An incoherent double Gaussian spectral broadband ASE light source

Abstract

This invention relates to an incoherent dual-Gaussian spectral broadband ASE light source. Two independent erbium-doped fibers share a 980nm pump laser via a coupler with 1×2 ports. The two 980nm beams, after being split, excite their respective erbium-doped fibers through the 980nm ports of their respective wavelength division multiplexers, forming two uncorrelated and independent forward ASE light sources. The backward ASE beams from each erbium-doped fiber are then input to the 1550nm port of the other wavelength division multiplexer, increasing the backward ASE wavelength and suppressing the forward ASE wavelength, thereby improving the light output efficiency of the light source. The two independent Gaussian spectral ASE beams are then combined using a wavelength division multiplexer, increasing the equivalent spectral width of the light source. The wavelength division multiplexer is a 1×2 wavelength division multiplexer with a wavelength of 1550nm. This invention combines two independent Gaussian spectral ASE beams as the output light, increasing the equivalent spectral width of the ASE light source, suppressing relative intensity noise, and improving the accuracy of fiber optic gyroscopes.

Description

Technical Field

[0001] This invention belongs to the field of fiber optic gyroscope technology, specifically relating to an incoherent dual-Gaussian spectral broadband ASE light source. Background Technology

[0002] Fiber optic gyroscopes are angular rate sensors based on the Sagnac effect, offering advantages such as small size, high precision, all-solid-state operation, long lifespan, and wide dynamic range. Inertial navigation systems based on fiber optic gyroscopes have been widely applied in aerospace, ship navigation, and other fields.

[0003] The main noise sources in fiber optic gyroscopes include shot noise, thermal noise, correlation intensity noise, and signal sampling quantization noise. Shot noise, thermal noise, and quantization noise can be suppressed by increasing the light source power and preamplifier gain. Correlation intensity noise is caused by the beat frequency of the ASE broadband light source; it is additional noise caused by the beat frequencies between various Fourier components in the ASE light source, and its magnitude is inversely proportional to the square root of the ASE light source's spectral width. Therefore, increasing the spectral width of the ASE light source is beneficial for suppressing correlation intensity noise.

[0004] Fiber optic gyroscopes, especially in long-endurance, high-precision applications, face increasingly stringent requirements regarding noise levels, scaling factor stability, asymmetry, and nonlinearity. Using a flat-spectrum ASE (associated acoustic wave) source can achieve a wider spectral width. High-precision fiber optic gyroscopes typically employ flat-spectrum ASE sources to improve the suppression of correlated intensity noise, thereby enhancing the gyroscope's accuracy. Compared to flat-spectrum ASE sources, Gaussian-spectrum ASE sources offer higher average wavelength stability and symmetrical spectral shape, which are beneficial for improving the scaling factor stability, symmetry, and nonlinearity of fiber optic gyroscopes.

[0005] Fiber optic gyroscopes employing flat-spectrum ASE (Alternating Current) and Gaussian-spectrum ASE (Alternating Current) light sources each have their advantages, but both present a trade-off between high precision and high scaling factor performance. Therefore, the field of high-precision fiber optic gyroscopes urgently needs an ASE light source that balances high power, wide spectrum, symmetrical spectrum, and a highly stable center wavelength. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an incoherent dual-Gaussian spectral broadband ASE light source to solve the technical problem of the incompatibility between high precision and high scaling factor performance in fiber optic gyroscopes. This invention provides an incoherent Gaussian spectral broadband ASE light source with the characteristics of wide equivalent spectrum, symmetrical spectral shape, and high center wavelength stability. This is beneficial for suppressing relative intensity noise, improving the precision, scaling factor stability, asymmetry, and nonlinearity of fiber optic gyroscopes, and ultimately enhancing the overall performance of the fiber optic gyroscope.

[0007] The objective of this invention is achieved through the following technical means: An incoherent dual-Gaussian broadband ASE light source comprises two independent erbium-doped fibers sharing a 980nm pump laser via a coupler with 1×2 ports. The two 980nm beams, after being split, excite their respective erbium-doped fibers through the 980nm ports of their respective wavelength division multiplexers, thus forming two uncorrelated and independent forward ASE light sources. The backward ASE beams from each erbium-doped fiber are input to the 1550nm port of the other's wavelength division multiplexer via a wavelength division multiplexer, increasing the forward ASE wavelength of the erbium-doped fiber and suppressing the backward ASE wavelength, thereby improving the light output efficiency of the light source. The two independent Gaussian ASE beams are combined via a wavelength division multiplexer, increasing the equivalent spectral width of the light source, which is beneficial for relative intensity noise suppression and improving the accuracy of the fiber optic gyroscope. The wavelength division multiplexer is a 1×2 wavelength division multiplexer with a wavelength of 1550nm.

[0008] The aforementioned incoherent dual-Gaussian spectral broadband ASE light source generates two incoherent Gaussian spectral ASE light sources by matching the power of a 980nm pump laser, the spectral shape of the Gaussian spectral filter, and the type and length of the erbium-doped fiber. Utilizing the high stability and symmetry of the center wavelength of the Gaussian spectral light source, the scaling factor stability, nonlinearity, and asymmetry of the fiber optic gyroscope are improved.

[0009] The aforementioned incoherent dual-Gaussian spectral broadband ASE light source includes a 980nm pump laser, a 980nm wavelength 1×2 coupler, a first 980 / 1550nm wavelength division multiplexer, a second 980 / 1550nm wavelength division multiplexer, a first erbium-doped fiber, a second erbium-doped fiber, a first isolator, a second isolator, a first Gaussian spectral filter, a second Gaussian spectral filter, and a 1550nm wavelength division multiplexer; The 980nm pump laser is connected to port a of a 1×2 coupler with a wavelength of 980nm. The b port of the 980nm wavelength 1×2 coupler is connected to the a port of the first 980 / 1550 wavelength division multiplexer. The C port of the 980nm wavelength 1×2 coupler is connected to the A port of the second 980 / 1550 wavelength division multiplexer. The B port of the first 980 / 1550 wavelength division multiplexer is connected to the B port of the second 980 / 1550 wavelength division multiplexer. The C port of the first 980 / 1550 wavelength division multiplexer is connected to the A port of the first erbium-doped fiber. The C port of the second 980 / 1550 wavelength division multiplexer is connected to the A port of the second erbium-doped fiber. The b port of the first erbium-doped fiber is connected to the a port of the first isolator. The b port of the second erbium-doped fiber is connected to the a port of the second isolator. The b port of the first isolator is connected to the a port of the first Gaussian spectrum filter. The b port of the second isolator is connected to the a port of the second Gaussian spectrum filter. The b port of the first Gaussian spectrum filter is connected to the a port of the 1550nm wavelength division multiplexer. The b-port of the second Gaussian spectrum filter is connected to the b-port of the 1550nm wavelength division multiplexer. The C port of the 1550nm wavelength division multiplexer is used as the ASE light source output.

[0010] The beneficial effects of this invention are: 1. In this invention, two independent erbium-doped optical fibers share a single 980nm pump laser via a coupler. This reduces costs while generating two incoherent and independent Gaussian spectral ASE beams, which feature high average wavelength stability and symmetrical spectral shape. This is beneficial for improving the scaling factor stability, symmetry, and nonlinearity of fiber optic gyroscopes.

[0011] 2. This invention uses a wavelength division multiplexer to input the backward ASE light of two erbium-doped optical fibers to the 1550nm port of the other wavelength division multiplexer, which can increase the forward ASE light wave of the erbium-doped optical fiber, suppress the backward ASE light wave, and improve the ASE light source efficiency.

[0012] 3. This invention combines two independent Gaussian spectrum ASE beams into a single output beam using a wavelength division multiplexer, which can improve the equivalent spectral width of the ASE light source, help suppress relative intensity noise, and improve the accuracy of fiber optic gyroscopes. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of an incoherent double Gaussian broadband ASE light source.

[0014] Figure 2 This is a schematic diagram of a typical forward-pumped ASE light source optical path structure.

[0015] Figure 3 This is a typical free-spectrum ASE light source spectrum.

[0016] Figure 4 This is a typical Gaussian spectrum ASE light source spectrum. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] An incoherent dual-Gaussian broadband ASE light source is composed of a 980nm pump laser, a 980nm wavelength 1×2 coupler, a first 980 / 1550nm wavelength division multiplexer, a second 980 / 1550nm wavelength division multiplexer, a first erbium-doped fiber, a second erbium-doped fiber, a first isolator, a second isolator, a first Gaussian spectrum filter, a second Gaussian spectrum filter, and a 1550nm wavelength division multiplexer connected by fiber fusion splicing.

[0019] like Figure 1 As shown: The 980nm pump laser 1 is connected to port a of the 980nm wavelength 1×2 coupler 2. The b port of the 980nm wavelength 1×2 coupler 2 is connected to the a port of the first 980 / 1550 wavelength division multiplexer 3. The c port of the 980nm wavelength 1×2 coupler 2 is connected to the a port of the second 980 / 1550 wavelength division multiplexer 4. The b port of the first 980 / 1550 wavelength division multiplexer 3 is connected to the b port of the second 980 / 1550 wavelength division multiplexer 4. The c port of the first 980 / 1550 wavelength division multiplexer 3 is connected to the a port of the first erbium-doped fiber 5. The c port of the second 980 / 1550 wavelength division multiplexer 4 is connected to the a port of the second erbium-doped fiber 6. The b port of the first erbium-doped fiber 5 is connected to the a port of the first isolator 7. The b port of the second erbium-doped fiber 6 is connected to the a port of the second isolator 8. The b port of the first isolator 7 is connected to the a port of the first Gaussian spectrum filter 9. The b port of the second isolator 8 is connected to the a port of the second Gaussian spectrum filter 10. The b port of the first Gaussian spectrum filter 9 is connected to the a port of the 1550nm wavelength division multiplexer 11. The b port of the second Gaussian spectrum filter 10 is connected to the b port of the 1550nm wavelength division multiplexer 11. The C port of the 1550nm wavelength division multiplexer 11 is used as the output light source.

[0020] Working principle of this invention: The shot noise of a fiber optic gyroscope is inversely proportional to the square root of the optical power of the input light source, and can be expressed as: (1) in, For shot noise amplitude, This represents the light power of the light source.

[0021] A typical forward-pumped ASE light source optical path structure is as follows: Figure 2 As shown, the backward ASE light of erbium-doped fiber is usually attenuated by fiber loops, while the forward ASE light is output as the light source.

[0022] This invention uses a wavelength division multiplexer to input the backward ASE light from two erbium-doped fibers to the 1550nm port of the other wavelength division multiplexer as part of the light source output. This can increase the forward ASE light wave of the erbium-doped fiber, suppress the backward ASE light wave, improve the ASE light source efficiency, thereby helping to reduce shot noise and ultimately improve the accuracy of the fiber optic gyroscope.

[0023] The amplitude of the correlated intensity noise of a fiber optic gyroscope is inversely proportional to the square root of the spectral width of the light source, which can be expressed as: (2) in, For the relevant intensity noise amplitude, The equivalent spectral width of the light source.

[0024] Figure 3 The image shows a typical free-spectrum ASE light source spectrum. This spectrum exhibits two main peaks at 1530 nm and 1560 nm. By changing the type and length of the erbium-doped fiber, the power of the 980 nm pump laser, and other factors, the relative heights of the 1530 nm and 1560 nm spectral peaks can be adjusted. Specifically, the 1530 nm peak can be higher than the 1560 nm peak, or vice versa, or the 1530 nm peak can be roughly equal to the 1560 nm peak.

[0025] In this invention, by independently adjusting the type and length of the two erbium fiber segments, the power of the 980nm pump laser, and matching the corresponding Gaussian spectral filter, two Gaussian spectral ASE light sources with highly symmetric spectral characteristics can be obtained. The center wavelengths of these two Gaussian spectral ASE light sources are 1530nm and 1560nm, respectively, corresponding to the two main spectral peaks of free-spectrum ASE light. Figure 4 The image shown is a typical Gaussian spectrum ASE light source spectrum.

[0026] This invention combines two incoherent Gaussian spectral ASE sources, increasing both the source power and spectral width, overcoming the narrow spectral width limitation of a single Gaussian spectral ASE source. This improves the suppression of correlated intensity noise and enhances the accuracy of the fiber optic gyroscope. Two independent erbium-doped fibers share a single 980nm pump laser via a coupler, reducing costs while generating two incoherent and independent Gaussian spectral ASE beams. These beams exhibit high average wavelength stability and symmetrical spectral shape, which improves the scaling factor stability, symmetry, and nonlinearity of the fiber optic gyroscope. A wavelength division multiplexer inputs the backward ASE beams from each erbium-doped fiber to the 1550nm port of the other fiber's wavelength division multiplexer, increasing the forward ASE beam and suppressing the backward ASE beam, thus improving the ASE source efficiency. Finally, combining two independent Gaussian spectral ASE beams into a single output beam using a wavelength division multiplexer increases the equivalent spectral width of the ASE source, further suppressing relative intensity noise and improving the accuracy of the fiber optic gyroscope. This method is easy to implement and highly adaptable.

[0027] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, all of which fall within the protection scope of the present invention. The protection scope of the present invention is defined by the appended claims and any equivalent technical solutions.

Claims

1. An incoherent double-Gaussian broadband ASE light source, characterized in that, Two independent erbium-doped optical fibers share a 980nm pump laser via a coupler with 1×2 ports; The two 980nm beams after beam splitting excite their respective erbium-doped fibers through the 980nm ports of their respective wavelength division multiplexers, thus forming two unrelated and independent forward ASE light sources; The backward ASE light from each of the two erbium-doped fibers passes through a wavelength division multiplexer and is input to the 1550nm port of the other wavelength division multiplexer, which increases the forward ASE light wave of the erbium-doped fiber and suppresses the backward ASE light wave, thereby improving the light output efficiency of the light source. Two independent Gaussian spectrum ASE beams are combined through a wavelength division multiplexer, which increases the equivalent spectral width of the light source, which is beneficial for suppressing relative intensity noise and improving the accuracy of the fiber optic gyroscope. The wavelength division multiplexer is a 1×2 wavelength division multiplexer with a wavelength of 1550nm.

2. The incoherent double-Gaussian broadband ASE light source according to claim 1, characterized in that, By matching the power of the 980nm pump laser, the spectral shape of the Gaussian spectral filter, and the type and length of the erbium-doped fiber, two incoherent Gaussian spectral ASE light sources are generated. The high stability and symmetry of the center wavelength of the Gaussian spectral light source are utilized to improve the scaling factor stability, nonlinearity, and asymmetry of the fiber optic gyroscope.

3. The incoherent double-Gaussian broadband ASE light source according to claim 1, characterized in that, It includes a 980nm pump laser (1), a 980nm wavelength 1×2 coupler (2), a first 980 / 1550nm wavelength division multiplexer (3), a second 980 / 1550nm wavelength division multiplexer (4), a first erbium-doped fiber (5), a second erbium-doped fiber (6), a first isolator (7), a second isolator (8), a first Gaussian spectrum filter (9), a second Gaussian spectrum filter (10), and a 1550nm wavelength division multiplexer (11). The 980nm pump laser (1) is connected to port a of the 980nm wavelength 1×2 coupler (2). The b port of the 980nm wavelength 1×2 coupler (2) is connected to the a port of the first 980 / 1550 wavelength division multiplexer (3). The c port of the 980nm wavelength 1×2 coupler (2) is connected to the a port of the second 980 / 1550 wavelength division multiplexer (4). The b port of the first 980 / 1550 wavelength division multiplexer (3) is connected to the b port of the second 980 / 1550 wavelength division multiplexer (4). The c port of the first 980 / 1550 wavelength division multiplexer (3) is connected to the a port of the first erbium-doped fiber (5). The c port of the second 980 / 1550 wavelength division multiplexer (4) is connected to the a port of the second erbium-doped fiber (6). The b port of the first erbium-doped fiber (5) is connected to the a port of the first isolator (7). The b port of the second erbium-doped fiber (6) is connected to the a port of the second isolator (8). The b port of the first isolator (7) is connected to the a port of the first Gaussian spectrum filter (9). The b port of the second isolator (8) is connected to the a port of the second Gaussian spectrum filter (10). The b port of the first Gaussian spectrum filter (9) is connected to the a port of the 1550nm wavelength division multiplexer (11). The b port of the second Gaussian spectrum filter (10) is connected to the b port of the 1550nm wavelength division multiplexer (11). The C port of the 1550nm wavelength division multiplexer (11) is used as the ASE light source output.

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