System installed on an aircraft

Abstract

A system installed on an aircraft. The system includes: a memory that stores static information in one or more fiber Bragg gratings; and an interrogator. The interrogator includes: a light source configured to send interrogation light to the memory; a receiver configured to receive return light from the memory; and an analyzer configured to analyze the return light to obtain the static information.

Description

Technical Field

[0001] The present invention relates to systems installed on an aircraft, such as avionics systems. Background Art

[0002] Avionics systems installed on an aircraft typically require static data to be stored, for example, to indicate the location of line replaceable units (LRUs) - an LRU is a modular component of the aircraft designed to be quickly replaced in an operating position. A known method of storing such static data is so-called hardware pin programming (HPP). Figure 1 System 100 using HPP is shown. System 100 includes three LRUs 102a, 102b, 102c. Each LRU is the same piece of hardware, and each LRU includes a number of software configurations 104, one of the number of software configurations 104 being executed at startup. The software configuration 104 that is executed depends on the location and intended function of LRUs 102a to 102c.

[0003] Each of LRUs 102a to 102c has a plurality of pins 106, and each pin is connected to hardware indicating a binary "1" or a binary "0". In this example, the first pin among the pins of LRU 102a is connected to a reference voltage 108, a pull-up resistor 110, and an analog-to-digital converter 112; and the second pin among the pins of LRU 102a is connected to the same hardware, but in this case is grounded at 114. Thus, the voltage on the first pin will be high (indicating a binary "1"), and the voltage on the second pin will be low (indicating a binary "0").

[0004] In this case, the hardware connected to LRU 102a stores static data represented by the binary number 111000; the hardware connected to LRU 102b stores static data represented by the binary number 101010; and the hardware connected to LRU 102c stores static data represented by the binary number 001101.

[0005] In this case, the static data is encoded by only six binary digits, but if a larger amount of static data is required, the number of pins and the associated hardware must be increased. The number of pins may often exceed sixteen. This increases the weight and size of the system, which is a particular problem on an aircraft due to the limited available space and the importance of minimizing weight to maximize fuel efficiency. Summary of the Invention

[0006] A first aspect of the present invention provides a system installed on an aircraft according to a preferred embodiment of the present invention.

[0007] Preferred aspects of the present invention are set out in the dependent claims.

[0008] The memory stores static information in one or more fiber Bragg gratings. Such a memory is well-suited for use on an aircraft because it is passive, compact, reliable, immune to electromagnetic interference, and does not degrade during flight.

[0009] The light source is configured to send interrogation light to the memory, the receiver is configured to receive light from the memory, and the analyzer is configured to analyze the light from the memory to obtain the static information.

[0010] The receiver receives light from the memory and typically outputs an electrical signal containing the static information. For example, the receiver can be a photodetector. The analyzer analyzes the light from the memory (e.g., by analyzing the electrical signal) to retrieve the static information. Optionally, for example, the receiver and the analyzer are part of a spectrometer.

[0011] The light from the memory may have passed through the memory. In this case, the light from the memory can represent the absorption spectrum of the memory. The interrogation light and the light from the memory can propagate to and from the memory along different optical paths, and the light source and the receiver can be physically separated.

[0012] More preferably, the light from the memory is the return light reflected from the memory. In this case, the return light can represent the reflection spectrum, and both the interrogation light and the return light can propagate along the same optical path.

[0013] Optionally, the light source, the receiver, and the analyzer are part of an interrogator - the interrogator can be a modular unit containing the light source, the receiver, and the analyzer.

[0014] In one embodiment of the present invention, neither the memory nor the interrogator is part of a replaceable unit. In this example, the memory or the interrogator can be part of a modular unit designed to be permanently connected to the system, rather than part of a replaceable unit. Thus, for example, the interrogator can be optically coupled to the memory through a splicing unit that permanently fuses the fiber on the memory side to the fiber on the interrogator side.

[0015] In another embodiment of the present invention, the memory is part of a replaceable unit that can be removed from the system by disconnecting one or more optical connections between the memory and the rest of the system.

[0016] Optionally, the light source, the receiver, and the analyzer are part of the interrogator, and the memory or the interrogator is part of a replaceable unit that can be removed from the system by disconnecting one or more optical connections between the memory and the interrogator.

[0017] Optionally, the optical connection includes a first optical fiber coupled to the receiver and the light source; a second optical fiber optically coupled to the memory; and an optical connector that optically couples the first optical fiber to the second optical fiber. In this case, the optical connection can be disconnected by decoupling the first optical fiber from the second optical fiber, for example, by removing the optical connector or by removing one of the optical fibers from the optical connector.

[0018] Optionally, the replaceable unit includes the first optical fiber or the second optical fiber, and the first optical fiber or the second optical fiber can be removed from the system together with the rest of the replaceable unit.

[0019] The optical connector can include a mechanical engagement unit, a beam expander unit, or any other arrangement that enables the replaceable unit to be disconnected from the rest of the system.

[0020] One or more fiber gratings can consist of a single fiber grating (e.g., a chirped fiber grating), but more typically, one or more fiber gratings are two or more fiber gratings arranged in a chain of fiber gratings. Description of the Drawings

[0021] Embodiments of the present invention will now be described with reference to the drawings, in which:

[0022] Figure 1 The HPP system is shown;

[0023] Figure 2 A chain of fiber Bragg gratings (FBGs) is shown;

[0024] Figure 3A An avionics system with a single LRU is shown;

[0025] Figure 3B An avionics system with two RDCs is shown;

[0026] Figure 4A The mechanical engagement unit is shown;

[0027] Figure 4B The beam expander is shown;

[0028] Figure 5 An avionics system with a single sensor LRU is shown;

[0029] Figure 6 An avionics system with a single actuator LRU is shown;

[0030] Figure 7 An avionics system with multiple actuator LRUs interrogated by wavelength division multiplexing is shown;

[0031] Figure 8 An avionics system is shown having a plurality of actuator LRUs connected by switches;

[0032] Figure 9 An avionics system is shown having a plurality of actuator LRUs interrogated by time division multiplexing; and

[0033] Figure 10 An aircraft having an installed avionics system is shown. DETAILED DESCRIPTION

[0034] The avionics system described below uses a fiber optic grating chain instead of an HPP to encode static data. First referring to Figure 2 , a fiber Bragg grating chain 200 is shown. The chain includes an optical fiber 202 and a plurality of fiber Bragg gratings 204 arranged in series along the optical fiber 202. The nature of each fiber Bragg grating 204 is such that there are periodically alternating refractive indices in the line of the optical fiber 202. Due to the periodically alternating refractive indices, constructive interference occurs only for light of a specific wavelength. The light of that wavelength is reflected and the remaining light is transmitted through the grating 204. The reflected wavelength can be adjusted by adjusting the spacing of the alternating refractive index regions.

[0035] A broadband light source (not shown) irradiates broadband light (having a spectrum indicated at 206) into the optical fiber 202. Light having a specific optical wavelength produced by the spacing of the alternating refractive index regions is reflected by the grating 204 to provide return light having a spectrum as indicated at 208. As indicated by the spectrum 210, the remaining light is transmitted.

[0036] Figure 2 Four fiber Bragg gratings 204 are shown, each having a different spacing between the alternating refractive index regions. In the illustrated gratings, the bright bands indicate regions having a first refractive index and the dark bands indicate regions having a second refractive index. The leftmost first grating 204 reflects light of wavelength λ 1 , the second grating 204 reflects light of wavelength λ 2 , the third grating 204 reflects light of wavelength λ 3 , and the fourth grating 204 reflects light of wavelength λ 4 . The fifth and last grating is a built-in test equipment (BITE) grating 212. The purpose of the BITE grating 212 is to indicate that all data has been collected from the chain 200 by reflecting light having a known wavelength. Failure to collect the reflected light having the characteristic wavelength peak of the BITE grating 212 can indicate that the optical fiber 202 has been damaged, meaning that data from the gratings 204 (including the BITE grating 212) after the damage has been lost.

[0037] At the end of the optical fiber 202 is a termination absorber 214. The termination absorber 214 absorbs any light that has transmitted through all of the gratings 204 in the optical fiber 202 to ensure that any such light is not reflected back through the optical fiber, which could interfere with the light reflected by the gratings 204.

[0038] Static information can be stored in the memory 302 in binary format. For example, to register a "1", the expected peak wavelength is within a specific range. If the peak wavelength does not appear within that range, either because the grating reflects a peak wavelength outside of that range or because the grating for that bit is omitted, a "0" will be registered.

[0039] Thus, in Figure 2 example, the chain 200 has four gratings 204 with wavelengths λ 1 , λ 2 , λ 3 and λ 4 , so the chain 200 stores the binary number 1111. If the chain only has three gratings 204 with wavelengths λ 1 , λ 2 and λ 4 , the chain stores the binary number 1101; if the chain only has two gratings 204 with wavelengths λ 1 and λ 3 , the chain stores the binary number 1010; and so on.

[0040] Alternatively, a non-binary numbering system with a radix higher than 2 can be used to store static information in the chain. For example, if the peak wavelength returns within a first range, the digit can be assigned "0", if the peak wavelength returns within a second range, the digit can be assigned "1", if the peak wavelength returns within a third range, the digit can be assigned "2", and so on. In this way, much more data can be stored in an optical fiber that is significantly shorter in length than an optical fiber using a binary numbering system. However, it is important that the ranges indicating each specific data value are set with sufficient tolerance such that there is no risk of overlap between adjacent data values due to temperature drift, which could lead to uncertainty in the returned data value. Although having a lower storage density, the binary storage system, especially a binary storage system where the gratings are present or absent (and thus light is reflected or not reflected), provides information with a much lower risk of facing uncertainty.

[0041] Now referring to Figure 3A , an avionics system 300 installed on an aircraft 1 in Figure 10 is shown. The system 300 includes a memory 302 and a line replaceable unit (LRU) 304. The memory 302 stores static information in an optical fiber Bragg grating chain using the principles discussed above with reference to Figure 2 .

[0042] The LRU 304 includes an interrogator 308 and a processor 310. The processor is capable of executing one of two software configurations 312a, 312b. The LRU 304 is a general hardware module capable of executing one of a plurality of specific functions determined by the executed software configuration. In this example, two software configurations 312a, 312b are executable, but for example, there may be a larger number of executable software configurations such as 30 or 1000. The executed software configuration 312a, 312b is determined by static information obtained from a memory 302, which may give an indication of the location of the LRU 304, the intended function of the LRU 304, or simply a direct indication of which software configuration 312a, 312b is to be executed.

[0043] The static information is obtained from the memory 302 by the interrogator 308. The interrogator 308 includes a light source 314 (e.g., a broadband light source such as a superluminescent diode or a frequency-swept laser), a receiver 316 (e.g., a photodetector), an analyzer 318 (e.g., a spectrometer), and a circulator 320. The receiver 316 has the function of generating a receiver output, such as an analog or digital electrical signal, based on the light received from the memory. The analyzer 318 has the function of converting the receiver output into digital information (if the receiver output is analog) and analyzing it to obtain the static information. The light source 314 sends interrogation light to the memory 302 via the circulator 320, an optical connector 306, and first and second optical fibers 307a and 307b. The first optical fiber 307a is optically coupled to the receiver and the light source; and the second optical fiber 307b is optically coupled to the memory.

[0044] Using the principles discussed above Figure 2 The interrogation light is reflected by a fiber Bragg grating chain in the memory 302 and the return light is received from the memory 302 by the receiver 316 via the optical connector 306, the optical fibers 307a, 307b, and the circulator 320. Thus, the return light consists of a series of narrow wavelength bands, where the specific wavelength peaks in the bands are determined by each grating in the fiber Bragg grating chain. Then, the analyzer 318 analyzes the return light received by the receiver 316 to extract the static information stored in the memory 302, which can be stored in binary or non-binary format as described above.

[0045] After analyzing the return light, the analyzer 318 sends the static information to the processor 310, which accordingly selects the appropriate software configuration 312a, 312b. Thus, for example, if the static information is 111111, configuration 312a is selected, while if the static information is 000000, configuration 312b is selected.

[0046] As mentioned above, the optical connectors 306 and the optical fibers 307a, 307b connect the interrogator 308 to the memory 302. The LRU 304 can be disconnected from the rest of the system 300 by disconnecting the optical connection formed by the optical connectors 306 and the optical fibers 307a, 307b, for example, by disconnecting or separating one of the optical fibers from the optical connector 306 or by removing the optical connector 306. Then, for example, the LRU 304 can be removed, replaced, or repaired during maintenance. Since each uninstalled LRU 304 is a general-purpose hardware module capable of performing many different functions, a batch of spare LRUs can be maintained at a significantly lower cost and inconvenience compared to the case where separate spare parts for each individual specific component must be supplied and maintained. An example of the optical connector 306 is discussed below.

[0047] Now referring to Figure 3B , an avionics system including the system shown in Figure 3A is illustrated. It can be seen that each in the system includes an LRU 304 and memories 322a, 322b. The static information stored in the first memory 322a is different from the static information stored in the second memory 322b. Since the static information stored in the first memory 322a is different from the static information stored in the second memory 322b, the LRU connected to the first memory 322a will execute a different software configuration from the LRU connected to the second memory 322b. Therefore, the two LRUs will perform different functions. The system is installed on the aircraft 1 and connected via the bus 326.

[0048] In the Figure 3B example, each LRU 304 can be a remote data concentrator (RDC) connected to three signal sources 328a or 328b via optical or electrical connectors, and the three signal sources 328a or 328b can be sensors, for example. The RDC obtains data from the signal sources. As an example, the signal source 328a can be a sensor on the main landing gear of the aircraft, and the signal source 328b can be a sensor on the nose landing gear of the aircraft. The static data stored in the first memory 322a informs the first RDC (as part of the RDC startup process) that the first RDC must configure itself as the RDC on the main landing gear, and the static data stored in the second memory 322a informs the second RDC (as part of the RDC startup process) that the second RDC must configure itself as the RDC on the nose landing gear. Thus, the two RDCs can be easily replaced or interchanged. The static data can also give the unique identity of the aircraft on which the LRU is installed.

[0049] The optical connector 306 can be a docking detachable optical connector, a beam-expanding optical connector, or any other suitable optical coupling device.Figure 4A and Figure 4B Two examples are given.

[0050] Figure 4A A first example of an optical connector 306 is shown - in this case a docking detachable optical connector. Each optical fiber 307a, 307b includes a core 404 and a housing 406. The ends of the cores 404 are butted against each other and held in place by a mechanical engagement unit 402. Alternatively, there may be a gap between the ends of the cores 404, and the gap is filled with a gel having the same refractive index as the refractive index of the core 404. The optical fibers 307a, 307b are not permanently fused, but are only held precisely together such that light can be transmitted from one optical fiber core 404 to the other optical fiber core 404. The optical connection can be disassembled by removing or loosening the engagement unit 402 and disconnecting the optical fibers 307a, 307b. Figure 4A of the optical connection.

[0051] Figure 4B An alternative optical connector 306 is shown, which in this case is a beam-expanding optical connector. The ends of the two optical fibers 307a, 307b are held at a certain distance by a unit 408, and two lenses 410 are held between the ends of the optical fibers. When light leaves the end of one optical fiber, since the light is no longer confined in the optical fiber, the light begins to expand. Then the light hits the first lens 410, where the light is collimated and directed towards the second lens 410. When passing through the second lens 410, the light is focused into the end of the second optical fiber.

[0052] The optical connection can be disconnected by removing one of the optical fibers 307a or 307b from the unit 408 or by disassembling the unit 408 and removing the two lenses. Figure 4B of the optical connections 306, 307a, 307b.

[0053] Compared with the docking connector or the engagement unit, the arrangement of the beam-expanding unit 408 provides the advantage of being less sensitive to dust contamination.

[0054] Due to the small size of the fiber Bragg grating and the ability to form chains in a very small space, the memory 302 can be a fully encapsulated part of the optical connector 306 (such as a small stub or wire) or be encapsulated in a connector having other pins / connections (such as an embedded power connector), where the second optical fiber 307b does not leave the connector 306.

[0055] Figure 5 An avionics system 500 installed on an aircraft 1 is shown. Some elements of the system are the same as the elements shown in Figure 3A and these elements will not be described again. In Figure 3AIn this case, the memory 302 is a permanent part of the avionics system 300 - in other words, the memory 302 is not part of the LRU and can be part of the aircraft wiring. In Figure 5 this case, the memory 302 is part of the sensor LRU 501.

[0056] In this case, the LRU is the sensor LRU 501 that includes a sensor 502 such as a temperature sensor or a strain gauge. The sensor 502 outputs a sensor signal such as a voltage to the processor 503 via an electrical connector 504. Calibration data is required to correlate the sensor signal with a measured parameter (such as temperature or strain). This calibration data is determined during the manufacture of the sensor 502, is represented by static information stored in the memory 302, and the sensor 502 and its associated memory 302 are encapsulated together within the sensor LRU 501. Thus, the sensor LRU 501 carries its own unique calibration data, which is encoded within the memory 302.

[0057] The processor 503 (which can be a permanent part of the system 500 such as a flight control computer or can itself be part of the RDC, where the RDC itself is an LRU) receives the sensor signal via the electrical connector 504, receives the static information from the interrogator 308, and processes the sensor signal according to the calibration data represented by the static information.

[0058] The static information can contain all the calibration data - for example, the coefficients of a linear or non - linear transformation function for converting the voltage into the desired measured parameter. Alternatively, if the calibration data can be reduced to one of a finite number of calibration data sets, these data sets can be stored in a look - up table, which is accessed by the processor 503 and selected based on the static information. Alternatively, the static information can be a serial number for obtaining a detailed calibration data set from the manufacturer, and then the detailed calibration data set can be data - loaded.

[0059] If the sensor LRU 501 is replaced, the new sensor LRU brings its own calibration data, so there is no need to re - configure the processor 503 or perform any other time - consuming tasks.

[0060] In this example, the sensor 502 outputs a sensor signal such as a voltage to the processor 503 via the electrical connector 504. In an alternative embodiment, the sensor can be an optical fiber sensor (such as a Bragg grating strain or temperature sensor) located on the same optical fiber as the memory 302. Thus, in this case, the sensor signal propagates via the same optical fibers 307a, 307b as the light to and from the interrogation unit 308.

[0061] Figure 6shows an avionics system 600 installed on an aircraft 1. Some elements of the system are the same as those shown in Figure 3A and will not be described again. In the case of Figure 6 , the memory 302 is part of the actuator LRU 601.

[0062] The actuator LRU 601 includes an actuator 602 such as a hydraulic cylinder or an electric motor. A flight control computer (FCC) 603 outputs control signals to the actuator 602 via an electrical connector 604. The static information etched in the memory 302 represents the unique ID of the actuator LRU 601, and this ID is used by the FCC 603 to address the actuator LRU 601 and ensure that the actuator 602 receives the correct control signals.

[0063] Figure 7 shows an avionics system 700 including the actuator LRU 601 and two additional actuator LRUs 601a, 601b, which are identical to the LRU 601 except that they have different IDs. The three actuator LRUs 601, 601a, 601b are connected to an interrogator 308 via an optical fiber network and to the FCC 603 via an electrical network.

[0064] In the case of Figure 3A , Figure 3B , Figure 5 and Figure 6 , there is a one-to-one relationship between the interrogator and the memory, but in the case of Figure 7 , a single interrogator interrogates multiple memories. The first LRU 601 has a first memory 302 storing first static information (the unique ID of the LRU 601), the second LRU 601a has a second memory 302a storing second static information (the unique ID of the LRU 601a), and the third LRU 601b has a third memory 302b storing third static information (the unique ID of the LRU 601b). The light source of the interrogator 308 is configured to simultaneously send interrogation light to the three memories 302, 302a, 302b via the optical fiber network, and the receiver of the interrogator 308 is configured to receive first return light, second return light, and third return light from the first memory 302, the second memory 302a, and the third memory 302b respectively via the same optical fiber network. The analyzer 318 is configured to analyze the first return light, second return light, and third return light from the memories 302, 302a, 302b to obtain three unique IDs forwarded to the FCC 603. Then, the FCC 603 can use the three unique IDs to address control signals to the LRUs via the electrical network.

[0065] The interrogator 308 of system 700 uses wavelength division multiplexing to interrogate three LRUs simultaneously. The interrogator 308 simultaneously sends interrogation light to the memory and receives return light from the memory substantially simultaneously. The analyzer of the interrogator 308 is configured to associate first static information with the first LRU 601, second static information with the second LRU 601a, and third static information with the third LRU 601b based on the wavelength characteristics of the first return light, the second return light, and the third return light. Thus, for example, the chain in the first memory 302 has up to four gratings with wavelengths of λ 1 , λ 2 , λ 3 , and λ 4 ; the chain in the second memory 302a has up to four gratings 204 with different wavelengths λ 5 , λ 6 , λ 7 , and λ 8 ; and the chain in the third memory 302b has up to four gratings with different wavelengths λ 9 , λ 10 , λ 11 , and λ 12 .

[0066] Figure 8 Illustrates an avionics system 800, some of whose components are the same as those shown in Figure 7 , and these components will not be described again. In this case, the LRU is interrogated sequentially via the switch 801 instead of in parallel. The advantage of this arrangement is that it enables the LRU to use the same wavelength, thus enabling the reuse of the same (but differently identified) LRU.

[0067] Figure 9 Illustrates an avionics system 900, some of whose components are the same as those shown in Figure 7 , and these components will not be described again. In this case, four LRUs 601, 601a, 601b, and 601c are interrogated simultaneously, but the interrogator 308 of system 800 uses time division multiplexing instead of wavelength division multiplexing to distinguish between the LRUs. The four LRUs 601, 601a, 601b, and 601c are at different distances from the separator / combiner (in this case 2m, 4m, 6m, and 8m), so their return light arrives at different times. This time difference is used to associate the static information encoded in the return light with the four LRUs. The system also knows the location of the LRU based on the distance to the separator / combiner.

[0068] Figures 7 to 9The LRU 601, 601a, 601b, 601c in [the context] are all actuator LRUs including actuators such as hydraulic cylinders or electric motors. A similar arrangement can be used to interrogate Figure 5 multiple sensor LRUs of the type shown in [the context].

[0069] Figure 7 and Figure 8 The actuator LRUs in [the context] are connected to the interrogator 308 via an optical fiber network and to the FCC 603 via an electrical network. In an alternative embodiment, the communication with the interrogator 308 and the FCC 603 can be via the same optical fiber network.

[0070] All of the avionics systems described above include LRUs, but in other embodiments of the present invention, the system may not include LRUs. For example, a memory storing static information in one or more fiber Bragg gratings can be used to store the serial numbers of the large structural elements of the aircraft fuselage. This can be used to record health data for use in data analysis.

[0071] In an alternative embodiment, the memory 302 can include chirped fiber Bragg gratings, long period gratings, or tilted fiber Bragg gratings. Chirped fiber Bragg gratings can encode a large amount of static information but are more susceptible to temperature drift.

[0072] All of the avionics systems described above are installed in Figure 10 the aircraft 1 shown in [the context]. As an example, the aircraft 1 is shown as being equipped with Figures 7 to 9 an actuator system of the type shown in [the context].

[0073] The aircraft 1 has an avionics bay in its nose cone, and in this example, the avionics bay houses the interrogator 308 and the FCC 603. Each wing has ailerons 2a, 2b. The port aileron 2a is driven by the actuator LRU 601a, and the starboard aileron 2b is driven by the actuator LRU 601b.

[0074] When the word "or" appears, this is interpreted to mean "and / or", such that the items involved are not necessarily mutually exclusive and can be used in any suitable combination.

[0075] Although the present invention has been described above with reference to one or more preferred embodiments, it will be understood that various changes or modifications can be made without departing from the scope of the present invention as defined by the appended claims.

Claims

1. An aircraft, the aircraft including an avionics system mounted on the aircraft, the avionics system comprising: a memory that stores static information in one or more fiber Bragg gratings; and a replaceable unit including an interrogator and one or more optical connections between the memory and the interrogator, the interrogator comprising: a light source configured to send interrogation light to the memory; a receiver configured to receive light from the memory; and an analyzer configured to analyze the light from the memory to obtain the static information, wherein the replaceable unit can be removed from the avionics system by disconnecting the one or more optical connections between the memory and the interrogator, wherein the replaceable unit further includes a processor capable of executing multiple software configurations, the processor being configured to execute a software configuration determined by the static information obtained from the memory, and wherein the analyzer is configured to send the static information to the processor, and the processor is configured to select an appropriate software configuration accordingly.

2. The aircraft according to claim 1, wherein, the light from the memory is return light reflected from the memory; the light source is configured to send the interrogation light to the memory via one of the one or more optical connections; the receiver is configured to receive the return light from the memory via the optical connection; and the replaceable unit can be removed from the avionics system by disconnecting the one of the one or more optical connections.

3. The aircraft according to claim 2, wherein, the optical connection includes a first optical fiber optically coupled to the receiver and the light source; a second optical fiber optically coupled to the memory; and an optical connector that optically couples the first optical fiber to the second optical fiber.

4. The aircraft according to claim 3, wherein, the optical connection can be disconnected by decoupling the first optical fiber from the second optical fiber.

5. The aircraft according to claim 3, wherein, the optical connection can be disconnected by removing the optical connector or removing one of the optical fibers from the optical connector.

6. The aircraft according to claim 1, wherein, the one or more fiber Bragg gratings are fiber Bragg gratings.

7. The aircraft according to claim 1, wherein, the one or more fiber Bragg gratings are two or more fiber Bragg gratings arranged in a fiber Bragg grating chain.

8. The aircraft according to claim 1, wherein, the one or more fiber Bragg gratings store the static information in binary format.

9. The aircraft according to claim 1, including a plurality of avionics systems each mounted on the aircraft, wherein, the memory stores different static information.

10. The aircraft according to any one of claims 1 to 9, wherein, The memory is a first memory, the static information is first static information, and the avionics system further includes a second memory that stores second static information in one or more fiber Bragg gratings, the second static information being different from the first static information, and wherein the light source is configured to send the interrogation light to the first memory and the second memory, the receiver is configured to receive first light and second light from the first memory and the second memory respectively, and the analyzer is configured to analyze the first light and the second light to obtain the first static information and the second static information.

11. The aircraft according to claim 10, wherein, the light source is configured to send the interrogation light to the first memory and the second memory simultaneously, the receiver is configured to receive the first light and the second light simultaneously, and the analyzer is configured to associate the first static information with the first memory and the second static information with the second memory based on the wavelength characteristics of the first light and the second light.

12. The aircraft according to claim 10, wherein, the light source is configured to send the interrogation light to the first memory and the second memory simultaneously, the receiver is configured to receive the first light and the second light from the first memory and the second memory at different times, and the analyzer is configured to associate the first static information with the first memory and the second static information with the second memory based on the times at which the first light and the second light are received.

13. An avionics system installed on an aircraft, the avionics system comprising: a replaceable unit, the replaceable unit including a memory that stores static information in one or more fiber Bragg gratings, an interrogator, and a processor capable of executing a plurality of software configurations determined by the static information obtained from the memory, the interrogator including: a light source configured to send interrogation light to the memory; a receiver configured to receive light from the memory; and an analyzer configured to analyze the light from the memory to obtain the static information, wherein the replaceable unit can be removed from the avionics system by disconnecting one or more optical connections between the memory and the rest of the avionics system.

14. The avionics system according to claim 13, wherein, the replaceable unit further includes an actuator, an avionics computer, or a remote data concentrator.

15. The avionics system according to claim 13, wherein, the replaceable unit further includes one or more sensors.

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