Methods and devices for characterizing resonator elements

Abstract

This invention provides a method and device for characterizing resonator elements. [Solution] The method includes the steps of supplying laser light having a tunable carrier frequency, coupling at least a first portion of the laser light to a resonator element 102 having a plurality of carrier resonances with respect to the carrier frequency of the laser light, modulating the intensity and / or phase of the first portion of the laser light with a first modulation frequency 1001 and a second modulation frequency 1002 to generate sideband resonances, and tuning the carrier frequency of the laser light at a predetermined tuning speed. The method also includes the steps of measuring the intensity of the laser light transmitted and / or reflected by the resonator element while tuning the carrier frequency, measuring the tuning time elapsed while tuning the carrier frequency, and using the measured tuning time to determine the spacing between the plurality of carrier resonances in the spectral region.

Description

[Technical Field]

[0001] Methods and devices for characterizing (understanding the characteristics of) resonator elements. Methods and devices for obtaining optical frequency references, LIDAR systems and gas detection systems A system is provided. Therefore, this disclosure relates to a system for obtaining an optical frequency standard. [Background technology]

[0002] Many applications require high-precision measurement of the time difference and / or spectral difference between multiple signals. The advantage is that it can be measured. In many applications, Non-Patent Document 1(D.) J. Jones, SA Diddams, JK Ranka, A. Stentz, RS Windeler, JL Hall, an d ST Cundiff, "Carrier-Envelope Phase Control of Femtosecond Mode-Locked Lase rs and Direct Optical Frequency Synthesis," Science 288, 635-639 (2000)), Patent document 2 (R. Holzwarth, Th. Udem, TW Hansch, JC Knight, WJ Wadsworth, a nd P. St. J. Russell, “Optical Frequency Synthesizer for Precision Spectroscopy,” Optical frequency combs like the one described in "Phys. Rev. Lett. 85, 2264-2267 (2000)" These technologies are used for the purpose of [the stated purpose]. Non-patent document 3 (M. Takamoto, I. Ushiji) ma, N. Ohmae, T. Yahagi, K. Kokado, H. Shinkai, and H. Katori, "Test of general relativity by a pair of transportable optical lattice clocks," Nat. Photonics 14 As described in 411-415 (2020), single-frequency measurement is possible with an accuracy of up to 18 digits. It has become that way.

[0003] In addition to single-frequency measurements, optical frequency combs are also used for high-precision, high-speed, broadband spectroscopy. It enjoys the benefits of a unique combination of wide bandwidth and high spectral resolution. Over the past 20 years, a variety of spectroscopic methods based on optical frequency combs have been developed, for example, direct frequency These include multi-comb spectroscopy, dual-comb spectroscopy, and Fourier transform spectroscopy.

[0004] Despite frequency combs being highly accurate and widely used, the power per comb line is - is low and is often affected by fluctuations in spectral size, Non-Patent Document 4 (T. Fortier and E. Baumann, "20 years of developments in optical frequency comb It's described in "technology and applications," Commun. Phys. 2, 1-16 (2019). This limits its use and presents challenges for further applications.

[0005] Furthermore, high-precision measurements based on optical frequency combs often require long-term coherence. A frequency comb light source with the following properties is required, as described in Non-Patent Document 5 (N. Picque and TW Hansch, "Fre as described in "Carrier-Envelope Phase Control of Femtosecond Mode-Locked Lasers and Direct Optical Frequency Synthesis," Science 288, 635-639 (2000); "Optical Frequency Synthesizer for Precision Spectroscopy," Phys. Rev. Lett. 85, 2264-2267 (2000); and "Test of general relativity by a pair of transportable optical lattice clocks," Nat. Photonics 14, 411-415 (2020). This involves an advanced servo loop, as described, for example, in D. J. Jones, S. A. Diddams, J. K. Ranka, A. Stentz, R. S. Windeler, J. L. Hall, and S. T. Cundiff, "Carrier-Envelope Phase Control of Femtosecond Mode-Locked Lasers and Direct Optical Frequency Synthesis," Science 288, 635-639 (2*00). [Prior Art Documents] [Non-Patent Documents]

[0006] [Non-Patent Document 1] D. J. Jones, S. A. Diddams, J. K. Ranka, A. Stentz, R. S. Windeler, J. L. Hall, and S. T. Cundiff, "Carrier-Envelope Phase Control of Femtosecond Mode-Locked Lasers and Direct Optical Frequency Synthesis," Science 288, 635-639 (2000). [Non-Patent Document 2] R. Holzwarth, Th. Udem, T. W. Hansch, J. C. Knight, W. J. Wadsworth, and P. St. J. Russell, "Optical Frequency Synthesizer for Precision Spectroscopy," Phys. Rev. Lett. 85, 2264-2267 (2000). [Non-Patent Document 3] M. Takamoto, I. Ushijima, N. Ohmae, T. Yahagi, K. Kokado, H. Shinkai, and H. Katori, "Test of general relativity by a pair of transportable optical lattice clocks," Nat. Photonics 14, 411-415 (2020). [Non-Patent Document 4] T. Fortier and E. Baumann, "20 years of developments in optical frequency comb technology and applications," Commun. Phys. 2, 1-16 (2019). [Non-Patent Document 5] N. Picque and T. W. Hansch, "Frequency comb spectroscopy," Nat. Photonics 13, 146-157 (2019). [Non-Patent Document 6] Baumann, Esther, et al. "Comb-calibrated frequency-modulated continuous-wave ladar for absolute distance measurements." Optics letters 38.12 (2013): 2026-2028 [Non-Patent Document 7] Baumann, Esther, et al. "Comb-calibrated laser ranging for three-dimensional surface profiling with micrometer-level precision at a distance." Optics express 22.21 (2014): 24914-24928; [Non-Patent Document 8] (Yu, Wenhui, et al. "Comb-calibrated frequency sweeping interferometry for absolute distance and vibration measurement." Optics Letters 44.20 (2019): 5069-5072) [Non-Patent Document 9] Nishiyama, Akiko, Daiki Ishikawa, and Masatoshi Misono. "High resolution molecular spectroscopic system assisted by an optical frequency comb." JOSA B 30.8 (2013): 2107-2112. [Non-Patent Document 10] Rieker, Gregory B., et al. "Frequency-comb-based remote sensing of greenhouse gases over kilometer air paths." Optica 1.5 (2014): 290-298 [Non-Patent Document 11] Herman, Daniel I., et al. "Precise multispecies agricultural gas flux determined using broadband open-path dual-comb spectroscopy." Science Advances 7.14 (2021): eabe9765 [Non-Patent Document 12] P. Del'Haye et al.: "Frequency comb assisted diode laser spectroscopy for measurement of microcavity dispersion," Nat. Photonics 3, 529-533 (2009) [Non-Patent Document 13] A. Frigg, et al., "Low loss CMOS-compatible silicon nitride photonics utilizing reactive sputtered thin films," Opt. Express 27, 37795-37805 (2019) [Non-Patent Document 14] IE Gordon et al. "The HITRAN2016 molecular spectroscopic database," J. Quant. Spectrosc. Radiat. Transf. 203, 3-69 (2017) [Non-Patent Document 15] J. Liu et al. "Frequency-comb-assisted broadband precision spectroscopy with cascaded diode lasers," Opt. Lett. 41, 3134-3137 (2016) [Non-Patent Document 16] A. Shkarin et al. "Nanoscopic Charge Fluctuations in a Gallium Phosphide Waveguide Measured by Single Molecules," Phys. Rev. Lett. 126, 133602 (2021) [Non-Patent Document 17] E. Baumann et al. "Comb-calibrated frequency-modulated continuous-wave lidar for absolute distance measurements," Opt. Lett. 38, 2026-2028 (2013) [Non-Patent Document 18] E. Baumann et al. "Comb-calibrated laser ranging for three-dimensional surface profiling with micrometer-level precision at a distance," Opt. Express 22, 24914-24928 (2014) [Non-Patent Document 19] Yang et al. "Frequency comb calibrated frequency-sweeping interferometry for absolute group refractive index measurement of air," Appl. Opt. 56, 3109-3115 (2017) [Non-Patent Document 20] V. Brasch et al. "Photonic chip-based optical frequency comb using soliton Cherenkov radiation," Science 351, 357-360 (2016) [Non-Patent Document 21] A. Nishiyama et al. "Precise frequency measurement and characterization of a continuous scanning single-mode laser with an optical frequency comb," Opt. Lett. 39, 4923-4926 (2014) [Non-Patent Document 22] S. Minardi, RJ Harris, and L. Labadie, "Astrophotonics: astronomy and modern optics," Astron. Astrophys. Rev. 29, 6 (2021) [Overview of the project] [Problems that the invention aims to solve]

[0007] Conventional technology generates a frequency comb by exciting a micro-resonator with a modulated laser. In many cases, however, the center frequency of the laser radiation coupled to the resonator element remains unchanged. It is maintained. The carrier frequency of the laser radiation coupled to the resonator element is generally stabilized. To generate a frequency comb, in many cases, octaves that spectrally overlap each other are needed. • It requires laser emission over a wide span, resulting in increased technical complexity and cost. .

[0008] Therefore, it is desirable to overcome the limitations mentioned above. [Means for solving the problem]

[0009] This problem concerns a resonator element having the characteristics of each independent claim in the patent claims. Methods and devices for characterizing offspring, tuner A method for supplying an optical frequency reference signal to laser light having a low carrier frequency, and This is solved by devices, LIDAR systems, and gas detection systems. Embodiments are provided in the dependent claims and specification. In one embodiment, a resonator element is characterized A method is provided. This method involves a laser light having a tunable carrier frequency. The steps of supplying and controlling at least a first portion of the laser light, the carrier frequency of the laser light A step of coupling to a resonator element having multiple carrier resonances, with respect to adjacent Carrier resonance occurs in the spectral region, with only the free spectral region separating them from each other. The steps include coupling at least a first portion of the laser light to a resonator element. This method further comprises the intensity of the portion of the laser light coupled to the resonant element and / or the phase is separated from each carrier resonance by the first modulation frequency by a small number of At the very least, the second modulation frequency is determined by the two sideband resonances and their respective carrier resonances. To generate at least two spaced-out sideband resonances, the first modulation frequency A step of modulating with wavenumber and second modulation frequency, wherein the first modulation frequency and the second modulation frequency The modulated s(s) are integer multiples of the free spectral region and are distinct from each other. It is equipped with a chip. Furthermore, this method allows the carrier frequency of the laser light to be set to a predetermined tuning speed. The steps involve tuning in degrees and tuning the carrier frequency while the resonator element Therefore, the step of measuring the intensity of the transmitted and / or reflected laser light, and the four adjacent sides Tuning process during the tuning of carrier frequencies across the id-band resonance This is a step to measure time, and this tuning time is the tunable carrier frequency. The wavenumber is calculated from the value corresponding to the first sideband resonance of the four sideband resonances. The amount of time required to change the sideband until the last sideband resonance is reached. A step of measuring the tuning time, which corresponds to the tuning time, This method further includes a first modulation frequency, a second modulation frequency, and four adjacent frequencies. Tuning process during the tuning of carrier frequencies across the id-band resonance Using time measurements, the laser light transmitted and / or reflected by the resonator element is measured. Based on the intensity, the spacing between multiple carrier resonances in the spectral region is determined. It is equipped with a top.

[0010] In another aspect, a device for characterizing a resonant element. A chair is provided. This device emits laser light with a tunable carrier frequency. A tunable laser light source for emission, and a resonant function for at least a portion of the laser light. It includes a coupling element for coupling to the component element. Furthermore, this device has each key At least two sideband resonances are spaced at the first modulation frequency from the carrier resonance. The first modulation frequency to be generated for each carrier resonance, and the respective carrier resonance At least two sideband resonances spaced by the second modulation frequency from the carrier resonance A second modulation frequency for each of these, coupled to the resonator element, It includes a modulator for modulating a portion of the intensity and / or phase. Furthermore, this device includes a modulator for modulating a portion of the intensity and / or phase. , detection for measuring the intensity of the portion of the laser light transmitted and / or reflected by the resonator element It is equipped with a device unit. This device further tunes the carrier frequency of the laser light. It includes a control unit configured to determine the tuning time. Determined, and based on the measured intensity of the laser light transmitted and / or reflected by the resonant element. Furthermore, the first modulation frequency, the second modulation frequency, and the four adjacent sideband resonances This refers to the tuning time elapsed when tuning the carrier frequency, and there are four of them. From the value corresponding to the first sideband resonance among the sideband resonances, the four sidebands The tunable carrier frequency reaches the last sideband resonance among the band resonances. The measured tuning time corresponds to the tuning time required to change the number. Based on the measured values, the spacing between multiple carrier resonances in the spectral region is determined.

[0011] In yet another embodiment, the optical frequency of a laser beam having a tunable carrier frequency A method is provided for supplying a numerical reference signal. This method is for the carrier frequency of laser light. The step of preparing a resonator element having multiple carrier resonances, wherein adjacent carriers A resonance occurs in the spectral region, where only the respective predetermined free spectral regions are separated from each other. The method comprises the step of preparing the resonator element, which has a gap between it and the other element. Furthermore, a first portion of the laser light is coupled to a resonator element, and the carrier frequency of the laser light is set to a predetermined value. It includes a step to tune at the tuning speed. Furthermore, this method is a resonator element A portion of the laser light transmitted and / or reflected by the child is spectrally swept. (Sweeping) A step of supplying as an optical frequency reference signal, which is transmitted by a resonant element The intensity of the over- and / or reflected laser light is spectrally separated from each other by the FSR. A portion of the laser light has local extrema at a specified frequency, and is based on optical frequency. It includes a step of supplying it as a quasi-signal.

[0012] In yet another embodiment, a spectral reference mark supplied by the method of this disclosure is used as a spectral reference mark. The use of an optical frequency reference signal is provided.

[0013] In yet another embodiment, a method for spectroscopically characterizing the analyte is provided, The law includes the steps of supplying an optical frequency reference signal by using the method disclosed and the object to be analyzed. Use an optical frequency reference signal as a spectral reference mark for spectroscopy characterization. The step includes using an optical frequency reference signal as a spectral reference mark. This is the relative spectral distance of multiple spectral features of the analyte based on one or more FSRs. This may include a step of determining the following.

[0014] In yet another embodiment, a laser beam having a tunable carrier frequency is used as the optical frequency A device is provided to supply a reference signal. This device can optionally be tuned. Equipped with a tunable laser light source for emitting laser light with a low carrier frequency. This device further allows for multiple carriers for the adjustable carrier frequency of the laser light. A resonator element having a rear resonance, wherein the carrier resonance is in the spectral region, Each of the devices is spaced apart from the others by a predetermined amount of its free spectral region. This includes a resonator element that can couple a portion of the laser light to the resonator element. The device further tunes the carrier frequency of the laser light at a predetermined tuning speed. It includes a control unit configured to transmit through a resonator element. A portion of the over- and / or reflected laser light is used as a spectrally swept optical frequency reference signal. It can be supplied, and the intensity of the laser light transmitted and / or reflected by the resonator element is The FSR exhibits local extrema at frequencies spectrally separated from each other. The device can optionally further transmit and / or reflect the radioactive material transmitted and / or reflected by the resonator element. It is equipped with a detector unit for measuring the intensity of a portion of the light. In addition, this device , at will, the measured intensity of a portion of the laser light transmitted and / or reflected by the resonator element The frequency of a tunable carrier frequency having a local extremum at a given degree is set to a predetermined free frequency. It is supplied as a spectral reference mark for an optical frequency reference signal defined by the vector region. It is equipped with a control unit configured to do so.

[0015] In yet another embodiment, a LIDAR system is provided. The LIDAR system is optical frequency The present disclosure comprises a device for supplying a wavenumber reference signal.

[0016] In yet another embodiment, a gas detection system is provided, the gas detection system is an optical frequency The present disclosure comprises a device for supplying a reference signal.

[0017] In yet another aspect, a method for characterizing a resonant element. This method provides a laser beam having a tunable carrier frequency. Step, and at least a first portion of the laser light, relative to the carrier frequency of the laser light. The step of coupling to a resonator element having multiple carrier resonances, wherein adjacent carriers In the REAR resonance, the free spectral region is the only space between them in the spectral region. The process involves coupling at least a first portion of the laser light to a resonator element, This method further includes the intensity of the portion of the laser light coupled to the resonator element and / or The phase is determined for each carrier resonance, and the first modulation frequency is derived from each carrier resonance. The first modulation frequency is varied to generate at least two spaced sideband resonances. The first modulation frequency is a step in which the first modulation frequency is different from an integer multiple of the free spectral region. The method comprises the step of modulating at the first modulation frequency. Furthermore, this method includes the step of ray The steps include tuning the carrier frequency of the light at a predetermined tuning speed, and While tuning the carrier frequency, the ray is transmitted and / or reflected by the resonator element. The method further comprises the step of measuring the intensity of the light. At the very least, measure the tuning time elapsed between multiple carrier resonances that are twice as far apart from each other. The method includes a step of using a resonator element with a first modulation frequency. The measured intensity of the transmitted and / or reflected laser light, and at least the first modulation frequency The measured tuning time elapsed between multiple carrier resonances that are twice as far apart from each other Based on this, the step of determining the spacing between multiple free spectral regions in the spectral region. It is equipped with.

[0018] A laser beam with a tunable carrier frequency can be tuned by a light source. It is coherent light having a center frequency. Carrier frequency tuning refers to the process of tuning the carrier frequency. This involves changing the rear frequency over time in a free and continuous manner. The adjustment process may include, for example, a step of sweeping the carrier frequency in a sinusoidal manner.

[0019] The resonant element exhibits specific transmission and / or absorption characteristics for tunable carrier frequencies. An element having a characteristic, for a predetermined value of a tunable carrier frequency, the resonator The element determines the local minimum and / or maximum values ​​of transmittance and / or absorptiveness and / or reflectance. This demonstrates that, in particular, this resonant element resonates with a specific value of the tunable carrier frequency. A resonant cavity that satisfies the conditions can be constructed. Specific values ​​for these carrier frequencies are... This is considered a carriage resonance. In the case of a resonator cavity, the transmittance is the length of the resonator cavity. Based on this, a local minimum is found at a frequency at which the tunable carrier frequency exhibits resonance. It is possible to possess it. While tuning the carrier frequency, the transmitted and / or reflected radio waves are transmitted through the resonant element. Measuring the intensity of the light allows for continuous tuning of the carrier frequency while maintaining resonance. This device measures the intensity and / or power of laser light transmitted and / or reflected by an instrument element. It means that.

[0020] The intensity and / or phase of a portion of the laser light are set to a first modulation frequency, and optionally to a second modulation frequency. Modulation by wavenumber involves changing the intensity and / or phase of the laser light at the first modulation frequency, and optionally... This means that the intensity of the laser light is periodically changed at the second modulation frequency. Modulating it at a first modulation frequency and optionally at a second modulation frequency is done with the first modulation frequency and As the modulated signal having a second modulation frequency progresses over time, the intensity decreases periodically. This leads to an increase. In the case of one or more modulated signals having one or more modulation frequencies, the modulation is actually Qualitatively, it can be a superposition of individual modulated signals. This is transmitted via a power combiner. This can be achieved by applying the first and second modulation frequencies. The first and second modulation frequencies are The first modulation frequency and may be higher than the free spectral range of the laser light and the resonator element. A first modulated signal and a second modulated signal having a second modulation frequency are explicitly mentioned. However, according to some discretionary embodiments, the laser light is modulated at two or more modulation frequencies. It should be noted that it can be modulated by more than one modulation signal. The first modulation frequency and the second modulation The modulation frequencies may each be within the radio frequency range. In particular, the first modulation frequency and the second The modulation frequencies can range from approximately 100 MHz to approximately 100 GHz. (Resonator) The free spectral range of the element can extend from 1 MHz to 100 GHz.

[0021] The modulation index for intensity modulation and / or phase modulation shall be in the range of approximately 0.6 to 2. It is possible.

[0022] Sideband resonances originating from modulation of the intensity and / or phase of the laser light are associated with the carrier frequency This can originate from the superposition of one or more modulation frequencies.

[0023] Modulation frequencies that are integer multiples of the free spectral range and are different from each other are modulated frequencies that cause a cap. The rear resonance does not completely overlap, and each other is derived from other modulation frequencies. This means generating sideband resonances that do not perfectly overlap with the main band resonances.

[0024] When tuning the carrier frequency across four adjacent sideband resonances The elapsed tuning time is measured across all four sidebands, using a tunable carrier frequency. From the value corresponding to the first sideband resonance of the vibration, of the four sideband resonances This corresponds to the tuning time required to change the band until the final sideband resonance is reached. However, according to other embodiments, the tuning of the carrier frequency is non-homogeneous. However, it can be implemented in a clearly defined manner. Furthermore, the four adjacent sides When the time distance of band resonance is sufficiently small, detailed knowledge of tuning characteristics is not necessary. It may not be essential. Based on the measured elapsed tuning time, sideburns The spectral difference between the beginning and end of the resonance can be determined.

[0025] A tunable laser light source may include or consist of a wavelength-tunable continuous-wave laser light source. A tunable, variable laser light source may include or consist of a diode laser.

[0026] The modulator may include or consist of an acousto-optic modulator and / or an electro-optic modulator. This can be achieved via / or through the modulation of the laser current and / or the laser current. Detector The unit operates within the tuning range of a laser beam with a tunable carrier frequency. It may include one or more photodiodes that have sensitivity to transmitted rays. In particular, the modulator transmits rays The intensity of the light and / or the phase of the transmitted laser light may be modulated.

[0027] The control unit is a computer, smartphone, integrated circuit and / or tablet computer. This may also be electrical and / or electronic equipment such as a computer. This control unit is a detector unit It can be connected to a detector unit to receive data measured by the nit. The Knit is further connected to a tunable light source and tunes the carrier frequency in a specific way. It can be configured to send instructions to a tunable light source for tuning.

[0028] In the measured intensity of the portion of the laser light transmitted and / or reflected by the resonant element The frequency of a tunable carrier frequency with local extrema is determined by a predetermined free spectrum. To supply a range-defined optical frequency reference signal as a spectral reference mark: The specific frequency that indicates the aforementioned local extremum is defined as a spectral reference mark. This means that the resonator element, in other words, has a spectral distance that is characterized according to this disclosure. Since it can be well determined and characterized by the process, it can be predetermined and well characterized It is used in a manner in which the marked carrier resonance is used as the optical frequency reference value. Well-characterized spectral distances between carrier resonances corresponding to the vector range, and / Alternatively, the spectral distance between sideband resonances is supplied as the optical reference frequency, and therefore It can be supplied as an optical frequency reference signal.

[0029] This disclosure offers the advantage of being able to supply optical frequency reference signals at a high-precision level. This disclosure provides a lower technical capability compared to conventional technologies that supply frequency reference signals, such as frequency combs. This enables the supply of high-precision frequency reference signals with minimal effort. The signal, in contrast to conventional frequency combs, is available as a standard optical component with low economic effort. And can be supplied based on electronic components. Optical frequency reference signals are often required in frequency combs. This requires octave-span spectra and nonlinear optical processes such as those described above. In addition, based on continuous wave lasers such as diode lasers, which can be supplied in accordance with this disclosure. This is emphasized. Therefore, this disclosure significantly reduces technical complexity and expensive components. This makes it possible to supply optical frequency reference signals without needing to use optical frequency reference signals, and therefore at low cost. It enables the supply of a reference signal. Furthermore, due to the low technical complexity of the device, These devices can be offered in smaller size and / or more compact dimensions. This device can be miniaturized and / or other compact optical and / or electronic components. It can be integrated into the product. In particular, according to this disclosure, a continuous wave laser can be used. The carrier frequency, i.e., the central frequency of the laser radiation, is within a predetermined spectral range, for example. It can be swept arbitrarily over a range of 10 free spectra. Carrier frequency and tuning The tuning speed allows for a predetermined sweep of the carrier frequency during the tuning time. Therefore, this disclosure may be known during the tuning process. This requires the use of other hardware that is significantly more expensive and significantly more complex. It does not enable the characterization of the resonator element and / or the supply of a frequency reference signal. It is possible. Therefore, according to this disclosure, it is not necessary to generate a frequency comb in the resonator element. For photo-optical applications, the carrier frequency falls within the desired spectral range for spectroscopic applications. Tuning can be performed over a predetermined tuning range that includes the specified area.

[0030] Therefore, this disclosure shows that the optical frequency reference signal is more efficient than that associated with conventional frequency combs. The advantages include lower technical complexity, smaller size, and the ability to be supplied at a lower cost. Provides octave-span and spectrally stabilized laser radiation relative to each other. Instead of requiring a metrical overlap, the methods and devices of this disclosure For example, it has a tunable carrier frequency and a free spectral range of, for example, 10. The carrier frequency is tuned at a predetermined tuning speed over a predetermined spectral range. It may be sufficient to supply laser light for shining. Therefore, compared to prior art, Technical complexity and requirements can be significantly reduced.

[0031] The difference between the first modulation frequency and the second modulation frequency is 10% or more of the resonant linewidth of the carrier resonance. The spectral range can be selected to be less than 50%. This allows for sideband resonance. Because the spacing in the frequency domain becomes appropriately large, the mutual and carrier of sideband resonances Appropriate discrimination against resonance can be ensured.

[0032] The first and second modulation frequencies are basically n+1 / 2 of the free spectral range. This corresponds to frequencies in the multiple neighborhood, where n is an integer. "Nearby" means that the frequency is within the free spectrum range. This means that the value is close to a multiple of n+1 / 2 of the range, but not identical. For example, the first modulation frequency. and / or the second modulation frequency is a free space between 100 MHz and 100 GHz, respectively. The spectral spacing can be created from multiples of n+1 / 2 of the metric range. This allows for side The band resonance will be spectrally positioned nicely between the carrier resonances.

[0033] Within at least one free spectral range, from one of the carrier resonances to the first modulation frequency Therefore, two sideband resonances are generated, and one of the carrier resonances is converted to the second modulation frequency. Therefore, at least two sideband resonances may be generated. This allows for the arrangement of these resonances. The spectral spacing between two adjacent carrier resonances, and consequently the spectrum of the free spectral range. The interval between the first and second modulation frequencies, in particular, and the relative carrier frequencies of the first and second modulation frequencies. It can be determined with high accuracy using the spectral interval from the numbers.

[0034] When tuning the carrier frequency across four adjacent sideband resonances The step of measuring the tuning time elapsed is located within a single free spectral range. When the carrier frequency is tuned across four adjacent sideband resonances This may include a step of measuring the tuning time that has elapsed. The spectral tuners needed to determine the information used to determine the interval of the rear resonance This offers the advantage of being able to limit the tuning range to a small spectral range. Maintain a constant tuning speed for the laser light source within the small spectral range to be covered. This makes it easier to determine the carrier resonance interval, thus eliminating undesirable measurements. Errors can be reduced or avoided. The method for characterizing the resonator element is further defined as A second portion of the laser beam is coupled to a calibration element having absolute transmission and / or reflection properties. The calibration element transmits and / or reflects while adjusting the step and carrier frequency. The method may include a step of measuring the intensity of a portion of the laser light. Furthermore, this method may include a frequency In several domains, it coincides with one of either carrier resonance or sideband resonance, or From there, at least one calibration element having a specified offset or a predetermined frequency The steps include identifying clear absolute transmission and / or reflection characteristics, and identifying the calibration element. Based on clear absolute transmission and / or reflection characteristics, carrier resonance or sidebands together The method may include the step of calibrating at least one absolute frequency of the oscillations. These additional steps based on the calibration element allow for the determination of carrier resonance and sideband resonance. The spectral frequency can be calibrated in an absolute manner. In the steps described above, We were able to calibrate the rear resonance and sideband resonance relative to each other, but these The additional step is to absolutely calibrate at least one of the carrier resonance and sideband resonance. And, through one absolutely calibrated carrier resonance or sideband resonance, the modulation frequency Through relative calibration based on this, all remaining carrier resonances and sideband resonances are calibrated. Therefore, this method enables absolute calibration of the resonator element, and absolute It can be used to supply an optical frequency reference signal. Therefore, the resonator element is particularly The marking device further has predetermined absolute transmission and / or reflection properties. The detector unit can be equipped with a calibration element, and can further adjust the carrier frequency. Furthermore, it measures the intensity of the portion of the laser light transmitted and / or reflected by the calibration element. It is possible. The control unit further controls carrier resonance or sideband resonance in the frequency domain. A predetermined oscillation that coincides with one of the oscillations, or has a specified offset from them. A calibration element having a frequency and at least one distinct absolute transmission and / or reflection characteristic. Based on the identified and clear absolute transmission and / or reflection characteristics of the calibration element, Calibrating the absolute frequency of at least one of the carriage resonance or sideband resonance. It is possible.

[0035] The calibration element has at least one distinct absolute transmission and / or reflection characteristic. It may include a gas cell filled with a specific gas. By using a gas cell, many gases can be used. The absorption characteristics were accurately characterized and are well known from the literature as clear absorption lines. This provides the advantage of being able to absorb and transmit signals from the resonator element. For absolute calibration when comparing the carrier resonance and / or sideband resonance of the two. It can be used as a reference. Alternatively or additionally, the calibration element is a frequency comb. It may include one or more of the following: a wave meter, or elements that produce transition lines of atoms and / or molecules.

[0036] The resonator element is a fiber cavity and / or integrated waveguide resonator and / or whisper Ring gallery mode resonators, and / or etalon resonators, and / or Fabry resonators. It may include a Perot resonator. This allows the resonator element to be a conventional optical and / or electronic set. It can be incorporated into top-ups and devices. Furthermore, such resonator elements can be used in devices. To implement the chair in small optical and / or electronic setups, the device is miniaturized. It can make transformation possible.

[0037] For supplying an optical frequency reference signal to laser light having a tunable carrier frequency. The method further involves spacing out by at least the first modulation frequency from each carrier resonance. There are also two sideband resonances, and the distance between each carrier resonance is the second modulation frequency. To generate at least two sideband resonances, a ray is coupled to the resonator element. - The intensity and / or phase of the first part of the light are modulated at the first modulation frequency and the second modulation frequency. The step is such that the first modulation frequency and the second modulation frequency are integers within the free spectral range. The frequencies of the sideband resonances are multiplied and differ from each other, and the spectral reference marks of the optical frequency reference signal are used. A step that can be supplied as a tool, modulated at the first and second modulation frequencies. It may be equipped with a prism. This reflects the calibration process for characterizing the resonator element. If the provided resonant element has already been calibrated and recalibration is not required, this step can be omitted. This is possible. However, in some embodiments, a tunable carrier frequency A method for supplying an optical frequency reference signal to a laser beam having multiple beams involves the calibration of a resonator element and / or may include a re-characterization process. This allows for periodic checking of the resonator element calibration. This allows for the connection of the supplied optical frequency reference signal, thereby ensuring accuracy in certain cases. Therefore, it can be improved. Related methods for characterizing resonator elements are Furthermore, the above-mentioned method can be used. In this case, the first modulation frequency and the second modulation frequency are These may be within the radio frequency range, and in particular, the first modulation frequency and the second modulation frequency These may each be within the range of approximately 100 MHz to approximately 10 GHz. The first modulation frequency and The difference from the second modulation frequency is 10% or more of the carrier resonance linewidth, and within the free spectrum range. It can be selected so that it is 50% or less. The first modulation frequency and the second modulation frequency are essentially, This corresponds to frequencies in the vicinity of multiples of n+1 / 2 within the free spectral range, where n is an integer.

[0038] Furthermore, this method may also include absolute calibration of the supplied optical frequency reference signal. This involves a calibration element having predetermined absolute transmission and / or reflection characteristics that transmits a second portion of the laser light. The steps involve coupling, and adjusting the carrier frequency, and transmitting and / or using a calibration element. This may include a step of measuring the intensity of the portion of the reflected laser light. This further includes a frequency In several domains, it coincides with one of the carrier resonances or sideband resonances, or At least one of the calibration elements having a specified offset or a predetermined frequency from one of the following The steps include identifying one clear absolute transmission and / or reflection property, and identifying the clear absolute Based on the relative transmission and / or reflection characteristics, carrier resonance and / or sideband resonance The method may include a step of calibrating the absolute frequency. By doing so, the method can achieve resonance This enables periodic absolute recalibration of the instrument components and, consequently, the supplied optical frequency reference signal. The element is filled with a predetermined gas having at least one distinct absolute transmission and / or reflection property. The added gas cell, and / or frequency comb, and / or wavelength meter, and / or atomic transition line This includes the system provided.

[0039] The carrier frequency of laser light has at least 10 free spectral ranges or more. It can be tuned over a range. The carrier frequency tuning is done by a predetermined adjustment process. This is done according to the turn. The predetermined adjustment pattern is a sinusoidal adjustment pattern of the carrier frequency. This includes a step of sweeping with a serrated and / or sawtooth adjustment pattern. This is based on the optical frequency reference. To supply signals quickly and reliably, and / or with reduced technical complexity and at low cost. This makes it possible to do so.

[0040] Laser light can be continuous wave laser light. This laser light is a resonator. The spectral width may be narrower than the linewidth of the element. The laser light has a tuning time and / or When the measurement time is within approximately 5 μs, it can typically have a short linewidth of 100 kHz or less. This could make it possible to perform highly accurate measurements.

[0041] Therefore, an optical frequency reference signal of laser light having a tunable carrier frequency is provided. The device for supplying the resonant element characterization and / or the resonant element and carrier resonance And / or relative and / or absolute calibration of sideband resonances may be performed. Therefore, it supplies an optical frequency reference signal for laser light having a tunable carrier frequency. The device for doing so further includes the intensity and / or of a portion of the laser light coupled to the resonator element. This modulator modulates the phase at the first modulation frequency, and for each carrier resonance, the corresponding key This generates at least two sideband resonances separated from the carrier resonance by the first modulation frequency. It may be equipped with a modulator. The control unit may further transmit through a resonant element. and / or based on the intensity of a portion of the reflected laser light, local poles due to sideband resonance A tunable carrier frequency having a value is set within a predetermined free spectrum range and a first modulation frequency. It is intended to supply a spectral reference mark for optical frequency reference signals defined by wavenumber. The resonator element may be a fiber cavity and / or an integrated waveguide, / or WGM (whispering gallery mode resonator), and / or etalon, and / or This may include a Fabry-Perot resonator. The modulator is electro-optical. It may include a specific intensity and / or phase modulator.

[0042] Furthermore, it supplies an optical frequency reference signal for laser light having a tunable carrier frequency. The device for this purpose may include a calibration element having predetermined absolute transmission and / or reflection characteristics. The detection unit further detects the intensity of a portion of the laser light transmitted and / or reflected by the calibration element. The degree can be measured while tuning the carrier frequency. (Control unit) Furthermore, within the frequency domain of the calibration element, a predetermined frequency is a carrier resonance or side frequency. At least one characteristic that matches one of the band resonances or has a specified offset. Identify the precise absolute transmission and / or reflection characteristics of the calibration element, and determine the specific and clear absolute transmission characteristics of the calibration element. and / or based on reflection characteristics, the absolute frequency of one or more carrier resonances or sideband resonances This can be used to calibrate the wavenumber. This allows for absolute calibration of the resonant element and the optical frequency reference signal. (Re)calibration may be possible. The calibration element is filled with a predetermined gas and has at least one light Gas cells and / or frequency combs having reliable and absolute transmission and / or reflection properties, and / or This may include a wavelength meter and / or an element or system that provides atomic transition lines or molecular transition lines. .

[0043] A tunable laser light source may include a tunable continuous-wave laser light source. A tunable laser light source may include a diode laser. A tunable laser light source is a resonant laser. A device that emits tunable laser light having a spectral width narrower than the linewidth of the device element. It is possible.

[0044] The LIDAR system including the device described herein is supplied by the device with an optical frequency reference. Using signals, a tunable laser is generated based on an optical reference signal supplied by the device. The device can be used for reference. In some systems known as prior art, Tuning lasers aim for high-precision, high-accuracy, and high-speed measurements by controlling the frequency. It is referenced based on the frequency comb. In this case, the frequency comb supplies the optical frequency reference signal. For example, the device is described in Non-Patent Document 6 (Baumann, Esther, et al. "Comb-calibrated fre quency-modulated continuous-wave ladar for absolute distance measurements." Opti cs letters 38.12 (2013): 2026-2028), non-patent document 7 (Baumann, Esther, et al. "Com b-calibrated laser ranging for three-dimensional surface profiling with micromet er-level precision at a distance." Optics express 22.21 (2014): 24914-24928;), and Non-patent document 8 (Yu, Wenhui, et al. "Comb-calibrated frequency sweeping interface rometry for absolute distance and vibration measurement." Optics Letters 44.20 ( It is described in (2019): 5069-5072).

[0045] However, frequency combs are technically complex, sensitive to environmental influences, and expensive. This often comes with the drawback of having a certain optical frequency reference signal. To supply the number, a file characterized and / or calibrated by the method disclosed herein It provides calibrated resonator elements such as vacuum cavities. This is high precision, high accuracy, and It enables high-speed measurement while being lower cost and less technically complex compared to frequency combs. It becomes available in this state. Therefore, the device for supplying an optical frequency reference signal according to this disclosure By using a sieve, high precision comparable to frequency combs can be achieved with significantly lower technical complexity and This can be achieved at a low cost. As a result, this disclosure applies to LIDAR and many other applications. In applications, while achieving high accuracy, low complexity, and high stability, the frequency comb is... It can also be applied to low-price range areas where installation is economically impossible. Furthermore, this disclosure In a LIDAR device that includes a device that supplies an optical frequency reference signal, calibration It is important to emphasize that having existing resonant elements is sufficient, and in some cases, a modulator is not necessary. However, in some embodiments, for example, to recalibrate the resonator element, A degree modulator can be installed.

[0046] Similarly, a gas sensing system including a device that supplies an optical frequency reference signal according to this disclosure The term refers to Non-Patent Document 9 (Nishiyama, Akiko, Daiki Ishikawa, and Masatoshi Misono. "H high resolution molecular spectroscopic system assisted by an optical frequency c omb." JOSA B 30.8 (2013): 2107-2112), Non-Patent Document 10 (Rieker, Gregory B., et al "Frequency-comb-based remote sensing of greenhouse gases over kilometer air pa ths." Optica 1.5 (2014): 290-298), Non-Patent Document 11 (Herman, Daniel I., et al. "P recise multispecies agricultural gas flux determined using broadband open-path d "ual-comb spectroscopy." (Science Advances 7.14 (2021): eabe9765) Similar to conventional systems for remote sensing based on greenhouse gas frequencies. It can be applied in this way.

[0047] In this case, the frequency comb is a resonant element calibrated according to the method disclosed herein. It can be replaced with a child-based device, which in turn allows for the replacement of a frequency comb-based device. Similarly, it is possible to achieve high-precision, high-accuracy, and high-speed measurement, but this can be significantly reduced. This makes it possible to offer products with low technical complexity, low manufacturing costs, and high robustness.

[0048] This invention is not limited to the disclosed embodiments and combinations thereof, but may be a technically realizable invention. It is understood that possible combinations and individual features are also included in the scope of this disclosure. Thereafter, with reference to the drawings, several arbitrary embodiments and specific examples illustrating the present disclosure are presented. The following will be explained, but these will not limit the embodiments of this disclosure.

[0049] Further optional embodiments and specific examples are described below with reference to the drawings. [Brief explanation of the drawing]

[0050] [Figure 1] A device of an optional embodiment for characterizing the resonator element is shown. [Figure 2] Figure 1 shows a method for characterizing a resonator element using the device described. [Figure 3] Carrier resonance and sideband resonance are schematically shown. [Figure 4] A device for characterizing a resonator element according to an optional embodiment is shown. [Figure 5] This device provides an optical frequency reference signal for laser light having a tunable carrier frequency. [Figure 6] A schematic method for supplying an optical frequency reference signal for laser light having a tunable carrier frequency is provided. [Figure 7] The results of a method for characterizing resonator elements using optional embodiments are shown. [Figure 8] The results of a method for characterizing resonator elements using optional embodiments are shown. [Figure 9] The results of a method for supplying an optical frequency reference signal are shown. [Figure 10] The results of absolute calibration using a calibration element are shown. [Figure 11] A schematic representation of a LiDAR using a discretionary embodiment is shown. [Figure 12] A gas sensing system based on a discretionary embodiment is schematically shown. [Modes for carrying out the invention]

[0051] In drawings, the same reference numeral is used for corresponding or similar features across different drawings. ru.

[0052] Figure 1 characterizes (characterizes) the resonator element 102 according to an optional embodiment. The device 100 for acterizing is shown. The resonator element 102 is connected to the fiber cavity. The device 100 is formed as a vibrator and is a test subject to be characterized by the device 100. It represents Vice.

[0053] Device 100 is for emitting laser light having a tunable carrier frequency It is equipped with a tunable laser light source 104. According to this embodiment, the output of the laser light source 104 The force is directly coupled to the optical fiber, which is coupled to the resonator element 102. Therefore, the optical fiber 106 directs at least a portion of the laser light to the resonator element 102. It can function as a coupling element 108 for bonding.

[0054] Furthermore, device 100 controls the intensity of a portion of the laser light coupled to the resonant element 102 and / or modulate the phase at the first modulation frequency 1001, and from each carrier resonance the first modulation frequency 1 It generates at least two sideband resonances separated by only 001 units, and the second modulation frequency Modulated at a frequency of several 1002, at least one second modulation frequency of 1002 away from each carrier resonance. Modulator 1 can also be prepared as an electro-optic modulator to generate two sideband resonances. It comprises 10. The modulator may be prepared as an electro-optic modulator, and the intensity of the laser light The phase of the laser light may be modulated, or alternatively or additionally modulated. The modulator uses a first modulation frequency 1001 and a second modulation frequency 100 as the modulated signal. One, two, or more modulated signals like 2 can be applied. However, several It should be emphasized that, depending on the discretionary embodiment, only one modulation frequency may be used. The modulation signal applied to the modulator 110 is a first modulation frequency 1001 and a second modulation frequency 10 It can be a superposition of 0 and 2. The first and second modulation frequencies 1001 and 1002 are, respectively This can represent sinusoidal oscillations at the modulation frequency. However, some arbitrary implementations are possible. Depending on the form, the modulated signal may be a waveform that covers a wide range in the spectral domain, or a sawtooth wave. It can be supplied as a more complex modulated signal, such as a continuous oscillation that deviates from a sine wave. Furthermore, in order to set the basic transmission characteristics of the modulator 110, for example, the bias voltage 10 04 can be applied to the modulator 110.

[0055] After the modulator 110, the laser light is incident on the device under test, namely the resonator element 102. ru.

[0056] Downstream of the resonator element 102, the device 100 transmits and / Alternatively, it includes a detection unit 112 for measuring the intensity of a portion of the reflected laser light. According to the configuration, the detection unit 112 detects the intensity of the laser light that has passed through the resonant element 102. It is configured to detect. The detection unit is sensitive to the carrier frequency of the laser light. It may include more than one photodiode. The detection unit 112 further includes a photodiode The output signal obtained by D112 is to be saved and / or visualized and / or evaluated. A data logger unit 114 is provided for this purpose, or can be connected to it.

[0057] Furthermore, device 100 is configured to tune the carrier frequency of the laser light. Then, the tuning time is determined, and the interval between multiple carrier resonances in the spectral region is A control unit 116 is configured to make a decision, which is made to the resonant element 102. Therefore, based on the measured intensity of the transmitted and / or reflected laser light, and the first modulation frequency 1 001, the second modulation frequency 1002, and the carrier frequency are shared across four adjacent sidebands. This is performed based on the measured tuning time that has elapsed when tuning over the vibration. The system includes the control unit 116. The control unit 116 includes the detection unit 112 and / or It is connected to the data logger and acquires data measured by the detection unit 112. The control unit 116 is also connected to the laser light source 104, and the laser light To tune the carrier frequency of the laser light emitted by source 104, The light source 104 can be controlled. Furthermore, the control unit 116 is connected to the modulator 110. Furthermore, modulated signals such as the first modulation frequency 1001 and the second modulation frequency 1002 are modulated This can be used to supply the container 110.

[0058] The carrier frequency, or central wavelength, of the laser light emitted by the laser light source 104 is By scanning, the laser light coupled to the resonator element 102 is used during the tuning process. Multiple carrier resonances are experienced within the resonator element 102. Regarding the frequency value, a considerable amount of the laser light energy is stored in the resonator element 102, As a result, the intensity transmitted through the resonator element 102 is low at the frequency corresponding to the carrier resonance. Therefore, the carrier resonance is the transmitted energy detected by the detection unit 112. It can be identified by the local minimum value of energy. In addition, it is connected to the resonator element 102. The intensity and / or phase of the combined laser light are modulated to a first modulation frequency 1001 and a second modulation frequency 1 Modulation at 002 results in the generation of two frequency sidebands, and these frequency sidebands The sidebands experience sideband resonance at frequencies corresponding to each modulation frequency, and also... These sideband resonances occur at specific frequencies different from the carrier resonance, as shown in Figure 3. As detailed below, the first and second modulation frequencies 1001 and 100 are derived from the carrier frequency. Only point 2 is separated in the spectral region.

[0059] Spec based on the measured intensity of the laser light transmitted and / or reflected by the resonant element 102 Based on the tuning time and interval between multiple carrier resonances within the ctor region, and also, The first modulation frequency is 1001, the second modulation frequency is 1002, and the carrier frequency is set to four adjacent frequencies. Based on the measured tuning time elapsed when tuning across sideband resonances. Subsequently, the control unit 116 determines the spectral spacing between carrier resonances, and thereby... The spectral range of the vibrator element 102 can be determined. In this way, the device This enables highly accurate characterization of the spectral characteristics of the resonator element 102.

[0060] Figure 2 shows a method for characterizing a resonator element using the device described in Figure 1. The details are explained below.

[0061] This method provides a laser beam with a tunable carrier frequency in the first step Includes P202.

[0062] Another step 204 involves having multiple carrier resonances with respect to the carrier frequency of the laser light. The step includes coupling at least a portion of the laser light to the resonator element 102, and adjacent Carrier resonances are spaced apart from each other in the spectral region by the free spectral range. It is positioned.

[0063] Step 206 controls the intensity and / or position of a portion of the laser light coupled to the resonant element 102. The phase is modulated with a first modulation frequency 1001 and a second modulation frequency 1002, and each carrier resonance is In contrast, the first modulation frequency 1001 is used to separate the carrier resonance from the carrier resonance at least Both sideband resonances and the second modulation frequency 1002 from the carrier resonance The first modification includes the step of generating at least two spaced sideband resonances. The first modulation frequency 1001 and the second modulation frequency 1002 are integer multiples of the free spectral range and mutually exclusive. These are different values.

[0064] Step 208 tunes the carrier frequency of the laser beam at a predetermined tuning speed. Includes steps to perform the action.

[0065] Step 210 is performed while tuning the carrier frequency to the resonator element 102 Therefore, the step includes measuring the intensity of the transmitted and / or reflected laser light.

[0066] Step 212 involves tuning the carrier frequency across four adjacent sideband resonances. This includes a step of measuring the tuning time elapsed during the tuning process.

[0067] Step 214 involves measuring the laser light transmitted and / or reflected by the resonant element 102. The intensity is used for the first modulation frequency 1001, the second modulation frequency 1002, and the carrier frequency. The measured tuner elapsed when tuning across four adjacent sideband resonances Based on the running time, the spacing between multiple carrier resonances in the spectral region is determined. Includes steps.

[0068] The intensity and / or phase of the laser light are controlled by the first modulation frequency 1001 and the second modulation frequency 100 By modulating with step 2, the carrier frequency is tuned, that is, the frequency of the laser light source. When scanning the wavenumber, as shown in Figure 3, two adjacent carrier resonances in the detected signal Four sideband resonances are generated within a single free spectral range (FSR) between them. Depending on the FSR of the vibrator element 102, f in Figure 3 mod1 and f mod2 The first is shown as The first modulation frequency 1001 and the second modulation frequency 1002 are near (n+1 / 2)×FSR. It can be set, where n is an integer and is constrained by the spectral bandwidth of the modulator. The frequency difference f between the first modulation frequency 1001 and the second modulation frequency 1002. d is a resonator element Depending on the structural linewidth of 10², it can be set to approximately a few MHz.

[0069] In Figure 3, resonance 3000 represents the carrier resonance, and resonances 3001 and 30 02 is the first modulation frequency 1001(f mod1 ) and the second modulation frequency 1002(f mo d2 This represents the sideband resonances caused by each of the following: The time interval between the carrier resonance within the FSR ranges FSRt1(t3) and t2(t4) and the sideband resonance due to modulation is not necessarily equal due to the non-linear operation in the frequency scanning of the laser light source 104. However, the frequency interval between these two sideband resonances, which is determined by the first or second modulation frequencies 1001, 1002 at frequency f or f respectively, is constant. Assuming that the FSR of the resonator element is constant within the modulation frequency range of 2×f corresponding to several 10 GHz, the FSR can be calibrated by (2n + 1)×FSR = 2f + f, where f is the frequency interval between two adjacent sideband resonances 3001 from the same modulation frequency f shown in Figure 3. This leaves the frequency interval f as the only uncertain variable due to the non-linear tunable laser scanning. However, it is desirable to calculate f in order to calculate the FSR. Regarding the method of using only a single modulation frequency f, the frequency interval f can be calculated considering the tuning time (t1 + t2) and the modulation frequency (2f) based on the average scanning speed of the laser light source 104. Although there remains some frequency uncertainty in f, it becomes possible to determine the FSR. The time interval between the carrier resonance within the FSR ranges FSRt1(t3) and t2(t4) and the sideband resonance due to modulation is not necessarily equal due to the non-linear operation in the frequency scanning of the laser light source 104. However, the frequency interval between these two sideband resonances, which is determined by the first or second modulation frequencies 1001, 1002 at frequency f or f respectively, is constant. mod1 or f mod2 However, the frequency interval between these two sideband resonances, which is determined by the first or second modulation frequencies 1001, 1002 at frequency f or f respectively, is constant. The frequency interval between these two sideband resonances is constant. Assuming that the FSR of the resonator element is constant within the modulation frequency range of 2×f corresponding to several 10 GHz, the FSR can be calibrated by (2n + 1)×FSR = 2f + f, where f is the frequency interval between two adjacent sideband resonances 3001 from the same modulation frequency f shown in Figure 3. mod1 the FSR can be calibrated by (2n + 1)×FSR = 2f + f, where f is the frequency interval between two adjacent sideband resonances 3001 from the same modulation frequency f shown in Figure 3. Based on the first modulation frequency (f), the FSR can be calibrated by (2n + 1)×FSR = 2f + f, where f is the frequency interval between two adjacent sideband resonances 3001 from the same modulation frequency f shown in Figure 3. mod1 Based on the first modulation frequency (f), the FSR can be calibrated by (2n + 1)×FSR = 2f + f, where f is the frequency interval between two adjacent sideband resonances 3001 from the same modulation frequency f shown in Figure 3. the FSR can be calibrated by (2n + 1)×FSR = 2f + f, where f is the frequency interval between two adjacent sideband resonances 3001 from the same modulation frequency f shown in Figure 3. mod1 + f ? the FSR can be calibrated by (2n + 1)×FSR = 2f + f, where f is the frequency interval between two adjacent sideband resonances 3001 from the same modulation frequency f shown in Figure 3. ? is the frequency interval between two adjacent sideband resonances 3001 from the same modulation frequency f shown in Figure 3. is the frequency interval between two adjacent sideband resonances 3001 from the same modulation frequency f shown in Figure 3. mod1 is the frequency interval between two adjacent sideband resonances 3001 from the same modulation frequency f shown in Figure 3. .

[0070] This leaves the frequency interval f as the only uncertain variable due to the non-linear tunable laser scanning. ? However, the frequency interval f is the only uncertain variable due to the non-linear tunable laser scanning. However, the frequency interval f is the only uncertain variable due to the non-linear tunable laser scanning. ? However, it is desirable to calculate f in order to calculate the FSR.<� However, it is desirable to calculate f in order to calculate the FSR. mod1 Regarding the method of using only a single modulation frequency f, f ? Regarding the method of using only a single modulation frequency f, the frequency interval f can be calculated considering the tuning time (t1 + t2) and the modulation frequency (2f) based on the average scanning speed of the laser light source 104. Regarding the method of using only a single modulation frequency f, the frequency interval f can be calculated considering the tuning time (t1 + t2) and the modulation frequency (2f) based on the average scanning speed of the laser light source 104. mod1 Regarding the method of using only a single modulation frequency f, the frequency interval f can be calculated considering the tuning time (t1 + t2) and the modulation frequency (2f) based on the average scanning speed of the laser light source 104. ? Regarding the method of using only a single modulation frequency f, the frequency interval f can be calculated considering the tuning time (t1 + t2) and the modulation frequency (2f) based on the average scanning speed of the laser light source 104. Regarding the method of using only a single modulation frequency f, the frequency interval f can be calculated considering the tuning time (t1 + t2) and the modulation frequency (2f) based on the average scanning speed of the laser light source 104. Although there remains some frequency uncertainty in f, it becomes possible to determine the FSR.

[0071] For comparison, the first modulation frequency is 1001(f mod1 ) and second modulation frequency 1002(f mod2 In dual RF modulation schemes using ), the frequency interval f ? This is shown on the right side of Figure 3. Within a short time scale T1+T2+T3, and within a very small frequency range of only a few MHz, this is possible. It can be determined within one free spectral range, the fixed interval between two sideband resonances. The frequency interval f d The first modulation frequency is 1001(f mod1 ) and the second modulation frequency 10 02(f mod2 It is clearly defined by a predetermined frequency difference between ) and the corresponding time interval. The intervals are indicated by the symbols T13003 and T23004 in Figure 3. As a result, frequency interval f ? T3×2f d It can be calculated by / (T1+T2). The interval T3 is indicated by the symbol 3005. The first modulation frequency 1001 and the second modulation frequency 1 By utilizing the flexibility of 002, two different modulation frequencies, 1001 and 1002, can be used. Fixed frequency interval f between sideband resonances d And the time interval T3 is determined by the resonator element 102 Very small values ​​related to FSR and cavity round-trip time. It becomes possible to set it to f. Therefore, the uncertainty of the frequency interval f ? Efficiently reduce Furthermore, this method allows for quasi-period modulation where the FSR is greater than the first and second modulation frequencies. When characterizing a device, or when using a resonator element with low FSR, dual R This method can also be applied to characterizing non-periodic devices by performing calibration using F-modulation. Therefore, this method allows for the spectral spacing of carrier resonances, i.e., high-precision free spectrum The determination of the torque range enables the characterization of the resonator element 102. This method allows for the characterization of the resonator element 102. A resonant element is used to create an optical frequency reference signal for laser light with a tunable carrier frequency. It becomes possible to supply numbers 3003, 3004, and As shown in 3005, there are four carrier frequencies over the time interval T1+T2+T3 Measure the time elapsed when tuning across adjacent sideband resonances. It is emphasized that this alone is sufficient.

[0072] Figure 4 characterizes the resonator element 102 based on the device 100 described with reference to Figure 1. A device 100 by an optional embodiment for this purpose is shown in Figure 4. The device, in its modified form, further includes a calibration element 118 compared to the device in Figure 1. It differs in that respect. The calibration element 118 has a predetermined absorption spectrum that includes precisely defined absorption lines. It has predetermined absolute transmission and / or reflection characteristics, such as the above. Furthermore, the detection unit is While tuning the carrier frequency, the calibration element 118 transmits and / or reflects the signal. It is possible to measure the intensity of a portion of the laser light. For this purpose, the detection unit A second photodiode 112 measures the intensity of the laser light that has passed through the calibration element 118. In some cases, the signal measured by the second photodiode 112 is used in the data logger. - It is supplied to 114 and evaluated by control unit 116. Control unit 116 is Furthermore, it coincides with either carrier resonance or sideband resonance in the frequency domain, or Then, at least one clear absolute transparency of the calibration element 118 having a predetermined offset The hyper-characteristics and / or reflective characteristics are identified, and the clear absolute transmission characteristics of the identified calibration element 118 are also determined. Based on the properties and / or reflection characteristics, carrier resonance 3000 or sideband resonance 3001 , the absolute frequency of 3002 can be calibrated. Presented Embodiment According to the report, the calibration element 118 accurately determines the transmission and / or reflection characteristics, for example, positive It comprises a gas cell containing a gas with a precisely determined absorption line. This is related to carrier resonance. The 3000, sideband resonances 3001 and 3002, and free spectral ranges are absolutely determined. Since the transmission and / or reflection characteristics of the calibration element can be referenced, the resonator element 116 This enables absolute calibration of spectral characteristics. As a result, the resonator element 102 can perform high-precision absolute calibration. It can be precisely characterized to supply a peer-to-optical frequency reference signal.

[0073] Figure 5 shows the supply of an optical frequency reference signal for laser light having a tunable carrier frequency. Device 200 for this purpose is shown. Similar to device 100 described in the previous figure, the device 200 is a tuner for emitting laser light with a tunable carrier frequency. It is equipped with a simple laser light source 104. Furthermore, the device 200 has a tunable laser beam. A well-characterized resonator element 1 having multiple carrier resonances with respect to carrier frequency It is equipped with 02, and these carrier resonances are within their respective predetermined free spectral ranges. These are separated from each other within the spectral region by (FSR), and This device can couple a portion of the laser light to the resonator element 102. Vice 200 is a part of the laser light transmitted and / or reflected by the resonant element 102. A detection unit 112 for measuring intensity, and a control unit 116 configured to supply, as a spectral reference mark of an optical frequency reference signal defined by a predetermined free spectral range, a tunable carrier frequency having a local extremum in the measured intensity of a part of the laser light transmitted and / or reflected by the resonator element 102. This device further comprises a calibration element 118 described with reference to FIG. 4. Different from the devices and methods described in relation to FIGS. 1 and FIG. 4, when using a resonator element 102 characterized sufficiently to supply an optical frequency reference signal, the modulator 110 is not necessarily required because a resonator element sufficiently characterized by applying the method according to the present disclosure to determine spectral characteristics can be used. However, according to another embodiment, a modulator can be additionally provided that enables recalibration of the resonator element 102 if necessary. According to the embodiment shown in FIG. 5, the resonator element 102 is used to supply an optical frequency reference signal for yet another application. This further application can include, for example, spectral characterization of a photonic device 120 such as the microring resonator 120 shown as an example in the figure. By comparing the obtained optical frequency reference and the optional calibration element 118, spectral characteristics such as the resonance frequency of the photonic device 120 can be characterized relatively and optionally also absolutely by comparing the obtained carrier resonance and / or sideband resonance of the resonator element 102 with a predetermined frequency. FIG. 6 shows supplying an optical frequency reference signal of laser light having a tunable carrier frequency

[0074]

[0075] which schematically shows a method. This method can be implemented using the device described with reference to FIG. 5. This method includes, at step 602, a step of preparing a resonator element 102 having a plurality of carrier resonances 3000 with respect to the carrier frequency of the laser light, where adjacent carrier resonances 3000 are spaced apart from each other by a respective predetermined free spectral range (FSR) within the spectral region, and the method includes the step of preparing the resonator element 102. Further, this method includes, at step 604, a step of coupling a part of the laser light to the resonator element 102, and at step 606, a step of measuring the intensity of a part of the laser light transmitted and / or reflected by the resonator element 102. Also, at step 608, the method includes a step of supplying a tunable carrier frequency having a local extremum in the measured intensity of a part of the laser light transmitted and / or reflected by the resonator element 102 as a spectral reference marker of an optical frequency reference signal defined by a predetermined free spectral range (FSR). Hereinafter, without limiting the present disclosure or embodiments to this detailed example, a detailed example for a proof-of-concept demonstration is presented. As a proof-of-concept demonstration, the resonator element 102 prepared in the form of a fiber cavity is characterized by measuring the optical dispersion of the resonator element 102, and the methods and devices shown in the present disclosure are verified. The fiber cavity is composed of a 10 dB fiber coupler and a 5 m standard communication fiber (SMF-28) with a zero-dispersion wavelength of about 1.310 nm.

[0076]

[0077] The free spectral range (FSR) of the fiber cavity is approximately 39 MHz, and the mode The linewidth is approximately 1 MHz, and this mode linewidth is described in Non-Patent Document 12 (P. Del'Haye et al.: " Frequency comb assisted diode laser spectroscopy for measurement of microcavity As described in "dispersion," Nat. Photonics 3, 529-533 (2009), measurement rate Limit it to approximately 1 THz / s.

[0078] To demonstrate the ultra-high frequency resolution of the methods and devices described herein, zero-dispersion wavelength frequency To elucidate the variation in the small free spectral range (FSR) of the edge, the wavelength range is 1.27 A 1.3 μm tunable laser with a wavelength of 0 to 1.330 nm is used as the laser light source. The tunable laser has a first modulation frequency of 1001 (f mod1 ) and second modulation frequency 1002(f mod2 ) obtained in each case, 20 GHz with a 4 MHz frequency difference It is modulated by two modulation signals. These two modulation signals are combined using a power combiner. Furthermore, it is applied to an electro-optic modulator (EOM) that functions as modulator 110. The laser light that passes through the cavity is directed towards the photodiode (PD) and the memory depth is 31. An oscilloscope as a data logger 114 to record 25 million measurements It is detected by the provided detection unit 112.

[0079] Subsection a) of Figure 7 shows the fiber optics at wavelengths of 1.270 nm to 1.330 nm. The image shows the transmission spectrum of the cavity, with the inset providing a detailed magnified view around 1,300 nm. This is shown. The vertical axis represents transmittance in arbitrary units, and the horizontal axis represents wavelength in nanometer units. The deep penetration dip is experienced by the laser light tuned to the carrier frequency. It is a fiber cavity, also known as carrier resonance 3000. One free spectrum The four additional small dips appearing within the full-sensor range (FSR) are results from the modulation sidebands. These occur as a result and are also referred to as sideband resonances 3001 and 3002. Figure 7 Subsection b) shows the fiber cable measured as a function of wavelength around the zero-dispersion region. This shows the progress of Biti's FSR. Trace 7000 in subsection b) of Figure 7 The left axis shows the results calculated from the dual RF modulation scheme, and the left vertical axis is offset. The FSR is calculated by subtracting 38,906 MHz, with the horizontal axis representing wavelength in nanometers. With a frequency resolution of less than 15 Hz, the Trace 7000 can operate in the 11 THz range. We clearly elucidated the small FSR fluctuations (<800Hz), and in the short wavelength range, the dispersion was normal, but zero. This study clarifies the complex cavity dispersion of fiber loops, which, after passing through dispersion, leads to anomalous dispersion in the long-wavelength region. It is being done. Trace 7002 is a quadratic polynomial with a zero-dispersion wavelength of 1.315 nm. The results of the fit are shown. For comparison, see the trace in subsection b) of Figure 7. 7004 (right axis) is used for measurements using a single modulation frequency (20 GHz) as the modulation signal. This shows the FSR progression calculated based on the use of two modulation frequencies. It is not possible to address small variations in cavity FSR in such detail. The vertical axis on the right is off. This represents the FSR (trace 7004) after subtracting the set 38,906MHz. Figure 7 shows Section c) shows that the measured FSR plotted on trace 7000 is trace 700 It shows the frequency difference (trace 7006) deviated from the fitted values plotted in 2, The vertical axis represents the residual (in Hz), and the horizontal axis represents the wavelength in nanometers. The sub- section d) of FIG. 7 shows the histograms 7008 and 7010 of the frequency difference based on trace 7006 in subsection c), showing a root mean square deviation of 14.2 Hz. These results demonstrate the ultra-high frequency resolution of the dual RF broadband modulation spectroscopy according to the present disclosure.

[0080] Based on the measurement results shown in subsection b) of FIG. 7, in the upper panel of FIG. 8, the group velocity dispersion β2 of the fiber cavity is shown as the calculation result in trace 8000, where the horizontal axis represents the wavelength in nanometers and the vertical axis represents the group velocity dispersion β2 (in ps / km). This result is in good agreement with the dispersion characteristics of standard communication fibers. In the lower panel of FIG. 8, 2 the corresponding group delay dispersion (GDD: group delay dispersion) of the 5m fiber cavity is shown in trace 8002, including the dispersion of the 1o dB coupler. The vertical axis represents the group delay dispersion (in fs units). By removing 3m of fiber from the fiber cavity, the GDD (trace 8004 in the lower panel) of a 2m fiber cavity with a zero dispersion wavelength of 1.318nm can be measured using the dual RF modulation method. Furthermore, by subtracting the GDD of the 2m fiber cavity from the GDD of the 5m fiber cavity, 2 the GDD of the 3m fiber can be obtained, which is plotted as trace 8 006 in the lower panel of FIG. 8, showing that the zero dispersion wavelength is 1.312nm. ​​​​​​Trace 8006 shows the difference between traces 8002 and 8004. The measurement results show that the zero-dispersion wavelength of the fiber cavity with a long fiber length is the same as that of the fiber itself. It is confirmed that the wavelength approaches the zero dispersion wavelength. This demonstration confirms that the method according to this disclosure is dispersion The optical properties of individual devices, such as operationally designed broadband mirrors and integrated photonic devices, are unique. It has been proven that it can be used for marking purposes.

[0081] The results shown above indicate that the dual RF modulation scheme according to this disclosure has low FSR (FSR < modulo It has been demonstrated that it has ultra-high frequency resolution for quasi-periodic structures of harmonic frequencies. Extending the scope of the method described herein, a high FSR can be achieved using the device shown in Figure 5. Measuring the mode spectrum of a device with (FSR > modulation frequency), such as an optical microresonator. In this measurement, the carrier resonance of the 5m fiber cavity is used as a frequency marker, that is, To supply it as an optical frequency reference signal, a fiber cavity is used as a resonator element. Next, the resonant frequency of individually manufactured Si3N4 resonators is measured. Si3N4 resonators have low Using a thermal reactive sputtering method, a 750 nm thick Si3N4 thin film is created on a silicon substrate. It is manufactured by forming a film via a 3 μm SiO2 layer, and this manufacturing method is not patented. Reference 13 (A. Frigg, et al., “Low loss CMOS-compatible silicon nitride photonics "Reactive sputtered thin films," Opt. Express 27, 37795-37805 (2019)) It is described there.

[0082] The inset in subsection a) of Figure 9 shows a waveguide with a diameter of 200 μm and a cross-sectional area of ​​1.8 μm. Scanning electron microscope images of the Si3N4 microcavity used in the m×750nm experiment. This indicates that the measured FSR and intrinsic optical quality factor are approximately 231 GHz and 231 GHz, respectively. The number is 2 million. As shown in Figure 5, a portion of the laser light follows the same path as in the experiment described above. It is held, modulated at two arbitrary modulation frequencies, and injected into the fiber cavity. The over-signal is detected by the photodiode 112 and on one channel of the oscilloscope 114. It is recorded. Another part of the laser light is transmitted to Si3N4 via two lensed fibers. It is coupled to the vibrator and also emitted from the Si3N4 resonator. The transmission spectrum is taken from another photon. Recorded on separate channels of iod 112 and oscilloscope 114. CW laser While scanning the frequency, the transmitted signals from the fiber cavity and Si3N4 resonator Simultaneously recorded. Subsection a) of Figure 9 shows the normalized transmission of a Si3N4 resonator. The spectrum is shown, and two different mode families are observed. Mode families with quality factors are marked with a star-shaped marker 9000. The vertical axis is The transmittance in arbitrary units is shown, and the horizontal axis shows the wavelength in nanometer units. Figure 9 Subsequent Action b) is one co-existence shown at trace 9002 near wavelength 1.271 nm. The vibration and frequency marker 9004 from the fiber cavity are shown. The FSR of the ty was first calculated based on the dual RF modulation scheme described above, and the calculated F The resonance of the fiber cavity is the mode structure of the Si3N4 resonator (e.g., FSR propagation, resonance). It is used as a frequency marker to measure line width, dispersion, etc. The vertical axis is in arbitrary units. The amplitude is shown, and the horizontal axis shows the wavelength in nanometer units.

[0083] The resonant frequencies of the mode family in a dispersive resonator are expressed as a Taylor series as follows: It is expressed.

number

[0084] To further emphasize the broad applicability and effectiveness of the method described herein, to non-periodic structures As an example of its application, we will demonstrate how to elucidate the absorption spectrum of a gas cell. The demonstration involved a fiber-optic coupled aqueous fluoride system with a pressure of 50 Torr and a path of 2.7 cm. A (H19F) gas cell is used. Again, laser light from a 1.3 μm CW laser source is used. The signal was split into two paths, one used to investigate the absorption spectroscopy of HF, and the other used for du Modulated with an AL RF signal, coupled to a 5m fiber loop cavity as a resonator element. At the same time, the laser frequency sweep is calibrated.

[0085] Subsection a) of Figure 10 shows strong HF molecular absorption lines in the O-band region (P-band). The graph shows the C and R branches, with the vertical axis representing transmittance in any unit and the horizontal axis representing nanometers. Wavelength in units is shown. Subsection b) shows the expanded spectrum of the P(2) absorption line. Trace 10000) is shown, indicating carrier resonance in the fiber cavity (frequency reference and This also includes 10002). The pressure spreading effect of HF gas is its Doppler spreading. Because the effect is much larger, the dashed line 10 in the Lorentz function (subsection b) 004) is used to fit the spectral profile.

[0086] Table 1 shows the measurement results of HF absorption lines compared with the HITRAN database (H Regarding the ITRAN database, see Non-Patent Document 14 (IE Gordon et al. "The HITRA") N2016 molecular spectroscopic database," J. Quant. Spectrosc. Radiat. Transf. 20 See 3, 3-69 (2017).

[0087] [Table 1] 1. The data from HITRAN shows the calibrated value for a 50 Torre pressure shift. 2. Uncertainty about pressure shift and pressure spread linewidth is based on a 20% uncertainty in pressure. It has been calculated. 3. The measured R(2) value is set to be equivalent to the value from HITRAN.

[0088] The second column of Table 1 shows the location of absorption lines calculated from the HITRAN database. These are values ​​corrected for the pressure shift from the vacuum transition wavelength. The third and fourth columns are, respectively This shows the calculated Gaussian and Lorentz linewidths (full width half-maximum, FWHM). The uncertainty is based on a 20% uncertainty in the gas pressure specified by the gas cell manufacturer. It is calculated as follows. The fifth column shows the position of the measured absorption line. In this demonstration, absolute frequency Because no wavenumber reference is provided, the wavelength of the measured R(2) absorption line is from HITRAN Data. It is set to be equal to the value calculated from the database. The 6th column shows the measurement result and HITRAN This shows the wavelength difference compared to the database. From this result, it can be seen that the measured values ​​are different from those in the HITRAN database. It can be confirmed that it matches very well. This small difference is due to uncertainty in gas pressure. This is thought to be the cause. The calculated Gaussian line width and Voigt function are shown in the third column. Using this method, the last column shows the measured Lorentz linewidth (FWHM) of different absorption lines. The wavelength of the measured absorption line position is smaller than the value calculated in the second column, and the measured Considering that the calculated Lorentz linewidth is larger than the calculated value, it can be used as a calibration element in the experiment. The pressure in the HF gas cell may be higher than the 50 Torre specified by the manufacturer. It is presumed that this is the case.

[0089] In conclusion, this disclosure relates to a fiber cavity with dual RF frequency modulation. Powerful broadband spectroscopy techniques based on a tunable CW laser with calibrated frequency sweep characteristics. We offer this technique and demonstrate its effectiveness. Using this method, we can achieve a frequency of 11 THz. Small FSR deviations in the fiber cavity near the zero dispersion region over a wide range (800H z) can be determined with a resolution of less than 15 Hz. Furthermore, the demonstrated measurement speed is 1 It is THz / s, and while conventional devices are limited by the measurement system, this method The law limits this by the line width of the fiber cavity (see Non-Patent Document 12). The measurement speed is 10 when the resonator element has a wider linewidth (3.2 MHz or more). It can be significantly improved to THz / s or more. Ultimately, the measurement speed is the laser light source. It is limited by the tuning speed. Also, the method demonstrated here is based on frequency combs. Conventional spectroscopy has stringent requirements regarding spectral flatness, combline power, and polarization. It can exceed [number]. The measurement spectral range of the method according to this disclosure is tunable C It is limited only by the range of the W laser, as shown in Non-Patent Document 15 (J. Liu et al. "Frequen cy-comb-assisted broadband precision spectroscopy with cascaded diode lasers," O As suggested in pt. Lett. 41, 3134-3137 (2016), multiple CW lasers are connected in series. It can be expanded by continuing. This makes it possible to use high-resolution wavelength meters and frequency combs. This makes it possible to apply the technology to spectral regions that were previously unreachable. Furthermore, the dispersion characteristics of molecular absorption spectra of integrated photonic devices and HF gases. The method disclosed herein was verified for applications in attachment. Known atomic / molecular transitions are absolute frequency groups. By using this method as a criterion, it can be applied to high-precision broadband molecular spectroscopy. (Non-patent document 16 (A. Shkarin et al. "Nanoscopic Charge Fluctuations in a Galli um Phosphide Waveguide Measured by Single Molecules," Phys. Rev. Lett. 126, 1336 See 02 (2021)). Furthermore, the method according to this disclosure is LIDAR (Non-Patent Document 17 (E. Baumann et al. "Comb-calibrated frequency-modulated continuous-wave lidar for ab Solute distance measurements," Opt. Lett. 38, 2026-2028 (2013) (see), 3D Measuring (Non-patent document 18 (E. Baumann et al. "Comb-calibrated laser ranging for three-dimensional surface profiling with micrometer-level precision at a distan See "ce," Opt. Express 22, 24914-24928 (2014)), refractive index measurement (Non-patent Literature 19( Yang et al. "Frequency comb calibrated frequency-sweeping interferometry for abs olute group refractive index measurement of air," Appl. Opt. 56, 3109-3115 (2017 (See Non-Patent Document 20 (V. Brasch))), accurate frequency measurement and photonic devices (see Non-Patent Document 20 (V. Brasch) et al. "Photonic chip-based optical frequency comb using soliton Cherenkov radi ation," Science 351, 357-360 (2016)) and non-patent document 21 (A. Nishiyama et al. "Pr. ecise frequency measurement and characterization of a continuous scanning single -mode laser with an optical frequency comb," Opt. Lett. 39, 4923-4926 (2014)) Characterization of astronomical photonic devices (see reference 22 (S. Minardi, R. J. Harris, and L. Labadie, "Astrophotonics: astronomy and modern optics," Astro It is widely applicable to various scenarios, such as (see n. Astrophys. Rev. 29, 6 (2021))). Everything is ready.

[0090] Figure 11 shows a device 200 that supplies an optical frequency reference signal according to an optional embodiment. Figure 12 schematically shows the LIDAR system 300. Figure 12 shows an optional embodiment. A gas sensing system 400 equipped with a device 200 that provides an optical frequency reference signal is described below. This is a simplified representation. [Explanation of Symbols]

[0091] 100 Devices for characterizing resonator elements 102 Resonator elements 104 Laser light source 106 Optical Fiber 108 coupling elements 110 Modulators for modulating intensity and / or phase 112 detection units 114 Data Logger 116 Control Unit 118 Calibration elements 120 Photonic Devices / Microring Resonators 200 Device for providing optical frequency reference signals 202-214 Steps of the Method 300 Lidar Systems 400 Gas Sensing System 602-608 Steps of the Method 1001 First Modulation Frequency 1002 Second Modulation Frequency 3000 Carrier Resonance 3001 Sideband resonance caused by the first modulation frequency 3002 Sideband resonance caused by the second modulation frequency 3003 Time between the first sideband resonances scanned from different modulation frequencies separation 3004 Time between second sideband resonances scanned from different modulation frequencies separation between 3005 Unknown time interval between adjacent carrier resonances Trace showing the results of the 7000 dual RF modulation scheme. 7002 Trace showing quadratic polynomial fit 7004 Evolution of FSR calculated using single RF modulation scheme 7006 Frequency difference where the measured FSR deviates from the fitted plot. Histogram of frequency difference between 7008 and 7010 8000 Calculated group velocity variance 8002, 8004, 8006 Group delay dispersion at different fiber lengths 9000 Mode family with high optical quality factor 9002 Resonance Profile at 1.271nm 9004 Frequency Marker 9006 Joint Dispersion Profile 9008 Fitted Curve 9010 Light spectrum of a single bright soliton 9012 Fitted Envelope Curve 10000 absorption line spectrum 10002 Carrier Resonance 10004 Fitted Lorentz function FSR Free Spectrum Range

Claims

1. A method for characterizing a resonator element (102), - A step of supplying laser light having a tunable carrier frequency, - A resonator having multiple carrier resonances (3000) with respect to the carrier frequency of the laser light. The step involves coupling at least a first portion of the laser beam to the element (102), and adjacent to The carrier resonance (3000) is within the free spectral range (FSR) of the spectral region. At least the first portion of the laser beam is arranged with space between them. The step of combining, - The intensity and / or phase of the portion of the laser light coupled to the resonant element (102) Modulated at the first modulation frequency (1001) and the second modulation frequency (1002), each carrier resonance (3000) is affected by the first modulation frequency (1001) and the carrier resonance (30 At least two sideband resonances (3001) spaced apart from 00), and second The modulation frequency (1002) is used to space out the carrier resonance (3000). This is a step that generates at least two sideband resonances (3002), and the first modulation frequency The number (1001) and the second modulation frequency (1002) are integer multiples of the free spectral range and mutually exclusive. The steps include generating the sideband resonance, which has different values, - A step of tuning the carrier frequency of the laser beam at a predetermined tuning speed. 、 - While tuning the carrier frequency, the transmission and A step of measuring the intensity of the emitted / or reflected laser light, - Carrier frequency across four adjacent sideband resonances (3001, 3002) This is a step in which the tuning time elapsed during tuning is measured, and this tuning The tuning time is calculated from the value corresponding to the first of the four sideband resonances to the value corresponding to the last one. This indicates the time required to change the tunable carrier frequency until it reaches that point. The steps include, and - Measurement intensity of the laser light transmitted and / or reflected by the resonator element (102), first variation The modulation frequency (1001), the second modulation frequency (1002), and the carrier frequency are set to four adjacent frequencies. Measured when tuning across the sideband resonances (3001, 3002) Using the tuning time, between multiple carrier resonances (3000) in the spectral region The steps include determining the interval and A method that includes [a certain feature].

2. The method according to claim 1, wherein the first modulation frequency (1001) and the second modulation frequency The wavenumbers (1002) are methods that each fall within the radio frequency (RF) band.

3. The method according to claim 1 or 2, wherein the first modulation frequency (1001) and the second The modulation frequencies (1002) are each within the range of approximately 100 MHz to approximately 100 GHz. method.

4. In the method according to any one of claims 1 to 3, the first modulation frequency (1001) The difference between this and the second modulation frequency (1002) is the resonant linewidth of the carrier resonance (3000). A method in which the value is 10% or more and 50% or less of the free spectral range (FSR).

5. In the method according to any one of claims 1 to 4, the first modulation frequency (1001) And the second modulation frequency (1002) is essentially the free spectral range (FSR) A method that corresponds to a frequency close to n+1 / 2 times, where n is an integer.

6. A method according to any one of claims 1 to 5, wherein at least one of the free spectrum Within the Torr range (FSR), the first modulation occurs from one of the carrier resonances (3000). The two sideband resonances (3001) and the same generated by frequency (1001) From the first carrier resonance (3000), the second modulation frequency (1002) is generated. A method wherein at least two of the aforementioned sideband resonances (3002) are located.

7. The method according to any one of claims 1 to 6, wherein four adjacent sidebands The time elapsed when tuning the carrier frequency over the resonance (3001, 3002) The step of measuring the tuning time is performed by arranging within one of the free spectral ranges. The key is located across the four adjacent sideband resonances (3001, 3002) that are positioned. A step of measuring the tuning time elapsed when tuning the carrier frequency. Methods that include...

8. The method according to any one of claims 1 to 7, wherein the resonant element (102) The free spectral range (FSR) is between 1 MHz and 100 GHz.

9. A method according to any one of claims 1 to 8, further, - The second portion of the laser light is calibrated to have predetermined absolute transmission and / or reflection characteristics. The steps of coupling to element (118), - While tuning the carrier frequency, the calibration element (118) A step of measuring the intensity of the portion of the transmitted and / or reflected laser light, - Within the frequency domain, the carrier resonance (3000) or the sideband resonance (300) A predetermined circumference that matches either of the following, or has a specified offset At least one clear absolute transmission and / or reflection of the calibration element (118) having a wavenumber Steps to identify characteristics, and Based on the clear absolute transmission and / or reflection characteristics of the identified calibration element (118) And the carrier resonance (3000) or the sideband resonance (3001, 300) 2) The step of calibrating at least one of the absolute frequencies, A method that includes [a certain feature].

10. In the method according to claim 9, the calibration element (118) is at least one distinct absolute A gas cell filled with a predetermined gas having specific permeability and / or reflectivity properties, and The elements below, namely frequency combs, wavelength meters, or transition lines of atoms and / or molecules A method that includes one or more elements that are dropped.

11. A device (100) that characterizes the resonator element (102), - A tunable laser for emitting laser light with a tunable carrier frequency - The light source (104), - A coupling element for coupling at least a portion of the laser light to the resonator element (102) 108) and, - For each carrier resonance (3000) at the first modulation frequency (1001), the carrier At least the first modulation frequency (1001) is spaced apart from the resonance frequency (3000). It generates two sideband resonances (3001) and also generates each key at the second modulation frequency (1002). With respect to the carrier resonance (3000), the second modulation frequency is obtained from the carrier resonance (3000) At least two of the sideband resonances (30) are spaced apart by the number (1002) A portion of the laser light coupled to the resonant element (102) generates 02). A modulator (110) for modulating the intensity and / or phase of, - The intensity of a portion of the laser light transmitted and / or reflected by the resonator element (102) A detection unit (112) for measuring the degree, and - The carrier frequency of the laser light is tuned, and the tuning time is determined. The measurement intensity of the laser light transmitted and / or reflected by the resonator element (102) Based on the first modulation frequency (1001), the second modulation frequency (1002), and And the carrier frequency is set to four adjacent sideband resonances (3001, 3002) Based on the measurement tuning time elapsed during tuning across the spectral region, A control unit configured to determine the spacing between multiple carrier resonances (3000) within the region The set (116) is the tuning time, and this tuning time is the maximum of the four sideband resonances. The tunable carrier frequency, from the value corresponding to the first one to the value corresponding to the last one The control unit (116) corresponds to the time required to change the number, A device equipped with the following features.

12. In the device (100) according to claim 11, the resonator element (102) is a Iberacavity and / or integrated waveguide resonator, and / or whispering gallery. Debye resonators, including mode resonators and / or etalons and / or Fabry-Perot resonators. vinegar.

13. In the device (100) according to claim 11 or 12, the modulator (110) is A device including an electro-optic intensity and / or phase modulator.

14. A device (100) according to any one of claims 11 to 13, further, A calibration element (118) having predetermined absolute transmission and / or reflection characteristics is provided, The detection unit (112) further performs the following while tuning the carrier frequency The intensity of a portion of the laser light transmitted and / or reflected by the calibration element (118) It is something that can be measured, and The control unit (116) controls the carrier resonance (3000) or within the frequency domain. Matching or specified sideband resonances (3001, 3002) At least one of the calibration elements (118) having a predetermined frequency and an offset Identify the clear absolute transmission and / or reflection properties of the identified absolute transmission and Based on the vibration / reflection characteristics, the carrier resonance (3000) or the sideband resonance It is possible to calibrate at least one absolute frequency of (3001, 3002), Deby S (100).

15. In the device according to claim 14, the calibration element (118) is at least one A gas cell filled with a predetermined gas having clear absolute transmission and / or reflection properties, and / or frequency combs, and / or wavelength meters, and / or atoms and / or molecules A device containing elements that bring about transition lines.

16. A method of supplying laser light with a tunable carrier frequency as an optical frequency reference signal. It is a law, - A resonator having multiple carrier resonances (3000) with respect to the carrier frequency of the laser light. This is the step of preparing the element (102), and the adjacent carrier resonance (3000) is, Within the culvert region, each is spaced apart by a predetermined free spectral range (FSR) The steps include preparing the resonator element, - A step of coupling the first portion of the laser light to the resonator element (102), The method further includes, - A step of tuning the carrier frequency of the laser beam at a predetermined tuning speed. 、 - A portion of the laser light transmitted and / or reflected by the resonator element (102) is spectrally controlled. This is a step of supplying an optical frequency reference signal that sweeps in a turbulent manner, and the resonator element (1 The intensity of the laser light transmitted and / or reflected by (02) is spectrally separated by FSR. One of the laser beams has local extrema at metrically spaced frequencies. The steps include supplying the part as an optical frequency reference signal, A method characterized by comprising:

17. In the method according to claim 16, the carrier frequency of the laser light is at least The spectral range is tuned over the 10 free spectral ranges (FSRs). ,method.

18. In the method according to claim 16 or 17, the tuning of the carrier frequency is A method that is performed according to a fixed tuning pattern.

19. The method according to claim 18, for tuning the carrier frequency The predetermined tuning pattern is a sinusoidal tuning pattern of the carrier frequency. A method comprising the step of sweeping with a sawtooth tuning pattern and / or a sawtooth wave pattern.

20. In the method according to any one of claims 16 to 19, the laser light is a continuous wave A method using laser light.

21. In the method according to any one of claims 16 to 19, the laser light is the A method having a spectral width smaller than the linewidth of the resonator element (102).

22. A method according to any one of claims 16 to 21, further comprising the resonator element The intensity and / or phase of the first portion of the laser light coupled to the child (102) is first modulated Modulated at frequency (1001) and second modulation frequency (1002), and each of the carrier resonances (3 With respect to 000), the carrier resonance (300) is determined by the first modulation frequency (1001). 0) At least two sideband resonances (3001) spaced apart from the second variable The harmonic frequency (1002) is spaced apart from the carrier resonance (3000) The first step is to generate at least two of the aforementioned sideband resonances (3002), and the first The modulation frequency (1001) and the second modulation frequency (1002) are within the free spectral range. Steps that generate the sideband resonances are integer multiples of (FSR) and have different values ​​from each other. The frequency of the sideband resonances (3001, 3002), as well as the frequency of the optical frequency base A method comprising the step of supplying a quasi-signal as a spectral reference mark.

23. In the method according to claim 22, the first modulation frequency (1001) and the second modulation frequency The numbers (1002) are methods, each located within the radio frequency (RF) band.

24. The method according to claim 22 or 23, wherein the first modulation frequency (1001) and the The second modulation frequencies (1002) are within the range of approximately 100 MHz to approximately 10 GHz. method.

25. The method according to any one of claims 22 to 24, wherein the first modulation frequency ( The difference between 1001) and the second modulation frequency (1002) is the carrier resonance (3000) The resonance linewidth is 10% or more, and the free spectral range (FSR) is 50% or less. method.

26. The method according to any one of claims 22 to 25, wherein the first modulation frequency (10 01) and the second modulation frequency (1002) are substantially within the free spectral range (FSR) A method that corresponds to a frequency close to n+1 / 2 times, where n is an integer.

27. A method according to any one of claims 22 to 26, further, - The second portion of the laser light is a calibration element having predetermined absolute transmission and / or reflection characteristics. The step of joining to the child (118), - While tuning the carrier frequency, the calibration element (118) transmits and / or a step of measuring the intensity of the portion of the reflected laser light, - Within the frequency domain, the carrier resonance (3000) or the sideband resonance (300) A predetermined frequency that matches any of the following, or has a specified offset: 1, 3002) The calibration element (118) having at least one distinct absolute transmission and / or reflection characteristic Steps to identify sex, and Based on the identified absolute transmission and / or reflection characteristics, the carrier resonance Calibrate the absolute frequencies of (3000) and / or sideband resonances (3001, 3002). The steps, A method that includes [a certain feature].

28. In the method according to claim 27, the calibration element (118) is at least one distinct A gas cell filled with a predetermined gas having absolute transmission and / or reflection properties, and / or A method comprising a frequency comb and / or a wavelength meter and / or an atomic transition line.

29. The optical frequency reference supplied by the method according to any one of claims 16 to 28. Use as a spectral reference mark for signals.

30. A method for spectrally characterizing an analyte, - The optical frequency reference signal is provided using the method described in any one of claims 16 to 29. The steps of supplying, and - To spectrally characterize the analyte, the optical frequency reference signal is used with a spectral reference mark. Steps for using as a tool, A method that includes [a certain feature].

31. In the method according to claim 30, the optical frequency reference signal is used as a spectral reference mark. The step used involves determining the analyte based on one or more free spectral ranges (FSRs). A method comprising the step of determining the relative spectral distance of multiple spectral properties.

32. To supply laser light with a tunable carrier frequency as an optical frequency reference signal The eye device (200), - A tunable laser for emitting laser light with a tunable carrier frequency - The light source (104), - A laser beam having the tunable carrier frequency, with multiple carriers The resonator element (102) has vibration (3000), and the carrier resonance (3000) is Each element is spaced apart from the others within its spectral region by a predetermined free spectral range (FSR). They are arranged with space between them, and the device (200) combines a portion of the laser light. The resonator element (102) obtained is, The device further includes, - A control configured to tune the carrier frequency at a predetermined tuning speed. Equipped with your unit, The device is one of the laser beams transmitted and / or reflected by the resonator element (102). The part can be obtained as an optical frequency reference signal that sweeps spectrally, and the resonance The intensity of the laser light transmitted and / or reflected by the device element (102) is the free spectrum. Local extrema at spectrally separated frequencies by the frequency range (FSR) A device (200) characterized by having the following.

33. The device according to claim 32, further, - The portion of the laser light transmitted and / or reflected by the resonator element (102) A detection unit (112) for measuring the intensity of, and - Measurement intensity of the laser light transmitted and / or reflected by the resonator element (102) The frequency of the tunable carrier frequency having the local extremum at a certain degree is The spectrum of the optical frequency reference signal defined by the specified free spectral range (FSR) A control unit (116) configured to supply as a criterion reference mark, A device equipped with the following features.

34. The device (200) according to claim 32 or 33, further comprising the resonator element ( The intensity and / or phase of the portion of the laser light coupled to 102) is set to a first modulation frequency ( Modulated at 1001), and for each of the carrier resonances (3000), the first modulation frequency ( 1001) At least two distanced from the carrier resonance (3000) It includes a modulator (110) for generating sideband resonance (3001), The control unit further transmits and / or reflects the front of the resonant element (102). In some of the measured intensity of the laser light, the preceding sideband resonance (3001) is caused by the preceding The frequency of the tunable carrier frequency having a local extremum is set to the predetermined free The spectral range (FSR) and the first modulation frequency (1001) are defined as A device configured to supply the optical frequency reference signal as the spectral reference mark. Chair (200).

35. In the device (200) according to any one of claims 32 to 34, the resonator element Child (102) is a fiber cavity and / or integrated waveguide and / or whispering Gallery mode resonators, and / or etalons, and / or Fabry-Perot resonators A device (200) including the above.

36. In the device (200) according to claim 34 or 35, the modulator (110) is electric A device (200) including a gas-optic intensity and / or phase modulator.

37. A device (200) according to any one of claims 32 to 36, further comprising: A calibration element (118) having absolute transmission and / or reflection characteristics is provided, The detection unit (112) further performs the following while tuning the carrier frequency The intensity of the portion of the laser light transmitted and / or reflected by the calibration element (118) It is something that can be measured, and The control unit (116) further determines the carrier resonance (3000) in the frequency domain. ) or matches either of the above sideband resonances (3001, 3002), or the specified At least one clear of the calibration element (118) having a predetermined frequency with an offset The absolute transmission and / or reflection characteristics of the identified calibration element (118) Based on clear absolute transmission and / or reflection characteristics, the carrier resonance (3000) or The absolute frequency of at least one sideband resonance (3001, 3002) can be calibrated. That is the case. Device (200).

38. In the device (200) according to claim 37, the calibration element (118) is at least Both are filled with a predetermined gas having a distinct absolute transmission and / or reflection property. Gas cell, and / or frequency comb, and / or wavelength meter, and / or atom and / or The device (200) includes molecular transition lines.

39. In the device according to any one of claims 32 to 38, the tunable radar The light source (104) is a device including a tunable continuous-wave laser light source.

40. In the device according to any one of claims 32 to 39, the tunable radar The light source (104) is a device including a diode laser.

41. In the device according to any one of claims 32 to 40, the tunable radar The light source has a spectral width smaller than the linewidth of the resonant element (102). A device capable of emitting a blue laser beam.

42. The LI according to any one of claims 32 to 41 for supplying the aforementioned optical frequency reference signal DAR system (300).

43. A device according to any one of claims 32 to 41 for supplying an optical frequency reference signal A gas sensing system (400) including (200).

44. A method for characterizing a resonator element (102), - A step of supplying laser light having a tunable carrier frequency, - At least a first portion of the laser light at the carrier frequency of the laser light A ste coupled to the resonator element (102) having multiple carrier resonances (3000) Top, - The intensity of the portion of the laser light coupled to the resonant element is set to the first modulation frequency (10 Modulated at 01), and for each of the carrier resonances (3000), the first modulation frequency (1001) ) at least two sides that are spaced apart from the carrier resonance (3000) The step is to generate a band resonance (3001), wherein the first modulation frequency (1001) is Higher than the free spectral range (FSR), and different from an integer multiple of the free spectral range. The steps include generating the sideband resonance, which is a value, - The carrier frequency of the laser beam is tuned at a predetermined tuning speed. Step and, - While tuning the carrier frequency, the resonator element (102) The steps include measuring the intensity of the transmitted and / or reflected laser light, Multiple carriers having intervals of at least twice the first modulation frequency (1001) A step of measuring the tuning time elapsed during vibration, and The measured intensity of the laser light transmitted and / or reflected by the resonator element (102), One modulation frequency (1001), and an interval of at least twice the first modulation frequency (1001) Using the tuning time measured between multiple carrier resonances (3000), the spec The steps include determining the spacing between multiple free spectral ranges (FSRs) within the lector region, A method that includes [a certain feature].

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