ASE light source capable of stabilizing average wavelength and optical fiber gyroscope

Abstract

The invention relates to the technical field of navigation instruments, in particular to an ASE (Accelerated Solvent Extraction) light source capable of stabilizing average wavelength and an optical fiber gyroscope, which adopt a two-way backward light path structure with high power, wide spectral width and stable average wavelength, and comprise a two-stage erbium-doped optical fiber structure in the light path. The temperature sensitivity of the average wavelength of output light of the ASE light source is reduced by adjusting the lengths of the two sections of erbium-doped optical fibers, a long-period fiber grating is designed in a light path, the average wavelength of a reflectivity peak of the long-period fiber grating and the average wavelength of the output light of the ASE light source are increased along with temperature rise, average wavelength drift caused by temperature is reduced, a Lyot depolarizer is designed in the light path, and the average wavelength drift of the output light of the ASE light source is reduced. The ASE light source is arranged behind the pump laser, the influence of polarization of output light of the pump laser on the average wavelength of the output light of the ASE light source is reduced, in addition, a Faraday rotating lens is designed, the reflected light is orthogonal to the polarization state of incident light, and the influence of polarization of the output light of the pump laser on the average wavelength of the output light of the ASE light source is further reduced.

Description

Technical Field

[0001] The invention relates to the technical field of navigation instruments, and in particular to an ASE light source and an optical fiber gyroscope capable of stabilizing an average wavelength. Background Art

[0002] Nowadays, ASE light sources are widely used in high-precision fiber optic gyroscopes due to their advantages such as high output light power and wide spectral width. In fiber optic gyroscopes, the stability of the average wavelength of the light source output light will greatly affect the important performance indicator of the gyroscope's zero-bias stability. Therefore, improving the average wavelength stability of the ASE light source output light is an important requirement that has always received much attention in the development of high-precision fiber optic gyroscope technology. The average wavelength stability of the ASE light source output light is mainly related to temperature, erbium-doped fiber length, pump laser output light power, wavelength stability, and polarization of the pump laser output light. The two factors with the greatest impact are temperature and polarization of the pump source laser output light.

[0003] Nowadays, most methods to improve the average wavelength stability of lasers are to optimize the length of erbium-doped fiber and control the wavelength stability and power stability of the output light of the pump source laser. However, this alone cannot effectively reduce the influence of temperature and pump source polarization on the average wavelength of the output light of the light source. The influence of temperature on the average wavelength is about 1ppm / ℃. The operating temperature range of common high-precision gyroscopes generally has a temperature difference of about 100℃. Therefore, the average wavelength change caused by temperature can reach 100ppm. The various polarization states of the output light of the pump source have a maximum influence on the average wavelength of the output light of the light source, which can also reach 100ppm. It can be seen that the two have an important influence on the stability of the average wavelength of the output light of the ASE light source, which will also lead to a reduction in the accuracy of the fiber optic gyroscope. Summary of the invention

[0004] The problem solved by the present invention is to propose an ASE light source with a stable average wavelength, which can improve the stability of the average wavelength of the output light of the ASE light source, thereby ensuring the accuracy of a high-precision fiber optic gyroscope.

[0005] To achieve the above objectives, the present invention adopts the following technical solutions:

[0006] On the one hand, the present application provides an ASE light source capable of stabilizing an average wavelength, comprising: a 980nm LD pump laser, a pump laser driver, a Lyot depolarizer, a 1×2 polarization-maintaining fiber coupler, a first wavelength division multiplexer, a second wavelength division multiplexer, a first erbium-doped fiber, a second erbium-doped fiber, a Faraday rotator mirror, a long-period fiber grating, and an optical isolator;

[0007] One end of the pump laser driving device is connected to an external power supply, and the other end is connected to the LD pump laser, and is used to inject current into the LD pump laser and control the temperature;

[0008] The LD pump laser is connected to the Lyot depolarizer, the Lyot depolarizer is connected to the 1×2 polarization-maintaining fiber coupler, and the 1×2 polarization-maintaining fiber coupler is respectively connected to the input ends of the first wavelength division multiplexer and the second wavelength division multiplexer, and the output light of the LD pump laser passes through the Lyot depolarizer, and the output light of the Lyot depolarizer will be randomly and evenly distributed in all possible polarization states thereof, and the output light of the Lyot depolarizer then passes through the 1×2 fiber coupler, and the 1×2 fiber coupler has a splitting ratio of 50:50, and is used as a splitting device to evenly distribute the optical power to the input ends of the first wavelength division multiplexer and the second wavelength division multiplexer;

[0009] The first wavelength division multiplexer is connected to the first section of erbium-doped fiber and the long-period fiber grating, respectively, and is used for the first wavelength division multiplexer to transmit the 980nm pump light to the first section of erbium-doped fiber, and stimulate the signal light with a wavelength of 1550nm, and then separate the backward signal light and output it to the long-period fiber grating;

[0010] The second wavelength division multiplexer is connected to the erbium-doped fiber and the second erbium-doped fiber respectively, and the second erbium-doped fiber is connected to the Faraday rotator, so that the second wavelength division multiplexer transmits the 980nm pump light to the second erbium-doped fiber and excites the signal light with a wavelength of 1550nm, and the backward signal light is then output to the long period fiber grating through the first wavelength division multiplexer and the second wavelength division multiplexer;

[0011] The long-period fiber grating is connected to the optical isolator, and is used for transmitting light modulated by the long-period fiber grating, and outputting light as highly polarized linearly polarized light after entering the optical isolator.

[0012] Furthermore, the above-mentioned ASE light source capable of stabilizing the average wavelength, the pump laser driving device comprises: a current driving and temperature control module;

[0013] The current driver is used to inject current into the LD pump laser;

[0014] The temperature control module is used to control the temperature of the LD pump laser.

[0015] Furthermore, the above-mentioned ASE light source capable of stabilizing the average wavelength further includes: an indicator light module;

[0016] The indicator light module is used to display the working status of the ASE light source.

[0017] Furthermore, the above-mentioned ASE light source capable of stabilizing the average wavelength further includes: a switch module;

[0018] The switch module is arranged between the pump laser driving device and an external power supply.

[0019] On the other hand, the present application provides a fiber optic gyroscope, comprising the ASE light source with a stable average wavelength as described in any of the above items.

[0020] The beneficial effects of the present invention are:

[0021] A double-pass backward optical path structure with high power, wide spectrum width and relatively stable average wavelength is adopted. The optical path design includes a more flexible dual-stage erbium-doped fiber structure, which can reduce the temperature sensitivity of the average wavelength of the output light of the ASE light source by adjusting the length of the two sections of erbium-doped fiber. A long-period fiber grating is also designed in the optical path. The average wavelength of its reflectivity peak and the average wavelength of the output light of the ASE light source increase with the increase of temperature. Therefore, after the transmission light signal of the long-period fiber grating is filtered by the grating, the average wavelength drift caused by temperature is reduced.

[0022] A Lyot depolarizer is also designed in the optical path, which is placed after the pump laser to reduce the influence of the polarization of the pump laser output light on the average wavelength of the ASE light source output light. In addition, a Faraday rotation lens is designed, and its reflected light is orthogonal to the polarization state of the incident light, so as to further reduce the influence of the polarization of the pump laser output light on the average wavelength of the ASE light source output light. In the temperature range of about 100°C (-45°C to 70°C), the average wavelength drift of the tested traditional ASE light source at full temperature is on the order of 200ppm. The ASE light source optical path designed by the present invention can reduce the average wavelength drift at full temperature to the order of 20ppm. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 It is a schematic diagram of a light path provided by an embodiment of an ASE light source capable of stabilizing an average wavelength of the present invention;

[0025] Figure 2 This is a graph showing the variation of the average wavelength of a traditional ASE light source with temperature, provided by an embodiment of an ASE light source capable of stabilizing the average wavelength of the present invention;

[0026] Figure 3 This is a graph showing the variation of the average wavelength of the ASE light source of the present application with temperature, provided in one embodiment of the ASE light source capable of stabilizing the average wavelength of the present invention.

[0027] Figure 1 In: 1-pump laser driver, 2-LD pump laser, 3-Lyot depolarizer, 4-1×2 fiber coupler, 5-first wavelength division multiplexer, 6-first erbium-doped fiber, 7-second wavelength division multiplexer, 8-second erbium-doped fiber, 9-Faraday rotation mirror, 10-long period fiber grating, 11-optical isolator. DETAILED DESCRIPTION

[0028] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0029] Figure 1 This is a schematic diagram of the optical path provided by an embodiment of an ASE light source capable of stabilizing the average wavelength of the present invention. Figure 1 , this embodiment may include:

[0030] 980nm LD pump laser, pump laser driver, Lyot depolarizer, 1×2 polarization-maintaining fiber coupler, first wavelength division multiplexer, second wavelength division multiplexer, first erbium-doped fiber, second erbium-doped fiber, Faraday rotator, long period fiber grating and optical isolator;

[0031] One end of the pump laser driver is connected to an external power source, and the other end is connected to the LD pump laser, and is used to inject current into the LD pump laser and control the temperature;

[0032] The LD pump laser is connected to a Lyot depolarizer, the Lyot depolarizer is connected to a 1×2 polarization-maintaining fiber coupler, and the 1×2 polarization-maintaining fiber coupler is respectively connected to the input ends of the first wavelength division multiplexer and the second wavelength division multiplexer. The output light of the LD pump laser passes through the Lyot depolarizer, and the output light of the Lyot depolarizer will be randomly and evenly distributed in all possible polarization states. The output light of the Lyot depolarizer then passes through the 1×2 fiber coupler, and the splitting ratio of the 1×2 fiber coupler is 50:50. The 1×2 fiber coupler is used as a splitting device to evenly distribute the optical power to the input ends of the first wavelength division multiplexer and the second wavelength division multiplexer.

[0033] The first wavelength division multiplexer is connected to the first section of erbium-doped fiber and the long-period fiber grating, and is used for the first wavelength division multiplexer to transmit the 980nm pump light to the first section of erbium-doped fiber, and stimulate the signal light with a wavelength of 1550nm, and then separate the backward signal light and output it to the long-period fiber grating;

[0034] The second wavelength division multiplexer is connected to the erbium-doped fiber and the second erbium-doped fiber respectively, and the second erbium-doped fiber is connected to the Faraday rotator mirror, so that the second wavelength division multiplexer transmits the 980nm pump light to the second erbium-doped fiber and excites the signal light with a wavelength of 1550nm, and the backward signal light is output to the long-period fiber grating through the first wavelength division multiplexer and the second wavelength division multiplexer;

[0035] The long-period fiber grating is connected to an optical isolator, and is used for transmitting light modulated by the long-period fiber grating. After entering the optical isolator, the output light is highly polarized linearly polarized light.

[0036] It can be understood that the pump laser driver consists of two parts: a temperature control system and a constant current system. It is connected to an LD pump laser with an output light wavelength of 980nm to provide injection current and temperature control to the LD pump laser. The output light of the LD pump laser passes through a Lyot depolarizer, and the output light of the Lyot depolarizer will be randomly and evenly distributed in all its possible polarization states. The output light signal of the Lyot depolarizer passes through a 1×2 fiber coupler, and the 1×2 fiber coupler 4 has a splitting ratio of 50:50. This is used as a splitting device to evenly distribute the optical power to its two output ends. One output end of the 1×2 fiber coupler is connected to the first wavelength division multiplexer, and the other output end is connected to the second wavelength division multiplexer.

[0037] Of the two input ports of the first wavelength division multiplexer, the input end connected to the 1×2 fiber coupler has an operating wavelength of 980±10nm, and the input end connected to the long period fiber grating 10 has an operating wavelength of 1550±30nm. Of the two input ports of the second wavelength division multiplexer, the input end connected to the 1×2 fiber coupler has an operating wavelength of 980±10nm, and the input end connected to the first erbium-doped fiber has an operating wavelength of 1550±30nm.

[0038] The first wavelength division multiplexer transmits the 980nm pump light to the first erbium-doped fiber, and excites the signal light with a wavelength of about 1550nm, and then separates the backward signal light and outputs it to the long-period fiber grating. The second wavelength division multiplexer also transmits the 980nm pump light to the second erbium-doped fiber, and excites the signal light with a wavelength of about 1550nm, and the backward signal light is separated and output to the long-period fiber grating 10 by two wavelength division multiplexers. The forward signal light excited by the two sections of erbium-doped fiber is reflected by the Faraday rotation mirror, and the polarization states of the signal light after reflection are orthogonal, and finally separated and output to the long-period fiber grating by two wavelength division multiplexers.

[0039] The signal light is transmitted through the long-period fiber grating and is modulated and filtered by the grating transmittance. Since the reflection peak of the long-period fiber grating and the average wavelength of the output light of the ASE light source increase with the increase of temperature, the signal light can be temperature compensated to reduce the temperature sensitivity of the average wavelength of the output light.

[0040] The transmitted light modulated by the long-period fiber grating is incident on the optical isolator, and the output light is highly polarized linear polarized light, which can meet the high polarization degree requirement of the light source output light of the full polarization-maintaining high-precision fiber gyroscope. If it is a mixed polarization type or depolarization type high-precision fiber gyroscope, a depolarizer can be added after the optical isolator to make the light source become a non-polarized or low-polarized light source to reduce the polarization-related error of the gyroscope. The optical isolator 11 also prevents the signal light transmitted in the rear optical path or the reflected light transmitted in the optical path from entering the light source to avoid causing the lasing of the broadband light source.

[0041] Preferably, the pump laser driving device comprises: a current driving and temperature control module;

[0042] Current drive, used to inject current into the LD pump laser;

[0043] Temperature control module, used to control the temperature of LD pump laser.

[0044] It can be understood that the current drive and temperature control module keeps the injection current of the LD pump laser unchanged, so that the output optical power of the LD pump laser is stable, thereby reducing the influence of the output optical power of the LD pump laser on the stability of the average wavelength of the output light of the ASE light source.

[0045] Preferably, it also includes: an indicator light module;

[0046] The indicator light module is used to display the working status of the ASE light source.

[0047] Preferably, it also includes: a switch module;

[0048] The switch module is arranged between the pump laser driving device and the external power supply.

[0049] In a specific embodiment, the present invention designs an optical path including a dipole structure, specifically: the splitting ratio of the 1×2 fiber coupler in the optical path is 50:50, which is used as a power divider, wherein the first output end is connected to the first wavelength division multiplexer, the first wavelength division multiplexer is connected to the first section of erbium-doped fiber, the second output end of the 1×2 fiber coupler and the other end of the first section of erbium-doped fiber are connected to the second wavelength division multiplexer, and the second wavelength division multiplexer is connected to the second section of erbium-doped fiber. There are two sections of erbium-doped fiber for spontaneous radiation gain, and the fiber lengths of the two ends of the fiber are variable. The lengths of the two sections of fiber are named L1 and L2, respectively. A group value (L1, L2) can always be found in the optical path, so that the temperature sensitivity of the average wavelength of the output light of the ASE light source is the lowest.

[0050] In a specific embodiment, a long-period fiber grating is designed, and the average wavelength of its reflectivity peak increases with the increase of temperature. Figure 2 and Figure 3 As shown in the figure, the average wavelength of the output light of the ASE light source also increases with the increase of temperature. Therefore, the transmission light signal of the long-period fiber grating is filtered by the grating and used as temperature compensation to reduce the average wavelength drift caused by temperature. In a temperature change of 100°C, the stability of the average wavelength can be improved from 100ppm to less than about 10ppm.

[0051] In a specific embodiment, the present invention designs a Lyot depolarizer between the pump laser and the 1×2 fiber coupler. The depolarizer is formed by fusing high-birefringence optical fibers with a length of 1:2 at both ends at a 45° angle. The depolarizer can reduce the average wavelength drift of the ASE light source output light caused by the polarization of the pump laser output light to below 10ppm.

[0052] In a specific embodiment, the present invention further designs a Faraday rotation lens, whose reflected light is orthogonal to the polarization state of the incident light, thereby further reducing the influence of the polarization of the pump laser output light on the average wavelength of the ASE light source output light.

[0053] The present application also provides a fiber optic gyroscope, comprising any of the above ASE light sources with a stable average wavelength.

[0054] It can be understood that the same or similar parts of the above embodiments can be referenced to each other, and the contents not described in detail in some embodiments can refer to the same or similar contents in other embodiments.

[0055] It should be noted that, in the description of the present invention, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, the meaning of "plurality" refers to at least two.

[0056] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code that includes one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present invention belong.

[0057] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0058] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0059] In addition, each functional unit in each embodiment of the present invention may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0060] The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc.

[0061] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0062] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. An ASE light source capable of stabilizing an average wavelength, characterized in that: include: 980nm LD pump laser, pump laser driver, Lyot depolarizer, 1×2 polarization-maintaining fiber coupler, first wavelength division multiplexer, second wavelength division multiplexer, first erbium-doped fiber, second erbium-doped fiber, Faraday rotator, long period fiber grating and optical isolator; One end of the pump laser driving device is connected to an external power supply, and the other end is connected to the LD pump laser, and is used to inject current into the LD pump laser and control the temperature; The LD pump laser is connected to the Lyot depolarizer, the Lyot depolarizer is connected to the 1×2 polarization-maintaining fiber coupler, and the 1×2 polarization-maintaining fiber coupler is respectively connected to the input ends of the first wavelength division multiplexer and the second wavelength division multiplexer, and the output light of the LD pump laser passes through the Lyot depolarizer, and the output light of the Lyot depolarizer will be randomly and evenly distributed in all possible polarization states thereof, and the output light of the Lyot depolarizer then passes through the 1×2 fiber coupler, and the 1×2 fiber coupler has a splitting ratio of 50:50, and is used as a splitting device to evenly distribute the optical power to the input ends of the first wavelength division multiplexer and the second wavelength division multiplexer; The first wavelength division multiplexer is connected to the first section of erbium-doped fiber and the long-period fiber grating, respectively, and is used for the first wavelength division multiplexer to transmit the 980nm pump light to the first section of erbium-doped fiber, and stimulate the signal light with a wavelength of 1550nm, and then separate the backward signal light and output it to the long-period fiber grating; The second wavelength division multiplexer is connected to the erbium-doped fiber and the second erbium-doped fiber respectively, and the second erbium-doped fiber is connected to the Faraday rotator, so that the second wavelength division multiplexer transmits the 980nm pump light to the second erbium-doped fiber and excites the signal light with a wavelength of 1550nm, and the backward signal light is then output to the long period fiber grating through the first wavelength division multiplexer and the second wavelength division multiplexer; The long-period fiber grating is connected to the optical isolator, and is used for transmitting light modulated by the long-period fiber grating, and outputting light as highly polarized linearly polarized light after entering the optical isolator.

2. The ASE light source with stable average wavelength according to claim 1, characterized in that: The pump laser driving device comprises: a current driving and temperature control module; The current driver is used to inject current into the LD pump laser; The temperature control module is used to control the temperature of the LD pump laser.

3. The ASE light source with stable average wavelength according to claim 2, characterized in that: Also includes: Indicator light module; The indicator light module is used to display the working status of the ASE light source.

4. The ASE light source with stable average wavelength according to claim 3, characterized in that: Also includes: Switch module; The switch module is arranged between the pump laser driving device and an external power supply.

5. A fiber optic gyroscope, characterized in that: An ASE light source with a stable average wavelength comprising any one of claims 1-4.

Images