A fast optical frequency detection device

Abstract

The utility model provides a kind of rapid optical frequency detection device, including the Michelson interferometer with one input light path, the Michelson interferometer has at least 2 interference arms, the interference arm tail is provided with the same mirror as the interference arm number, input light is reflected after entering interference arm Michelson interferometer, generates multipath output light, the output light is received by first photoelectric detector, and the first photoelectric detection signal generated is used to calculate the optical frequency variation of input light;One light path in the input light is input to wavelength division multiplexer, and the two light output by the wavelength division multiplexer is received by two second photoelectric detectors, and second photoelectric detection signal is generated to calculate the absolute optical frequency of input light.

Description

Technical Field

[0001] This invention belongs to the field of photonics technology, specifically relating to a fast optical frequency detection device. Background Technology

[0002] The detection of optical frequency information has a wide range of applications, such as laser frequency measurement and control, frequency-modulated continuous-wave lidar, optical coherence tomography, optical frequency domain reflectance measurement, optical sensing based on fiber Bragg gratings, and optical computation based on microring resonators. In these applications, accurate measurement or acquisition of high-resolution, wide-range, and rapid optical frequency variation information is crucial, even decisive.

[0003] In the prior art, the detection of optical frequency information can be achieved through many different methods, such as: (1) a spectrometer based on a diffraction grating or a tunable narrowband filter has extremely high measurement accuracy, but its measurement speed, measurement accuracy, and resolution are mutually constrained, and it cannot simultaneously achieve accurate measurement of all three parameters; (2) an optical frequency measurement method based on an unbalanced Mach-Zehnder interferometer, whose resolution is equal to the delay. The ratio is inversely proportional, but it has the problem of polarization fading. At the same time, long-distance optical fiber will cause the laser frequency noise to increase, resulting in the incorrect generation of the f clock with equal frequency intervals; (3) The optical frequency measurement method based on Hilbert transform can correct the nonlinearity of laser frequency scanning in data processing, but it needs to obtain a long phase data before Hilbert transform, which is not suitable for real-time optical frequency measurement; (4) The optical frequency measurement method based on differential group delay (DGD) element can realize high resolution, large range and high speed optical frequency measurement, but its optical element is large in size and sensitive to polarization state changes during transmission.

[0004] Therefore, the above-mentioned optical frequency measurement methods all have disadvantages in terms of frequency measurement resolution, frequency measurement range, and frequency measurement speed. Thus, a device for high-resolution, fast, real-time optical frequency change and absolute optical frequency measurement is needed. Utility Model Content

[0005] This invention provides a rapid optical frequency detection device that can quickly and in real-time measure optical frequency changes and absolute optical frequency measurements.

[0006] Other objects and advantages of this utility model can be further understood from the technical features disclosed herein.

[0007] To achieve one, some, or all of the above objectives or other objectives, this utility model provides a fast optical frequency detection device, comprising a Michelson interferometer with one input optical path, wherein the Michelson interferometer has at least two interferometer arms, and the tail of each interferometer arm is provided with a mirror equal to the number of interferometer arms. After the input light enters the interferometer arm, it is reflected out of the Michelson interferometer, generating multiple output lights. The output lights are received by a first photodetector, and the generated first photodetector signal is used to calculate the optical frequency change of the input light. One of the input optical paths is input to a wavelength division multiplexer, and the two output lights of the wavelength division multiplexer are received by two second photodetectors, generating second photodetector signals used to calculate the absolute optical frequency of the input light.

[0008] The Michelson interferometer includes one Optical coupler, the input light passes through the... The optical coupler splits the light into three input beams, with two beams entering the interferometer arm respectively.

[0009] The Of the three input beams split by the optical coupler, in addition to the two input beams that enter the interferometer arm, the remaining input beam enters a wavelength division multiplexer.

[0010] The two interference arms have an optical path difference.

[0011] The optical path difference between the two interference arms is a variable optical path difference.

[0012] The reflector is a Faraday rotator, which reflects the light path back to the [reflector]. The optical coupler splits the reflected light path into three output light paths, which are received by three first photodetectors.

[0013] One of the three output optical paths shares the input optical path, and is connected through a... The optical coupler splits into two optical paths, which are then transmitted through the aforementioned... The optical paths after the optical coupler splits the light are used for input light and connection to the first photodetector.

[0014] The phase difference between the output signals of the three output optical paths after the optical coupler splits the light is around 120°.

[0015] The intensity of the first photoelectric detection signal varies with a sine or cosine function, and the change in the intensity of the first photoelectric detection signal corresponds to the change in the optical frequency of the input light.

[0016] The wavelength division multiplexer operates at the two ends of the wavelength of the light to be measured, and the ratio of the two output signals of the wavelength division multiplexer corresponds to the absolute optical frequency of the input light.

[0017] Compared with the prior art, the beneficial effects of this utility model mainly include: 1. This utility model divides the optical frequency to be measured into two parts, one part is connected to an interferometer and the other part is connected to a wavelength division multiplexer. By using sine / cosine demodulation algorithm and absolute frequency demodulation algorithm, the optical frequency change and absolute optical frequency can be measured simultaneously. This utility model can realize high-frequency, wide-range and fast optical frequency change measurement.

[0018] To make the above and other objects, features and advantages of this utility model more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the specific embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the fast optical frequency detection device according to Embodiment 1 of this utility model.

[0021] Figure 2 The results show the ideal output signals of the three photodetectors of the Michelson interferometer in Embodiment 1 of this utility model when the input light wavelength is in the range of 1500~1630nm.

[0022] Figure 3 The actual output signal results of the three photodetectors of the Michelson interferometer in the fast optical frequency detection device of Embodiment 1 of this utility model when the input light has a wavelength range of 1500~1630nm and the wavelength step change interval is 10nm.

[0023] Figure 4 The actual output signal results of the two photodetectors of the wavelength division multiplexer in the fast optical frequency detection device of Embodiment 1 of this utility model when the input light is in the wavelength range of 1500~1630nm and the wavelength step change interval is 10nm.

[0024] Figure 5 This is a flowchart of the Michelson interferometer optical frequency change demodulation parameter calibration method in the demodulation parameter calibration method of the fast optical frequency detection device in Embodiment 2 of this utility model.

[0025] Figure 6The figure shows the ellipse fitting result of calculating the demodulation parameter of the optical frequency change at 1550nm using the Lissajous ellipse fitting method in the calibration method of the Michelson interferometer optical frequency change demodulation parameter at embodiment 2 of this utility model.

[0026] Figure 7 The figure shows the experimental results of the demodulation parameters C1(λ) and B1(λ) corresponding to the optical frequency change at each 1nm wavelength in the range of 1500~1630nm, obtained by calibration using the Lissajous ellipse fitting method in the Michelson interferometer optical frequency change demodulation parameter calibration method of Embodiment 2 of this utility model.

[0027] Figure 8 The demodulation parameters for optical frequency change at each 1 nm wavelength in the 1500~1630 nm range are phase differences β2(λ) and β3(λ) obtained by Lissajous ellipse fitting method in the Michelson interferometer optical frequency change demodulation parameter calibration method of Embodiment 2 of this utility model.

[0028] Figure 9 This is a flowchart of the wavelength division multiplexer's splitting ratio calibration method at different wavelengths in the demodulation parameter calibration method of the fast optical frequency detection device in Embodiment 2 of this utility model.

[0029] Figure 10 This is a graph showing the relationship between the ratio of the light intensity difference to the sum of the light intensity at the two output ports of the wavelength division multiplexer in the wavelength range of 1500~1630nm, obtained by the method of splitting ratio calibration of the wavelength division multiplexer under different wavelengths, and the input light wavelength.

[0030] Figure 11 This is a flowchart of a fast optical frequency demodulation method according to Embodiment 3 of this utility model.

[0031] Figure 12 The absolute optical frequency and optical frequency variation graph of the input light with a wavelength range of 1500~1630nm and a wavelength step change interval of 10nm are calculated using the fast optical frequency demodulation method of Example 3 of this utility model.

[0032] Figure 13 The graph shows the absolute optical frequency and frequency variation of the input light with a wavelength range of 1500~1630nm, continuous wavelength variation, and a sweep rate of 200nm / s (25THz / s) calculated by the fast optical frequency demodulation method in Embodiment 3 of this utility model.

[0033] Figure 14 This is a graph showing the optical frequency variation of input light with a wavelength step change interval of 10 pm, calculated by the fast optical frequency demodulation method of Embodiment 3 of this utility model. Detailed Implementation

[0034] The foregoing and other technical contents, features, and effects of this utility model will be clearly presented in the following detailed description of a preferred embodiment with reference to the accompanying drawings. The directional terms mentioned in the following embodiments, such as up, down, left, right, front, or back, are only for reference to the accompanying drawings. Therefore, the directional terms used are for illustrative purposes and not for limiting the scope of this utility model.

[0035] Example 1

[0036] Example 1 provides a fast optical frequency detection device, including a Michelson interferometer with an input optical path, wherein the Michelson interferometer includes a Optical coupler, input light from the An optical coupler enters the Michelson interferometer; An optical coupler splits the input optical path into three paths. Two paths enter two interferometer arms with optical path differences, and the remaining path enters a wavelength division multiplexer. Two Faraday rotators are positioned at the ends of the two interferometer arms, and these Faraday rotators reflect the optical path back to the coupler. The optical coupler splits the reflected light path into three output light paths, which are received by three first photodetectors. The three first photodetectors are used to obtain the change in the optical frequency of the input light. The two light paths output by the wavelength division multiplexer are received by two second photodetectors. The two second photodetectors are used to obtain the absolute optical frequency of the input light.

[0037] The rapid optical frequency detection device in Embodiment 1 will be explained in detail below with reference to the accompanying drawings. See Figure 1 The fast optical frequency detection device of this invention includes a Michelson interferometer 113 with one input optical path, the Michelson interferometer 113 including a Optical coupler 102, Optical coupler 102 splits the incoming input light into three paths, which enter the first interferometer arm 103 and the second interferometer arm 104 respectively. A variable optical path difference ΔL exists between the first interferometer arm 103 and the second interferometer arm 104. The ends of the first interferometer arm 103 and the second interferometer arm 104 are respectively a first Faraday rotator 106 and a second Faraday rotator 107. The first Faraday rotator 106 and the second Faraday rotator 107 interfere with the incident light and reflect it back. Optical coupler 102 is used to split the optical path into three paths, one of which overlaps with the input optical path and passes through a... The optical coupler 101 is divided into two paths: one is the input optical path, and the other is connected to the first photodetector 110. The other two optical paths reflected by the optical coupler 102 are connected to two first photodetectors 111 and 112, respectively. The three first photodetectors 110, 111, and 112 generate first photodetection signals, which are used to calculate the change in the optical frequency of the input light.

[0038] The input optical path After the optical coupler 102 splits the light, in addition to entering the first interferometer arm 103 and the second interferometer arm 104, another optical path enters the wavelength division multiplexer 105. The two optical paths output by the wavelength division multiplexer 105 are received by two second photodetectors 108 and 109 to generate second photodetector signals, which are used to calculate the absolute optical frequency of the input light.

[0039] The optical coupler has a phase difference of about 120°, which facilitates the subsequent demodulation of phase information. The three first photoelectric detection signals change with sine or cosine functions, and the change of the sine or cosine function corresponds to the change in the optical frequency of the input light.

[0040] The wavelength division multiplexer operates at the two ends of the wavelength of the light to be measured, and the ratio of the two output signals of the wavelength division multiplexer corresponds to the absolute frequency information of the input light.

[0041] Figure 2 The ideal output signal results of the three photodetectors of the Michelson interferometer in Example 1 are shown when the fast optical frequency detection device has an input light wavelength range of 1500~1630nm.

[0042] Figure 3 The actual output signal results of the three photodetectors of the Michelson interferometer in the fast optical frequency detection device of Embodiment 1 of this utility model when the input light has a wavelength range of 1500~1630nm and the wavelength step change interval is 10nm.

[0043] Figure 4 The actual output signal results of the two photodetectors of the wavelength division multiplexer in the fast optical frequency detection device of Embodiment 1 of this utility model when the input light is in the wavelength range of 1500~1630nm and the wavelength step change interval is 10nm.

[0044] Example 2

[0045] Example 2 provides a method for calibrating demodulation parameters of a fast optical frequency detection device, which is used to calibrate the demodulation parameters of the optical frequency change of the Michelson interferometer in a fast optical frequency detection device of Example 1 and to calibrate the splitting ratio of the wavelength division multiplexer at different wavelengths;

[0046] See Figure 5The calibration method for the demodulation parameters of optical frequency variation of a Michelson interferometer includes: inputting an optical signal into a fast optical frequency detection device using a laser to obtain three output interference signals; acquiring the three interference signals and the laser output wavelength monitoring pulse; determining the specific wavelength value and the three interference signals at the corresponding wavelength through the wavelength monitoring pulse; selecting three sets of interference signals with optical frequency variation near a certain wavelength that are equal to the period corresponding to the free spectral range of the Michelson interferometer and performing cubic Lissajous ellipse fitting to obtain all wavelength-related optical frequency variation demodulation parameters at a certain wavelength.

[0047] See Figure 9 The method for calibrating the splitting ratio of a wavelength division multiplexer at different wavelengths includes inputting a continuous spectrum over a wide wavelength range into a fast optical frequency detection device, and then... One spectral signal from the optical coupler is input to the wavelength division multiplexer, which outputs two spectral signals. The spectra of the two spectral signals are acquired, and the difference and ratio of the spectral results of the two spectral signals at the same wavelength are calculated to obtain the difference and ratio of the two output signals of the wavelength division multiplexer at different wavelengths and a wavelength lookup table.

[0048] The input light uses a wide-wavelength swept laser in continuous wavelength scanning mode to output the optical signal into a Michelson interferometer. Simultaneously, calibration is performed at wavelength intervals of 0.1 nm to 10 nm across a wide wavelength range to obtain demodulation parameters for optical frequency variation and a lookup table of parameters for wavelength intervals of 0.1 nm to 10 nm at different wavelengths.

[0049] In the method for calibrating the splitting ratio of a wavelength division multiplexer at different wavelengths, calibration is performed at intervals of 0.1 nm to 10 nm within a large wavelength range. The difference and ratio of the spectral results of the two spectral signals at the same wavelength are calculated, and a parameter lookup table of the difference and ratio of the two output signals of the wavelength division multiplexer at wavelength intervals of 0.1 nm to 10 nm is obtained.

[0050] The following section uses the example of a delay imbalance of 2ΔL between the two interferometer arms of a Michelson interferometer 113 to illustrate the calculation process for specific demodulation parameter calibration.

[0051] The three output signals of the Michelson interferometer 113 are:

[0052]

[0053] Among them, V i (t)(i=1,2,3) represents the output voltages of the three output channels of the interferometer; C i (λ)(i=1,2,3) is the bias coefficient caused by the DC bias of the circuit in each channel; B i (λ)(i=1,2,3) represents the amplitude of the sine and cosine functions received in each channel; βi (λ)(i=1,2,3) represents the phase change of the three laser beams caused by the coupler. Ideally, the phase difference between them is 120°. This is the phase change caused by the frequency Δƒ(t) of the light being measured. Where C... i B i β i It is usually related to weak wavelengths.

[0054] The above C i B i β i The demodulation parameters for the optical frequency variation of the Michelson interferometer.

[0055] The free spectral range (FSR) of an interferometer is defined as:

[0056]

[0057] Where τ is the delay time between the two arms of the Michelson interferometer, and the optical path length difference Δl between the two arms of the interferometer is a set 2ΔL.

[0058] The phase change caused by the frequency Δƒ(t) of the light being measured can be expressed as:

[0059]

[0060] Figure 2 Showing from Figure 1 The phase relationship of the three output optical paths of the Michelson interferometer in the fast optical frequency detection device can be used to determine the optical frequency change from the three output signals according to the following formula 6.

[0061] Δƒ(t):

[0062]

[0063] During demodulation, β1 is set to 0. At this point, β2 and β3 represent the phase difference between their respective channels and the channel corresponding to β1. The phase demodulation algorithm can be used to calculate phase changes exceeding 2π, thereby obtaining the optical frequency change Δƒ and its direction. Optical frequency calculation requires demodulation parameters; therefore, these parameters must first be calibrated. Voltages within multiple channels are obtained using three photodetectors, and these channel voltages are then substituted into the calculation to obtain the optical frequency change. Furthermore, due to the very small FSR, ultra-high frequency change resolution can be achieved. The relationship between frequency change resolution and FSR is: frequency resolution = FSR / (2^M), where M is the number of bits in the acquisition card plus one. Therefore, the smaller the FSR, the higher the resolution.

[0064] Equation 6 above is used to calculate the amount and direction of optical frequency change, where the demodulation parameter B... iC i β i Wavelength correlation, demodulation parameter B i C i β i The calibration method is as follows Figure 5 As shown, the process includes using laser wavelength scanning input to acquire three interference signals and laser output wavelength monitoring pulses. The specific wavelength value and the corresponding three interference signals at that wavelength are determined through the wavelength monitoring pulses. An interference signal corresponding to one FSR time length within the wavelength range is selected for Lissajous ellipse fitting to calculate the demodulation parameter B. i C i β i Repeat the above steps until all wavelengths have been calculated. The following section explains the calculation process for Lissajous ellipse fitting for the selected wavelengths.

[0065] Figure 6 Taking a set of signals V1(t) and V2(t) with an ideal phase difference of 120° as an example, the demodulation parameters are calibrated at 1550nm using the Lissajous elliptic fitting method. For any two interference signals with a phase difference of α (α≠π), they can be expressed using trigonometric functions as follows:

[0066]

[0067] Where C1(λ) and C2(λ) are the DC components of the interference signal, B1(λ) and B2(λ) are the amplitudes of the interference signal, and α is the actual phase difference between the two interference signals. Expanding Equations 7 and 8 above, we get:

[0068]

[0069] According to the trigonometric formula:

[0070]

[0071] Substituting into the above equation, we get:

[0072]

[0073] Meanwhile, the standard equation of an ellipse is:

[0074]

[0075] Where A, B, C, D, and E are the coefficients of the standard equation of the ellipse. Equation 11 is derived by fitting Lissajous ellipse to V1(t) and V2(t). By analogy between the derived equation 11 and the standard equation 12 of the ellipse, the demodulation parameters of the DC component, amplitude, and actual phase difference of the interference signal can be obtained. The calculation results are shown in Equations 13-17 below.

[0076]

[0077] Therefore, all demodulation parameters for calculating the change in optical frequency at a certain wavelength can be obtained by using the Lissajous ellipse fitting method of two interference signals. Figures 7-8 The calibration results of the demodulation parameters C1(λ), ​​B1(λ), ​​β2(λ), and β3(λ) for one output of a Michelson interferometer in the wavelength range of 1500–1630 nm are shown. Here, β2(λ) is the phase difference between the phase interference signals V1(t) and V2(t), and β3(λ) is the phase difference between the phase interference signals V1(t) and V3(t). The demodulation parameters C1(λ), ​​B1(λ), ​​β2(λ), and β3(λ) are also shown for the other two outputs of the Michelson interferometer. i (λ), B i (λ) and Figure 7 Consistent.

[0078] During the measurement of absolute frequency, the splitting ratio of the wavelength division multiplexer (WDM) at different wavelengths needs to be calibrated in advance. The calibration method for the splitting ratio of the WDM at different wavelengths is as follows: Figure 9 This involves using a supercontinuum spectrum with a wide wavelength range as the device input. The wavelength division multiplexer obtains two output beams, which are then connected to a spectrum analyzer to obtain the spectra of the two output signals. By calculating the sum of the differences between the two signals at the same wavelength, a lookup table of the sum of the differences between the two output signals of the wavelength division multiplexer at different wavelengths and wavelength λ can be obtained. Figure 10 The graph shows the relationship between the ratio R1(t) of the optical intensity difference to the sum of optical intensities at the two output ports of the wavelength division multiplexer and the input wavelength λ.

[0079] All demodulation parameters calculated from the optical frequency change obtained in Example 2, as well as the difference ratio of the two output signals of the wavelength division multiplexer at different wavelengths and the lookup table with wavelength λ, are used for optical frequency demodulation.

[0080] Example 3

[0081] Example 3 provides a fast optical frequency demodulation method. The absolute optical frequency and the optical frequency change are calculated using the calibration results obtained from the fast optical frequency detection device demodulation parameter calibration method in Example 2. Figure 11As shown, the process includes: using a wide-wavelength swept-frequency laser as the light source in a fast optical frequency detection device to acquire three interference signals and two wavelength division multiplexer (WDM) signals; calculating the difference ratio of the two output signals of the WDM; obtaining the absolute wavelength of the input light by using the difference ratio of the two output signals of the WDM at different wavelengths obtained from calibration and a wavelength lookup table, and calculating the absolute frequency of the input light; repeatedly inputting the light source at different time points and calculating the absolute frequency of the input light to obtain the initial absolute frequency of the input light, and establishing the relationship between the absolute frequency of the input light and time; determining the corresponding optical frequency change demodulation parameters at each sampling point based on the acquired absolute wavelength of the input light and the calibrated optical frequency change demodulation parameters and wavelength lookup table; and calculating the optical frequency change based on the three interference signals and the optical frequency change demodulation parameters.

[0082] The specific calculation process is as follows:

[0083] Depend on Figure 10 It can be seen that R1(t) reaches its minimum value at 1260nm and its maximum value at 1480nm. Within the ranges of 1260nm~1480nm and 1480nm~1700nm, it varies unidirectionally with wavelength, exhibiting a one-to-one correspondence with the wavelength, i.e.:

[0084]

[0085] Where λ is the input light wavelength, and ƒ1 and ƒ2 are invertible functions.

[0086] When measuring the absolute frequency of the input light, the ratio of the difference between the output signals of the two second photodetectors connected to the two output ports of the wavelength division multiplexer to the sum of their values ​​is:

[0087]

[0088] Where P1(t) is the output voltage of photodetector 108 and P2(t) is the output voltage of photodetector 109.

[0089] If the wavelength of the input light is known to be within a specific range, the absolute wavelength λ(t) of the input light can be obtained quickly and in real time by calculating the ratio R1(t) of the light intensity difference to the sum of the light intensities at the two output ports at the current moment, and then mapping it to R1(λ).

[0090]

[0091] The absolute frequency ƒ0 of the input light satisfies the following relationship with λ(t):

[0092]

[0093] In Equation 6 of Example 2, the amount of optical frequency change is calculated, and the demodulation parameter C in Equation 6 is...i B i β i All parameters are wavelength-dependent, and the demodulation parameter C is called based on the absolute wavelength ƒ0(t). i B i β i This reduces the influence of wavelength on the measurement results of optical frequency changes. As described earlier, demodulation parameters were calibrated for demodulating relative frequencies at different wavelengths. Here, the relative wavelength demodulation parameters corresponding to the absolute wavelength are called to reduce the influence of wavelength variations on relative frequency demodulation. Otherwise, only one set of demodulation parameters could be used to demodulate relative frequency changes across the entire wavelength range, resulting in significant errors.

[0094] Figure 4 Demonstrated the use of Figure 1 The optical frequency detection device measures the actual signal measured by two photodetectors when the TSL-570 laser is unidirectionally scanned in the wavelength range of 1500~1630 nm with a wavelength step change interval of 10 nm.

[0095] The second photodetector on the output optical path of the wavelength division multiplexer receives the optical signal and generates a second photodetector signal, thereby calculating the absolute frequency of the input light ƒ0(t). The three signals output from the Michelson interferometer are received by the first photodetector and generate a first photodetector signal. Combined with the optical frequency increment demodulation parameters, the optical frequency change Δƒ(t) is calculated. From the calculated absolute frequency of the input light ƒ0(t) and the optical frequency change Δƒ(t), the absolute optical frequency can be obtained, i.e.:

[0096]

[0097] Where t0 is the point where Δƒ(t) is 0, and is generally set as the starting time.

[0098] Using the absolute frequency of the first point measured by the wavelength division multiplexer as the starting point for the relative frequency, the result of the absolute frequency of the light under test is more accurate and has higher resolution than the absolute frequency measured by the wavelength division multiplexer alone.

[0099] Figure 13 This figure shows the absolute optical frequency and frequency variation of the input light with a wavelength range of 1500~1630nm, continuously varying wavelength, and a sweep rate of 200nm / s (25THz / s) calculated by the fast optical frequency demodulation method in Embodiment 3 of this utility model. As can be seen from the figure, the fast optical frequency detection device in Embodiment 1 can achieve the measurement of the absolute optical frequency with a continuously varying wavelength of 1500~1630 nm.

[0100] Figure 14This is a graph showing the optical frequency variation of input light with a wavelength step change interval of 10 pm, calculated by the fast optical frequency demodulation method of Embodiment 3 of this utility model. Figure 14 As can be seen, the fast optical frequency detection device in Example 1 can achieve optical frequency change measurement with ultra-high optical frequency resolution. At the same time, the transient dynamic process of the transition between wavelengths can be clearly observed, reflecting the deviation of laser wavelength tuning.

[0101] The above provides a detailed description of the fast optical frequency detection device, demodulation parameter calibration method, and optical frequency demodulation method provided by this utility model. Specific examples have been used to illustrate the structure and working principle of this utility model. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core idea of ​​this utility model. It should be noted that those skilled in the art can make various improvements and modifications to this utility model without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims of this utility model.

Claims

1. A rapid optical frequency detection device, characterized in that, The system includes a Michelson interferometer with one input optical path. The Michelson interferometer has at least two interferometer arms. The tail of each interferometer arm is provided with a mirror equal to the number of interferometer arms. After the input light enters the interferometer arm, it is reflected out of the Michelson interferometer to generate multiple output lights. The output lights are received by a first photodetector. The generated first photodetector signal is used to calculate the change in the optical frequency of the input light. One of the input light paths is input to a wavelength division multiplexer, and the two light paths output by the wavelength division multiplexer are received by two second photodetectors to generate second photodetector signals for calculating the absolute optical frequency of the input light.

2. The fast optical frequency detection device according to claim 1, characterized in that, The Michelson interferometer includes one Optical coupler, the input light passes through the... The optical coupler splits the light into three input beams, with two beams entering the interferometer arm respectively.

3. The rapid optical frequency detection device according to claim 2, characterized in that, The Of the three input beams split by the optical coupler, in addition to the two input beams that enter the interferometer arm, the remaining input beam enters a wavelength division multiplexer.

4. The fast optical frequency detection device according to claim 1, characterized in that, The two interference arms have an optical path difference.

5. The rapid optical frequency detection device according to claim 4, characterized in that, The optical path difference between the two interference arms is a variable optical path difference.

6. The rapid optical frequency detection device according to claim 2, characterized in that, The reflector is a Faraday rotator, which reflects the light path back to the [reflector]. The optical coupler splits the reflected light path into three output light paths, which are received by three first photodetectors.

7. A fast optical frequency detection device according to claim 6, characterized in that, One of the three output optical paths shares the input optical path, and is connected through a... The optical coupler splits into two optical paths, which are then transmitted through the aforementioned... The optical paths after the optical coupler splits the light are used for input light and connection to the first photodetector.

8. A fast optical frequency detection device according to claim 6, characterized in that, The phase difference between the output signals of the three output optical paths after the optical coupler splits the light is around 120°.

9. A fast optical frequency detection device according to claim 8, characterized in that, The intensity of the first photoelectric detection signal varies with a sine or cosine function, and the change in the intensity of the first photoelectric detection signal corresponds to the change in the optical frequency of the input light.

10. A fast optical frequency detection device according to claim 1, characterized in that, The wavelength division multiplexer operates at the two ends of the wavelength of the light to be measured, and the ratio of the two output signals of the wavelength division multiplexer corresponds to the absolute optical frequency of the input light.

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