Interferometric spectrum analyzer

Abstract

The utility model provides an interference type spectrum analyzer which comprises a reference light source for generating a reference light signal; the coupler is used for coupling the input optical signal and the reference optical signal into a combined optical signal; the reflection cavity is used for receiving the combined light signal, moving the reflector and outputting a combined light interference signal; a circulator outputting the combined optical interference signal to the first optical filter and the second optical filter; the first optical filter is used for filtering the reference light interference signal to obtain an input light interference signal; the second optical filter is used for filtering the input light interference signal to obtain a reference light interference signal; the first optical signal detection unit is used for detecting the total power of an input optical signal; the second optical signal detection unit is used for detecting the power of the input optical interference signal; the third optical signal detection unit is used for detecting the power of the reference light interference signal; and the CPU is used for controlling the movement of the reflecting mirror in the reflecting cavity and acquiring the total power of the input light signal, the power of the input light interference signal and the power of the reference light interference signal.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of spectrum technology, in particular to an interference type spectrum analyzer. BACKGROUND

[0002] The existing spectrum analyzer is usually structured as follows:

[0003] 1: dispersion type spectrum analyzer, its principle is to utilize grating to disperse different wavelength light, and the dispersed light is analyzed by a detector array.

[0004] The spectral resolution of the grating type spectrum analyzer is determined by the grating, and the higher the required spectral resolution, the higher the grating manufacturing cost, and the accuracy and cost of the grating restrict the performance of the grating type spectrum analyzer.

[0005] 2: interference type spectrum analyzer, its principle is to utilize the interference of light, and the spectrum analysis result is obtained by analyzing the interference image generated by the optical reflection cavity during the change.

[0006] The resolution of the interference type spectrum analyzer is only determined by the length of the reflection cavity. The longer the reflection cavity, the higher the spectral resolution. However, the interference type spectrum analyzer requires a cavity control system to accurately control the change of the cavity. The wavelength range of optical communication is 1300nm-1600nm, and the wavelength is nm level. To control the change of the reflection cavity to nm level can achieve nm level spectral resolution. The cost of the cavity control system with large stroke and high precision is high, which greatly restricts the development of the interference type spectrum analyzer.

[0007] Therefore, it is necessary to provide an interference type spectrum analyzer to effectively solve the problems of the existing interference type spectrum analyzer. UTILITY MODEL CONTENT

[0008] The utility model provides an interference type spectrum analyzer, introduces a reference light source, compares and analyzes the known reference light signal and the input light signal in the same light path, calculates the spectral composition of the input light signal, and reduces the dependence of the interference type spectrum analyzer on the large stroke and high precision cavity control system.

[0009] The utility model embodiment provides an interference type spectrum analyzer, which comprises:

[0010] The reference light source is used to generate a reference light signal;

[0011] The coupler is used to couple the input light signal to be analyzed and the reference light signal into a combined light signal;

[0012] a reflecting cavity, comprising a cavity and a movable mirror arranged in the cavity, the reflecting cavity receiving the combined light signal; moving the mirror to output a combined light interference signal;

[0013] a circulator, outputting the combined light interference signal outputted by the reflecting cavity to a first optical filter and a second optical filter; the first optical filter is used to filter out the reference light interference signal in the combined light interference signal to obtain an input light interference signal; the second optical filter is used to filter out the input light interference signal in the combined light interference signal to obtain the reference light interference signal;

[0014] a first light signal detection unit, collecting the input light signal to detect the total power of the input light signal;

[0015] a second light signal detection unit, connected to the first optical filter to detect the power of the input light interference signal;

[0016] a third light signal detection unit, connected to the second optical filter to detect the power of the reference light interference signal;

[0017] a CPU, used to control the movement of the mirror in the reflecting cavity, and obtain the total power of the input light signal, the power of the input light interference signal and the power of the reference light interference signal.

[0018] Preferably, the reflecting cavity is arranged at the back side of the coupler, and the mirror is arranged vertically in the cavity to make the combined light signal vertically irradiate the mirror; moving the mirror, the combined light signal inputted into the reflecting cavity interferes with the reflected light signal of the mirror reflecting the combined light signal to return the combined light interference signal.

[0019] Preferably, the reference wavelength of the reference light signal generated by the reference light source is known, and the CPU obtains the wavelength of the input light signal and the power corresponding to the wavelength by combining the known reference wavelength of the reference light signal with the obtained total power of the input light signal, the power of the input light interference signal and the power of the reference light interference signal.

[0020] Preferably, the circulator is arranged between the coupler and the reflecting cavity to isolate the combined light signal and the combined light interference signal returned via the reflecting cavity, and output the combined light interference signal to the first optical filter and the second optical filter.

[0021] Preferably, an isolator is arranged at the front side of the coupler, and the input light signal enters the coupler via the isolator.

[0022] Preferably, a collimator is arranged at the entrance of the reflection cavity, and the collimator is used for emitting the combined light signal to the reflection cavity, and the end surface of the collimator which is connected with the light path of the reflection cavity is the interference point of the combined light signal and the reflected light signal of the combined light signal.

[0023] Preferably, the first light signal detection unit comprises a first photodiode and a first analog-to-digital converter connected in sequence, the first analog-to-digital converter is connected with the CPU, the first photodiode collects the input light signal, obtains the total power of the input light signal and converts the total power into a digital signal by the first analog-to-digital converter and sends the digital signal to the CPU.

[0024] Preferably, the second light signal detection unit comprises a second photodiode and a second analog-to-digital converter connected in sequence, the second analog-to-digital converter is connected with the CPU, the second photodiode collects the input light interference signal, obtains the power of the input light interference signal and converts the power into a digital signal by the second analog-to-digital converter and sends the digital signal to the CPU.

[0025] Preferably, the third light signal detection unit comprises a third photodiode and a third analog-to-digital converter connected in sequence, the third analog-to-digital converter is connected with the CPU, the third photodiode collects the reference light interference signal, obtains the power of the reference light interference signal and converts the power into a digital signal by the third analog-to-digital converter and sends the digital signal to the CPU.

[0026] Compared with the prior art, the technical scheme of the embodiment of the utility model has the following beneficial effects:

[0027] The utility model discloses an interference type spectrum analyzer, introduce reference light source, utilize digital signal processing's method to the interference signal of known reference light signal with the input light signal of the analysis of the same light path is compared and analyzed, through known reference light signal, the spectral composition of input light signal is calculated, and the control requirement of nm level precision cavity length is converted to the wavelength stability requirement of reference light source, reduces the control precision requirement of interference type spectrum analyzer to the reflection cavity, and the precision of spectrum analysis is improved to the same 0.01nm level with reference light source, improves the performance of interference type spectrum analyzer, and reduces the system cost. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical scheme in the embodiment of the utility model or prior art, the drawings needed to be used in the embodiment or prior art description will be simply introduced below, and obviously, the drawings in the following description are some embodiments of the utility model, not all embodiments. For ordinary skilled in the art, without paying the creative labor, other drawings can also be obtained according to these drawings.

[0029] Figure 1 The structure schematic diagram of the interferometric spectral analyzer is provided for an embodiment of the present application.

[0030] In the figure:

[0031] 1-reference light source; 2-isolator; 3-coupler; 4-reflection cavity; 41-cavity; 42-mirror; 43-collimator; 5-circulator; 6-first optical filter; 7-second optical filter; 8-first optical signal detection unit; 81-first photodiode; 82-first analog-to-digital converter; 9-second optical signal detection unit; 91-second photodiode; 92-second analog-to-digital converter; 10-third optical signal detection unit; 101-third photodiode; 102-third analog-to-digital converter; 11-CPU. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0033] The technical scheme of the present application will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes can not be described in some embodiments.

[0034] Based on the problems in the prior art, the embodiments of the present application provide an interferometric spectral analyzer, a reference light source is introduced, by comparative analysis of the known reference light signal and the input light signal in the same light path, the spectral composition of the input light signal is calculated, and the dependence of the interferometric spectral analyzer on the large-stroke and high-precision cavity control system is reduced.

[0035] Figure 1 The structure schematic diagram of the interferometric spectral analyzer is provided for an embodiment of the present application.

[0036] Now referring to Figure 1 The embodiments of the present application provide an interferometric spectral analyzer, which comprises:

[0037] The reference light source 1 is used to generate a reference light signal;

[0038] The coupler 3 is used to couple the input light signal to be analyzed and the reference light signal into a combined light signal;

[0039] The reflection cavity 4 receives the combined light signal, and comprises a cavity 41 and a movable mirror 42 arranged in the cavity 41; the movable mirror 42 outputs the combined light interference signal;

[0040] The circulator 5 outputs the combined light interference signal output by the reflection cavity 4 to the first optical filter 6 and the second optical filter 7;

[0041] The first optical filter 6 is used to filter out the reference light interference signal in the combined light interference signal to obtain the input light interference signal;

[0042] The second optical filter 7 is used to filter out the input light interference signal in the combined light interference signal to obtain the reference light interference signal;

[0043] The first light signal detection unit 8 collects the input light signal and is used to detect the total power of the input light signal;

[0044] The second light signal detection unit 9 is connected to the first optical filter 6 and is used to detect the power of the input light interference signal;

[0045] The third light signal detection unit 10 is connected to the second optical filter 7 and is used to detect the power of the reference light interference signal;

[0046] The CPU (Central Processing Unit) 11 is used to control the movement of the mirror 42 in the reflection cavity 4, and obtain the total power of the input light signal, the power of the input light interference signal and the power of the reference light interference signal.

[0047] In some embodiments, the reflection cavity 4 is arranged at the back side of the coupler 3, and the mirror 42 is arranged vertically in the cavity 41, so that the combined light signal is vertically irradiated to the mirror 42; the combined light signal input to the reflection cavity 4 interferes with the reflected light signal of the mirror 42 reflecting the combined light signal, and returns the combined light interference signal.

[0048] Specifically, the reference light source 1 adopts a high-precision laser light source, and the high-precision laser light source emits wavelength-stable laser light, which is used as the reference light. Due to the development of laser technology, through a low-cost two-stage temperature control loop, the temperature change of a common DFB (Distributed Feedback Laser) laser can be controlled within 0.03℃, so that the wavelength of the laser emitted by the DFB laser is stabilized within 0.001nm.

[0049] In some embodiments, the reference wavelength of the reference light signal generated by the reference light source 1 is known. The CPU 11 calculates the wavelength of the input light signal and the power corresponding to the wavelength based on the total power of the input light signal, the power of the input light interference signal, and the power of the reference light interference signal, combined with the known reference wavelength of the reference light signal.

[0050] In some embodiments, the circulator 5 is disposed between the coupler 3 and the reflective cavity 4, isolates the combined optical signal and the combined optical interference signal returned via the reflective cavity 4, and outputs the combined optical interference signal to the first optical filter 6 and the second optical filter 7.

[0051] In some embodiments, an isolator 2 is provided on the front side of the coupler 3, and the input optical signal enters the coupler 3 through the isolator 2; to prevent the reference optical signal of the reference light source 1 from interfering with the input optical path and causing interference to the first optical signal detection unit 8.

[0052] Specifically, the circulator 5 isolates the combined optical signal and the combined optical interference signal returned via the reflector cavity 4, preventing the returned optical signal from interfering with the reference light source 1 and causing the reference light source 1 to become unstable.

[0053] Specifically, the wavelength range of the input light is typically 1300nm-1600nm, while the wavelength range of the laser used as the reference light is typically 200nm-600nm. The wavelength difference between the two is significant, and the first optical filter 6 and the second optical filter 7 perform optical filtering based on the wavelength range.

[0054] In some embodiments, a collimator 43 is provided at the entrance of the reflecting cavity 4. The collimator 43 is used to transmit the combined optical signal to the reflecting cavity 4. The end face of the collimator 43 connected to the optical path interface of the reflecting cavity 4 is the interference point between the combined optical signal and the reflected optical signal of the combined optical signal.

[0055] In some embodiments, the first optical signal detection unit 8 includes a first photodiode 81 and a first analog-to-digital converter 82 connected in sequence. The first analog-to-digital converter 82 is connected to the CPU 11. The first photodiode 81 collects the input optical signal, obtains the total power of the input optical signal, and converts it into a digital signal by the first analog-to-digital converter 82 and sends it to the CPU 11.

[0056] In some embodiments, the second optical signal detection unit 9 includes a second photodiode 91 and a second analog-to-digital converter 92 connected in sequence. The second analog-to-digital converter 92 is connected to the CPU 11. The second photodiode 91 collects the input optical interference signal, obtains the power of the input optical interference signal, and converts it into a digital signal by the second analog-to-digital converter 92 and sends it to the CPU 11.

[0057] In some embodiments, the third optical signal detection unit 10 includes a third photodiode 101 and a third analog-to-digital converter 102 connected in sequence. The third analog-to-digital converter 102 is connected to the CPU 11. The third photodiode 101 collects the reference light interference signal, obtains the power of the reference light interference signal, and converts it into a digital signal by the third analog-to-digital converter 102 and sends it to the CPU 11.

[0058] To better illustrate the interferometric spectrometer of this invention, an analytical method for using the interferometric spectrometer is also provided, comprising the following steps:

[0059] S1: CPU 11 obtains the total power of the input optical signal through the first optical signal detection unit 8;

[0060] S2: Turn on the reference light source 1, and the CPU 11 controls the reflector 42 in the reflective cavity 4 to move at the set speed;

[0061] S3: While the reflector 42 moves, the CPU 11 obtains the power of the reference light interference signal through the third light signal detection unit 10; the CPU 11 obtains the power of the input light interference signal through the second light signal detection unit 9;

[0062] S4: After performing a Fourier transform on the power of the reference light interference signal, the center point is solved to obtain the interference frequency of the reference light signal;

[0063] S5: Perform a Fourier transform on the power of the input optical interference signal to obtain the proportional relationship between the interference frequency and the amplitude of each frequency point of the input optical signal; the proportional relationship of the amplitude of each frequency point of the input optical signal is the proportional relationship of the power of each frequency point of the input optical signal.

[0064] S6: Based on the relationship between the wavelength and interference frequency of the input optical signal and the wavelength and interference frequency of the reference optical signal, the wavelength of the input optical signal corresponding to each frequency point is calculated;

[0065] S7: The power of each frequency point of the input optical signal is calculated based on the fact that the total power of the input optical signal is equal to the sum of the powers of each frequency point of the input optical signal.

[0066] Specifically, in step S2, the CPU 11 controls the mirror 42 in the reflecting cavity 4 to move at a rate of Lnm / s; during the process of the reference light changing the length of the cavity 41 by Lnm, the number of times the reference light and its reflected light interfere with each other, superimposed or canceled is... Let λ be the wavelength of the reference light, then the interference frequency of the reference light is expressed as:

[0067]

[0068] Assuming the wavelength of the input optical signal is Then, during the length change Lnm of the input light in cavity 41, the number of times the input light and its reflected light interfere with each other, superimposed or canceled is: The interference frequency of the input light is then expressed as:

[0069]

[0070] The wavelength and interference frequency of the input optical signal satisfy the following formula with the wavelength and interference frequency of the reference optical signal:

[0071]

[0072] in, The wavelength of the input optical signal; F in The interference frequency of the input optical signal; The wavelength of the reference optical signal; F ref The interference frequency of the reference optical signal.

[0073] Following the same logic for single-wavelength signals, when the input optical signal is a broadband signal, Fourier transform analysis of the interference signal of the input light yields the wavelength of the input optical signal at each frequency point, calculated using the following formula:

[0074]

[0075] Where n = 0, 1, 2, ..., (1 / 2)f s f s Sampling frequency, F is the wavelength of the nth frequency point of the input optical signal; in-n The frequency of the nth frequency point of the input optical signal; The wavelength of the reference optical signal; F ref The interference frequency of the reference optical signal.

[0076] In some embodiments, the power of the input optical signal at each frequency point is calculated using the following formulas:

[0077] P total =∑P in-n

[0078] P in-0 :P in-1 :...:P in-n =FFT_0:FFT_1:...:FFT_n

[0079] Where n = 0, 1, 2, ..., (1 / 2)f s f s P is the sampling frequency.total P represents the total power of the input optical signal. in-n The power of the nth frequency point of the input optical signal; FFT_0:FFT_1:...:FFT_n represents the proportional relationship of the amplitudes of each frequency point obtained by performing a Fourier transform on the power signal of the input optical interference signal.

[0080] Compared to existing technologies, by performing Fourier transform analysis on the interference signal of the input light, the frequencies of the input light signal corresponding to each frequency point are obtained, and then based on... By calculating the wavelength of the input optical signal corresponding to each frequency point, this invention transforms the control requirement of the cavity length 41 with nm-level precision into the wavelength stability requirement of the reference light source 1, thereby reducing the control precision requirements of the interferometric spectral analyzer on the reflective cavity.

[0081] In summary, the interferometric spectrometer provided by this utility model introduces a reference light source 1 and uses digital signal processing to compare and analyze the interference signals of a known reference light signal and the input light signal to be analyzed in the same optical path. The spectral composition of the input light signal is calculated from the known reference light signal. The control requirements for the length of the cavity 41 with nm-level precision are transformed into the wavelength stability requirements of the reference light source 1. This reduces the control precision requirements of the interferometric spectrometer on the reflection cavity while improving the spectral analysis precision to the same 0.01 nm level as the reference light source 1. This improves the performance of the interferometric spectrometer while reducing the system cost.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. An interferometric spectrometer, characterized in that, include: A reference light source is used to generate a reference light signal; A coupler is used to couple the input optical signal to be analyzed with a reference optical signal into a combined optical signal; A reflecting cavity includes a cavity body and a movable reflecting mirror disposed within the cavity body. The reflecting cavity receives combined optical signals; by moving the reflecting mirror, it outputs combined optical interference signals. The circulator outputs the combined optical interference signal from the reflecting cavity to a first optical filter and a second optical filter; the first optical filter is used to filter out the reference optical interference signal in the combined optical interference signal to obtain the input optical interference signal; the second optical filter is used to filter out the input optical interference signal in the combined optical interference signal to obtain the reference optical interference signal. The first optical signal detection unit collects the input optical signal to detect the total power of the input optical signal; The second optical signal detection unit is connected to the first optical filter and is used to detect the power of the input optical interference signal; The third optical signal detection unit is connected to the second optical filter and is used to detect the power of the reference optical interference signal; The CPU is used to control the movement of the mirror in the reflecting cavity and to obtain the total power of the input optical signal, the power of the input optical interference signal, and the power of the reference optical interference signal.

2. The interferometric spectrometer according to claim 1, characterized in that, The reflecting cavity is located on the rear side of the coupler, and the reflecting mirror is vertically positioned in the cavity so that the combined optical signal is perpendicularly irradiated onto the reflecting mirror. When the reflecting mirror is moved, the combined optical signal input to the reflecting cavity interferes with the reflected optical signal reflected by the reflecting mirror, and a combined optical interference signal is returned.

3. The interferometric spectrometer according to claim 1, characterized in that, The reference wavelength of the reference light signal generated by the reference light source is known. The CPU calculates the wavelength of the input light signal and the power corresponding to the wavelength based on the total power of the input light signal, the power of the input light interference signal, and the power of the reference light interference signal, combined with the known reference wavelength of the reference light signal.

4. The interferometric spectrometer according to claim 1, characterized in that, The circulator is positioned between the coupler and the reflecting cavity to isolate the combined optical signal and the combined optical interference signal returning via the reflecting cavity, and outputs the combined optical interference signal to the first optical filter and the second optical filter.

5. The interferometric spectrometer according to claim 1, characterized in that, An isolator is provided on the front side of the coupler, and the input optical signal enters the coupler through the isolator.

6. The interferometric spectrometer according to claim 1, characterized in that, A collimator is provided at the entrance of the reflecting cavity. The collimator is used to transmit the combined optical signal into the reflecting cavity. The end face of the collimator connected to the optical path interface of the reflecting cavity is the interference point between the combined optical signal and the reflected optical signal of the combined optical signal.

7. The interferometric spectrometer according to claim 1, characterized in that, The first optical signal detection unit includes a first photodiode and a first analog-to-digital converter connected in sequence. The first analog-to-digital converter is connected to the CPU. The first photodiode collects the input optical signal, obtains the total power of the input optical signal, and converts it into a digital signal by the first analog-to-digital converter and sends it to the CPU.

8. The interferometric spectrometer according to claim 1, characterized in that, The second optical signal detection unit includes a second photodiode and a second analog-to-digital converter connected in sequence. The second analog-to-digital converter is connected to the CPU. The second photodiode collects the input optical interference signal, obtains the power of the input optical interference signal, and converts it into a digital signal by the second analog-to-digital converter and sends it to the CPU.

9. The interferometric spectrometer according to claim 1, characterized in that, The third optical signal detection unit includes a third photodiode and a third analog-to-digital converter connected in sequence. The third analog-to-digital converter is connected to the CPU. The third photodiode collects the reference light interference signal, obtains the power of the reference light interference signal, and converts it into a digital signal by the third analog-to-digital converter and sends it to the CPU.

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