrum of chirped light, whose frequency increases or decreases over time, modulates the discretized time-varying light with a signal to be measured, and analyzes the spectrum of the modulated time-varying light.
  • a time waveform measuring device includes a filter that discretizes the spectrum of time-varying spectrum light whose frequency increases or decreases over time, and a modulator that modulates the time-varying spectrum light, the spectrum of which has been discretized by the filter, with a signal to be measured.
  • the time waveform measurement method or time waveform measurement device disclosed herein can measure the time waveform of the signal to be measured without using a wideband oscilloscope.
  • FIG. 1 is a block diagram showing a configuration of a time waveform measuring device according to an embodiment.
  • FIG. 2A is a diagram showing a time waveform of discretized time-varying spectrum light.
  • FIG. 2B is a diagram showing the spectrum of discretized time-varying spectrum light.
  • FIG. 3A is a diagram showing the time waveform of modulated time-varying spectrum light.
  • FIG. 3B is a diagram showing the spectrum of modulated time-varying spectrum light.
  • FIG. 4 is a flowchart showing a time waveform measuring method according to the embodiment.
  • FIG. 5 is a flowchart showing a part of a time waveform measuring method according to an embodiment.
  • each figure is a schematic diagram in which emphasis, omissions, or adjustments to the ratio have been made as appropriate to illustrate the present disclosure, and is not necessarily an exact illustration, and may differ from the actual shape, positional relationship, and ratio.
  • the same reference numerals are used for substantially the same configuration, and duplicate explanations may be omitted or simplified.
  • Fig. 1 is a block diagram showing the configuration of the time waveform measuring apparatus 100 according to the present embodiment.
  • halftones indicate the wavelength (frequency) of light, and the lower the density, the longer the wavelength.
  • the light source 200 is a broadband pulse light source, and can emit, for example, super continuum (SC) light as the broadband optical pulse 10.
  • SC super continuum
  • the frequency of the signal to be measured is about 500 GHz, for example, SC light having a bandwidth of about 1000 nm can be used as the broadband optical pulse 10.
  • the time waveform measuring device 100 can measure the time waveform of the measured signal 16 by using the broadband optical pulse 10 received from the light source 200 as a probe light. As shown in FIG. 1, the time waveform measuring device 100 includes a disperser 102, a filter 104, a modulator 106, an optical spectrum analyzer 108, and an information processor 110.
  • the disperser 102 can generate chirped light 12 by dispersing the broadband optical pulse 10.
  • the chirped light 12 is light whose frequency increases or decreases over time.
  • the chirped light 12 generated by the disperser 102 is propagated to the filter 104 via the optical transmission medium 112.
  • the disperser 102 can be, but is not limited to, a high-dispersion optical fiber, a chirped fiber bragg grating (FBG), an arrayed waveguide grating (AWG), or any combination thereof.
  • the time waveform measuring device 100 may receive the time-varying spectrum light 12 from an external source. In this case, the disperser 102 does not need to be included in the time waveform measuring device 100.
  • the filter 104 can discretize the time-varying spectrum light 12.
  • the filter 104 is an optical filter having multiple discrete passbands, and can selectively pass multiple discrete frequency components.
  • the time-varying spectrum light discretized by the filter 104 (hereinafter referred to as discretized time-varying spectrum light 14) is propagated to the modulator 106 via the optical transmission medium 114.
  • the filter 104 can be, but is not limited to, an AWG or the like.
  • the filter 104 may be integrated with the disperser 102.
  • the discretized time-varying spectrum light 14 will be described later with reference to Figures 2A and 2B.
  • the modulator 106 can modulate the discretized time-varying spectrum light 14 with the measured signal 16.
  • the modulator 106 is an intensity modulator, and the discretized time-varying spectrum light 14 modulated by the modulator 106 (hereinafter referred to as modulated time-varying spectrum light 18) is propagated to the optical spectrum analyzer 108 via the optical transmission medium 116.
  • the modulator 106 can be, but is not limited to, an EA (Electro-Absorption) modulator and/or an ER (Electro-Refractive) modulator.
  • EA Electro-Absorption
  • ER Electro-Refractive
  • the information processor 110 can reconstruct the time waveform of the measured signal by processing the spectral information of the modulated time-varying spectrum light 18. Specifically, the information processor 110 accumulates the spectrum of the modulated time-varying spectrum light 18 for each of a plurality of bands based on the spectral information of the modulated time-varying spectrum light 18. In other words, the information processor 110 adds up the intensity of light of each frequency for each band. The plurality of bands will be described later with reference to FIG. 3B. Based on the spectrum of the modulated time-varying spectrum light 18 accumulated for each band in this manner, the time waveform of the measured signal 16 can be reconstructed. The reconstructed time waveform of the measured signal 16 may be displayed on a display.
  • the information processor 110 can be realized by a computer having a processor and memory.
  • the information processor 110 may also be realized as one or more dedicated electronic circuits. In such a case, the information processor 110 may be included in the optical spectrum analyzer 108.
  • the optical transmission media 112, 114, and 116 respectively connect between the disperser 102 and the filter 104, between the filter 104 and the modulator 106, and between the modulator 106 and the optical spectrum analyzer 108.
  • the optical transmission media 112, 114, and 116 may be, for example, optical fiber or an optical waveguide device, but are not limited to these. Note that the optical transmission media 112, 114, and 116 do not have to be included in the time waveform measurement device 100.
  • FIG. 2A is a diagram showing the time waveform of the discretized time-varying spectrum light 14.
  • Fig. 2B is a diagram showing the spectrum of the discretized time-varying spectrum light 14.
  • the discretized time-varying spectrum light 14 includes seven frequency components 141 to 147 whose frequencies change discretely in time intervals Tint 1 to Tint 6.
  • the frequency components 141 to 147 have discrete frequencies fc 1 to fc 7 in periods centered around times t 1 to t 7 , respectively.
  • fm (Hz) indicates the frequency of the measured signal 16.
  • the time intervals Tint n are approximately the same, but may be different from each other.
  • the intensities of the frequency components 141 to 147 are approximately the same, but the intensities of some of the frequency components 141 to 147 may be different from the intensities of other parts of the frequency components 141 to 147.
  • the number of frequency components 141 to 147 in Figures 2A and 2B is an example and is not limited to seven. In other words, the number of frequency components contained in the discretized time-varying spectrum light 14 may be less than seven or more than seven.
  • Fig. 3A is a diagram showing the time waveform of the modulated time-varying spectrum light 18.
  • Fig. 3B is a diagram showing the spectrum of the modulated time-varying spectrum light 18.
  • the modulated time varying spectrum light 18 includes frequency components 181 to 187 whose frequencies change discretely in time intervals Tint 1 to Tint 6.
  • the frequency components 181 to 187 have discrete frequencies fc 1 to fc 7 in periods centered around times t 1 to t 7 , respectively, like the frequency components 141 to 147.
  • the frequency components 181 to 187 have intensities that change over time based on the signal 16 to be measured. Therefore, if the time waveform of the modulated time varying spectrum light 18 can be obtained, the time waveform of the signal 16 to be measured can also be obtained.
  • the spectrum of the modulated time varying spectrum light 18 corresponds to the time waveform of the modulated time varying spectrum light 18. Therefore, if the spectrum of the modulated time varying spectrum light 18 can be obtained, the time waveform of the signal 16 to be measured can be obtained.
  • the time interval Tint n during which the frequency of the discretized time-varying spectrum light 14 changes is preferably equal to or less than 1/2fm (s) based on the sampling theorem. This makes it possible to more accurately reconstruct the time waveform of the measured signal 16 of frequency fm.
  • each of the frequency components 181 to 187 includes, in addition to the original components of frequencies fc1 to fc7 (hereinafter referred to as main components), components shifted from frequencies fc1 to fc7 to the negative side and the positive side by the frequency fm of the signal to be measured 16 (hereinafter referred to as low-shift components and high-shift components, respectively).
  • the two shift components generated from the main component by such intensity modulation are components that should be included in the main component in terms of their correspondence with the time waveform. Therefore, in order to more accurately determine the time waveform of the signal to be measured 16, it is desirable to integrate the main component and the two shift components.
  • the frequency interval Fint n between adjacent frequency components in the frequency domain is 2fm (Hz) or more, which can suppress interference between the shifted components of the adjacent frequency components.
  • the graphs of light or signals shown in Figures 1 to 3B are examples and are not limited to these.
  • the amplitudes of the time-varying spectrum light 12 and the discretized time-varying spectrum light 14 do not have to be constant.
  • the time-varying spectrum light 12 and the discretized time-varying spectrum light 14 do not have to be rectangular.
  • the time waveform of the measured signal 16 can be measured based on the relative change in the spectrum of the modulated time-varying spectrum light 18 with respect to the discretized time-varying spectrum light 14.
  • the disperser 102 converts the broadband optical pulse 10 into time-varying spectrum light 12 (S100).
  • the time-varying spectrum light 12 which is the output of the disperser 102, is transmitted to the filter 104.
  • the modulator 106 modulates the discretized time-varying spectrum light 14 with the measured signal 16 (S120).
  • the output of the modulator 106, the modulated time-varying spectrum light 18, is transmitted to the optical spectrum analyzer 108.
  • the optical spectrum analyzer 108 analyzes the spectrum of the modulated time-varying spectrum light 18 (S130).
  • the output of the optical spectrum analyzer 108, that is, the spectral information, is sent to the information processor 110.
  • the information processor 110 reconstructs the time waveform of the measured signal 16 based on the spectral information of the modulated time-varying spectrum light 18 (S140). Note that step S140 does not have to be included in the time waveform measurement method. Details of this step S140 will be described with reference to FIG. 5.
  • the information processor 110 acquires the spectrum information of the modulated time-varying spectrum light 18 from the optical spectrum analyzer 108 (S142).
  • the information processor 110 integrates the spectrum for each band (S144). For example, in FIG. 3B, in the band Bw1 , the sum of the main component of frequency fc1 , the low-shift component of frequency fc1 -fm, and the high-shift component of frequency fc1 +fm is calculated.
  • the sum of the main component and the two shift components is calculated in the same manner as in the band Bw1 .
  • the information processor 110 reconstructs the time waveform of the measured signal 16 from the spectrum integration results for each band thus obtained (S146). Specifically, the information processor 110 reconstructs the time waveform of the measured signal 16 by mapping multiple bands into the time domain.
  • the time waveform measurement method discretizes the spectrum of the time-varying spectrum light 12, whose frequency increases or decreases over time (S110), modulates the discretized time-varying spectrum light 14 with the signal to be measured 16 (S120), and analyzes the spectrum of the modulated time-varying spectrum light 18 (S130).
  • the time waveform measuring device 100 also includes a filter 104 that discretizes the spectrum of the time-varying spectrum light 12 whose frequency increases or decreases over time, and a modulator 106 that modulates the discretized time-varying spectrum light 14 discretized by the filter 104 with the signal to be measured 16.
  • the time waveform measuring device 100 may further include an optical spectrum analyzer 108 that analyzes the spectrum of the modulated time-varying spectrum light 18 modulated by the modulator 106.
  • the time waveform of the measured signal 16 can be measured without using a wideband oscilloscope.
  • the spectrum of the modulated time-varying spectrum light 18 is discretized, it is possible to suppress interference between adjacent frequency components caused by the shift components generated by the modulation, and it is possible to measure the time waveform of the measured signal 16 more accurately.
  • the time interval T int n during which the frequency of the discretized time-varying spectrum light 14 changes discretely may be equal to or smaller than 1 ⁇ 2 f, where f may be the frequency of the signal 16 to be measured.
  • the time waveform measuring apparatus 100 may further include an information processor 110, which may accumulate the spectrum of the modulated time-varying spectrum light 18 analyzed by the optical spectrum analyzer 108 in each of a plurality of bands Bw n , each of which may include a plurality of discrete frequencies fc n of the discretized time-varying spectrum light 14 and may have a bandwidth based on the frequency fm of the signal to be measured 16, and may reconstruct the time waveform of the signal to be measured 16 based on the accumulated spectrum.
  • an information processor 110 may accumulate the spectrum of the modulated time-varying spectrum light 18 analyzed by the optical spectrum analyzer 108 in each of a plurality of bands Bw n , each of which may include a plurality of discrete frequencies fc n of the discretized time-varying spectrum light 14 and may have a bandwidth based on the frequency fm of the signal to be measured 16, and may reconstruct the time waveform of the signal to be measured 16 based on the accumulated spectrum.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Photometry And Measurement Of Optical Pulse Characteristics (AREA)

Abstract

This temporal waveform measuring method includes: subjecting the spectrum of time variable spectrum light (12), the frequency of which increases or decreases over time, to discretization (S110); modulating the discretisized time variable spectrum light (14) using a measured signal (16); and analyzing the spectrum of the modulated time variable spectrum light (18).

Description

時間波形計測方法及び時間波形計測装置Time waveform measuring method and time waveform measuring device
　本開示は、時間波形計測方法及び時間波形計測装置に関する。 This disclosure relates to a time waveform measurement method and a time waveform measurement device.
　従来、オシロスコープだけでは計測することが難しい周波数帯の被計測信号（例えばテラヘルツ波、サブテラヘルツ波等）の時間波形を計測するための技術が提案されている。例えば、非特許文献１では、時間的に波長が変化するチャープ光キャリア（時変スペクトル光）が被計測信号で変調され、変調されたチャープ光キャリアが時間的に伸長され、時間的に伸長されたチャープ光キャリアの時間波形が広帯域オシロスコープで計測される。 　Conventionally, techniques have been proposed for measuring the time waveform of a measured signal (e.g., terahertz waves, sub-terahertz waves, etc.) in a frequency band that is difficult to measure using only an oscilloscope. For example, in Non-Patent Document 1, a chirped optical carrier (time-varying spectrum light) whose wavelength changes over time is modulated by the measured signal, the modulated chirped optical carrier is stretched over time, and the time waveform of the time-stretched chirped optical carrier is measured using a wideband oscilloscope.
　しかしながら、上記従来の技術では、時間波形を計測するために高価な広帯域オシロスコープが必要となる。 However, the above conventional technology requires an expensive wideband oscilloscope to measure the time waveform.
　そこで、本開示は、被計測信号の時間波形を広帯域オシロスコープを用いずに計測することができる時間波形計測方法又は時間波形計測装置を提供する。 The present disclosure provides a time waveform measurement method or device that can measure the time waveform of a signal to be measured without using a wideband oscilloscope.
　本開示の一態様に係る時間波形計測方法は、時間とともに周波数が増加又は減少する時変スペクトル光（chirped light）のスペクトルを離散化し、前記スペクトルが離散化された前記時変スペクトル光を被計測信号で変調し、変調された前記時変スペクトル光のスペクトルを分析する。 A time waveform measurement method according to one aspect of the present disclosure discretizes the spectrum of chirped light, whose frequency increases or decreases over time, modulates the discretized time-varying light with a signal to be measured, and analyzes the spectrum of the modulated time-varying light.
　本開示の一態様に係る時間波形計測装置は、時間とともに周波数が増加又は減少する時変スペクトル光のスペクトルを離散化するフィルタと、前記フィルタによって前記スペクトルが離散化された前記時変スペクトル光を被計測信号で変調する変調器と、を備える。 A time waveform measuring device according to one aspect of the present disclosure includes a filter that discretizes the spectrum of time-varying spectrum light whose frequency increases or decreases over time, and a modulator that modulates the time-varying spectrum light, the spectrum of which has been discretized by the filter, with a signal to be measured.
　なお、これらの包括的又は具体的な態様は、システム又はプログラムとして実現されてもよく、装置、システム、方法及びプログラムの任意な組み合わせで実現されてもよい。 These comprehensive or specific aspects may be realized as a system or program, or may be realized as any combination of devices, systems, methods, and programs.
　本開示に係る時間波形計測方法又は時間波形計測装置によれば、被計測信号の時間波形を広帯域オシロスコープを用いずに計測することができる。 The time waveform measurement method or time waveform measurement device disclosed herein can measure the time waveform of the signal to be measured without using a wideband oscilloscope.
図１は、実施の形態に係る時間波形計測装置の構成を示すブロック図である。FIG. 1 is a block diagram showing a configuration of a time waveform measuring device according to an embodiment. 図２Ａは、離散化時変スペクトル光の時間波形を示す図である。FIG. 2A is a diagram showing a time waveform of discretized time-varying spectrum light. 図２Ｂは、離散化時変スペクトル光のスペクトルを示す図である。FIG. 2B is a diagram showing the spectrum of discretized time-varying spectrum light. 図３Ａは、変調時変スペクトル光の時間波形を示す図である。FIG. 3A is a diagram showing the time waveform of modulated time-varying spectrum light. 図３Ｂは、変調時変スペクトル光のスペクトルを示す図である。FIG. 3B is a diagram showing the spectrum of modulated time-varying spectrum light. 図４は、実施の形態に係る時間波形計測方法を示すフローチャートである。FIG. 4 is a flowchart showing a time waveform measuring method according to the embodiment. 図５は、実施の形態に係る時間波形計測方法の一部を示すフローチャートである。FIG. 5 is a flowchart showing a part of a time waveform measuring method according to an embodiment.
　以下、実施の形態について、図面を用いて詳細に説明する。なお、以下で説明する実施の形態は、いずれも包括的又は具体的な例を示すものである。以下の実施の形態で示される数値、形状、材料、構成要素、構成要素の配置及び接続形態などは、一例であり、本開示を限定する主旨ではない。 The following describes the embodiments in detail with reference to the drawings. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, arrangements and connection forms of the components shown in the following embodiments are merely examples and are not intended to limit the present disclosure.
　なお、各図は、本開示を示すために適宜強調、省略、又は比率の調整を行った模式図であり、必ずしも厳密に図示されたものではなく、実際の形状、位置関係、及び比率とは異なる場合がある。各図において、実質的に同一の構成に対しては同一の符号を付しており、重複する説明は省略又は簡素化される場合がある。 Note that each figure is a schematic diagram in which emphasis, omissions, or adjustments to the ratio have been made as appropriate to illustrate the present disclosure, and is not necessarily an exact illustration, and may differ from the actual shape, positional relationship, and ratio. In each figure, the same reference numerals are used for substantially the same configuration, and duplicate explanations may be omitted or simplified.
　また、以下の説明において、平行及び垂直などの要素間の関係性を示す用語、及び、矩形状などの要素の形状を示す用語、並びに、数値範囲は、厳格な意味のみを表すのではなく、実質的に同等な範囲、例えば数％程度の差異をも含むことを意味する。 In addition, in the following explanation, terms indicating the relationship between elements, such as parallel and perpendicular, terms indicating the shape of an element, such as rectangular, and numerical ranges do not only indicate the strict meaning, but also include a substantially equivalent range, for example, a difference of about a few percent.
　（実施の形態）
　［１．時間波形計測装置１００の構成］
　まず、実施の形態に係る時間波形計測装置１００の構成について図１を参照しながら説明する。図１は、本実施の形態に係る時間波形計測装置１００の構成を示すブロック図である。図１において、ハーフトーンは、光の波長（周波数）を示し、濃度が低いほど波長が長いことを表す。 (Embodiment)
1. Configuration of the time waveform measuring device 100
First, a configuration of a time waveform measuring apparatus 100 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a block diagram showing the configuration of the time waveform measuring apparatus 100 according to the present embodiment. In Fig. 1, halftones indicate the wavelength (frequency) of light, and the lower the density, the longer the wavelength.
　光源２００は、広帯域パルス光源であり、例えばスーパーコンティニューム（ＳＣ：Super Continuum）光を広帯域光パルス１０として出射するができる。被計測信号の周波数が５００ＧＨｚ程度である場合には、広帯域光パルス１０として、例えば１０００ｎｍ程度の帯域幅を持つＳＣ光を用いることができる。 The light source 200 is a broadband pulse light source, and can emit, for example, super continuum (SC) light as the broadband optical pulse 10. When the frequency of the signal to be measured is about 500 GHz, for example, SC light having a bandwidth of about 1000 nm can be used as the broadband optical pulse 10.
　時間波形計測装置１００は、光源２００から受けた広帯域光パルス１０をプローブ光として用いて被計測信号１６の時間波形を計測することができる。図１に示すように、時間波形計測装置１００は、分散器１０２と、フィルタ１０４と、変調器１０６と、光スペクトル分析器１０８と、情報処理器１１０と、を備える。 The time waveform measuring device 100 can measure the time waveform of the measured signal 16 by using the broadband optical pulse 10 received from the light source 200 as a probe light. As shown in FIG. 1, the time waveform measuring device 100 includes a disperser 102, a filter 104, a modulator 106, an optical spectrum analyzer 108, and an information processor 110.
　分散器１０２は、広帯域光パルス１０を分散することにより時変スペクトル光（chirped light）１２を生成することができる。時変スペクトル光１２とは、時間とともに周波数が増加又は減少する光である。分散器１０２によって生成された時変スペクトル光１２は、光伝送媒体１１２を介してフィルタ１０４に伝搬される。分散器１０２には、高分散光ファイバ、チャープＦＢＧ（Chirped Fiber Bragg Grating）、アレイ導波路回折格子（ＡＷＧ：Arrayed Waveguide Grating）、又は、それらの任意の組み合わせを用いることができるが、これらに限定されない。 The disperser 102 can generate chirped light 12 by dispersing the broadband optical pulse 10. The chirped light 12 is light whose frequency increases or decreases over time. The chirped light 12 generated by the disperser 102 is propagated to the filter 104 via the optical transmission medium 112. The disperser 102 can be, but is not limited to, a high-dispersion optical fiber, a chirped fiber bragg grating (FBG), an arrayed waveguide grating (AWG), or any combination thereof.
　なお、時間波形計測装置１００は、外部から時変スペクトル光１２を受けてもよい。この場合、分散器１０２は、時間波形計測装置１００に含まれなくてもよい。 The time waveform measuring device 100 may receive the time-varying spectrum light 12 from an external source. In this case, the disperser 102 does not need to be included in the time waveform measuring device 100.
　フィルタ１０４は、時変スペクトル光１２を離散化することができる。つまり、フィルタ１０４は、複数の離散的な通過帯域を有する光学フィルタであり、複数の離散的な周波数成分を選択的に通過させることができる。フィルタ１０４によって離散化された時変スペクトル光（以下、離散化時変スペクトル光１４と呼ぶ）は、光伝送媒体１１４を介して変調器１０６に伝搬される。フィルタ１０４としては、ＡＷＧなどを用いることができるが、これに限定されない。なお、フィルタ１０４は、分散器１０２と一体化されてもよい。離散化時変スペクトル光１４については、図２Ａ及び図２Ｂを用いて後述する。 The filter 104 can discretize the time-varying spectrum light 12. In other words, the filter 104 is an optical filter having multiple discrete passbands, and can selectively pass multiple discrete frequency components. The time-varying spectrum light discretized by the filter 104 (hereinafter referred to as discretized time-varying spectrum light 14) is propagated to the modulator 106 via the optical transmission medium 114. The filter 104 can be, but is not limited to, an AWG or the like. The filter 104 may be integrated with the disperser 102. The discretized time-varying spectrum light 14 will be described later with reference to Figures 2A and 2B.
　変調器１０６は、被計測信号１６で離散化時変スペクトル光１４を変調することができる。具体的には、変調器１０６は、強度変調器であり、変調器１０６によって変調された離散化時変スペクトル光１４（以下、変調時変スペクトル光１８と呼ぶ）は、光伝送媒体１１６を介して光スペクトル分析器１０８に伝搬される。変調器１０６としては、ＥＡ（Electro-Absorption）変調器、及び／又は、ＥＲ（Electro-Refractive）変調器を用いることができるが、これらに限定されない。なお、変調時変スペクトル光１８については、図３Ａ及び図３Ｂを用いて後述する。 The modulator 106 can modulate the discretized time-varying spectrum light 14 with the measured signal 16. Specifically, the modulator 106 is an intensity modulator, and the discretized time-varying spectrum light 14 modulated by the modulator 106 (hereinafter referred to as modulated time-varying spectrum light 18) is propagated to the optical spectrum analyzer 108 via the optical transmission medium 116. The modulator 106 can be, but is not limited to, an EA (Electro-Absorption) modulator and/or an ER (Electro-Refractive) modulator. The modulated time-varying spectrum light 18 will be described later with reference to Figures 3A and 3B.
　光スペクトル分析器１０８は、分光器であり、変調時変スペクトル光１８のスペクトルを分析することができる。具体的には、光スペクトル分析器１０８は、変調時変スペクトル光１８をその周波数（波長）で分離し、分離された各周波数の光の強度を測定することができる。光スペクトル分析器１０８によって測定された各周波数の光の強度を示す情報（つまり、変調時変スペクトル光１８のスペクトル情報）は、情報処理器１１０に伝送される。 The optical spectrum analyzer 108 is a spectroscope and can analyze the spectrum of the modulated time-varying spectrum light 18. Specifically, the optical spectrum analyzer 108 can separate the modulated time-varying spectrum light 18 by its frequency (wavelength) and measure the intensity of light at each separated frequency. Information indicating the intensity of light at each frequency measured by the optical spectrum analyzer 108 (i.e., the spectrum information of the modulated time-varying spectrum light 18) is transmitted to the information processor 110.
　情報処理器１１０は、変調時変スペクトル光１８のスペクトル情報を処理することで被計測信号の時間波形を再構成することができる。具体的には、情報処理器１１０は、変調時変スペクトル光１８のスペクトル情報に基づいて、変調時変スペクトル光１８のスペクトルを複数の帯域の各々で積算する。言い換えると、情報処理器１１０は、各周波数の光の強度を帯域ごとに加算する。複数の帯域については図３Ｂを用いて後述する。このように帯域ごとに積算された変調時変スペクトル光１８のスペクトルに基づいて、被計測信号１６の時間波形を再構成することができる。再構成された被計測信号１６の時間波形は、ディスプレイに表示されてもよい。 The information processor 110 can reconstruct the time waveform of the measured signal by processing the spectral information of the modulated time-varying spectrum light 18. Specifically, the information processor 110 accumulates the spectrum of the modulated time-varying spectrum light 18 for each of a plurality of bands based on the spectral information of the modulated time-varying spectrum light 18. In other words, the information processor 110 adds up the intensity of light of each frequency for each band. The plurality of bands will be described later with reference to FIG. 3B. Based on the spectrum of the modulated time-varying spectrum light 18 accumulated for each band in this manner, the time waveform of the measured signal 16 can be reconstructed. The reconstructed time waveform of the measured signal 16 may be displayed on a display.
　情報処理器１１０は、プロセッサ及びメモリを有するコンピュータで実現することができる。なお、情報処理器１１０は、専用の１以上の電子回路として実現されてもよい。このような場合には、情報処理器１１０は、光スペクトル分析器１０８に包含されてもよい。 The information processor 110 can be realized by a computer having a processor and memory. The information processor 110 may also be realized as one or more dedicated electronic circuits. In such a case, the information processor 110 may be included in the optical spectrum analyzer 108.
　光伝送媒体１１２、１１４及び１１６は、分散器１０２及びフィルタ１０４の間、フィルタ１０４及び変調器１０６の間、並びに、変調器１０６及び光スペクトル分析器１０８の間をそれぞれ接続する。光伝送媒体１１２、１１４及び１１６としては、例えば光ファイバ又は光導波路デバイスを用いることができるが、これらに限定されない。なお、光伝送媒体１１２、１１４及び１１６は、時間波形計測装置１００に含まれなくてもよい。 The optical transmission media 112, 114, and 116 respectively connect between the disperser 102 and the filter 104, between the filter 104 and the modulator 106, and between the modulator 106 and the optical spectrum analyzer 108. The optical transmission media 112, 114, and 116 may be, for example, optical fiber or an optical waveguide device, but are not limited to these. Note that the optical transmission media 112, 114, and 116 do not have to be included in the time waveform measurement device 100.
　［２．離散化時変スペクトル光１４］
　ここで、離散化時変スペクトル光１４について図２Ａ及び図２Ｂを参照しながら説明する。図２Ａは、離散化時変スペクトル光１４の時間波形を示す図である。図２Ｂは、離散化時変スペクトル光１４のスペクトルを示す図である。 [2. Discretized time-varying spectrum light 14]
2A and 2B, the discretized time-varying spectrum light 14 will be described. Fig. 2A is a diagram showing the time waveform of the discretized time-varying spectrum light 14. Fig. 2B is a diagram showing the spectrum of the discretized time-varying spectrum light 14.
　離散化時変スペクトル光１４は、時間間隔Ｔｉｎｔ１～Ｔｉｎｔ６で周波数が離散的に変化する７つの周波数成分１４１～１４７を含む。周波数成分１４１～１４７は、時刻ｔ１～ｔ７をそれぞれ中心とする期間に、離散的な周波数ｆｃ１～ｆｃ７をそれぞれ有する。このとき、時刻ｔｎと時刻ｔｎ＋１の間の時間間隔Ｔｉｎｔｎ（ｎ＝１～６）は、１／２ｆｍ（ｓ）以下であることが望ましく、周波数ｆｃｎと周波数ｆｃｎ＋１との間の周波数間隔Ｆｉｎｔｎ（ｎ＝１～６）は、２ｆｍ（Ｈｚ）以上であることが望ましい。ここで、ｆｍ（Ｈｚ）は、被計測信号１６の周波数を示す。 The discretized time-varying spectrum light 14 includes seven frequency components 141 to 147 whose frequencies change discretely in time intervals Tint 1 to Tint 6. The frequency components 141 to 147 have discrete frequencies fc 1 to fc 7 in periods centered around times t 1 to t 7 , respectively. In this case, the time interval Tint n (n=1 to 6) between times t n and t n+1 is preferably 1/2 fm (s) or less, and the frequency interval Fint n (n=1 to 6) between frequencies fc n and fc n+1 is preferably 2 fm (Hz) or more. Here, fm (Hz) indicates the frequency of the measured signal 16.
　なお、図２Ａにおいて、時間間隔Ｔｉｎｔｎは、ほぼ同一であるが、互いに異なってもよい。また、図２Ｂにおいて、周波数成分１４１～１４７の強度は、ほぼ同一であるが、周波数成分１４１～１４７の一部の強度が周波数成分１４１～１４７の他部の強度と異なってもよい。 In Fig. 2A, the time intervals Tint n are approximately the same, but may be different from each other. Also, in Fig. 2B, the intensities of the frequency components 141 to 147 are approximately the same, but the intensities of some of the frequency components 141 to 147 may be different from the intensities of other parts of the frequency components 141 to 147.
　なお、図２Ａ及び図２Ｂにおける周波数成分１４１～１４７の数は、例示であり、７つに限定されない。つまり、離散化時変スペクトル光１４に含まれる周波数成分の数は、７つより少なくてもよく、７つより多くてもよい。 Note that the number of frequency components 141 to 147 in Figures 2A and 2B is an example and is not limited to seven. In other words, the number of frequency components contained in the discretized time-varying spectrum light 14 may be less than seven or more than seven.
　［３．変調時変スペクトル光１８］
　次に、変調時変スペクトル光１８について図３Ａ及び図３Ｂを参照しながら説明する。図３Ａは、変調時変スペクトル光１８の時間波形を示す図である。図３Ｂは、変調時変スペクトル光１８のスペクトルを示す図である。 [3. Modulated time-varying spectrum light 18]
3A and 3B, the modulated time-varying spectrum light 18 will be described. Fig. 3A is a diagram showing the time waveform of the modulated time-varying spectrum light 18. Fig. 3B is a diagram showing the spectrum of the modulated time-varying spectrum light 18.
　変調時変スペクトル光１８は、時間間隔Ｔｉｎｔ１～Ｔｉｎｔ６で周波数が離散的に変化する周波数成分１８１～１８７を含む。周波数成分１８１～１８７は、周波数成分１４１～１４７と同様に、時刻ｔ１～ｔ７をそれぞれ中心とする期間に離散的な周波数ｆｃ１～ｆｃ７をそれぞれ有する。ただし、周波数成分１８１～１８７は、周波数成分１４１～１４７と異なり、その強度が被計測信号１６に基づいて時間的に変化する。したがって、変調時変スペクトル光１８の時間波形を求めることができれば、被計測信号１６の時間波形も求めることができる。変調時変スペクトル光１８は、時間とともに周波数が離散的に変化するので、変調時変スペクトル光１８のスペクトルは、変調時変スペクトル光１８の時間波形に対応する。したがって、変調時変スペクトル光１８のスペクトルを求めることができれば、被計測信号１６の時間波形を求めることができる。 The modulated time varying spectrum light 18 includes frequency components 181 to 187 whose frequencies change discretely in time intervals Tint 1 to Tint 6. The frequency components 181 to 187 have discrete frequencies fc 1 to fc 7 in periods centered around times t 1 to t 7 , respectively, like the frequency components 141 to 147. However, unlike the frequency components 141 to 147, the frequency components 181 to 187 have intensities that change over time based on the signal 16 to be measured. Therefore, if the time waveform of the modulated time varying spectrum light 18 can be obtained, the time waveform of the signal 16 to be measured can also be obtained. Since the frequency of the modulated time varying spectrum light 18 changes discretely over time, the spectrum of the modulated time varying spectrum light 18 corresponds to the time waveform of the modulated time varying spectrum light 18. Therefore, if the spectrum of the modulated time varying spectrum light 18 can be obtained, the time waveform of the signal 16 to be measured can be obtained.
　そこで、図２Ａで説明したように、離散化時変スペクトル光１４の周波数が変化する時間間隔Ｔｉｎｔｎは、標本化定理に基づいて、１／２ｆｍ（ｓ）以下であることが望ましい。これにより、周波数ｆｍの被計測信号１６を時間波形をより正確に再構成することができる。 2A, the time interval Tint n during which the frequency of the discretized time-varying spectrum light 14 changes is preferably equal to or less than 1/2fm (s) based on the sampling theorem. This makes it possible to more accurately reconstruct the time waveform of the measured signal 16 of frequency fm.
　ただし、周波数成分１８１～１８７の各々には、元の周波数ｆｃ１～ｆｃ７の成分（以下、主成分という）に加えて、周波数ｆｃ１～ｆｃ７から被計測信号１６の周波数ｆｍだけ負側及び正側にシフトした成分（以下、低シフト成分及び高シフト成分とそれぞれいう）が含まれる。このような強度変調によって主成分から生じた２つのシフト成分は、時間波形との対応関係において主成分に含まれるべき成分である。したがって、被計測信号１６の時間波形をより正確に求めるためには、主成分と２つのシフト成分とが積算されることが望ましい。 However, each of the frequency components 181 to 187 includes, in addition to the original components of frequencies fc1 to fc7 (hereinafter referred to as main components), components shifted from frequencies fc1 to fc7 to the negative side and the positive side by the frequency fm of the signal to be measured 16 (hereinafter referred to as low-shift components and high-shift components, respectively). The two shift components generated from the main component by such intensity modulation are components that should be included in the main component in terms of their correspondence with the time waveform. Therefore, in order to more accurately determine the time waveform of the signal to be measured 16, it is desirable to integrate the main component and the two shift components.
　そこで、図２Ｂで説明したように、周波数領域において隣り合う周波数成分の周波数間隔Ｆｉｎｔｎは２ｆｍ（Ｈｚ）以上であることが望ましい。これにより、シフト成分が隣接する周波数成分のシフト成分と干渉することを抑制することができる。 Therefore, as described in Fig. 2B, it is desirable that the frequency interval Fint n between adjacent frequency components in the frequency domain is 2fm (Hz) or more, which can suppress interference between the shifted components of the adjacent frequency components.
　なお、図３Ｂには、情報処理器１１０によって光の強度を積算するための帯域Ｂｗ１～Ｂｗ７が図示されている。ここでは、帯域Ｂｗｎ（ｎ＝１～７）は、複数の離散的な周波数ｆｃ１～ｆｃ７をそれぞれ含むように設定される。さらに、帯域Ｂｗｎは、被計測信号１６の周波数ｆｍに基づく帯域幅を有するように設定される。より具体的には、帯域Ｂｗｎの帯域幅は、２ｆｍよりも大きいことが望ましい。これにより、主成分に加えて２つのシフト成分を１つの帯域に含めることができ、主成分及び２つのシフト成分の積算が可能となる。 3B shows bands Bw 1 to Bw 7 for integrating the light intensity by the information processor 110. Here, the bands Bw n (n=1 to 7) are set to include a plurality of discrete frequencies fc 1 to fc 7 , respectively. Furthermore, the band Bw n is set to have a bandwidth based on the frequency fm of the measured signal 16. More specifically, it is desirable that the bandwidth of the band Bw n is larger than 2fm. This allows the two shift components in addition to the main component to be included in one band, making it possible to integrate the main component and the two shift components.
　なお、図１～図３Ｂに示した光又は信号の各グラフは、例示であり、これに限定されない。例えば、時変スペクトル光１２及び離散化時変スペクトル光１４の振幅は一定でなくてもよい。つまり、図１等に示すグラフにおいて、時変スペクトル光１２及び離散化時変スペクトル光１４は矩形状でなくてもよい。このような場合であっても、被計測信号１６の時間波形は、離散化時変スペクトル光１４に対する変調時変スペクトル光１８のスペクトルの相対的な変化に基づいて計測され得る。 Note that the graphs of light or signals shown in Figures 1 to 3B are examples and are not limited to these. For example, the amplitudes of the time-varying spectrum light 12 and the discretized time-varying spectrum light 14 do not have to be constant. In other words, in the graphs shown in Figure 1 and elsewhere, the time-varying spectrum light 12 and the discretized time-varying spectrum light 14 do not have to be rectangular. Even in such cases, the time waveform of the measured signal 16 can be measured based on the relative change in the spectrum of the modulated time-varying spectrum light 18 with respect to the discretized time-varying spectrum light 14.
　［４．時間波形計測方法］
　次に、以上のように構成された時間波形計測装置１００による時間波形計測方法について図４及び図５を参照しながら説明する。図４は、本実施の形態に係る時間波形計測方法を示すフローチャートである。図５は、本実施の形態に係る時間波形計測方法の一部を示すフローチャートであり、図４のステップＳ１４０の詳細を示す。 [4. Time waveform measurement method]
Next, a time waveform measuring method using the time waveform measuring apparatus 100 configured as above will be described with reference to Fig. 4 and Fig. 5. Fig. 4 is a flowchart showing the time waveform measuring method according to the present embodiment. Fig. 5 is a flowchart showing a part of the time waveform measuring method according to the present embodiment, and shows details of step S140 in Fig. 4.
　まず、図４を参照しながら、時間波形計測方法について説明する。 First, we will explain the time waveform measurement method with reference to Figure 4.
　分散器１０２は、広帯域光パルス１０を時変スペクトル光１２に変換する（Ｓ１００）。分散器１０２の出力である時変スペクトル光１２は、フィルタ１０４に伝送される。 The disperser 102 converts the broadband optical pulse 10 into time-varying spectrum light 12 (S100). The time-varying spectrum light 12, which is the output of the disperser 102, is transmitted to the filter 104.
　フィルタ１０４は、時変スペクトル光１２を離散化する（Ｓ１１０）。フィルタ１０４の出力である離散化時変スペクトル光１４は、変調器１０６に伝送される。なお、ステップＳ１１０は、時間波形計測方法に含まれなくてもよい。 The filter 104 discretizes the time-varying spectral light 12 (S110). The output of the filter 104, the discretized time-varying spectral light 14, is transmitted to the modulator 106. Note that step S110 does not have to be included in the time waveform measurement method.
　変調器１０６は、被計測信号１６で離散化時変スペクトル光１４を変調する（Ｓ１２０）。変調器１０６の出力である変調時変スペクトル光１８は、光スペクトル分析器１０８に伝送される。 The modulator 106 modulates the discretized time-varying spectrum light 14 with the measured signal 16 (S120). The output of the modulator 106, the modulated time-varying spectrum light 18, is transmitted to the optical spectrum analyzer 108.
　光スペクトル分析器１０８は、変調時変スペクトル光１８のスペクトルを分析する（Ｓ１３０）。光スペクトル分析器１０８の出力であるスペクトル情報は、情報処理器１１０に送信される。 The optical spectrum analyzer 108 analyzes the spectrum of the modulated time-varying spectrum light 18 (S130). The output of the optical spectrum analyzer 108, that is, the spectral information, is sent to the information processor 110.
　情報処理器１１０は、変調時変スペクトル光１８のスペクトル情報に基づいて、被計測信号１６の時間波形を再構成する（Ｓ１４０）。なお、ステップＳ１４０は、時間波形計測方法に含まれなくてもよい。このステップＳ１４０の詳細について、図５を参照しながら説明する。 The information processor 110 reconstructs the time waveform of the measured signal 16 based on the spectral information of the modulated time-varying spectrum light 18 (S140). Note that step S140 does not have to be included in the time waveform measurement method. Details of this step S140 will be described with reference to FIG. 5.
　まず、情報処理器１１０は、変調時変スペクトル光１８のスペクトル情報を光スペクトル分析器１０８から取得する（Ｓ１４２）。次に、情報処理器１１０は、帯域ごとにスペクトルを積算する（Ｓ１４４）。例えば、図３Ｂにおいて、帯域Ｂｗ１では、周波数ｆｃ１の主成分と、周波数ｆｃ１－ｆｍの低シフト成分と、周波数ｆｃ１＋ｆｍの高シフト成分との総和が算出される。帯域Ｂｗ２～Ｂｗ７の各々についても、帯域Ｂｗ１と同様に、主成分及び２つのシフト成分の総和が算出される。 First, the information processor 110 acquires the spectrum information of the modulated time-varying spectrum light 18 from the optical spectrum analyzer 108 (S142). Next, the information processor 110 integrates the spectrum for each band (S144). For example, in FIG. 3B, in the band Bw1 , the sum of the main component of frequency fc1 , the low-shift component of frequency fc1 -fm, and the high-shift component of frequency fc1 +fm is calculated. For each of the bands Bw2 to Bw7 , the sum of the main component and the two shift components is calculated in the same manner as in the band Bw1 .
　最後に、情報処理器１１０は、このように求められた帯域ごとのスペクトルの積算結果から、被計測信号１６の時間波形を再構成する（Ｓ１４６）。具体的には、情報処理器１１０は、複数の帯域を時間領域にマッピングすることで被計測信号１６の時間波形を再構成する。 Finally, the information processor 110 reconstructs the time waveform of the measured signal 16 from the spectrum integration results for each band thus obtained (S146). Specifically, the information processor 110 reconstructs the time waveform of the measured signal 16 by mapping multiple bands into the time domain.
　［５．効果など］
　以上のように、本実施の形態に係る時間波形計測方法は、時間とともに周波数が増加又は減少する時変スペクトル光１２のスペクトルを離散化し（Ｓ１１０）、離散化時変スペクトル光１４を被計測信号１６で変調し（Ｓ１２０）、変調時変スペクトル光１８のスペクトルを分析する（Ｓ１３０）。 [5. Effects, etc.]
As described above, the time waveform measurement method according to the present embodiment discretizes the spectrum of the time-varying spectrum light 12, whose frequency increases or decreases over time (S110), modulates the discretized time-varying spectrum light 14 with the signal to be measured 16 (S120), and analyzes the spectrum of the modulated time-varying spectrum light 18 (S130).
　また、本実施の形態に係る時間波形計測装置１００は、時間とともに周波数が増加又は減少する時変スペクトル光１２のスペクトルを離散化するフィルタ１０４と、フィルタ１０４によって離散化された離散化時変スペクトル光１４を被計測信号１６で変調する変調器１０６と、を備える。このとき、時間波形計測装置１００は、さらに、変調器１０６で変調された変調時変スペクトル光１８のスペクトルを分析する光スペクトル分析器１０８を備えてもよい。 The time waveform measuring device 100 according to this embodiment also includes a filter 104 that discretizes the spectrum of the time-varying spectrum light 12 whose frequency increases or decreases over time, and a modulator 106 that modulates the discretized time-varying spectrum light 14 discretized by the filter 104 with the signal to be measured 16. In this case, the time waveform measuring device 100 may further include an optical spectrum analyzer 108 that analyzes the spectrum of the modulated time-varying spectrum light 18 modulated by the modulator 106.
　これらによれば、変調時変スペクトル光１８のスペクトルを分析すればよいので、被計測信号１６の時間波形を広帯域オシロスコープを用いずに計測することができる。特に、変調時変スペクトル光１８では、スペクトルが離散化されているので、変調によって生じるシフト成分が隣り合う周波数成分の間で干渉することを抑制することができ、被計測信号１６の時間波形をより正確に計測することができる。 According to these, it is only necessary to analyze the spectrum of the modulated time-varying spectrum light 18, so the time waveform of the measured signal 16 can be measured without using a wideband oscilloscope. In particular, since the spectrum of the modulated time-varying spectrum light 18 is discretized, it is possible to suppress interference between adjacent frequency components caused by the shift components generated by the modulation, and it is possible to measure the time waveform of the measured signal 16 more accurately.
　また例えば、本実施の形態に係る時間波形計測方法又は時間波形計測装置１００において、離散化時変スペクトル光１４の隣り合う周波数成分の周波数間隔Ｆｉｎｔｎは、２ｆｍ以上であってもよく、ｆｍは被計測信号１６の周波数であってもよい。 Furthermore, for example, in the time waveform measuring method or time waveform measuring apparatus 100 according to the present embodiment, the frequency interval Fint n between adjacent frequency components of the discretized time-varying spectrum light 14 may be 2fm or more, and fm may be the frequency of the signal 16 to be measured.
　これによれば、主成分の周波数ｆｃｎから被計測信号１６の周波数ｆｍだけ負側及び正側にシフトした周波数（ｆｃｎ－ｆｍ、ｆｃｎ＋ｆｍ）に生じるシフト成分が隣りの周波数成分に干渉することを抑制することができ、被計測信号１６の時間波形をより正確に計測することができる。 This makes it possible to suppress interference between the shift components occurring at frequencies (fc n -fm, fc n +fm) shifted from the main component frequency fc n to the negative and positive sides by the frequency fm of the signal to be measured 16 and the adjacent frequency components, and thus makes it possible to measure the time waveform of the signal to be measured 16 more accurately.
　また例えば、本実施の形態に係る時間波形計測方法又は時間波形計測装置１００において、離散化時変スペクトル光１４の周波数が離散的に変化する時間間隔Ｔｉｎｔｎは、１／２ｆｍ以下であってもよく、ｆｍは被計測信号１６の周波数であってもよい。 Furthermore, for example, in the time waveform measuring method or time waveform measuring apparatus 100 according to the present embodiment, the time interval T int n during which the frequency of the discretized time-varying spectrum light 14 changes discretely may be equal to or smaller than ½ f, where f may be the frequency of the signal 16 to be measured.
　これによれば、離散化時変スペクトル光１４のスペクトルを用いて被計測信号１６の時間波形を再構成する際に標本化定理を満たすことができ、被計測信号１６の時間波形をより正確に計測することができる。 This makes it possible to satisfy the sampling theorem when reconstructing the time waveform of the measured signal 16 using the spectrum of the discretized time-varying spectrum light 14, and thus makes it possible to measure the time waveform of the measured signal 16 more accurately.
　また例えば、本実施の形態に係る時間波形計測方法は、さらに、分析された変調時変スペクトル光１８のスペクトルを複数の帯域Ｂｗｎの各々で積算してもよく、複数の帯域Ｂｗｎは、離散化時変スペクトル光１４の複数の離散的な周波数ｆｃｎをそれぞれ含んでもよく、かつ、被計測信号１６の周波数ｆｍに基づく帯域幅を有してもよく、積算されたスペクトルに基づいて、被計測信号１６の時間波形を再構成してもよい。 Furthermore, for example, the time waveform measuring method according to the present embodiment may further accumulate the spectrum of the analyzed modulated time-varying spectrum light 18 in each of a plurality of bands Bw n , each of which may include a plurality of discrete frequencies fc n of the discretized time-varying spectrum light 14 and may have a bandwidth based on the frequency fm of the signal to be measured 16, and may reconstruct the time waveform of the signal to be measured 16 based on the accumulated spectrum.
　また例えば、本実施の形態に係る時間波形計測装置１００は、さらに、情報処理器１１０を備えてもよく、情報処理器１１０は、光スペクトル分析器１０８で分析された変調時変スペクトル光１８のスペクトルを複数の帯域Ｂｗｎの各々で積算してもよく、複数の帯域Ｂｗｎは、離散化時変スペクトル光１４の複数の離散的な周波数ｆｃｎをそれぞれ含んでもよく、かつ、被計測信号１６の周波数ｆｍに基づく帯域幅を有してもよく、積算されたスペクトルに基づいて、被計測信号１６の時間波形を再構成してもよい。 For example, the time waveform measuring apparatus 100 according to the present embodiment may further include an information processor 110, which may accumulate the spectrum of the modulated time-varying spectrum light 18 analyzed by the optical spectrum analyzer 108 in each of a plurality of bands Bw n , each of which may include a plurality of discrete frequencies fc n of the discretized time-varying spectrum light 14 and may have a bandwidth based on the frequency fm of the signal to be measured 16, and may reconstruct the time waveform of the signal to be measured 16 based on the accumulated spectrum.
　これらによれば、変調によって生じるシフト成分を主成分と合算することができ、再構成される被計測信号１６の時間波形の正確さがシフト成分によって低下することを抑制することができる。 This makes it possible to add the shift component caused by modulation to the main component, and to prevent the accuracy of the reconstructed time waveform of the measured signal 16 from being reduced by the shift component.
　また例えば、本実施の形態に係る時間波形計測装置１００は、さらに、広帯域光パルス１０を分散することにより時変スペクトル光１２を生成する分散器１０２を備えてもよい。 Also, for example, the time waveform measuring device 100 according to this embodiment may further include a disperser 102 that generates time-varying spectrum light 12 by dispersing the broadband optical pulse 10.
　これによれば、時間波形計測装置１００によって広帯域光パルス１０から時変スペクトル光１２を生成することができ、時間波形計測装置１００の利用範囲を拡げることができる。 This allows the time waveform measuring device 100 to generate time-varying spectrum light 12 from a broadband optical pulse 10, thereby expanding the range of applications of the time waveform measuring device 100.
　（他の実施の形態及び変形例）
　以上、時間波形計測装置１００及び時間波形計測方法について、実施の形態に基づいて説明したが、本開示に係る時間波形計測装置１００及び時間波形計測方法は、上記実施の形態に限定されるものではない。上記実施の形態における任意の構成要素を組み合わせて実現される別の実施の形態や、上記実施の形態に対して本開示の主旨を逸脱しない範囲で当業者が思いつく各種変形を施して得られる変形例も本開示に含まれる。 (Other embodiments and modifications)
Although the time waveform measuring device 100 and the time waveform measuring method have been described above based on the embodiments, the time waveform measuring device 100 and the time waveform measuring method according to the present disclosure are not limited to the above-mentioned embodiments. This disclosure also includes other embodiments realized by combining any of the components in the above-mentioned embodiments, and modified examples obtained by applying various modifications to the above-mentioned embodiments that would come to mind by a person skilled in the art without departing from the spirit of this disclosure.
　例えば、上記実施の形態では、帯域ごとにスペクトルが積算されていたが、これに限定されない。例えば、主成分のみに基づいて被計測信号の時間波形が再構成されてもよい。この場合、帯域ごとにスペクトルが積算されなくてもよく、主成分のみが抽出されてもよい。 For example, in the above embodiment, the spectrum is accumulated for each band, but this is not limiting. For example, the time waveform of the measured signal may be reconstructed based only on the principal component. In this case, the spectrum does not need to be accumulated for each band, and only the principal component may be extracted.
　本開示は、テラヘルツ波及びサブテラヘルツ波等の時間波形を計測する時間波形計測装置に広く利用可能である。 This disclosure can be widely used in time waveform measurement devices that measure the time waveforms of terahertz waves, sub-terahertz waves, etc.
　１０　広帯域光パルス
　１２　時変スペクトル光
　１４　離散化時変スペクトル光
　１６　被計測信号
　１８　変調時変スペクトル光
　１００　時間波形計測装置
　１０２　分散器
　１０４　フィルタ
　１０６　変調器
　１０８　光スペクトル分析器
　１１０　情報処理器
　１１２、１１４、１１６　光伝送媒体
　２００　光源 REFERENCE SIGNS LIST 10 Broadband optical pulse 12 Time-varying spectrum light 14 Discretized time-varying spectrum light 16 Signal to be measured 18 Modulated time-varying spectrum light 100 Time waveform measuring device 102 Disperser 104 Filter 106 Modulator 108 Optical spectrum analyzer 110 Information processor 112, 114, 116 Optical transmission medium 200 Light source

Claims (10)

  1. 　時間とともに周波数が増加又は減少する時変スペクトル光（chirped light）のスペクトルを離散化し、
    　前記スペクトルが離散化された前記時変スペクトル光を被計測信号で変調し、
    　変調された前記時変スペクトル光のスペクトルを分析する、
    　時間波形計測方法。     Discretize the spectrum of chirped light, whose frequency increases or decreases over time;
    modulating the time-varying spectrum light having the discretized spectrum with a signal to be measured;
    analyzing a spectrum of the modulated time-varying spectrum light;
    Time waveform measurement method.
  2. 　前記スペクトルが離散化された前記時変スペクトル光の隣り合う周波数成分の周波数間隔は、２ｆｍ以上であり、ｆｍは前記被計測信号の周波数である、
    　請求項１に記載の時間波形計測方法。     a frequency interval between adjacent frequency components of the time-varying spectrum light, the spectrum of which is discretized, is 2 fm or more, where fm is a frequency of the signal to be measured.
    The time waveform measuring method according to claim 1 .
  3. 　前記スペクトルが離散化された前記時変スペクトル光の周波数が離散的に変化する時間間隔は、１／２ｆｍ以下であり、ｆｍは前記被計測信号の周波数である、
    　請求項１又は２に記載の時間波形計測方法。     a time interval during which the frequency of the time-varying spectrum light, the spectrum of which is discretized, changes discretely is equal to or smaller than ½ fm, where fm is a frequency of the signal to be measured;
    The method for measuring a time waveform according to claim 1 or 2.
  4. 　前記時間波形計測方法は、さらに、
    　分析された前記時変スペクトル光のスペクトルを複数の帯域の各々で積算し、前記複数の帯域は、離散化された前記時変スペクトル光の複数の離散的な周波数をそれぞれ含み、かつ、前記被計測信号の周波数に基づく帯域幅を有し、
    　積算された前記スペクトルに基づいて、前記被計測信号の時間波形を再構成する、
    　請求項１に記載の時間波形計測方法。     The time waveform measuring method further includes:
    integrating the analyzed spectrum of the time-varying spectrum light in each of a plurality of bands, the plurality of bands including a plurality of discrete frequencies of the discretized time-varying spectrum light, and having a bandwidth based on the frequency of the measured signal;
    reconstructing a time waveform of the measured signal based on the integrated spectrum;
    The time waveform measuring method according to claim 1 .
  5. 　時間とともに周波数が増加又は減少する時変スペクトル光のスペクトルを離散化するフィルタと、
    　前記フィルタによって前記スペクトルが離散化された前記時変スペクトル光を被計測信号で変調する変調器と、を備える、
    　時間波形計測装置。     A filter for discretizing the spectrum of time-varying spectrum light whose frequency increases or decreases over time;
    a modulator that modulates the time-varying spectrum light, the spectrum of which has been discretized by the filter, with a signal to be measured.
    Time waveform measurement device.
  6. 　前記フィルタによって前記スペクトルが離散化された前記時変スペクトル光の隣り合う周波数成分の周波数間隔は、２ｆｍ以上であり、ｆｍは前記被計測信号の周波数である、
    　請求項５に記載の時間波形計測装置。     a frequency interval between adjacent frequency components of the time-varying spectrum light, the spectrum of which is discretized by the filter, is 2 fm or more, where fm is a frequency of the signal to be measured;
    The time waveform measuring device according to claim 5 .
  7. 　前記フィルタによって前記スペクトルが離散化された前記時変スペクトル光の周波数が離散的に変化する時間間隔は、１／２ｆｍ以下であり、ｆｍは前記被計測信号の周波数である、
    　請求項５又は６に記載の時間波形計測装置。     a time interval during which the frequency of the time-varying spectrum light, the spectrum of which is discretized by the filter, changes discretely is equal to or smaller than ½ fm, where fm is a frequency of the signal to be measured;
    7. The time waveform measuring device according to claim 5 or 6.
  8. 　前記時間波形計測装置は、さらに、前記変調器によって変調された前記時変スペクトル光のスペクトルを分析する光スペクトル分析器を備える、
    　請求項５に記載の時間波形計測装置。     The time waveform measurement device further includes an optical spectrum analyzer that analyzes the spectrum of the time-varying spectrum light modulated by the modulator.
    The time waveform measuring device according to claim 5 .
  9. 　前記時間波形計測装置は、さらに、情報処理器を備え、
    　前記情報処理器は、
    　前記光スペクトル分析器で分析された前記時変スペクトル光のスペクトルを複数の帯域の各々で積算し、前記複数の帯域は、離散化された前記時変スペクトル光の複数の離散的な周波数をそれぞれ含み、かつ、前記被計測信号の周波数に基づく帯域幅を有し、
    　積算された前記スペクトルに基づいて、前記被計測信号の時間波形を再構成する、
    　請求項８に記載の時間波形計測装置。     The time waveform measuring device further includes an information processor,
    The information processor includes:
    a spectrum of the time-varying spectrum light analyzed by the optical spectrum analyzer is integrated in each of a plurality of bands, the plurality of bands including a plurality of discrete frequencies of the discretized time-varying spectrum light, and having a bandwidth based on a frequency of the measured signal;
    reconstructing a time waveform of the measured signal based on the integrated spectrum;
    The time waveform measuring device according to claim 8.
  10. 　前記時間波形計測装置は、さらに、光パルスを分散することにより前記時変スペクトル光を生成する分散器を備える、
    　請求項５に記載の時間波形計測装置。     The time waveform measurement device further includes a disperser that generates the time-varying spectrum light by dispersing an optical pulse.
    The time waveform measuring device according to claim 5 .
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