Er: YAG derived optical fiber-containing ASE light source for optical fiber gyroscope

Abstract

An ASE light source containing an Er: YAG derived optical fiber for an optical fiber gyroscope belongs to the technical field of laser materials and lasers and comprises a Faraday polariscope, a single-mode laser diode, a wavelength division multiplexer, the Er: YAG derived optical fiber and an isolator. The Faraday polariscope is connected with a signal end port of the wavelength division multiplexer and is used for reflecting light with a specific wavelength; the output end of the single-mode laser diode is connected with the pumping end of the wavelength division multiplexer; and the common end of the wavelength division multiplexer is connected with one end of the Er: YAG derivative optical fiber serving as a gain medium. The ASE light source prepared from the Er: YAG derived optical fiber replaces a quartz optical fiber in a traditional EDFA, the ASE light source can serve as a common light source of the IFOG, and due to the fact that the ASE light source can use a shorter active optical fiber and has better performance, the temperature control cost is saved, the structure of the IFOG can be more compact, the cost is reduced, and high-precision guarantee provided for the IFOG by the ASE light source is kept.

Description

Technical Field

[0001] The present invention belongs to the fields of laser materials and laser technology, and more specifically, relates to an ASE light source for a fiber optic gyroscope that includes Er:YAG-derived optical fiber. Background Art

[0002] A fiber optic gyroscope (FOG) is an important high-precision optical inertial measurement instrument. Compared with other gyroscopes, the fiber optic gyroscope has advantages such as a wide dynamic range, high sensitivity, long lifespan, and anti-interference. Fiber optic gyroscopes can be divided into interferometric, resonant, and stimulated Brillouin types. Among them, the interferometric fiber optic gyroscope (IFOG) has been developed earlier. Its essence is a ring interferometer based on the Sagnac effect. By detecting the change in light intensity caused by the Sagnac effect, the real-time angular rate of the carrier can be deduced. After decades of development, the basic theory and technology of IFOG have been very mature and industrialized, and it has been widely used in military, civilian, scientific research, and other fields such as aviation, navigation, and earth rotation monitoring. In response to the current application trend of IFOG from medium-low precision to medium-high precision, its main development directions are: one is to improve accuracy, that is, to enhance the stability of the gyroscope and reduce its temperature drift; the other is low cost, miniaturization, and high integration.

[0003] To achieve the above optimizations, simplifying the optical path and integrating the circuit are necessary research goals, and the light source is an important component in the optical path of IFOG. For IFOG, its light source must be an incoherent broadband light source. Considering the requirements for the scale factor and bias stability, IFOG has higher requirements for the light source bandwidth and stability. The commonly used superluminescent light-emitting diode (SLD) is no longer an ideal light source for high-precision IFOG and is difficult to meet its requirements for light source bandwidth, wavelength stability, output power, lifespan, etc. With the development of the optical communication industry, the technology of erbium-doped fiber amplifier (EDFA) has become increasingly mature. The amplified spontaneous emission (ASE) light source generated by EDFA is in the low-loss transmission window of silica fiber (1.55 μm band). Through technical means such as filtering and modulation, its advantages in spectral bandwidth and power stability provide an important guarantee for current high-precision IFOG.

[0004] However, to further simplify the optical path structure and drive IFOG towards more miniaturization, a compact and stable EDFA is necessary. The erbium-doped concentration of silica fiber used in commercial EDFA is low, the usage length is long, and its spectrum is easily shifted by temperature changes, affecting the bias stability of IFOG and making it difficult to meet the working requirements of IFOG in a wide temperature range or extreme environments. Summary of the Invention

[0005] The present invention provides an ASE light source for a fiber optic gyroscope that includes Er:YAG-derived optical fiber to solve the defects in the prior art.

[0006] The present invention is achieved through the following technical solutions:

[0007] An ASE light source for a fiber optic gyroscope comprising an Er:YAG-derived optical fiber, including a Faraday rotator, a single-mode laser diode, a wavelength division multiplexer, an Er:YAG-derived optical fiber, and an isolator; the Faraday rotator is connected to the signal end port of the wavelength division multiplexer for reflecting light of a specific wavelength; the output end of the single-mode laser diode is connected to the pump end of the wavelength division multiplexer; the common end of the wavelength division multiplexer is connected to one end of the Er:YAG-derived optical fiber serving as a gain medium; the other end of the Er:YAG-derived optical fiber is connected to the isolator to ensure unidirectional light transmission.

[0008] For an ASE light source for a fiber optic gyroscope as described above, the Er:YAG-derived optical fiber includes a core and a cladding, the diameter of the core is 4 - 8 μm, the diameter of the cladding is 125 μm, and the numerical aperture of the core is 0.1 - 0.3.

[0009] For an ASE light source for a fiber optic gyroscope as described above, the core material of the Er:YAG-derived optical fiber is Er:YAG crystal or Er:YAG transparent ceramic, and the cladding material is quartz glass.

[0010] For an ASE light source for a fiber optic gyroscope as described above, Er in the core of the Er:YAG-derived optical fiber 3+ ion doping concentration is 0.5 - 4 wt.%.

[0011] For an ASE light source for a fiber optic gyroscope as described above, Yb can also be doped in the Er:YAG-derived optical fiber 3+ ion, and the doping concentration of the Yb 3+ ion is 1 - 6 times that of the Er 3+ ion doping concentration.

[0012] For an ASE light source for a fiber optic gyroscope as described above, the preparation operation of the Er:YAG-derived optical fiber is to coat the outer layer of the core with a cladding to prepare an optical fiber preform, and the optical fiber preform is drawn at 2000 - 2100 °C and then cooled to obtain the Er:YAG-derived optical fiber.

[0013] For an ASE light source for a fiber optic gyroscope as described above, the use length of the Er:YAG-derived optical fiber is 20 - 80 cm.

[0014] An ASE light source for an optical fiber gyroscope as described above, which includes an Er:YAG-derived optical fiber. The center wavelength of the single-mode laser diode is 976 nm or 1480 nm. The output fiber cladding diameter of the single-mode laser diode is 125 μm, and the power is greater than 300 mW.

[0015] An ASE light source for an optical fiber gyroscope as described above, which includes an Er:YAG-derived optical fiber. The center wavelength of the isolator is 1530 - 1560 nm, the working bandwidth is ±10 - 20 nm, and the power tolerance > 300 mW.

[0016] An ASE light source for an optical fiber gyroscope as described above, which includes an Er:YAG-derived optical fiber. The center wavelength of the Faraday rotator mirror 1 is 1530 - 1560 nm, the reflection bandwidth is ±10 - 20 nm, the reflectivity > 98%, and the power tolerance > 300 mW.

[0017] The advantages of the present invention are:

[0018] The present invention utilizes the high rare earth ion solubility of Er:YAG-derived optical fiber, its inhibitory effect on the high-concentration luminescence quenching of Er ions, and the luminescence spectrum broadening effect to prepare an erbium-doped optical fiber with high gain and wide luminescence spectrum. A broadband and spectrally flat ASE light source that meets the requirements such as the power of IFOG can be prepared using a shorter length of active optical fiber. 3+ The present invention utilizes the high rare earth ion solubility of Er:YAG-derived optical fiber, its inhibitory effect on the high-concentration luminescence quenching of Er ions, and the luminescence spectrum broadening effect to prepare an erbium-doped optical fiber with high gain and wide luminescence spectrum. A broadband and spectrally flat ASE light source that meets the requirements such as the power of IFOG can be prepared using a shorter length of active optical fiber.

[0019] In the present invention, using YAG crystal or YAG transparent ceramic as the main material of the core of the derived optical fiber can introduce Y 3+ and Al 3+ ions, reduce the temperature dependence of the luminescence of the erbium-doped optical fiber, and improve the high performance of the ASE light source.

[0020] The present invention replaces the quartz optical fiber in the traditional EDFA with an ASE light source prepared from Er:YAG-derived optical fiber, which can be used as a common light source for IFOG. Since it can use a shorter active optical fiber and has better high performance, it can save the temperature control cost, make the IFOG structure more compact, reduce the cost, and maintain the high precision provided by the ASE light source for IFOG. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1It is a schematic structural diagram of the present invention;

[0023] Figure 2 It is a physical diagram of the end face of the Er:YAG-derived optical fiber prepared in Example 1 of the present invention;

[0024] Figure 3 It is the spectrum diagram of the ASE light source prepared in Example 1 of the present invention.

[0025] Reference numerals: 1, Faraday rotator; 2, single-mode laser diode; 3, wavelength division multiplexer; 4, Er:YAG-derived optical fiber; 5, isolator. Specific embodiments

[0026] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0027] As Figure 1 shown, an ASE light source for a fiber optic gyroscope including an Er:YAG-derived optical fiber 4 includes a Faraday rotator 1, a single-mode laser diode 2, a wavelength division multiplexer 3, an Er:YAG-derived optical fiber 4, and an isolator 5; the Faraday rotator 1 is connected to the signal end port of the wavelength division multiplexer 3 for reflecting light of a specific wavelength; the output end of the single-mode laser diode 2 is connected to the pump end of the wavelength division multiplexer 3; the common end of the wavelength division multiplexer 3 is connected to one end of the Er:YAG-derived optical fiber 4 serving as a gain medium, so that the pump light is coupled into the Er:YAG-derived optical fiber 4; the other end of the Er:YAG-derived optical fiber 4 is connected to the isolator 5 to ensure unidirectional light transmission.

[0028] Specifically, the Er:YAG-derived optical fiber 4 described in this embodiment includes a core and a cladding. The diameter of the core is 4-8 μm, the diameter of the cladding is 125 μm, and the numerical aperture of the core is 0.1-0.3, which is numerically matched with commercial optical fibers.

[0029] Specifically, the core material of the Er:YAG-derived optical fiber 4 described in this embodiment is Er:YAG crystal or Er:YAG transparent ceramic, and the cladding material is quartz glass.

[0030] More specifically, Er in the core of the Er:YAG-derived optical fiber 4 described in this embodiment 3+The ion doping concentration is 0.5 to 4 wt.%, and the core of the Er:YAG-derived optical fiber 4 is composed of Er:YAG crystal or Er:YAG transparent ceramic and SiO 2 formed by mutual diffusion and melting to form Er-doped 3+ ion yttrium aluminosilicate glass.

[0031] More specifically, Yb ions can also be doped in the Er:YAG-derived optical fiber 4 described in this embodiment. The doping concentration of the Yb 3+ ions is 1 to 6 times that of the Er 3+ ion doping concentration. Through the energy transfer between Er 3+ and Yb 3+ ions and the high absorption of Yb 3+ ions at 976 nm, the gain coefficient and optical conversion efficiency of the YAG-derived optical fiber are further improved. 3+ ions at 976 nm, the gain coefficient and optical conversion efficiency of the YAG-derived optical fiber are further improved.

[0032] More specifically, the preparation operation of the Er:YAG-derived optical fiber 4 described in this embodiment coats the outer layer of the core with a cladding to prepare an optical fiber preform, and the optical fiber preform is drawn and cooled at 2000 to 2100 °C to obtain the Er:YAG-derived optical fiber 4.

[0033] Furthermore, the use length of the Er:YAG-derived optical fiber 4 described in this embodiment is 20 to 80 cm.

[0034] Furthermore, the central wavelength of the single-mode laser diode 2 described in this embodiment is 976 nm or 1480 nm, the output fiber cladding diameter of the single-mode laser diode 2 is 125 μm, and the power is greater than 300 mW.

[0035] Even further, the central wavelength of the isolator 5 described in this embodiment is 1530 to 1560 nm, the working bandwidth is ±10 to 20 nm, and the power withstand is > 300 mW.

[0036] Even further, the central wavelength of the Faraday rotator mirror 1 described in this embodiment is 1530 to 1560 nm, the reflection bandwidth is ±10 to 20 nm, the reflectivity is > 98%, and the power withstand is > 300 mW.

[0037] Example 1:

[0038] In this example: a single-mode laser diode 2 with a central wavelength of 976 nm, an output power of 500 mW, and an output fiber core / cladding diameter of 6 / 125 μm; a wavelength division multiplexer 3 with a central wavelength of 1550 nm, a power withstand of 500 mW, and a common end and signal end fiber core / cladding diameter of 8 / 125 μm; an Er:YAG-derived optical fiber 4 (as Figure 2 shown), using Er 3+The Er:YAG crystal with an ion doping concentration of 3 mol% is used as the preform core rod, and is drawn into an Er 3+ gain fiber with an Er ion concentration of 2.5 wt.%, core / cladding diameter 8 / 125 μm, numerical aperture 0.14, core Si content 28 wt.%, Al content 6 wt.%, Y content 15 wt.%, and a length of 70 cm; an isolator 5 with a central wavelength of 1550 nm, a power handling capacity of 500 mW, input / output fiber core / cladding diameter 8 / 125 μm, ensuring unidirectional light transmission; a Faraday rotator mirror 1 with a reflection bandwidth of 1540 - 1580 nm, a reflectivity > 98%, a power handling capacity of 500 mW, input / output fiber core / cladding diameter 8 / 125 μm. Finally, an ASE light source with a central wavelength of 1560 nm, a bandwidth of 22.8 nm, and an output power of 12 mW is obtained. In the temperature range of 30 - 90 °C, the spectrum of the light source has no obvious fluctuation, as Figure 3 shown.

[0039] Example 2:

[0040] In this example: a single-mode laser diode 2 with a central wavelength of 976 nm and an output power of 500 mW, output fiber core / cladding diameter 6 / 125 μm; a wavelength division multiplexer 3 with a central wavelength of 1550 nm, a power handling capacity of 500 mW, common end and signal end fiber core / cladding diameter 8 / 125 μm; an Er:YAG derived fiber 4, using an Er 3+ The Er:YAG crystal with an ion doping concentration of 3 mol% is used as the preform core rod, and is drawn into an Er 3+ gain fiber with an Er ion concentration of 2.5 wt.%, core / cladding diameter 8 / 125 μm, numerical aperture 0.14, core Si content 28 wt.%, Al content 6 wt.%, Y content 15 wt.%, and a length of 70 cm; an isolator 5 with a central wavelength of 1550 nm, a power handling capacity of 500 mW, input / output fiber core / cladding diameter 8 / 125 μm, ensuring unidirectional light transmission; a Faraday rotator mirror 1 with a reflection bandwidth of 1540 - 1580 nm, a reflectivity > 98%, a power handling capacity of 500 mW, input / output fiber core / cladding diameter 8 / 125 μm. Finally, an ASE light source with a central wavelength of 1560 nm, a bandwidth of 25 nm, and an output power of 15 mW is obtained. In the temperature range of 30 - 90 °C, the spectrum of the light source has no obvious fluctuation.

[0041] Example 3:

[0042] In this example: a single-mode laser diode 2 with a central wavelength of 976 nm and an output power of 500 mW, output fiber core / cladding diameter 6 / 125 μm; a wavelength division multiplexer 3 with a central wavelength of 1550 nm, a power handling capacity of 500 mW, common end and signal end fiber core / cladding diameter 8 / 125 μm; an Er:YAG derived fiber 4, using an Er3+ The Er:YAG crystal with an ion doping concentration of 3 mol% of Yb 3+ and an ion doping concentration of 6 mol% of Er is used as the preform core rod, and is drawn into an Er 3+ gain fiber with an ion concentration of 2.5 wt.% of Yb 3+ and an ion concentration of 5 wt.%. The core / cladding diameter is 8 / 125 μm, the numerical aperture is 0.14, the Si content in the core is 28 wt.%, the Al content is 6 wt.%, and the Y content is 15 wt.%. The usable length is 40 cm; there are 5 isolators, the central wavelength is 1550 nm, the power it can withstand is 500 mW, the input and output fiber core / cladding diameters are 8 / 125 μm, ensuring unidirectional light transmission; there is 1 Faraday rotator mirror, the reflection bandwidth is 1540 - 1580 nm, the reflectivity > 98%, the power it can withstand is 500 mW, and the input and output fiber core / cladding diameters are 8 / 125 μm. Finally, an ASE light source with a central wavelength of 1560 nm, a bandwidth of 20 nm, and an output power of 20 mW is obtained. In the temperature range of 30 - 90 °C, the spectrum of the light source has no obvious fluctuation.

[0043] In summary, for the ASE light sources prepared in Examples 1 - 3, in the temperature range of 30 - 90 °C, the spectra of the light sources have no obvious fluctuation, thus having good high performance and saving temperature control costs, which can make the IFOG structure more compact, reduce costs, and maintain the high-precision guarantee provided by the ASE light source for the IFOG.

[0044] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An ASE light source comprising Er:YAG derived optical fiber for a fiber optic gyroscope, characterized in that: The invention comprises a Faraday rotator, a single-mode laser diode, a wavelength division multiplexer, an Er:YAG derivative optical fiber and an isolator; the Faraday rotator is connected to the signal end port of the wavelength division multiplexer for reflecting light of a specific wavelength; the output end of the single-mode laser diode is connected to the pump end of the wavelength division multiplexer; the common end of the wavelength division multiplexer is connected to one end of the Er:YAG derivative optical fiber as a gain medium; the other end of the Er:YAG derivative optical fiber is connected to the isolator to ensure unidirectional transmission of light.

2. The ASE light source comprising Er:YAG derived optical fiber for a fiber optic gyroscope according to claim 1, characterized in that: The Er:YAG derived optical fiber comprises a core and a cladding, the diameter of the core is 4-8 μm, the diameter of the cladding is 125 μm, and the numerical aperture of the core is 0.1-0.

3.

3. The ASE light source comprising Er:YAG derived optical fiber for a fiber optic gyroscope according to claim 2, characterized in that: The core material of the Er:YAG derived optical fiber is Er:YAG crystal or Er:YAG transparent ceramic, and the cladding material is quartz glass.

4. The ASE light source comprising Er:YAG derived optical fiber for a fiber optic gyroscope according to claim 2, characterized in that: The Er in the Er:YAG derived optical fiber 3+ The ion doping concentration is 0.5 to 4 wt.%.

5. The ASE light source comprising Er:YAG derived optical fiber for a fiber optic gyroscope according to claim 4, characterized in that: The Er:YAG derived optical fiber can also be doped with Yb 3+ ions, the Yb 3+ The ion doping concentration is Er 3+ 1 to 6 times the ion doping concentration.

6. The ASE light source comprising Er:YAG derived optical fiber for a fiber optic gyroscope according to claim 2, characterized in that: The preparation operation of the Er:YAG derived optical fiber is to coat the outer layer of the fiber core with the cladding layer to prepare an optical fiber preform rod. The optical fiber preform rod is drawn at 2000-2100°C and then cooled to obtain the Er:YAG derived optical fiber.

7. The ASE light source comprising Er:YAG derived optical fiber for a fiber optic gyroscope according to claim 1, characterized in that: The use length of the Er:YAG derived optical fiber is 20 to 80 cm.

8. The ASE light source comprising Er:YAG derived optical fiber for a fiber optic gyroscope according to claim 1, characterized in that: The central wavelength of the single-mode laser diode is 976nm or 1480nm, the output optical fiber cladding diameter of the single-mode laser diode is 125μm, and the power is greater than 300mW.

9. The ASE light source comprising Er:YAG derived optical fiber for a fiber optic gyroscope according to claim 1, characterized in that: The central wavelength of the isolator is 1530-1560nm, the working bandwidth is ±10-20nm, and the withstand power is greater than 300mW.

10. The ASE light source comprising Er:YAG derived optical fiber for a fiber optic gyroscope according to claim 1, characterized in that: The central wavelength of the Faraday rotator 1 is 1530-1560nm, the reflection bandwidth is ±10-20nm, the reflectivity is greater than 98%, and the withstand power is greater than 300mW.

Images