WO2022176018A1 - Light sensing device and light sensing method - Google Patents

Abstract

This light sensing device (20) comprises: a light circulator (21) that is connected in an interposed manner in the middle of an optical fiber (12) connected in a reciprocating manner to a communication device (11) that transmits and receives signal light including a specific wavelength (λ1); and FBGs (22a to 22k) that are connected in a subordinate manner to the light circulator (21) and reflect only the signal light of the specific wavelength (λ1) when an environmental condition is a set environmental condition. The light sensing device (20) comprises: a delay measuring unit (24) that measures a delay time period between transmission and reception from the difference between transmission and reception times of the signal light at the communication device (11) after the reflection by any one of the FBGs (22a to 22k); and a specifying unit (25) that specifies an FBG (22a to 22k) having a reciprocating transmission distance in a DB (26) that matches a measured transmission distance between the transmission and reception of the signal light derived on the basis of the measured delay time period.

Description

Optical sensing device and optical sensing method

The present invention relates to an optical sensing device and an optical sensing method for measuring environmental conditions such as temperature and pressure using signal light transmitted through an optical fiber.

Optical sensing technology using optical fibers has been proposed, and in recent years there has been a demand for highly accurate delay measurement technology. As this type of optical sensing technology, there is an optical fiber sensor system described in Patent Document 1, for example. This system utilizes the properties of optical fibers to reflect a specific wavelength by periodically changing the refractive index of the optical fiber. ) (Non-Patent Document 1).

In addition, in recent years, low-delay services such as e-sports and autonomous driving have been required, and network control such as grasping the accurate amount of delay and delay fluctuation in the network and selecting the optimum path based on that information has become necessary. rice field. Non-Patent Document 2 proposes a technique for monitoring the network state in detail. Non-Patent Document 3 discloses another technique related to optical sensing.

JP-A-2000-352524

However, the conventional optical sensing technology mentioned above has the following problems. Optical sensing technology usually requires an ASE (Amplified Spontaneous Emission) light source, which is a broadband light source, and a spectrum analyzer, so the optical sensing device is expensive. In addition, since the broadband light source is inserted into the optical fiber, the optical fiber is exclusively used for optical sensing and cannot be used for communication.

Furthermore, there is also a method of sensing by correlating the packet loss rate and fiber sensing information by using FBG or LPFG (Long Period Fiber Grating) between communication switches. However, this method is not suitable for communication applications because of packet loss. Furthermore, if observation is performed by sensing for a long period of time at short measurement intervals, the amount of measurement data becomes enormous, and a dedicated program is required for this data analysis, resulting in a long analysis time.

The present invention has been made in view of such circumstances, and aims to enable optical sensing of environmental conditions that facilitate data analysis at low cost and to enable the use of optical fibers for communication purposes. Make it an issue.

In order to solve the above problems, the optical sensing device of the present invention is inserted and connected in the middle of an optical transmission line that is connected back and forth to a communication device that transmits and receives signal light of a specific wavelength or a plurality of different wavelengths including the specific wavelength. an optical circulator, which is cascade-connected to the optical circulator by an optical fiber, and in the case of environmental conditions set in advance, reflects signal light of a specific wavelength from the optical circulator and emits signal light of a wavelength other than the specific wavelength; Through a plurality of FBGs (Fiber Bragg Gratings) each having different set environmental conditions for sensing transmitted light, and the optical circulator, after being reflected by any one of the plurality of FBGs, through an optical transmission line A DB (Data Base) in which the round-trip propagation distance of the signal light transmitted and received by the communication device is associated with each of the plurality of FBGs, and information on the set environmental conditions for each of the FBGs is associated and stored; a delay measuring unit for measuring a delay time between transmission and reception from a difference in transmission and reception times of signal light transmitted and received by the communication device after being reflected by any one of the plurality of FBGs via the optical circulator; an identifying unit that obtains a measured propagation distance between transmission and reception of signal light based on the delay time obtained, and identifies an FBG associated with the round-trip propagation distance in the DB that matches the obtained measured propagation distance. characterized by

According to the present invention, the optical fiber can be used for optical sensing under environmental conditions that facilitate data analysis at low cost, and can also be used for communication purposes.

1 is a block diagram showing the configuration of a communication network using optical sensing devices according to an embodiment of the present invention; FIG. It is a figure which shows the storage information of DB of the optical sensing apparatus which concerns on this embodiment. 4 is a flow chart for explaining a light sensing operation by the light sensing device according to the embodiment; FIG. 4 is a block diagram showing the configuration of a communication network using the optical sensing device according to Modification 1 of the embodiment of the present invention; 8 is a diagram showing information stored in a DB of the optical sensing device according to Modification 1; FIG. FIG. 10 is a block diagram showing the configuration of a communication network using the optical sensing device according to Modification 2 of the embodiment of the present invention; FIG. 11 is a block diagram showing the configuration of a communication network using a light sensing device according to Modification 3 of the embodiment of the present invention; 1 is a block diagram showing the configuration of a communication network according to Example 1; FIG. FIG. 11 is a block diagram showing a configuration for monitoring the state of communication equipment according to the second embodiment; FIG. 11 is a block diagram showing a configuration for monitoring the state of equipment in a no-entry area according to Embodiment 3;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, in all the drawings of this specification, the same reference numerals are given to components having corresponding functions, and descriptions thereof will be omitted as appropriate.
<Configuration of Embodiment>
FIG. 1 is a block diagram showing the configuration of a communication network using optical sensing devices according to an embodiment of the present invention.

A communication network (also referred to as NW) 10 shown in FIG. . The communication device 11 has a transmission port 1p1 for transmitting signal light and a reception port 1p2 for receiving signal light, and an optical fiber 12 that makes a round trip over a predetermined distance is connected. However, the communication device 11 transmits and receives signal light of a plurality of different wavelengths including a specific wavelength (for example, wavelength λ1). In some cases, signal light with only a specific wavelength is transmitted and received. Note that the wavelength λ1 is also simply referred to as λ1. Also, the optical fiber 12 constitutes an optical transmission line described in the claims.

The optical sensing device 20 includes an optical circulator 21, a plurality of FBGs 22a, 22b, . However, the delay measuring unit 24 , the environmental condition identifying unit 25 and the DB 26 may be provided inside the communication device 11 . The environmental condition specifying unit 25 constitutes the specifying unit described in the claims.

The optical circulator 21 is inserted and connected to the middle of the optical fiber 12 . A plurality of FBGs 22a to 22k are cascade-connected to the optical circulator 21 by optical fibers. That is, the first-stage FBG 22a is connected to the optical circulator 21, and the second-stage FBG 22b, .

The optical circulator 21 transmits the signal light transmitted from the transmission port 1p1 of the communication device 11 and passed through the optical fiber 12 only in the clockwise direction indicated by the arrow 21a. This optical circulator 21 passes the signal light input from the optical fiber 12 on the side of the transmission port 1p1 through the first-stage FBG 22a in the direction of the last k-th stage FBG 22k (forward direction), as indicated by the arrow Y1. Y1). A direction opposite to the forward direction Y1 is referred to as a backward direction Y2. The optical circulator 21 also outputs the signal light reflected by any of the FBGs 22a to 22k and traveling in the backward direction Y2 through the optical fiber 12 to the reciprocating end 12a side.

The FBGs 22a to 22k perform optical sensing by reflecting only the specific wavelength λ1 and transmitting wavelengths other than the specific wavelength λ1 when preset environmental conditions (eg, temperature x°C) are reached. Further, when the temperature of the FBGs 22a to 22k changes to a temperature other than the temperature x° C. (for example, y° C.) due to a change in the ambient temperature, the FBGs 22a to 22k reflect only a specific wavelength (for example, a wavelength λ2) different from the specific wavelength λ1. Sensing light that passes through the wavelength of

In this example, the FBGs 22a to 22k are arranged close to each other, and are set so as to reflect the signal light of the wavelength from the optical circulator 21 under different environmental conditions. For example, when the temperature of the FBG 22a is 20° C. as the set environmental condition, the optical circulator 21 reflects the signal light of wavelength λ1 in the forward direction Y1, the FBG 22b reflects the signal light of λ1 at 21° C., and the FBG 22k It is set to reflect the signal light of λ1 at 25°C. These reflected signal lights are transmitted to the optical circulator 21 in the backward direction Y2. Further, the FBGs 22a to 22k transmit the signal light of wavelength λ1 traveling in the forward direction Y1 at temperatures other than the set temperature.

Also, the interval between each of the FBGs 22a to 22k is d [m], as representatively shown between the FBGs 22a and 22b. The delay time when the signal light travels back and forth between the FBGs 22a and 22b is (d×2)÷(c/n) [seconds]. However, c is the speed of light, and n is the refractive index of the core of the optical fiber.

The communication device 11 receives the signal light returned via the reciprocating end 12a of the optical fiber 12 at the reception port 1p2. This received signal light is reflected by any one of the FBGs 22 a to 22 k and transmitted from the optical circulator 21 toward the reciprocating end 12 a of the optical fiber 12 .

The DB 26 associates the round-trip propagation distance from the transmission port 1p1 of the communication device 11 to the reception port 1p2 via the round-trip end 12a of the optical fiber 12 for each of the FBGs 22a to 22k. I remember. However, the round-trip propagation distance means that the signal light transmitted from the transmission port 1p1 passes through the optical fiber 12 and the optical circulator 21, is reflected by any one of the FBGs 22a to 22k, returns to the optical circulator 21, and further This is the distance from the reciprocating end 12a of the optical fiber 12 to the reception port 1p2.

That is, in the DB 26, as shown in FIG. 2, the round-trip propagation distance La between the transmitting/receiving ports 1p1 and 1p2 reflected by the first-stage FBG 22a as the reflection position is stored in association with the FBG 22a. The round-trip propagation distance Lb between the transmission/reception ports 1p1 and 1p2 reflected by the FBG 22b at the k-th stage is stored in association with the FBG 22b, and the round-trip propagation distance Lk between the transmission/reception ports 1p1 and 1p2 reflected by the k-th FBG 22k is stored in the FBG 22k. are associated and stored.

Furthermore, in the DB 26, each FBG 22a to 22k is associated with a temperature as a set environmental condition. A temperature of 20°C is associated with the FBG 22a, a temperature of 21°C is associated with the FBG 22b, and a temperature of 25°C is associated with the FBG 22k.

Returning to FIG. 1, the delay measurement unit 24 measures the delay time between transmission and reception, which is the difference between the transmission and reception times at the transmission port 1p1 and the reception port 1p2 of the communication device 11.

An environmental condition specifying unit (also referred to as a specifying unit) 25 obtains a measured propagation distance (for example, a measured propagation distance La) between transmission and reception of signal light based on the measured delay time, and matches the obtained measured propagation distance La. Search the DB 26 for the round-trip propagation distance La. The identifying unit 25 detects the FBG 22a associated with the searched round-trip propagation distance La, and identifies temperature=20° C. as the set environmental condition associated with the detected FBG 22a.

However, the reflection wavelengths of the FBGs 22a to 22k also change when the external pressure applied to the FBGs changes, in the same way that the reflection wavelengths change when the temperature around the FBGs changes. Therefore, like the temperature of the environmental conditions, the pressure and the like, which are the environmental conditions around the FBGs 22a to 22k, can also be specified.

<Operation of Embodiment>
Next, the light sensing operation of the light sensing device 20 according to this embodiment will be described with reference to the flowchart of FIG. However, it is assumed that the DB 26 stores information on the reflection position, the round-trip propagation distance, and the temperature as the set environmental condition shown in FIG. The FBG 22a reflects the signal light of wavelength λ1 when the environmental temperature is 20°C, the FBG 22b reflects the signal light of λ1 when the temperature is 21°C, and the FBG 22k reflects the signal light of λ1 when the temperature is 25°C. Suppose it is set to be reflective.

　In step S1 shown in FIG. 3, it is assumed that a signal light having a wavelength λ1 is transmitted from the transmission port 1p1 of the communication device 11 to the optical fiber 12.

In step S2, when the transmitted signal light is input to the optical circulator 21 via the optical fiber 12, the optical circulator 21 outputs the signal light in the outward direction Y1.

In step S3, the signal light in the forward direction Y1 is reflected in the backward direction Y2 by any one of the FBGs 22a to 22k as reflection position elements. For example, if the temperature of the environmental condition is 21°C, the signal light is reflected by the FBG 22b that reflects the signal light at 21°C. The optical signal reflected in this manner is transmitted in the backward direction Y 2 and input to the optical circulator 21 .

In step S<b>4 , the optical circulator 21 outputs the input signal light toward the reciprocating end 12 a of the optical fiber 12 .

In step S5, the output signal light passes through the reciprocating end 12a of the optical fiber 12 and is received by the communication device 11 via the reception port 1p2.

In step S6, the delay measurement unit 24 measures the delay time between transmission and reception of the signal light from the difference between the transmission and reception times at the transmission port 1p1 and the reception port 1p2 of the communication device 11.

In step S7, the environmental condition specifying unit 25 obtains the measured propagation distance between signal light transmission and reception based on the measured delay time, and determines the round-trip propagation distances La to Lk in the DB 26 that match the obtained measured propagation distances. Search for. For example, assume that the measured propagation distance Lb is obtained, and the round-trip propagation distance Lb in the DB 26 that matches the measured propagation distance Lb is searched.

In step S8, the specifying unit 25 detects the FBG 22b as the reflection position element associated with the retrieved round-trip propagation distance Lb.

In step S9, the identifying unit 25 identifies, for example, temperature = 21°C associated with the detected FBG 22b as an environmental condition. By this identification, for example, the administrator of the NW 10 can grasp that the temperature of the locations where the FBGs 22a to 22k are arranged is 21.degree.

<Effects of Embodiment>
Effects of the optical sensing device 20 according to the embodiment of the present invention will be described.

The optical sensing device 20 includes an optical circulator 21, a plurality of FBGs 22a to 22k, a delay measuring section 24, an environmental condition identifying section 25, and a DB 26.
The optical circulator 21 is inserted and connected in the middle of the optical fiber 12 that is connected back and forth to the communication device 11 that transmits and receives signal light of a specific wavelength (for example, a specific wavelength λ1) or a plurality of different wavelengths including the specific wavelength.

The FBGs 22a to 22k are cascade-connected to the optical circulator 21 by optical fibers, and reflect the signal light of the specific wavelength λ1 from the optical circulator 21 when the environmental conditions are set in advance, Optical sensing is performed by transmitting signal light. The FBGs 22a to 22k have different set environment conditions.

In the DB 26, the round-trip propagation distance of the signal light transmitted and received by the communication device 11 via the optical fiber 12 after being reflected by any one of the plurality of FBGs 22a to 22k via the optical circulator 21 is stored in the plurality of FBGs 22a to 22k. 22k, and the information of the setting environment conditions for each of the FBGs 22a to 22k is stored in correspondence.

The delay measuring unit 24 measures the delay time between transmission and reception from the difference in the transmission and reception times of the signal light transmitted and received by the communication device 11 after being reflected by any one of the plurality of FBGs 22a to 22k via the optical circulator 21.
The specifying unit 25 obtains the measured propagation distance between transmission and reception of the signal light based on the measured delay time, and FBGs 22a to 22k associated with the round-trip propagation distance in the DB 26 that matches the obtained measured propagation distance. It was configured to specify

According to this configuration, the following effects can be obtained. A plurality of FBGs 22a to 22k for performing optical sensing are cascade-connected to an optical circulator 21 inserted and connected in the middle of an optical fiber that is reciprocally connected to the communication device 11. FIG. Assume that the signal light of wavelength λ1, for example, transmitted from the communication device 11 to the optical fiber is transmitted to the FBGs 22a to 22k via the optical circulator 21. FIG. At this time, it is assumed that the temperature of the environmental condition is the same as the temperature of the environmental condition (for example, 20° C.) for reflecting the signal light of λ1 in the FBG 22 a closest to the optical circulator 21 . In this case, the signal light of wavelengths other than λ1 is transmitted through the FBG 22a, and the signal light of λ1 is reflected. This reflected signal light is transmitted to the reciprocating end of the optical fiber by the optical circulator 21 and received by the communication device 11 .

The delay measurement unit 24 measures the delay time between transmission and reception of the signal light of λ1 from the difference between the transmission and reception times in the communication device 11 . The specifying unit 25 obtains the measured propagation distance between signal light transmission and reception based on the measured delay time, and searches the DB 26 for a round-trip propagation distance La that matches the obtained measured propagation distance. Further, the identifying unit 25 detects the FBG 22a associated with the searched round-trip propagation distance La. By this detection, the temperature of 20 degrees can be identified as the environmental condition associated with the FBG 22a.

The optical sensing device 20 with this configuration is configured by connecting a plurality of general-purpose FBGs 22a to 22k via optical fibers to an optical fiber 12 used for communication via an optical circulator 21, which is a general-purpose component. Since the optical circulator 21 and the FBGs 22a to 22k are general-purpose products, they can be constructed at low cost. Since the optical sensing device 20 is configured by branching and connecting to the optical fiber 12 as an optical transmission line, the optical fiber 12 is not exclusively used for optical sensing, and packet loss of signal light does not occur. It can also be used for communication purposes. In addition, since the optical sensing can be performed by measuring only the transmission/reception delay time from the transmission/reception time in the communication device 11, the amount of measured data does not become enormous even if the sensing is performed for a long period of time. Since it is not necessary, analysis time is eliminated.

Therefore, according to the optical sensing device 20 of the present embodiment, it is possible to perform optical sensing under environmental conditions that facilitate data analysis at low cost using an optical fiber, and it can also be used for communication purposes.

<Modification 1 of Embodiment>
FIG. 4 is a block diagram showing the configuration of a communication network using the optical sensing device according to Modification 1 of the embodiment of the present invention.

The optical sensing device 20A of Modification 1 shown in FIG. 4 further includes a fiber mirror 22m that reflects signal light of all wavelengths in addition to the optical sensing device 20 of the above-described embodiment (FIG. 1). In addition, as shown in FIG. 5, the DB 26 additionally stores information on the fiber mirror 22m as the reflection position element, information on the round-trip propagation distance Lm, and abnormal state as specific information.

The fiber mirror 22m is connected to the k-th stage (end) FBG 22k as the last stage of cascade connection. The signal light reflected by the fiber mirror 22m passes through each of the FBGs 22k to 22a toward the backward direction Y2 and is input to the optical circulator 21. FIG.

In the DB 26, as shown in FIG. 5, the round-trip propagation distance Lm between the transmitting/receiving ports 1p1 and 1p2 reflected by the last-stage fiber mirror 22m is associated with the fiber mirror 22m. Anomalies are associated. The abnormal state indicates temperature abnormality when the temperature as an environmental condition is out of the temperature range associated with each of the FBGs 22a to 22k, or functional abnormality of the FBGs 22a to 22k.

The delay measuring unit 24 measures the difference between the transmission and reception times at the transmission port 1p1 and the reception port 1p2 of the communication device 11, including the delay time of the signal light reflected by one of the FBGs 22a to 22k or the fiber mirror 22m. Measure the delay time between

The specifying unit 25 obtains the measured propagation distance (for example, the measured propagation distance La) between transmission and reception of the signal light based on the measured delay time, and determines the round-trip propagation distance La in the DB 26 that matches the obtained measured propagation distance La. Search for When detecting the fiber mirror 22m associated with the round-trip propagation distance Lm, the identifying unit 25 identifies the abnormal state associated with the fiber mirror 22m.

Effects of the optical sensing device 20A of Modification 1 will be described.
In the optical sensing device 20A, the FBG 22k at the end of the plurality of FBGs 22a to 22k cascade-connected to the optical circulator 21 is cascade-connected to a fiber mirror 22m that reflects all wavelengths. Furthermore, in addition to the information stored in the DB 26, the round-trip propagation distance of the signal light transmitted and received by the communication device 11 after being reflected by the fiber mirror 22m is associated with the fiber mirror 22m, and the specific information of the fiber mirror 22m is associated and stored. .

The delay measurement unit 24 measures the delay time between transmission and reception from the difference in the transmission and reception times of the signal light transmitted and received by the communication device 11 after being reflected by the fiber mirror 22m. The identifying unit 25 obtains the measured propagation distance between transmission and reception of the signal light based on the measured delay time, and selects the fiber mirror 22m associated with the round-trip propagation distance in the DB 26 that matches the obtained measured propagation distance. It has a specific configuration.

According to this configuration, when the signal light transmitted from the communication device 11 passes through all the FBGs 22a to 22k, after being reflected by the fiber mirror 22m, the communication device 11 passes through the optical circulator 21 and the optical fiber 12 as the optical transmission line. received at. In this case, the delay measurement unit 24 measures the transmission/reception delay time associated with the reflection at the fiber mirror 22m. Next, the specifying unit 25 searches for the round-trip propagation distance Lm related to the fiber mirror 22m in the DB 26 that matches the measured propagation distance between transmission and reception based on the measured delay time, and associates it with this round-trip propagation distance Lm. detected the fiber mirror 22m. Furthermore, the identifying unit 25 can identify the abnormal state as the specific information associated with the detected fiber mirror 22m. This optical sensing device 20A can also perform optical sensing under environmental conditions that facilitate data analysis at low cost using an optical fiber, and can also be used for communication purposes.

<Modification 2 of Embodiment>
FIG. 6 is a block diagram showing the configuration of a communication network using the optical sensing device according to Modification 2 of the embodiment of the present invention.

The optical sensing device 20B of Modification 2 shown in FIG. 6 differs from the optical sensing device 20 of the above-described embodiment (FIG. 1) in that the communication device 11 (FIG. Instead of 1), it is inserted and connected in the middle of the optical fiber 12 between the communication devices 11a and 11b (also called between the communication devices 11a and 11b). The communication device 11 a transmits to the optical fiber 12 signal lights of a plurality of different wavelengths including the above-described specific wavelength λ1. The communication device 11 b receives the transmitted signal light via the optical fiber 12 . The communication device 11a constitutes the first communication device described in the claims, and the communication device 11b constitutes the second communication device described in the claims.

In addition, the delay measuring unit 24 and the environmental condition specifying unit 25 of the optical sensing device 20B perform the processing described later, and the information described later is stored in the DB 26.

That is, the DB 26 stores a plurality of propagation distances of signal light received by the communication device 11b after the signal light transmitted from the communication device 11a is reflected by any one of the plurality of FBGs 22a to 22k via the optical circulator 21. are associated with each of the FBGs 22a to 22k, and set environmental conditions (temperatures) for each of the FBGs 22a to 22k are associated and stored.

The delay measurement unit 24 measures the delay time between transmission and reception from the difference in the transmission and reception times of the signal light transmitted and received between the communication devices 11a and 11b.

The specifying unit 25 obtains the measured propagation distance between transmission and reception of the signal light based on the measured delay time, and selects the FBGs 22a to 22k associated with the propagation distance in the DB 26 that matches the obtained measured propagation distance. Identify.

A light sensing process using the light sensing device 20B having such a configuration will be described.
When the signal light of wavelength λ1 is transmitted from the communication device 11a to the optical fiber 12, this signal light is transmitted in the outward direction Y1 via the optical circulator 21. FIG.

Here, a temperature of 21°C is set as the set environmental condition in the FBG 22b, and the temperature of the environmental condition is 21°C. In this case, the signal light transmitted in the forward direction Y1 is reflected by the FBG 22b, transmitted in the backward direction Y2, and input to the optical circulator 21. FIG. The optical circulator 21 transmits the input signal light through the optical fiber 12 toward the communication device 11b. This optical signal is received by the communication device 11b.

At the time of this reception, the delay measurement unit 24 measures the delay time between transmission and reception from the difference between the transmission and reception times of the signal light transmitted and received between the communication devices 11a and 11b.

Next, the specifying unit 25 obtains the measured propagation distance between transmission and reception of the signal light based on the measured delay time, and the FBG 22b associated with the propagation distance in the DB 26 that matches the obtained measured propagation distance. to detect (identify) Furthermore, the identifying unit 25 identifies the temperature=21° C. associated with the detected FBG 22b. By this identification, for example, the administrator of the NW 10 can grasp that the temperature of the place where the FBG 22b is arranged is 21.degree.

According to the optical sensing device 20B of Modification 2 having such a configuration, that is, the optical sensing device 20B connected to the optical fiber 12 between the communication devices 11a and 11b via the optical circulator 21, the light of the above-described embodiment is Similar to the sensing device 20 (FIG. 1), it is possible to perform optical sensing of environmental conditions that facilitate data analysis at a low cost, and it can also be used for communication applications.

<Modification 3 of Embodiment>
FIG. 7 is a block diagram showing the configuration of a communication network using a light sensing device according to Modification 3 of the embodiment of the present invention.

The optical sensing device 20C of Modified Example 3 shown in FIG. 7 differs from the optical sensing device 20B of Modified Example 2 (FIG. 6) described above in that a fiber for reflecting signal light of all wavelengths is provided behind the FBGs 22a to 22k. The reason is that the mirrors 22m are further connected in cascade. Furthermore, the following information is additionally stored in the DB 26.

That is, in the DB 26, the propagation distance between the communication devices 11a and 11b, including the reflection path at the last-stage fiber mirror 22m, is associated with the fiber mirror 22m, and the above-described abnormal state as specific information is associated with the fiber mirror 22m. I remembered.

The delay measurement unit 24 measures the delay time between transmission and reception, which is the difference between the transmission and reception times of the communication devices 11a and 11b, including the delay time of the signal light reflected by one of the FBGs 22a to 22k or the fiber mirror 22m. do.

The specifying unit 25 obtains the measured propagation distance between transmission and reception of the signal light based on the measured delay time, and searches the DB 26 for the propagation distance that matches the obtained measured propagation distance. Here, for example, it is assumed that the propagation distance related to the reflection at the fiber mirror 22m is retrieved. Next, the identifying unit 25 detects the fiber mirror 22m associated with the found propagation distance, and identifies the abnormal state associated with the detected fiber mirror 22m.

According to this configuration, as described above, the identifying unit 25 of the optical sensing device 20C can identify the abnormal state as the specific information associated with the detected fiber mirror 22m. Therefore, as in the second modification, the optical fiber can be used for optical sensing under environmental conditions that facilitate data analysis at low cost, and can be used for communication purposes.

Next, examples 1, 2, and 3 of communication networks using the optical sensing device described above will be described.

<Example 1>
FIG. 8 is a block diagram showing the configuration of the communication network 10A according to the first embodiment. A communication network 10A of the first embodiment shown in FIG. 8 uses a light sensing device 20C1 as an application example of the light sensing device 20C (FIG. 7) of the third modification described above.

The communication network 10A connects the optical fiber 12 connected between the communication device 11a in the communication station 61 and the communication device 11b in the station 62 via three optical circulators 21 to three optical sensing means. 1, 2 and 3 are connected. It is assumed that the office buildings 61 and 62 are separated from each other.

The delay measurement unit 24, the environmental condition identification unit 25, and the DB 26 of the optical sensing device 20C1 are arranged in the office building 62. Each of the optical sensing means 1 to 3 is arranged on the optical fiber 12 between the communication devices 11a and 11b at a predetermined interval, and comprises a plurality of cascade-connected FBGs 22a to 22k and a fiber mirror 22m. It is

For each of the FBGs 22a to 22k of the optical sensing means 1 to 3, temperature, pressure, tension, etc., which are the environmental conditions around the FBG, are set as set environmental conditions.

In the DB 26, the signal light transmitted from the communication device 11a is sent to any one of the FBGs 22a to 22k of the optical sensing means 1 to 3 via the optical circulators 21 or The propagation distance of the signal light received by the communication device 11b after being reflected by the combination of the fiber mirrors 22m is associated with each of the FBGs 22a to 22k or the fiber mirror 22m, and the set environmental conditions (eg temperature) for each of the FBGs 22a to 22k are associated. I have attached it and memorized it. The fiber mirror 22m is stored in association with the above-described abnormal state as specific information.

For example, in the DB 26, the propagation distance of the signal light received by the communication device 11b after being reflected by the combination of the FBG 22a of the optical sensing means 1, the FBG 22b of the optical sensing means 2, and the fiber mirror 22m of the optical sensing means 3 is stored in each FBG 22a. , FBG 22b or fiber mirror 22m, and the temperature of each FBG 22a and FBG 22b is stored in association with each other.

The delay measurement unit 24 measures the difference in transmission/reception time between the communication devices 11a and 11b, including the delay time of the signal light reflected by one of the FBGs 22a to 22k or the fiber mirror 22m in each of the optical sensing means 1 to 3. Measure the delay time between certain transmissions and receptions.

Next, the specifying unit 25 obtains the measured propagation distance between transmission and reception of the signal light based on the measured delay time, and searches the DB 26 for the propagation distance that matches the obtained measured propagation distance. Here, for example, it is assumed that propagation distances related to reflection at the FBG 22a of the optical sensing means 1, reflection at the FBG 22b of the optical sensing means 2, and reflection at the fiber mirror 22m of the optical sensing means 3 are retrieved.

Next, the identifying unit 25 detects the FBG 22a of the optical sensing means 1, the FBG 22b of the optical sensing means 2, and the fiber mirror 22m of the optical sensing means 3 associated with the retrieved propagation distance. The identification unit 25 detects the temperature of the FBG 22a of the optical sensing means 1 (eg, 20° C.), the temperature of the FBG 22b of the optical sensing means 2 (eg, 21° C.), and the state associated with the fiber mirror 22m of the optical sensing means 3. Identify anomalies.

By this identification, the administrator of the office building 62 or the like can determine that the temperature at the location where the FBG 22a of the optical sensing means 1 is arranged is 20°C and the temperature at the location where the FBG 22b of the optical sensing means 2 is arranged is 21°C. I can recognize that. Furthermore, it can be recognized that the location where the fiber mirror 22m of the optical sensing means 3 is arranged is in an abnormal state.

<Example 2>
FIG. 9 is a block diagram showing a configuration for monitoring the state of communication equipment according to the second embodiment. In the communication equipment of the second embodiment shown in FIG. 9, the optical sensing device as an application example of the optical sensing device 20C (FIG. 7) of the modified example 3 described above is installed in the communication racks 41, 42, 43 related to communication such as the Internet. 20C2 is used.

Each of the communication racks 41 to 43 has a vertically long rectangular parallelepiped shape, and the side indicated by the arrow Y21 is an air conditioner (not shown) inside the rack that sucks outside air from an air supply port (not shown) to the internal equipment. It is a cold aisle (cold aisle Y21) for cooling. The side indicated by the arrow Y22 is the hot aisle (hot aisle Y22) where the air conditioner exhausts heat from the plurality of exhaust ports 45. As shown in FIG.

Five optical sensing means 1a (arrows 1a) are connected via optical circulators 21 to an optical fiber (not shown) between the communication device 11a arranged on the communication rack 41 and the communication device 11b arranged on the communication rack 43. , 1b, 2a (arrow 2a), 2b, 3 are connected.

However, the optical sensing means 1b and 2b represent a plurality of FBGs 22a to 22k and a fiber mirror 22m cascade-connected to the optical circulator 21 arranged on the hot aisle Y22 side. However, the optical sensing means 1a and 2a are arranged on the cold aisle Y21 side in the same way as on the hot aisle Y22 side by arrows 1a and 2a alone. The optical sensing means 3 also shows a plurality of FBGs 22a-22k and a fiber mirror 22m cascaded to the optical circulator 21 disposed on the side of the communication rack 43 between the cold aisle Y21 and the hot aisle Y22. The optical sensing means 1a, 1b, 2a, 2b, and 3 are referred to as optical sensing means 1a-3.

For each of the FBGs 22a to 22k of the optical sensing means 1a to 3, temperature, pressure, tension, etc., which are environmental conditions around the FBG, are set as set environmental conditions.

In the DB 26, the signal light transmitted from the communication device 11a is sent to any one of the FBGs 22a to 22k of the optical sensing means 1a to 3 via the optical circulators 21, or The propagation distance of the signal light received by the communication device 11b after being reflected by the combination of the fiber mirrors 22m is associated with each of the FBGs 22a to 22k or the fiber mirror 22m, and the set environmental conditions (eg temperature) for each of the FBGs 22a to 22k are associated. I have attached it and memorized it. The fiber mirror 22m is stored in association with the above-described abnormal state (temperature abnormality) as specific information.

For example, the DB 26 includes reflections from the FBG 22a (not shown) of the light sensing means 1a, reflections from the FBG 22a of the light sensing means 1b, reflection from the FBGs 22b (not shown) of the light sensing means 2a, and light sensing means 2b. The propagation distance of the signal light received by the communication device 11b after being reflected by the combination of the FBG 22b of the optical sensing means 3 and the FBG 22b of the optical sensing means 3 is associated with the FBG 22a and the FBG 22b, and the temperature of each of the FBG 22a and the FBG 22b is associated. I have attached it and memorized it.

The delay measurement unit 24 is the difference in the transmission and reception times between the communication devices 11a and 11b, including the delay time of the signal light reflected by one of the FBGs 22a to 22k in each of the optical sensing means 1a to 3 or the fiber mirror 22m. Measure the delay time between certain transmissions and receptions.

Next, the specifying unit 25 obtains the measured propagation distance between transmission and reception of the signal light based on the measured delay time, and searches the DB 26 for the propagation distance that matches the obtained measured propagation distance. Here, for example, reflection at the FBG 22a (not shown) of the optical sensing means 1a, reflection at the FBG 22a of the optical sensing means 1b, reflection at the FBG 22b (not shown) of the optical sensing means 2a, and reflection at the FBG 22b (not shown) of the optical sensing means 2b Suppose that the propagation distance related to the reflection at the FBG 22b and the reflection at the FBG 22b of the light sensing means 3 is retrieved.

Next, the identifying unit 25 determines the FBG 22a (not shown) of the optical sensing means 1a, the FBG 22a of the optical sensing means 1b, the FBG 22b (not shown) of the optical sensing means 2a, and the FBG 22b of the optical sensing means 2a, which are associated with the searched propagation distance. The FBG 22b of the optical sensing means 2b and the FBG 22b of the optical sensing means 3 are detected.

Next, the identifying unit 25 detects the temperature of the FBG 22a (not shown) of the optical sensing means 1a (eg, 20° C.), the temperature of the FBG 22a of the optical sensing means 1b (eg, 30° C.), and the FBG 22b of the optical sensing means 2a. (not shown) (for example, 21° C.), the temperature of the FBG 22b of the optical sensing means 2b (for example, 31° C.), and the temperature of the FBG 22b of the optical sensing means 3 (for example, 25° C.).

By this identification, the administrators of the communication racks 41 to 43 can recognize that the temperature on the cold aisle Y21 side is 20°C to 21°C and the temperature on the hot aisle Y22 side is 30°C to 31°C.

On the other hand, the specifying unit 25 is reflected by the FBG 22a (not shown) of the optical sensing means 1a, reflected by the fiber mirror 22m of the optical sensing means 1b, reflected by the FBG 22b (not shown) of the optical sensing means 2a, light Suppose that the propagation distance related to the reflection at the fiber mirror 22m of the sensing means 2b and the reflection at the FBG 22k of the optical sensing means 3 is retrieved.

In this case, the identification unit 25 identifies the abnormal state associated with the fiber mirror 22m of the optical sensing means 1b, 2b, so that the administrator or the like can confirm that the temperature on the hot aisle Y22 side of the communication racks 41 to 43 is abnormal. can recognize something.

<Example 3>
FIG. 10 is a block diagram showing a configuration for monitoring the state of equipment in a no-entry area according to the third embodiment. The no-entry area equipment of the third embodiment shown in FIG. It uses the optical sensing device 20A1.

The delay measurement unit 24, the environmental condition identification unit 25 and the DB 26 of the optical sensing device 20A1 are arranged in the management station 30. Also, the FBGs 22a to 22k including the optical circulator 21 of the optical sensing device 20A1 and the fiber mirror 22m are arranged in a no-entry area as will be described later.

A no-entry area has, for example, a vast area, and pillars 71, 72, 73, 74, 75, and 76 are fixed to the ground of the area in a hexagonal shape. The optical fiber 12 is wound around and stretched vertically on each of the posts 71 to 76 . One end of the optical fiber 12 is connected to a transmission port (not shown) of the communication device 11a connected to the control station 30, and the other end is connected to a reception port (not shown). That is, the optical fiber 12 that goes around the supports 71 to 76 is connected to the transmission/reception port of the communication device 11a. This circular connection of the optical fiber 12 is similar to the round-trip connection of the optical fiber 12 to the transmission/reception ports 1p1 and 1p2 of the communication device 11 shown in FIG.

The optical circulators 21 arranged on the supports 71, 73, and 75 are inserted and connected to the optical fibers 12 that go around the supports 71 to 76 shown in FIG. A plurality of FBGs 22a to 22k and a fiber mirror 22m as optical sensing means 1 are cascade-connected to the optical circulator 21 of the post 71. FIG. A plurality of FBGs 22a to 22k and a fiber mirror 22m as the optical sensing means 2 are cascade-connected to the optical circulator 21 of the post 73. FIG. A plurality of FBGs 22a to 22k and a fiber mirror 22m as optical sensing means 3 are cascade-connected to the optical circulator 21 of the post 75. FIG.

The optical circulator 21 of the support 71 is connected to the communication device 11a provided on the support 71 via an optical fiber 12. The optical circulator 21 of the support 73 is connected to the communication device 11b provided on the support 73 via the optical fiber 12 . The optical circulator 21 of the support 75 is connected to the communication device 11 c provided on the support 75 via the optical fiber 12 .

In addition, a camera 32a that can rotate in the direction of arrow Y11 or in the opposite direction is arranged at the upper end of the column 71 and connected to the optical fiber 12. A camera 32 b that can rotate in the direction of arrow Y 12 or in the opposite direction is provided at the upper end of the support 73 and connected to the optical fiber 12 . A camera 32 c rotatable in the direction of arrow Y 13 or in the opposite direction is arranged at the upper end of the support 75 and connected to the optical fiber 12 .

Each of the cameras 32a to 32c can be freely rotated under the control of the control unit 32 provided in the management station 30.

For each of the FBGs 22a-22k of the optical sensing means 1-3, the pressure, which is the environmental condition around the FBG, is set as the set environmental condition. For example, the FBG 22a is set to a pressure P1 as a set environmental condition, the FBG 22b is set to a pressure P2 higher than the pressure P1, and the FBG 22k is set to a pressure P3 higher than the pressure P2.

The FBG 22a reflects signal light with a specific wavelength λ1 from the optical circulator 21 and transmits signal light with other wavelengths when pressure P1 is applied from the surroundings. The FBG 22b reflects the specific wavelength λ1 when pressure P2 is applied, and transmits signal light of other wavelengths. The FBG 22k reflects the specific wavelength λ1 when pressure P3 is applied, and transmits signal light of other wavelengths. When a pressure P4 larger than the pressure P3 is applied to each of the FBGs 22a to 22k, the specific wavelength λ1 is transmitted. This transmitted specific wavelength λ 1 is reflected by the fiber mirror 22 m and transmitted to the optical circulator 21 .

In the DB 26, the signal light transmitted from the communication device 11a to the optical fiber 12 is reflected by any of the FBGs 22a to 22k of the optical sensing means 1 to 3, circulates the posts 71 to 76, and is received by the communication device 11a. Each propagation distance up to the point of reflection is stored in association with one of the reflected FBGs 22a to 22k.

Furthermore, in the DB 26, each FBG 22a to 22k is associated with pressure as a set environmental condition. The pressure P1 is associated with the FBG 22a, the pressure P2 is associated with the FBG 22b, and the pressure P3 is associated with the FBG 22k. The fiber mirror 22m is associated with the above-described abnormal state (abnormal pressure) as specific information.

The delay measurement unit 24 measures the difference between the transmission and reception times in the communication device 11a, including the delay time of the signal light reflected by one of the FBGs 22a to 22k or the fiber mirror 22m in each of the optical sensing means 1 to 3. Measure the delay time between

Next, the specifying unit 25 obtains the measured propagation distance between transmission and reception of the signal light based on the measured delay time, and searches the DB 26 for the propagation distance that matches the obtained measured propagation distance. Here, for example, it is assumed that the propagation distance related to the reflection at the FBG 22a of each of the optical sensing means 1-3 is retrieved.

Next, the specifying unit 25 detects the FBGs 22a of the optical sensing means 1 to 3 associated with the searched propagation distance. The identifying unit 25 identifies the detected pressure P1 of the FBG 22a of each of the optical sensing means 1-3. By this identification, the manager or the like of the management station 30 can recognize that there is no intruder in the intrusion prohibited area.

On the other hand, it is assumed that a person climbs over the optical fiber 12 and intrudes at the position of the optical sensing means 2 in the no-entry area, as indicated by the notched circle 50 . In this case, the specifying unit 25 searches for the propagation distance related to the reflection of the signal light of the specific wavelength λ1 at the fiber mirror 22m of the optical sensing means 2, and specifies the abnormal condition associated with the searched propagation distance. . The camera 32b of the post 73 is directed toward the fiber mirror 22m by the control of the control unit 32 according to this specification. As a result, the administrator or the like can recognize that an intruder is at the position of the light sensing means 2 in the no-entry area.

In addition, signal light with a specific wavelength λ1 is transmitted from the communication device 11b or the communication device 11c to the optical fiber 12 counterclockwise and clockwise, and is reflected by the FBGs 22a to 22k and the fiber mirror 22m of the optical sensing means 1 to 3. The received signal light is received by the communication device 11a. The delay time between transmission and reception may be measured, and environmental conditions and abnormal states may be specified by the specifying unit 25 in the same manner as in Modification 3 above.

<effect>
(1) An optical circulator interposed and connected in the middle of an optical transmission line that is connected back and forth to a communication device that transmits and receives signal light of a specific wavelength or a plurality of different wavelengths including the specific wavelength, and an optical circulator that is dependent on the optical circulator. When the optical circulator is connected and environmental conditions are set in advance, optical sensing is performed by reflecting signal light with a specific wavelength from the optical circulator and transmitting signal light with a wavelength other than the specific wavelength. Through a plurality of FBGs (Fiber Bragg Gratings) different from each other and the optical circulator, round-trip propagation of signal light transmitted and received by the communication device via an optical transmission line after being reflected by any one of the plurality of FBGs. A DB (data base) in which a distance is associated with each of the plurality of FBGs and information on the set environmental conditions for each of the FBGs is associated and stored; a delay measuring unit for measuring a delay time between transmission and reception from a difference in transmission and reception times of signal light transmitted and received by the communication device after being reflected by one; an identifying unit that obtains a measured propagation distance and identifies an FBG associated with the round-trip propagation distance in the DB that matches the obtained measured propagation distance.

According to this configuration, the following effects can be obtained. The optical sensing device of the present invention is constructed by connecting a plurality of FBGs, which are general-purpose components, cascaded with optical fibers via optical circulators, which are general-purpose components, to an optical transmission line using optical fibers for communication purposes. Since the optical circulator and FBG are general-purpose products, they can be configured at low cost. Since the optical sensing device is branch-connected to an optical transmission line, the optical fiber is not exclusively used for optical sensing, and packet loss of signal light does not occur, so it can be used for communication purposes. In addition, optical sensing can be performed by measuring only the transmission/reception delay time from the transmission/reception time of the communication device, so the amount of measurement data does not become enormous even if the measurement is performed for a long time, and a dedicated program is required for data analysis. Therefore, the analysis time is not required.

Therefore, according to the optical sensing device of the present invention, the optical fiber can be used for optical sensing under environmental conditions that facilitate data analysis at low cost, and can also be used for communication purposes.

(2) A fiber mirror that reflects all wavelengths is cascade-connected to the last FBG in the plurality of FBGs, and in addition to the information stored in the DB, a signal that is transmitted and received by the communication device after being reflected by the fiber mirror A round-trip propagation distance of light is associated with the fiber mirror, and specific information of the fiber mirror is associated and stored. the delay time between transmission and reception is measured from the difference between the transmission and reception, the specifying unit obtains the measured propagation distance between transmission and reception of the signal light based on the measured delay time, and The optical sensing device according to (1) above, wherein the fiber mirror and the specific information associated with the round-trip propagation distance in the DB are specified.

According to this configuration, when the signal light transmitted from the communication device passes through all the FBGs, it is received by the communication device via the optical circulator and the optical transmission line after being reflected by the fiber mirror. In this case, the delay measurement unit measures the transmission/reception delay time associated with the reflection on the fiber mirror. Next, the specifying unit searches for the round-trip propagation distance related to the fiber mirror in the DB that matches the measured propagation distance between transmission and reception based on the measured delay time, and searches the fiber mirror associated with this round-trip propagation distance. to detect Furthermore, the identification unit can identify, for example, the above-described abnormal condition as identification information associated with the detected fiber mirror. Therefore, as in (1) above, the optical fiber can be used for optical sensing under environmental conditions that facilitate data analysis at low cost, and can also be used for communication purposes.

(3) Interposed connection in the middle of an optical transmission line between a first communication device that transmits a specific wavelength or a plurality of different wavelengths of signal light including the specific wavelength and a second communication device that receives the transmitted signal light and an optical circulator cascade-connected to the optical circulator by an optical fiber, and in the case of environmental conditions set in advance, the signal light of a specific wavelength from the optical circulator is reflected, and the signal of a wavelength other than the specific wavelength is reflected. a plurality of FBGs having different set environmental conditions for performing optical sensing that transmits light; and the signal light transmitted from the first communication device is reflected by any one of the plurality of FBGs via the optical circulator a DB in which a propagation distance of the signal light to be received later by the second communication device is associated with each of the plurality of FBGs and a set environmental condition for each of the FBGs is associated and stored; a delay measurement unit for measuring a delay time between transmission and reception from the difference in transmission and reception times of signal light transmitted from and received by the second communication device; an identifying unit that obtains a measured propagation distance and identifies an FBG associated with the propagation distance in the DB that matches the obtained measured propagation distance.

According to this configuration, in the optical sensing device connected to the optical transmission line between the first communication device and the second communication device via the optical circulator, data analysis is performed on the optical fiber at low cost, as in (1) above. It is possible to perform optical sensing of environmental conditions that facilitate

(4) A fiber mirror that reflects all wavelengths is subordinately connected to the last FBG in the plurality of FBGs, and in addition to the information stored in the DB, transmitted from the first communication device and reflected by the fiber mirror The propagation distance of the signal light received later by the second communication device is associated with the fiber mirror, and the specific information of the fiber mirror is associated and stored, and the delay measurement unit measures the transmission and reception after being reflected by the fiber mirror. The delay time between transmission and reception is measured from the difference between the transmission and reception times of the signal light, and the specifying unit obtains the measured propagation distance between transmission and reception of the signal light based on the measured delay time. The optical sensing device according to (3) above, wherein the fiber mirror associated with the propagation distance in the DB that matches the measured propagation distance is specified.

According to this configuration, when the signal light transmitted from the first communication device passes through all the FBGs, it is received by the second communication device via the optical circulator and the optical transmission line after being reflected by the fiber mirror. In this case, the delay measurement unit measures the transmission/reception delay time associated with the reflection on the fiber mirror. Next, the identification unit searches for the propagation distance related to the fiber mirror in the DB that matches the measured propagation distance between transmission and reception based on the measured delay time, and detects the fiber mirror associated with this propagation distance. do. Furthermore, the identification unit can identify, for example, the above-described abnormal condition as identification information associated with the detected fiber mirror. Therefore, as in (3) above, the optical fiber can be used for optical sensing under environmental conditions that facilitate data analysis at low cost, and can be used for communication purposes.

In addition, the specific configuration can be changed as appropriate without departing from the gist of the present invention.

10 communication network 11 communication device 12 optical fiber 20, 20A, 20B, 20C optical sensing device 21 optical circulator 22a to 22k FBG
22m fiber mirror 24 delay measurement unit 25 environmental condition identification unit (identification unit)
26 DBs

Claims (6)

1. an optical circulator interposed and connected in the middle of an optical transmission line that is connected back and forth to a communication device that transmits and receives signal light of a specific wavelength or a plurality of different wavelengths including the specific wavelength;
   Optical sensing that is cascade-connected to the optical circulator with an optical fiber, and reflects signal light of a specific wavelength from the optical circulator and transmits signal light of a wavelength other than the specific wavelength when environmental conditions are preset environmental conditions. a plurality of FBGs (Fiber Bragg Gratings) each having different set environmental conditions;
   A round-trip propagation distance of signal light transmitted and received by the communication device via an optical transmission line after being reflected by any one of the plurality of FBGs via the optical circulator is associated with each of the plurality of FBGs. together with a DB (data base) in which information on the set environmental conditions for each FBG is associated and stored;
   a delay measurement unit that measures a delay time between transmission and reception from a difference in transmission and reception times of signal light transmitted and received by the communication device after being reflected by any one of the plurality of FBGs via the optical circulator;
   a specifying unit that obtains a measured propagation distance between transmission and reception of signal light based on the measured delay time, and identifies an FBG associated with the round-trip propagation distance in the DB that matches the obtained measured propagation distance; An optical sensing device comprising:
2. cascade-connecting a fiber mirror that reflects all wavelengths to the last FBG in the plurality of FBGs;
   In addition to the information stored in the DB, the round-trip propagation distance of the signal light transmitted and received by the communication device after being reflected by the fiber mirror is associated with the fiber mirror, and the specific information of the fiber mirror is associated and stored. ,
   The delay measurement unit measures a delay time between transmission and reception from a difference in transmission and reception times of signal light transmitted and received by the communication device after being reflected by the fiber mirror,
   The identifying unit obtains a measured propagation distance between transmission and reception of signal light based on the measured delay time, and the fiber mirror associated with the round-trip propagation distance in the DB that matches the obtained measured propagation distance. and the specific information are specified.
3. Light inserted and connected in the middle of an optical transmission line between a first communication device that transmits a specific wavelength or a plurality of different wavelengths of signal light including the specific wavelength and a second communication device that receives the transmitted signal light a circulator;
   Optical sensing that is cascade-connected to the optical circulator with an optical fiber, and reflects signal light of a specific wavelength from the optical circulator and transmits signal light of a wavelength other than the specific wavelength when environmental conditions are preset environmental conditions. a plurality of FBGs each having different set environmental conditions,
   The signal light transmitted from the first communication device is reflected by any one of the plurality of FBGs via the optical circulator, and the propagation distance of the signal light received by the second communication device is determined for each of the plurality of FBGs. and a DB in which setting environment conditions for each FBG are associated and stored;
   a delay measuring unit that measures a delay time between transmission and reception from a difference between transmission and reception times of signal light transmitted from the first communication device and received by the second communication device;
   a specifying unit that obtains a measured propagation distance between transmission and reception of signal light based on the measured delay time, and identifies an FBG associated with the propagation distance in the DB that matches the obtained measured propagation distance; A light sensing device comprising:
4. cascade-connecting a fiber mirror that reflects all wavelengths to the last FBG in the plurality of FBGs;
   In addition to the information stored in the DB, the propagation distance of the signal light transmitted from the first communication device and received by the second communication device after being reflected by the fiber mirror is associated with the fiber mirror, and and stores the specific information of
   The delay measuring unit measures a delay time between transmission and reception from a difference in transmission and reception times of the signal light transmitted and received after being reflected by the fiber mirror,
   The identifying unit obtains a measured propagation distance between transmission and reception of signal light based on the measured delay time, and selects a fiber mirror associated with the propagation distance in the DB that matches the obtained measured propagation distance. The optical sensing device according to claim 3, characterized in that:
5. An optical sensing method using an optical sensing device that performs optical sensing using signal light,
   The optical sensing device is
   an optical circulator interposed and connected in the middle of an optical transmission line that is connected back and forth to a communication device that transmits and receives signal light of a specific wavelength or a plurality of different wavelengths including the specific wavelength;
   Optical sensing that is cascade-connected to the optical circulator with an optical fiber, and reflects signal light of a specific wavelength from the optical circulator and transmits signal light of a wavelength other than the specific wavelength when environmental conditions are preset environmental conditions. a plurality of FBGs each having different set environmental conditions,
   A round-trip propagation distance of signal light transmitted and received by the communication device via an optical transmission line after being reflected by any one of the plurality of FBGs via the optical circulator is associated with each of the plurality of FBGs. and a DB in which information on the set environmental conditions for each FBG is associated and stored,
   a step of measuring a delay time between transmission and reception from the difference in transmission and reception times of signal light transmitted and received by the communication device after being reflected by any one of the plurality of FBGs via the optical circulator;
   obtaining a measured propagation distance between transmission and reception of signal light based on the measured delay time, and identifying an FBG associated with the round-trip propagation distance in the DB that matches the obtained measured propagation distance; An optical sensing method, characterized by performing:
6. An optical sensing method using an optical sensing device that performs optical sensing using signal light,
   The optical sensing device is
   Light inserted and connected in the middle of an optical transmission line between a first communication device that transmits a specific wavelength or a plurality of different wavelengths of signal light including the specific wavelength and a second communication device that receives the transmitted signal light a circulator;
   Optical sensing that is cascade-connected to the optical circulator with an optical fiber, and reflects signal light of a specific wavelength from the optical circulator and transmits signal light of a wavelength other than the specific wavelength when environmental conditions are preset environmental conditions. a plurality of FBGs each having different set environmental conditions,
   The signal light transmitted from the first communication device is reflected by any one of the plurality of FBGs via the optical circulator, and the propagation distance of the signal light received by the second communication device is determined for each of the plurality of FBGs. and a DB in which the setting environment conditions for each FBG are associated and stored,
   a step of measuring a delay time between transmission and reception from a difference in transmission and reception times of signal light transmitted from the first communication device and received by the second communication device;
   obtaining a measured propagation distance between transmission and reception of signal light based on the measured delay time, and identifying an FBG associated with the propagation distance in the DB that matches the obtained measured propagation distance; An optical sensing method characterized by:

Images