Spectroscopic polarization characteristic measuring device and spectroscopic polarization characteristic measuring method

Abstract

To provide a spectral polarization characteristic measuring device with which it is possible to acquire the polarization state of a measurement object and its wavelength dispersion at high speed with high accuracy, without requiring polarization modulation.SOLUTION: The spectral polarization characteristic measuring device comprises: a division unit 14 for dividing discrete spectral light from a first discrete spectral light source 12; polarization control units 15, 16 for controlling the polarization of divided discrete spectral light to mutually different states and time delay control units 17, 18 for controlling a time delay to mutually different states; a first superimposition unit 19 for superimposing a plurality of discrete spectral lights one on top of another; an irradiation unit for irradiating a sample 100 with a row of polarization controlled discrete spectral lights differing in polarization state and time delay; a second superimposition unit 21 for superimposing discrete spectral light from a second discrete spectral light source 13 on a row of polarization controlled discrete spectral lights including sample information and generating an interference signal; and a detection unit 40 for acquiring a mode decomposition spectrum regarding the optical amplitude and phase of orthogonal polarization components of the interference signal that includes the sample information.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a spectroscopic polarization characteristic measuring device and a spectroscopic polarization characteristic measuring method for measuring the polarization characteristics of an object to be measured. [Background technology]

[0002] Conventionally, the rotating analyzer method and the rotating retarder method have been used to measure the polarization state, such as the ellipticity, of light to be analyzed (Patent Document 1). However, in the rotating analyzer method, the ellipticity is given by a cosine function, so measurement accuracy deteriorates when the birefringence phase difference of the sample is around 0° or 180°. Furthermore, because birefringence and optical rotation are wavelength-dependent, evaluation is required for each wavelength. However, in the rotating retarder method, the polarization state must be measured by changing the retarder for each wavelength, making it impossible to efficiently measure the wavelength dispersion of the polarization state.

[0003] The double rotation method, which rotates a retarder and an analyzer, allows measurement of chromatic dispersion of the polarization state without changing the retarder for each wavelength (Patent Document 2). However, both measurement methods require a driving unit such as a motor as a mechanism for rotating the retarder and analyzer, which increases the size of the device, and the measurement time is long because the retarder and analyzer are rotated mechanically. Furthermore, when polarization modulation is performed using optical materials such as an electro-optic modulator or a photoelastic modulator (PEM), high voltage and power consumption are required.

[0004] Known devices and methods for performing polarization modulation using a liquid crystal variable retarder instead of a rotating retarder or analyzer are disclosed in Patent Documents 3 and 4. However, while the device and method of Patent Document 3 can measure the optical properties of a sample, they cannot measure the polarization state of an arbitrary measurement target. Furthermore, the device and method of Patent Document 4 requires measuring the polarization state for each wavelength, making it impossible to efficiently measure the wavelength dispersion of the polarization state. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-292028 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-085853 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-145332 [Patent Document 4] U.S. Patent No. 6,744,509 Summary of the Invention [Problem to be solved by the invention]

[0006] The above-mentioned method requires time-series polarization modulation, which makes it impossible to perform measurements in real time, and therefore has the problem that it is not suitable for cases where the object to be measured changes over time.

[0007] Furthermore, the above-mentioned method has the problem that it is not possible to measure the wavelength dependency of polarization characteristics (spectroscopic polarization characteristics) with high accuracy, and is not suitable for cases where the measurement object has complex spectroscopic polarization characteristics.

[0008] The present invention has been made to solve the above problems, and provides a spectroscopic polarization characteristic measuring device and a spectroscopic polarization characteristic measuring method that can acquire the polarization state and its wavelength dispersion (spectroscopic polarization characteristics) of an object to be measured quickly and with high accuracy without requiring polarization modulation. [Means for solving the problem]

[0009] The present invention provides a spectroscopic polarization characteristic measurement device for measuring the spectroscopic polarization characteristics of a measurement target, comprising: a first discrete spectrum light source (first optical comb light source) that emits discrete spectrum light including two or more spectra distributed at different frequencies; a splitting unit that spatially splits the discrete spectrum light (pulsed light) emitted from the first discrete spectrum light source; a plurality of polarization control units that independently control the polarization states of the plurality of discrete spectrum light beams split by the splitting unit, each of which has a different polarization state; a plurality of time delay control units that independently control the time delays of the plurality of discrete spectrum light beams polarization-controlled by the polarization control units, each of which has a different time delay; a first superposition unit that spatially superposes the plurality of discrete spectrum light beams whose time delays are controlled by the time delay control units; and the polarization-controlled discrete spectrum light train, which is composed of a plurality of discrete spectrum light beams having different polarization states and time delays and which are superimposed on one another, onto a sample; a second discrete spectrum light source (second optical comb light source) which emits discrete spectrum light containing two or more spectra distributed at different frequencies; a second superposition unit which spatially superimposes the discrete spectrum light (pulsed light) emitted from the second discrete spectrum light source on the polarization-controlled discrete spectrum light train containing information about the sample by the irradiation unit to generate an interference signal (interferogram train); and a detection unit which acquires a mode-resolved spectrum relating to the optical amplitude and phase of orthogonal polarization components of individual interferograms containing information about the sample from the interference signal (interferogram train) generated by the superposition unit. In this specification, the term "mode decomposition spectrum" refers to a spectrum that can be individually separated from discrete spectral light. The spectroscopic polarization characteristic measurement device according to the present invention can acquire mode decomposition spectra of amplitude and phase (hereinafter referred to as mode decomposition amplitude spectrum and mode decomposition phase spectrum). In the following, when there is no need to distinguish between the mode decomposition amplitude spectrum and the mode decomposition phase spectrum, they may be simply referred to as "mode decomposition spectrum."

[0010] Furthermore, the spectroscopic polarization characteristic measurement according to the present invention is a spectroscopic polarization characteristic measurement method for measuring the spectroscopic polarization characteristics of an object to be measured, and includes the steps of dividing discrete spectral light into a plurality of parts, individually controlling the polarization states of the spatially divided discrete spectral light, individually controlling the time delay of the polarization-controlled discrete spectral light, superimposing the plurality of discrete spectral light beams whose polarization and time delay are controlled, and time-dividing the individual polarization-controlled discrete spectral light beams to perform spectroscopic polarization measurement.

[0011] According to the above configuration, a polarization-controlled discrete-spectrum light train consisting of a plurality of discrete-spectrum light beams with different polarization states and separated in time is generated and irradiated onto a sample. Therefore, the spectropolarization characteristics of the sample are imparted to each of the polarization-controlled discrete-spectrum light beams constituting the polarization-controlled discrete-spectrum light train. The polarization-controlled discrete-spectrum light to which the spectropolarization characteristics of the sample have been imparted can be detected by the detection unit.

[0012] In the above-described spectropolarization characteristic measurement device, the discrete spectrum light source may be a first comb light source that emits, as the discrete spectrum light, a first optical frequency comb spectrum in which first adjacent frequency intervals, which are intervals between frequencies of the spectrum that are adjacent in frequency position on a frequency axis, are consistent with each other.

[0013] The above configuration may further include a second comb light source emitting a second optical frequency comb spectrum, in which the frequency intervals of the spectra adjacent to each other on the frequency axis are different from the first adjacent frequency interval and the second adjacent frequency intervals are the same. The detector may acquire the mode-resolved spectrum based on an interference signal (interference spectrum or interferogram) generated by interfering the first optical frequency comb spectrum with the second optical frequency comb spectrum (dual optical comb spectroscopy). In this case, the interference spectrum is an optical beat spectrum of the first and second optical frequency comb spectra obtained by frequency downscaling the first optical frequency comb spectrum. Furthermore, dual optical comb spectroscopy can acquire not only a mode-resolved amplitude spectrum but also a mode-resolved phase spectrum.

[0014] Furthermore, in the above-described spectroscopic polarization characteristic measuring device, the splitting unit may include a splitting element that spatially splits incident light, and the discrete spectrum light emitted from the first discrete spectrum light source may be spatially split into a plurality of discrete spectrum light beams by the splitting element. On the other hand, the first superposing unit may spatially superpose the plurality of discrete spectrum lights transmitted through the polarization control unit and the time delay control unit.

[0015] According to the above configuration, the polarization control unit may include a polarization control optical system that adjusts the polarization of the incident light, and may control the discrete spectrum light split by the splitting unit to an arbitrary polarization state. The polarization control optical system may be configured with a three-axis polarization controller. Meanwhile, the time delay control unit may include a time delay control optical system that adjusts the time delay of incident light, and may add an arbitrary time delay to the discrete spectrum light polarization-controlled by the polarization control unit. The time delay control unit may be configured with a time delay stage.

[0016] In the above spectroscopic polarization characteristic measuring device, the polarization state of the two discrete spectral lights spatially superimposed by the first superimposing unit may be set so that the polarization characteristics of the sample can be calculated. On the other hand, the time delay of the two discrete spectrum lights spatially superimposed by the first superimposing unit may be set so as to enable high-resolution measurement of the spectral characteristics of the sample. [Effects of the Invention]

[0017] The spectropolarimetric measurement device of the present invention can simultaneously acquire information about the sample (spectropolarimetric characteristics) added to the different polarization-controlled discrete spectrum light beams by irradiating the beam with a single polarization-controlled discrete spectrum light train without polarization modulation. Furthermore, by acquiring a mode-resolved spectrum relating to the optical amplitude and phase of the orthogonal polarization components of the polarization-controlled discrete spectrum light, it is possible to acquire the polarization characteristics and their chromatic dispersion of the object to be measured in a wide bandwidth, with high sensitivity, high resolution, and at high speed. Therefore, according to the present invention, it is possible to provide a spectroscopic polarization characteristic measuring device that can quickly acquire the polarization characteristics and chromatic dispersion of an object to be measured while maintaining high accuracy, without requiring polarization modulation. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic diagram of a spectroscopic polarization characteristic measuring device according to an embodiment of the present invention; [Figure 2] 1 is a schematic diagram for explaining discrete spectrum light in the present invention. FIG. [Figure 3] 1 is a schematic diagram showing a first configuration example of a discrete spectrum light source in a spectroscopic polarization characteristic measurement device according to an embodiment of the present invention. FIG. [Figure 4] FIG. 10 is a schematic diagram showing a second configuration example of a discrete spectrum light source in the spectroscopic polarization characteristic measurement device according to the embodiment of the present invention. [Figure 5] FIG. 10 is a schematic diagram showing a third configuration example of a discrete spectrum light source in the spectroscopic polarization characteristic measurement device according to an embodiment of the present invention. [Figure 6] FIG. 10 is a schematic diagram showing a fourth configuration example of a discrete spectrum light source in the spectroscopic polarization characteristic measurement device according to an embodiment of the present invention. [Figure 7] 1A and 1B are schematic diagrams for explaining a generation process of an interference spectrum in a spectroscopic polarization characteristic measurement device according to an embodiment of the present invention. [Figure 8] FIG. 1 is a schematic diagram for explaining the manipulation of light (generation of dual polarization-controlled discrete spectrum light strings) performed by a first discrete spectrum light source, a splitting unit, a polarization control unit, a time delay control unit, and a first superposition unit in a spectroscopic polarization characteristic measurement device according to an embodiment of the present invention. [Figure 9] 10 is a graph showing the time waveform of an interferogram sequence relating to the high-order quarter-wave plate used in Example 1. [Figure 10] 1 is a graph showing a mode resolved amplitude ratio (φ) spectrum of a first interferogram for the high-order quarter-wave plate used in Example 1. [Figure 11]1 is a graph showing a mode-resolved phase difference (Δ) spectrum of a first interferogram for the high-order quarter-wave plate used in Example 1. [Figure 12] 10 is a graph showing the mode resolved amplitude ratio (φ) spectrum of the second interferogram for the high-order quarter-wave plate used in Example 1. [Figure 13] 10 is a graph showing a mode-resolved phase difference (Δ) spectrum of a second interferogram for the high-order quarter-wave plate used in Example 1. [Figure 14] 1 is a graph showing the time waveform of an interferogram sequence related to the Faraday rotator used in Example 1. [Figure 15] 1 is a graph showing a mode resolved amplitude ratio (φ) spectrum of a first interferogram for the Faraday rotator used in Example 1. [Figure 16] 1 is a graph showing a mode-resolved phase difference (Δ) spectrum of a first interferogram for the Faraday rotator used in Example 1. [Figure 17] 10 is a graph showing a mode resolved amplitude ratio (φ) spectrum of a second interferogram for the Faraday rotator used in Example 1. [Figure 18] 10 is a graph showing a mode-resolved phase difference (Δ) spectrum of a second interferogram for the Faraday rotator used in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of a spectroscopic polarization characteristic measuring device according to the present invention will be described with reference to the drawings. Note that the drawings used in the following description are schematic, and the ratios of length, width, and thickness are not necessarily the same as those in the actual device and can be changed as appropriate.

[0020] (Embodiment) First, an embodiment of a spectroscopic polarization characteristic measurement device for measuring Jones matrices in a transmission configuration to which the present invention is applied will be described with reference to Figures 1 to 18 and Tables 1 and 2. Figure 1 is a schematic diagram of a spectroscopic polarization characteristic measurement device 10A of this embodiment.

[0021] [Configuration of Spectroscopic Polarization Characteristic Measurement Apparatus 10A] As shown in FIG. 1, the spectroscopic polarization characteristic measurement device 10A is a spectroscopic polarization characteristic measurement device capable of acquiring optical information such as the polarization characteristics and wavelength dependency of a sample 100, and includes a first discrete spectrum light source (first optical comb light source) 12, a splitting unit 14, multiple polarization control units 15 and 16, multiple time delay control units 17 and 18, a first superposition unit 19, an irradiation unit 20, a second superposition unit 21, a second discrete spectrum light source (second optical comb light source) 13, a discrete spectrum control unit 45, a third polarization control unit 36, and a detection unit 40.

[0022] The first discrete spectrum light source 12 is a light source that emits discrete spectrum light LA.

[0023] FIG. 2 is a schematic diagram for explaining discrete spectrum light LA. As shown in FIG. 2, discrete spectrum light LA ​​includes two or more spectra MA that are distributed at different frequencies. An example of such discrete spectrum light LA ​​is an optical frequency comb spectrum LX0. The optical frequency comb spectrum LX0 includes two or more spectra MA that are distributed at a frequency interval fr on the frequency axis (the f-axis shown in FIG. 2), for example. Hereinafter, the number of spectra MA is defined as n. In other words, the frequency interval fr is the frequency interval between spectra MA, MA that are adjacent in frequency position on the frequency axis. In terms of frequency characteristics, n spectra MA are arranged in a manner such that the carrier, envelope, and offset frequency f0 (hereinafter referred to as offset frequency f0) and a predetermined optical intensity |E(f)| 2 The spectral envelope NA has a distribution of NA, which is distributed on the frequency axis. The time characteristics of the optical frequency comb spectrum LX0 show a distribution of multiple pulses Φ1, Φ2, ..., Φm. The time interval between adjacent pulses Φ1, Φ2, ..., Φm is 1 / fr. The optical carrier electric field CA of the multiple pulses Φ1, Φ2, ..., Φm has a time distribution obtained by inverse Fourier transform of the multiple spectra MA. The pulse envelope WA of the multiple pulses Φ1, Φ2, ..., Φn has a time distribution obtained by inverse Fourier transform of the spectral envelope NA.

[0024] By determining the carrier envelope offset frequency f0 and the order of the spectrum MA having the carrier envelope offset frequency f0, the frequency of the spectrum MA in a given order is determined. For example, the frequency νn of the nth spectrum MA for the spectrum MA having the offset frequency f0 is determined as shown in the following equation (1).

[0025]

number

[0026] In the optical frequency comb spectrum LX0, the frequency spacing fr and offset frequency f0 are stabilized based on a frequency standard, so that the frequency of the spectrum MA remains almost constant on the frequency axis. Furthermore, all spectra MA are phase-synchronized while maintaining equal spacing.

[0027] The discrete spectrum light source 12 may be a known comb light source capable of emitting the optical frequency comb spectrum LX0 described above. The following describes examples of the configuration of the discrete spectrum light source 12. In each example, detailed descriptions of known components will be omitted. The configuration of the discrete spectrum light source 12 is not limited to the following examples.

[0028] FIG. 3 is a schematic diagram of a comb light source, which is a first example of the discrete spectrum light source 12. As shown in FIG. 3, the comb light source includes a mode-locked fiber laser 77 and an amplifier 78. The mode-locked fiber laser 77 includes a pumping semiconductor laser 82, an optical fiber 80G equipped with an optical isolator 87A, an optical coupler 84A, an optical fiber 80A equipped with an ytterbium (Yb)-doped fiber 86A, optical fibers 80B and 80C, and an optical isolator 85A. The amplifier 78 is connected to the mode-locked fiber laser 77 via an optical coupler 84D located between the optical fibers 80B and 80C. The amplifier 78 includes an optical fiber 80D connected to the output side of the optical coupler 84D, an optical isolator 85B, a pumping semiconductor laser 83, an optical fiber 80F equipped with an optical isolator 87B, an optical coupler 84C, an optical fiber 80H equipped with an ytterbium (Yb)-doped fiber 86B, and an optical isolator 85C.

[0029] In the configuration shown in Figure 3, mode-locked fiber laser 77 emits highly frequency-stable pulses from optical isolator 85A toward optical coupler 84A. Some of the emitted pulses are extracted by optical coupler 84D, and some of the pulses travel through optical fiber 80D and are amplified in intensity by amplifier 78. Meanwhile, the remaining pulses travel through optical fiber 80C and are looped inside mode-locked fiber laser 77. Based on this operating principle, optical isolator 85C emits a high-power optical frequency comb spectrum LX0.

[0030] 4 is a schematic diagram of a comb light source, which is a second configuration example of the discrete spectrum light source 12. As shown in FIG. 4, the comb light source includes an optical modulator 90 and a microwave oscillator 93. The optical modulator 90 is composed of mirrors 92A and 92B spaced a predetermined distance apart, and an electro-optic crystal 94 disposed between the two mirrors 92A and 92B. The electro-optic crystal 94 is made of, for example, lithium niobate (LiNbO3).

[0031] In the configuration shown in Figure 4, single-spectrum light incident on the optical modulator 90 is externally phase-modulated by a microwave oscillator 93. Meanwhile, the electro-optic crystal 94 is placed within a Fabry-Perot cavity consisting of two mirrors 92A and 92B, as described above, resulting in deep modulation and the generation of approximately 1,000 or more spectra MA. The frequency spacing fr of the spectra MA matches the modulation frequency of the microwave oscillator 93. Furthermore, because the optical modulator 90 is composed of passive components, an optical frequency comb spectrum LX0 is generated, containing two or more spectra MA that are highly stable on the frequency axis. The center frequency of the spectral envelope NA is determined by the input light source (not shown).

[0032] 5 is a schematic diagram of a comb light source, which is a third example of the discrete spectrum light source 12. As shown in FIG. 5, the comb light source includes a waveguide-type Mach-Zehnder modulator (MZM) ultra-flat optical comb generator (MZ-FCG) 95. The MZ-FCG 95 includes an input waveguide 96A, two branch waveguides 96B and 96C, and an output waveguide 96D. Each of the two branch waveguides 96B and 96C is coupled to a waveguide that can input a radio frequency (RF) signal and a phase-modulated signal.

[0033] In the configuration shown in Figure 5, when an RF signal is input to the two branch waveguides 96B and 96C under certain conditions, two optical frequency comb spectra are generated from the single spectrum in each of the branch waveguides 96B and 96C. At the coupling point between the two branch waveguides 96B and 96C, the two optical frequency comb spectra compensate for the imbalance in their respective optical intensities. As a result, an optical frequency comb spectrum LX0 with excellent flatness in the spectral envelope NA is generated and output from the output waveguide 96D.

[0034] 6 is a schematic diagram of a comb light source, which is a fourth example of the discrete spectrum light source 12. The comb light source is a broadband comb / ultrashort pulse light source that uses the MZ-FCG 95 of the comb light source 22C. As shown in FIG. 6, the comb light source 22D includes a pumping semiconductor laser 98, a polarization controller (PC) 99, an MZM 100, a single-mode fiber (SMF) 108, an erbium-doped fiber amplifier 109, and a dispersion-flattened, dispersion-decreasing fiber (DF-DDF) 110. In the configuration shown in Figure 6, the optical comb signal generated by the MZ-FCG95 is input into a standard SMF108 and then input into the DF-DDF, generating an optical frequency comb spectrum LX0 spanning approximately 20 THz.

[0035] In addition to the above, optical comb light sources based on micro optical combs and quantum cascade lasers can also be used.

[0036] 1, a splitter 14 is disposed in the emission direction of the first discrete spectrum light source 12 described above. The splitter 14 is an optical element that spatially separates the discrete spectrum light LA ​​emitted from the first discrete spectrum light source 12 into two optical paths, a first optical path 11A and a second optical path 11B. Therefore, various parameters of the splitter 14 include the frequency ν and power |E(ν)| of the spectrum MA. 2 The splitting section 14 is not particularly limited and is set taking into consideration the above factors. A plate-type beam splitter, a cube-type beam splitter, or the like can be used as the splitting section 14.

[0037] The first optical path 11A is disposed between the splitting unit 14 and the first superposing unit 19, and is configured to control the polarization and time delay of the first discrete spectrum light LA ​​that has passed through the splitting unit 14. The first optical path 11A of this embodiment includes a first polarization control optical unit 15 and a first time delay control unit 17. In FIG. 1 , the first polarization control unit 15 is composed of a polarizer 22, a half-wave plate 23, and a quarter-wave plate 24. The first polarization control unit 15 has a function of arbitrarily controlling the known polarization state of the first discrete spectrum light LA. Examples of the first polarization control unit 15 having such a function include a three-axis polarization controller and a Babinet-Soleil compensator. 1, the first time delay control unit 17 is composed of a roof mirror 30, a time delay stage 31, and a corner reflector 32. The time delay stage 31 has a function of arbitrarily controlling the time delay of the first discrete spectrum light LA. Examples of the first time delay control unit 30 having such a function include a time delay stage, a time delay fiber, etc. It should be noted that there is no problem if the first polarization control unit 15 and the first time delay control unit 30 are arranged in the opposite order in the first optical path 11A. Furthermore, the first optical path 11A is not limited to the above configuration as long as it can arbitrarily control the polarization and time delay of the first discrete spectrum light LA.

[0038] The second optical path 11B is disposed between the splitting unit 14 and the superimposing unit 19 and is configured to control the polarization and time delay of the first discrete-spectrum light LA ​​reflected by the splitting unit 14. The second optical path 11B of this embodiment includes a second polarization control unit 16 and a second time delay control unit 18. In FIG. 1 , the first polarization control unit 16 is configured with a polarizer 25, a half-wave plate 26, and a quarter-wave plate 27. The second time delay control unit 18 is configured with a roof mirror 33, a time delay stage 34, and a corner reflector 35. Similar to the first optical path 11A, the second polarization control unit 16 and the second time delay control unit 18 have the function of arbitrarily controlling the polarization and time delay of the first discrete-spectrum light LA ​​to be different from those of the first optical path 11A and known in advance.

[0039] The first superimposing unit 19 is disposed between the splitter 14 and the irradiator 20 and is configured to spatially superimpose a first polarization-controlled discrete-spectrum light 11C, whose polarization and time delay are controlled in the first optical path 11A, and a second polarization-controlled discrete-spectrum light 11D, whose polarization and time delay are controlled in the second optical path 11B. The spatially superimposed first polarization-controlled discrete-spectrum light 11C and second polarization-controlled discrete-spectrum light 11D are temporally multiplexed to form a dual polarization-controlled discrete-spectrum light string 11E having different polarization states. The polarization states of the discrete-spectrum lights in the dual polarization-controlled discrete-spectrum light string 11E must have a relationship that allows the Jones matrix, described below, to be calculated. Furthermore, the first polarization-controlled discrete-spectrum light 11C and the second polarization-controlled discrete-spectrum light 11D of the dual polarization-controlled discrete-spectrum light string 11E are preferably separated in time by approximately half the repetition period of the first discrete-spectrum light source. For the first overlapping portion 19, a plate-type beam splitter, a cube-type beam splitter, or the like can be used.

[0040] The irradiation unit 20 is disposed between the first superposition unit 19 and the sample 100, and is configured to irradiate the sample 100 with the dual polarization-controlled discrete spectrum light train 11E generated by the first superposition unit 19. Figure 1 shows a case where a transmission configuration is used, which is suitable for measuring highly transparent samples. For thin film samples, for example, a grazing incidence reflection configuration can also be used instead of the transmission configuration.

[0041] The sample 100 is disposed between the irradiation unit 20 and the second superposition unit 21. In the transmission configuration, the sample 100 may be any object, such as an optical element, that transmits the dual polarization-controlled discrete spectrum light train and can add information to each polarization-controlled discrete spectrum light by modulating the amplitude or phase, etc., and is not particularly limited. In the oblique incidence reflection configuration, the sample 100 may be any object, such as a thin film material, that multiple-reflects the dual polarization-controlled discrete spectrum light train within a film and can add information to each polarization-controlled discrete spectrum light by modulating the amplitude or phase, etc., and is not particularly limited.

[0042] The second superposition unit 21 is disposed between the irradiation unit 20 and the detection unit 40. The mirror surface of the second superposition unit 21 is inclined at a predetermined angle with respect to the optical axis. A plate-type beam splitter, a cube-type beam splitter, or the like can be used for the second superposition unit 21.

[0043] The second discrete spectrum light source (second comb light source) 13 is a light source that emits discrete spectrum light LB. The discrete spectrum light LB includes two or more spectra MA2 that are distributed at different frequencies (see FIG. 7). An example of such discrete spectrum light LB is an optical frequency comb spectrum (second optical frequency comb spectrum) LX2. It is desirable that the frequency interval fr2 of the second discrete spectrum light source (second comb light source) 13 be controlled by the discrete spectrum control unit 45 so as to maintain a certain offset frequency (Δfr=fr2−fr1) relative to the frequency interval fr1 of the first discrete spectrum light source 12 described above. 1, a third polarization control unit 36 ​​is disposed in the emission direction of the second discrete spectrum light source (second comb light source) 13. In FIG. 1, the third polarization control unit 36 ​​is composed of a polarizer 37, a half-wave plate 38, and a quarter-wave plate 39. The second discrete spectrum light source (second comb light source) 13 is arranged so as to make the discrete spectrum light LB incident on the second overlapping unit 21 at a predetermined angle.

[0044] FIG. 7 is a schematic diagram for explaining the process of generating an interference spectrum (i.e., dual optical comb spectroscopy) between the discrete-spectrum light of the first polarization-controlled discrete-spectrum light 11C (or the second polarization-controlled discrete-spectrum light 11D) containing optical information such as the polarization characteristics and wavelength dependency of the sample 100 and the discrete-spectrum light LB emitted from the second discrete-spectrum light source (second optical comb light source) 13. 7, for the discrete spectrum light containing information about the sample 100, the frequency interval between mode decomposition spectra MA1 and MA1 that are adjacent in frequency position on the frequency axis of the optical domain is a first adjacent frequency interval fr1. The first adjacent frequency intervals fr1 are the same. On the other hand, for the discrete spectrum light LB, the frequency interval between the mode decomposition spectra MA2 and MA2 that are adjacent to each other on the frequency axis of the optical domain is a second adjacent frequency interval fr2 that is different from the first adjacent frequency interval fr1. The second adjacent frequency intervals fr2 also match each other. That is, the discrete spectrum light 11C and LB each include n spectra MA1 and MA2 distributed at equal intervals on the frequency axis, and the first adjacent frequency interval fr1 and the second adjacent frequency interval fr2 are different from each other.

[0045] A double interferogram train is generated, which is composed of a first interferogram resulting from interference between the discrete spectrum light of the first polarization-controlled discrete spectrum light 11C and the discrete spectrum light LB emitted from the second discrete spectrum light source (second comb light source) 13, and a second interferogram resulting from interference between the discrete spectrum light of the second polarization-controlled discrete spectrum light 11D and the discrete spectrum light LB emitted from the second discrete spectrum light source (second comb light source) 13.

[0046] The detector 40 is disposed at the rear end of the spectroscopic polarization characteristic measurement device 10A. The detector 40 is configured to separate the dual interferogram train into orthogonal polarization components (horizontal polarization component and vertical polarization component) to obtain a mode decomposition spectrum relating to optical amplitude and phase. The detector 40 includes a bandpass filter 41, a polarizing prism 42, a first detector 43a, a second detector 43b, and a signal processor 44.

[0047] The bandpass filter 41 limits the optical spectrum band of the generated dual interferogram sequence to avoid aliasing in dual optical comb spectroscopy. The polarizing prism 42 is an optical element that separates the double interferogram train into a horizontally polarized component and a vertically polarized component. Various parameters of the polarizing prism 42 are set in consideration of the optical frequency (wavelength) of the interferogram, the desired extinction ratio for acquiring information on the sample 100, and the like, and are not particularly limited. For example, a polarizing beam splitter or the like can also be used instead of a polarizing prism. The first detector 43a and the second detector 43b convert the time waveforms of the horizontally polarized component and the vertically polarized component of the double interferogram train into electrical signals and acquire them. The signal processing unit 44 divides the acquired double interferogram sequence into a first interferogram and a second interferogram, and performs a Fourier transform on each interferogram separately to obtain a mode-resolved amplitude spectrum and a mode-resolved phase spectrum for each frequency (wavelength). In this embodiment, the Jones matrix is ​​calculated using a two-ream polarization-controlled discrete spectrum light sequence. However, if a four-ream polarization-controlled discrete spectrum light sequence is used, the Mueller matrix can also be calculated.

[0048] [Measurement using the spectropolarimetric measurement device 10A] Next, the principle of measurement using the spectroscopic polarization characteristic measuring device 10A shown in FIG. 1 will be described. The first discrete spectrum light LA ​​emitted from the first discrete spectrum light source (first comb light source) 12 is incident on the splitting section 14 and split into the first discrete spectrum light transmitted through the first optical path 11A and the first discrete spectrum light reflected through the second optical path 11B.

[0049] The transmitted first discrete-spectrum light LA ​​is set to a known polarization state by the first polarization control unit 15. Then, a known time delay is set by the first time delay control unit 17 (first polarization-controlled discrete-spectrum light 11C). Furthermore, the reflected first discrete-spectrum light LA ​​is set to a known polarization state different from that of the first polarization-controlled discrete-spectrum light 11C by the second polarization control unit 16. Thereafter, a known time delay different from that of the first polarization-controlled discrete-spectrum light 11C is set by the second time delay control unit 18 (second polarization-controlled discrete-spectrum light 11D).

[0050] The first polarization-controlled discrete-spectrum light 11C on the first optical path 11A and the second polarization-controlled discrete-spectrum light 11D on the second optical path 11B are spatially superimposed by the first superimposing unit 19. As a result, a dual polarization-controlled discrete-spectrum light string 11E, which is temporally separated and has a different polarization state, is generated. By irradiating the sample 100 with the dual polarization-controlled discrete-spectrum light train 11E by the irradiation unit 18, the spectroscopic polarization characteristics of the sample 100 are imparted to the first polarization-controlled discrete-spectrum light 11C and the second polarization-controlled discrete-spectrum light 11D.

[0051] The dual polarization-controlled discrete-spectrum light sequence 11E containing information about the sample 100 and the discrete-spectrum light LB emitted from the second discrete-spectrum light source (second comb light source) 13 are spatially superimposed by the second superimposing unit 21 to generate an interference signal (a dual interferogram sequence). The generated dual interferogram sequence is composed of a first interferogram corresponding to the first polarization-controlled discrete-spectrum light 11C and a second interferogram corresponding to the second polarization-controlled discrete-spectrum light 11D. The generated double interferogram train is passed through a bandpass filter 41 to limit the optical spectrum band, and then separated by a polarizing prism 42 into a vertically polarized component and a horizontally polarized component. The horizontally polarized component of the double interferogram sequence is acquired as an electrical signal by a first detector 43a, and the vertically polarized component is acquired as an electrical signal by a second detector 43b.

[0052] The time waveform of the horizontally polarized component of the double interferogram sequence acquired by the first detector 43a is divided into a first interferogram and a second interferogram, and then each is Fourier transformed to obtain a mode-resolved amplitude spectrum and a mode-resolved phase spectrum for the horizontally polarized component of the first interferogram and the second interferogram, or to calculate a mode-resolved amplitude ratio spectrum and a mode-resolved phase difference spectrum. Furthermore, the time waveform of the vertically polarized component of the double interferogram sequence acquired by the second detector 43b is divided into the first interferogram and the second interferogram, and then each is Fourier transformed to obtain a mode decomposition amplitude spectrum and a mode decomposition phase spectrum for the vertically polarized component of the first interferogram and the second interferogram, or to calculate a mode decomposition amplitude ratio spectrum and a mode decomposition phase difference spectrum. These make it possible to determine the polarization state of the first polarization-controlled discrete-spectrum light 11C after it has passed through the sample 100. Similarly, the polarization state of the second polarization-controlled discrete-spectrum light 11D can also be determined. The Jones matrix of the sample 100 can be calculated from the polarization states of the first polarization-controlled discrete-spectrum light 11C and the second polarization-controlled discrete-spectrum light 11D after passing through the sample 100.

[0053] Next, a method for calculating the Jones matrix of the sample 100 will be described using mathematical formulas. In the Jones calculation method, the polarization state is described using a Jones vector J, and the Jones vector at each wavelength of the light to be analyzed is expressed by the following formula:

[0054]

number

[0055] where E x and E y are the electric field amplitudes of the horizontally polarized component (x component) and the vertically polarized component (y component), δ x and δ yindicates the phase of the horizontally polarized component (x component) and the vertically polarized component (y component). This is called the amplitude ratio Ψ(=E x / E y ) and phase difference Δ(=δ x - δ y ), we generalize it as follows:

[0056]

number

[0057] For example, the Jones matrices for horizontally polarized light, vertically polarized light, θ polarized light, +45° linearly polarized light, −45° linearly polarized light, right-handed circularly polarized light, and left-handed circularly polarized light are as follows:

[0058]

number

[0059] On the other hand, the polarization characteristics of the sample 100 are expressed by the Jones matrix J M It is described as:

[0060]

number

[0061] where r ij and θ ij indicate the amplitude and phase, respectively.

[0062] Jones matrix J of the optically active sample OR is the angle of rotation θ r Using

[0063]

number

[0064] In addition, the Jones matrix J of the birefringent sample is BR is the angle θ of the crystal optical axis b and retardance Δb Using

[0065]

number

[0066] It is expressed as:

[0067] Jones vector J of incident polarization IN , Jones matrix J M , the Jones vector of the output polarization J OUT The relationship is as follows:

[0068]

number

[0069] Here, J out and J. in is the Jones vector of the outgoing and incoming polarizations, J out_x and J. out_y are the horizontal polarization component (x component) and vertical polarization component (y component) of the Jones vector of the outgoing polarization, J in_x and J. in_y indicates the horizontal polarization component (x component) and vertical polarization component (y component) of the Jones vector of the incident polarized light.

[0070] Jones matrix J for sample 100 M is the four unknown matrix elements (J 00 , J 01 , J 10 , J 11 ), so to determine it, two different Jones vectors of incident polarization 1 and incident polarization 2 and the corresponding output polarization 1 and output polarization 2 are required. The output polarization 1 and output polarization 2 after passing through the sample for incident polarization 1 and incident polarization 2 can be written as follows:

[0071]

number

[0072] Here, J out1_x and J out1_y are the x and y components of the output polarization 1 Jones vector, J in1_x and J in1_y are the x and y components of the incident polarized light 1 Jones vector, J out2_x and J out2_y are the x and y components of the output polarization 2 Jones vector, J in2_x and J in2_y are the x and y components of the incident polarized light 2 Jones vector. Expanding and transforming the above equation gives the following:

[0073]

number

[0074] From these two simultaneous equations, the Jones matrix J for sample 100 is M Each element of can be calculated as follows:

[0075]

number

[0076] To solve the two simultaneous equations above, the inverse of matrix A must exist.

[0077]

number

[0078] The conditions for the existence of an inverse matrix of matrix A are as follows:

[0079]

number

[0080] It is necessary to set appropriate incident polarization 1 and incident polarization 2 so that the inverse matrix of matrix A exists. For example, if incident polarization 1 is set to +45-degree linear polarization and incident polarization 2 is set to -45-degree linear polarization, the above equation becomes as follows, and the inverse matrix of matrix A exists.

[0081]

number

[0082] According to the above procedure, the polarization states of the first polarization-controlled discrete-spectrum light and the second polarization-controlled discrete-spectrum light are set, and the polarization states of the first polarization-controlled discrete-spectrum light and the second polarization-controlled discrete-spectrum light after passing through the sample 100 are measured, thereby calculating the Jones matrix of the sample 100.

[0083] [Function and effect of the spectropolarization characteristic measuring device 10A] Next, the effects of the spectroscopic polarization characteristic measuring apparatus 10A of this embodiment will be described with reference to Fig. 8. Fig. 8 is a schematic diagram for explaining the light manipulation (generation of a dual polarization-controlled discrete-spectrum light train 11E) performed by the first discrete-spectrum light source 12, the splitting unit 14, the polarization control units 15 and 16, the time delay control units 17 and 18, and the first superposition unit 19. Here, as an example, a case will be described in which the polarization of the discrete-spectrum light LA, which is emitted from the first discrete-spectrum light source 12 and includes two or more spectra MA that are independent of each other on the frequency axis, is set to 0° linear polarization (horizontally linear polarization), and a dual polarization-controlled discrete-spectrum light train of +45° linear polarization and -45° linear polarization is generated. 8, in the spectropolarization characteristic measurement device 10A described above, when the discrete-spectrum light LA ​​emitted from the first discrete-spectrum light source 12 is incident on the splitting unit 14, it is split into first discrete-spectrum light that is transmitted through the first optical path 11A and first discrete-spectrum light that is reflected through the second optical path 11B. This makes it possible to independently control the polarization and time delay of the split first discrete-spectrum light.

[0084] The 0° linearly polarized light of the transmitted first discrete spectrum light LA ​​is converted into +45° linearly polarized light by the first polarization control unit 15. On the other hand, the 0° linearly polarized light of the reflected first discrete spectrum light LA ​​is converted into −45° linearly polarized light by the second polarization control unit 16. Next, a known amount of time delay is added to the first discrete-spectrum light LA ​​converted into +45° linearly polarized light by a first time delay controller 17 (first polarization-controlled discrete-spectrum light 11C). On the other hand, a known amount of time delay is added to the first discrete-spectrum light LA ​​converted into -45° linearly polarized light by a second time delay controller 18 (second polarization-controlled discrete-spectrum light 11D). Here, the time delay difference between the first polarization-controlled discrete-spectrum light 11C and the second polarization-controlled discrete-spectrum light 11D is set to be half the repetition period of the first discrete-spectrum light source 12.

[0085] The first polarization-controlled discrete-spectrum light 11C and the second polarization-controlled discrete-spectrum light 11D, whose polarization and time delay are independently controlled, are spatially superimposed in the first superimposing unit 19 to generate a dual polarization-controlled discrete-spectrum light sequence 11E in which +45° linearly polarized light and 45° linearly polarized light are multiplexed in the time domain. Therefore, it is possible to generate a dual polarization-controlled discrete-spectrum light sequence 11E corresponding to the matrix A in equation (22).

[0086] Furthermore, according to the spectroscopic polarization characteristic measuring device 10A of this embodiment, the dual polarization-controlled discrete spectrum light sequence 11E to which information about the sample 100 has been added and the discrete spectrum light LB emitted from the second discrete spectrum light source (second comb light source) 13 are spatially superimposed by the second superimposing unit 19 to generate an interference signal (dual interferogram sequence). By using the detection unit 40 to measure the mode-resolved amplitude spectrum and mode-resolved phase spectrum of the horizontally polarized component and the vertically polarized component of the first interferogram and the second interferogram that make up the double interferogram train, the Jones vectors of the outgoing polarized light in Equations (20) and (21) can be obtained collectively for each wavelength component. As described above, the spectroscopic polarization characteristic measuring apparatus 10A of this embodiment can acquire spectroscopic polarization information of the sample 100 at high speed while maintaining high accuracy.

[0087] The spectroscopic polarization characteristic measurement device 10A, which has the above-described effects, has significantly improved speed and resolution compared to conventional spectroscopic polarization characteristic measurement devices, and can obtain a variety of polarization information (birefringence, optical rotation, dichroism, circular dichroism, etc.) and their wavelength dependence with a single shot of a dual polarization-controlled discrete spectral light train. As a result, it is believed that new knowledge can be obtained in industrial fields such as dynamic optical property evaluation and in bio-fields such as biological function analysis. [Industrial Applicability]

[0088] A spectroscopic polarization characteristic measuring device to which the present invention is applied can obtain a variety of spectroscopic polarization information at ultra-high speed while maintaining high accuracy, and can be applied to optical industrial products, optical functional materials, nanostructures, pharmaceuticals, protein structures, etc. Therefore, a spectroscopic polarization characteristic measuring device to which the present invention is applied can be used in a wide range of fields, including the industrial, pharmaceutical, and bio fields. [Example]

[0089] Next, examples will be described that were carried out to demonstrate the effects of the spectroscopic polarization characteristic measuring apparatus 10A of each embodiment to which the present invention is applied, but the present invention is not limited to the following examples.

[0090] The characteristics of the first polarization control unit 15 were set to +45° linear polarization, and the characteristics of the second polarization control unit were set to +135° linear polarization. A dual polarization-controlled discrete spectrum light train 11E was generated by multiplexing in the time domain so that the time delay difference between the first time delay control unit 17 and the second time delay control unit 18 was 7.5 nanoseconds, and irradiated onto the sample 100. A high-order quarter-wave plate with birefringence (for a wavelength of 1550 nm, birefringence amount = λ / 4) was used for the sample 100. The high-order quarter-wave plate was positioned so that its optical axis was set to 90°.

[0091] Figure 9 shows the time waveform (A) of the acquired interferogram sequence, and it can be seen that (B) is the first interferogram corresponding to +45° linearly polarized light incidence, and (C) is the second interferogram corresponding to +135° linearly polarized light incidence, which can be observed separated in time. The first and second interferograms were separated in time and subjected to Fourier transformation. Then, the mode-resolved amplitude ratio (φ) spectrum and mode-resolved phase difference (Δ) spectrum of the first and second interferograms were calculated from the mode-resolved amplitude spectrum and mode-resolved phase spectrum of the vertically polarized component and the horizontally polarized component. The mode-resolved amplitude ratio (φ) spectrum and mode-resolved phase difference (Δ) spectrum of the first interferogram are shown in Figures 10 and 11, and the mode-resolved amplitude ratio (φ) spectrum and mode-resolved phase difference (Δ) spectrum of the second interferogram are shown in Figures 12 and 13. Because the optical axis of the high-order quarter-wave plate is set midway between the polarization angle of first polarization control unit 15 and the polarization angle of second polarization control unit 16, similar mode-resolved amplitude ratio (φ) spectrum and mode-resolved phase difference (Δ) spectrum are obtained between the two.

[0092] The wavelength spectrum (spectropolarization characteristics) of the Jones matrix of the high-order quarter-wave plate was calculated from the measurement results in Figures 10, 11, 12, and 13. Table 1 shows a comparison of the experimental and theoretical values ​​of the Jones matrix at a wavelength of 1550 nm. It can be seen that the experimental and theoretical values ​​show good agreement.

[0093] [Table 1]

[0094] Next, a Faraday rotator (wavelength = 1500 to 600 nm, angle of rotation 45±1°) with optical rotation was used as the sample 100. Because the Faraday rotator does not have an optical axis, it was positioned at an arbitrary angle. The first polarization control unit 15 had a characteristic of +67.5° linear polarization, and the second polarization control unit 16 had a characteristic of -22.5° linear polarization. A dual polarization-controlled discrete spectrum light train was generated by multiplexing in the time domain so that the time delay difference between the first discrete spectrum light LA ​​and the second discrete spectrum light LA ​​was 4 nanoseconds, and the sample 100 was irradiated with this.

[0095] Figure 14 shows the time waveform (A) of the acquired interferogram sequence, and it can be seen that (B) is the first interferogram corresponding to +67.5° linearly polarized light incidence, and (C) is the second interferogram corresponding to -22.5° linearly polarized light incidence, which can be observed separated in time. The mode-resolved amplitude ratio (φ) spectrum and mode-resolved phase difference (Δ) spectrum of the first interferogram are shown in Figures 15 and 16, and the mode-resolved amplitude ratio (φ) spectrum and mode-resolved phase difference (Δ) spectrum of the second interferogram are shown in Figures 17 and 18. In both cases, results that reflect the optical rotation of the Faraday rotator are obtained.

[0096] The wavelength spectrum (spectropolarization characteristics) of the Jones matrix of the Faraday rotator was calculated from the measurement results in Figures 15, 16, 17, and 18. Table 2 shows a comparison of the experimental and theoretical values ​​of the Jones matrix at a wavelength of 1550 nm. It can be seen that the experimental and theoretical values ​​roughly match.

[0097] [Table 2]

[0098] As shown in the above examples, according to the present invention, information reflecting the optical response of a sample can be simultaneously obtained from multiple polarization-controlled discrete spectral light trains that are multiplexed in time, without performing polarization modulation, and the spectropolarization characteristics of the sample can be obtained quickly while maintaining high accuracy. [Explanation of symbols]

[0099] 10A...Spectropolarization characteristic measuring device 12...First discrete spectrum light source (first optical comb light source) 13...Second discrete spectrum light source (second optical comb light source) 14...Divided part 15...First polarization control unit 16...Second polarization control section 17...First time delay control section 18...Second time delay control section 19...First overlapping section 21...Second overlapping portion 36...Third polarization control section 40...Detection unit 100...Sample 11A…First optical path 11B…Second optical path 11C...First polarization-controlled discrete spectrum light 11D...Second polarization-controlled discrete spectrum light 11E…Two-series polarization-controlled discrete spectrum light array 11F...Optical beat spectrum

Claims

1. a first optical frequency comb source that emits pulsed light including two or more spectra that are distributed at different frequencies from each other; a splitter that spatially splits the pulsed light emitted from the first optical frequency comb source; and a plurality of polarization controllers that independently control the polarization states of the pulsed light split by the splitter, each of which has a different polarization state; a first superposition unit that spatially superposes the plurality of pulsed beams whose time delays are controlled by the time delay control unit; an irradiation unit that irradiates a sample with a polarization-controlled discrete spectrum light train consisting of the plurality of pulsed beams whose polarization states and time delays are different and which are superposed by the first superposition unit; a second optical frequency comb source that emits pulsed beams including two or more spectra distributed at different frequencies; a second superposition unit that generates an interferogram train by spatially superposing the pulsed beam emitted from the second optical frequency comb source with the polarization-controlled discrete spectrum light train containing information about the sample by the irradiation unit; and a detection unit that acquires mode decomposition spectra related to the optical amplitudes and phases of orthogonal polarization components of each interferogram train containing information about the sample, the first optical comb light source is a light source that emits a first optical frequency comb spectrum in which first adjacent frequency intervals, which are intervals between frequencies of the spectrum that are adjacent to each other on a frequency axis, are matched to each other; The second optical frequency comb light source is a light source that emits a second optical frequency comb spectrum, in which the frequency intervals of the spectrum are second adjacent frequency intervals that are different from the first adjacent frequency intervals and the second adjacent frequency intervals are the same. A spectroscopic polarization characteristic measuring device characterized by:

2. the splitting unit includes a splitting element that spatially splits incident light, and the pulsed light emitted from the first optical frequency comb source is spatially split into a plurality of pulsed lights by the splitting element; 2. The spectroscopic polarization characteristic measuring device according to claim 1, wherein the first superimposing unit spatially superimposes the plurality of pulsed lights that have passed through the polarization control unit and the time delay control unit.

3. the polarization control unit includes a polarization control optical system that adjusts the polarization of incident light, and controls the pulsed light split by the splitting unit to an arbitrary polarization state; 3. The spectroscopic polarization characteristic measuring device according to claim 1, wherein the time delay control unit includes a time delay control optical system that adjusts the time delay of incident light, and adds an arbitrary time delay to the pulsed light that has been polarization-controlled by the polarization control unit.

4. 4. The spectroscopic polarization characteristic measuring device according to claim 3, wherein the polarization control optical system comprises a polarizer, a half-wave plate, and a quarter-wave plate.

5. 4. The spectroscopic polarization characteristic measuring device according to claim 3, wherein the time delay control optical system comprises a roof mirror, a time delay stage, and a corner reflector.

6. 6. The spectroscopic polarization characteristic measuring device according to claim 1, wherein the polarization state of the plurality of spatially superimposed pulsed beams is set so that Jones matrices and Mueller matrices can be calculated by inverse matrix calculation, and the spectroscopic polarization characteristics of the sample can be measured.

7. 6. The spectroscopic polarization characteristic measuring device according to claim 1, wherein the time delay of the plurality of spatially superimposed pulsed beams is controlled so that the pulsed beams have equal time intervals within a repetition period of the first optical frequency comb light source, thereby enabling measurement of the spectroscopic polarization characteristics of a sample.

8. 8. The spectroscopic polarization characteristic measuring device according to claim 1, wherein the spectroscopic polarization characteristic of the sample is calculated from the mode decomposition spectrum acquired by the detector.

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