JP2002543738A - Intrinsic protection of fiber optic communication links - Google Patents

Abstract

SUMMARY An optical waveguide system for protecting an active fiber in a fiber optic communication link from unauthorized interference and interception of data is disclosed. The communication link extends from one location to another and has a waveguide (1000) for transmitting data signals. The data transmitting means (20) transmits a data signal to the fiber (1000), and the data receiving means (22) receives the data signal. The detection signal transmitting means (40) transmits a detection signal to the fiber (1000), and the detection signal receiving means (42) receives the detection signal to the fiber (1000). The transmitting means (20 and 40) are connected to the fiber (1000) by the wavelength multiplexing / demultiplexing coupler (30) via the input arms (76 and 66) of the coupler (30). The signal is transmitted by another wavelength multiplexing / demultiplexing coupler (32) to the receiving means (22 and 42) via the output arms (7c and 6c). The couplers (30 and 32) combine the signals with minimal power loss, separate for transmission to the detection means with minimal power loss, and propagate substantially all data signals to the receiving means (22); All detection signals are transmitted to the receiving means (42).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an optical waveguide system configured to protect an active fiber in a fiber optic communication link from unauthorized interference and interception of data.

[0002]

[Prior art]

Optical devices including laser cavities, waveguides, lenses, filters and other optical elements, and combinations thereof, are commonly used in industrial and scientific fields. Such optical devices are used in various instruments and devices.

[0003] Optical technology has revolutionized the communications and sensor fields. This is mainly due to the rapid development of optical and optoelectronic devices. A wide variety of glass materials,
Doping materials and waveguide mechanisms are available, the provisional specification relates to an optical waveguide system configured to protect the active fiber of a fiber optic communication link from unauthorized interference and interception of data.

[0004] Communication using optical fibers has many attractive properties and advantages over conventional communication means. These advantages include the following. • Greater bandwidth and capacity • Electrical isolation • Low error rate • Immunity to extrinsic influences • Immunity to fraudulent interference and interference • Signal security • Robustness and adaptability • Potential low-cost communication systems The high expectations for optical fiber as an information communication medium in Japan have been demonstrated by its performance over the past 20 years. Due to its large bandwidth, low attenuation and mechanical properties, each fiber can replace more than 1000 copper wires in a telecommunications system. It is not surprising that these properties have made optical fiber the most affordable and efficient medium used in the telecommunications field. Also, increased capacity, ease of system expansion, and reduced equipment, work, and technical maintenance costs have had a significant impact on industry, and are replacing many conventional communication systems.

[0005] The use of optical fibers as the backbone of most communication systems means that large amounts of information can be efficiently and cost effectively communicated from one location to another. Recent fiber optic communication networks have spread over millions of kilometers around the world and carry important and confidential information about government, military, financial and personal characteristics. Initially, fiber optic communications were considered inherently secure, but "intercepted" information from the fiber optics with only minimal interference with the optical signal.
It is known to be relatively easy to do. It has been found that it is sufficient to slightly bend or tighten the fiber somewhere to extract 100% of the information transmitted over the fiber optic cable, and that photons leak to the intruder's receiver. Even if the 0.1 dB (2%) signal is leaking, it contains all of the information communicated by each photon. The user at the other end cannot know that the information has been tampered with, since the user at the other end does not know a clear fraudulent interference regarding communication. 0.1dB
Is the smallest optical loss that can be actually detected in a fiber system by modern test facilities and network management systems. The same techniques can be used to derive false information and to tamper with the current information flow. This has significant implications for the safety of a large number of users of fiber optic communication systems, especially telecommunications companies, banks, brokers, finance, defense agencies, government agencies, embassies and businesses. These information carriers and users are generally vulnerable to data intrusion, fraudulent interference and interception. This weakness has not been publicly identified to date because providers and users did not understand potential threats and because there was no effective solution. Most people still believe that fiber is the safest means of communication, albeit not true.

Until now, the following have been used as effective defense techniques against intrusion into optical fiber telecommunications. • encryption of transmitted information; • physical security systems based on physical barriers (ie thick coatings on fibers, thick hard protective jackets on cables,
And storage of cables in conduits), and • Static or sloW varying measurements using an optical time domain reflectometer (OTDR) to detect fiber spallation, sharp bends,? Ber attenuation, or connector loss.

Cryptographic techniques are costly, often slow system speeds to a considerable degree / unacceptable, and are not totally secure.

[0008] Physical security measures are truly effective when the fiber optic communication system link is exposed to fraudulent interference because the fiber needs to be cut, crushed, or severely bent before a problem can be detected. is not.

[0009] OTDR is not effective in detecting dynamic or momentary disturbances to fiber cables. Also, since only optical loss is measured with a relatively low sensitivity in function, practically only a large and steady or quasi-static (and sometimes destructive) effect on the cable is detected.

[0010] For millions of kilometers of optical fiber spanning the globe, inspection, maintenance, and anticipation of signs of failure or damage to fiber cables are important to the safety and reliability of fiber communication systems. is there. The most common techniques for checking fiber optic cables for fraud or integrity are based on static or quasi-static measurements using OTDR. However, the ability to obtain real-time, quasi-static and dynamic information about some non-destructive disturbance of the fiber cable is a breakthrough in technology. This has the additional advantage that any disturbance to the cable, near the cable or any structure or object to which the cable is attached can be inspected. With this performance, optical fiber communication, structure maintenance inspection, leak detection, ground inspection,
Inspection of a machine state and detection such as intrusion detection can be simultaneously performed in real time.

This is possible because optical fibers can be more than just signal propagation media. The light transmitted to and confined to the fiber core propagates through its normal fiber along its length, unless affected by external influences. Characteristics of incident light (
That is, a special detection device is configured so that any disturbance to the fiber that causes a change in the amplitude, phase, wavelength, polarization, mode distribution, and time of flight can be examined and related to the degree of influence of the disturbance. May be.

[0012] Such light modulation allows measurement of a wide range of events and conditions, including:・ Strain / residual strain ・ Displacement ・ Damage ・ Crushing ・ Vibration / frequency ・ Deformation ・ Impact ・ Acoustic emission ・ Water level ・ Pressure ・ Temperature ・ Load

Optical fiber sensor technology has evolved rapidly over the last decade. A variety of fiber detection element arrangements differing in the principle of light modulation have been developed to test for special parameters. An optical fiber sensor is an essential or ancillary component depending on whether the fiber is a detection element or an information propagation medium. Fiber optic sensors are referred to as "point-type" sensors if the sensing gauge length is in a discrete area. If the sensor is capable of continuous detection of the measurement area over its entire length, it is known as a "distributed" sensor. "Quasi-dispersive" sensors use point sensors at various locations in the fiber. The fiber optic sensor can be made transmissive or can be used in a reflection mechanism by mirror-finishing the fiber end face.

For this reason, optical fiber sensors actually belong to the class of detection elements. Fiber optic sensors, unlike many conventional sensors such as electric strain gauges and piezoelectric transducers, are not limited to a single form or function. Thus, to the extent that we see many of the detection techniques and applications that have been employed for profit, fibers are replacing conventional detection electronics.

However, since most fiber optic sensor systems today are based on point-type sensing elements, large numbers of sensors are required to cover an object over a large area and over long distances. The associated cost and complexity of the system is either binding or impractical.

[0016] Few distributed technologies have been developed and made commercially available. Most of the developed techniques are for temperature testing, and few have the ability to actually measure fiber detection parameters or the area or location of the disturbance.
They simply detect, monitor, or sometimes quantify the occurrence of an event. Also, many of these techniques require the measurement and averaging of very small time-of-flight, low-power reflected light pulses (often based on OTDR principles), thus testing static or quasi-static parameters. Often limited to.

However, real-time, quasi-static and dynamic information can be obtained for all forms of disturbances in the optical fiber and their locations, especially for instantaneous events that occur so quickly that they cannot be detected by the OTDR. Is a great benefit. This can be implemented by combining a distributed detection technique where event location is not possible with an opposing technique where event location is possible. The performance can inspect any structure or object near the fiber or to which the fiber is attached (structure integrity inspection, pipeline leak detection, ground inspection, mechanical condition inspection and invasion of areas where high safety is required) Detection), and enables a distributed detection application technique such as detection of illegal interference to a fiber cable or unauthorized interference by a third party.

Our International Application No. PCT / AU95 / 00568 discloses fiber optic distributed vibration detection technology. The detection technology was based on a unique fiber optic mode sensor configuration. The technique overcomes the weaknesses inherent in most multi-mode fiber optic sensors that provide truly local, mechanically stable and linear detection. In a multimode optical fiber, detection is performed using a modal interference effect based on the modulation of the mode distribution due to extrinsic perturbations (effectively changing the intensity).
In this way, the sensor response is a direct function of the disturbance to the detector of the fiber. Disturbances take the form of physical fluctuations (i.e., compression, extension, torsion, vibration, etc. (radially or axially)) or microphonic effects (i.e., propagation of stress waves or acoustic emission). The ability to adjust the detection length to suit a particular application is a major and unique advantage of the technology. This is particularly relevant where long detection lengths are required, such as when combining detection techniques with fiber optic communications. The detection length is limited by the optical power limit of the system. Therefore, if a longer detection length is desired, a higher power laser is required.

The system according to the present international application provides a simple, effective and inexpensive technique for detecting and identifying real-time large and small disturbances of any fiber optic cable. This allows the simultaneous use of fiber optic communication cables as detection cables for fraudulent interference monitoring, intrusion monitoring, or maintenance testing. Also,
It enables continuous real-time inspection of fiber cables and structures near the cables (ground, tunnels, ducts, pipes, buildings, equipment, vessels, etc.).

One of the key features of the technology is its flexibility in form because it is wavelength independent. This allows the use of any type of optical fiber. Thus, it can be simultaneously reorganized and integrated into existing fiber optic communication cables without the need for new cable installations and costs.

Thus, the present technology adds great value to any communication system in terms of security and allows easy integration into existing fiber optic networks, while simultaneously working with the communication system in the same optical fiber or cable. Can be done. To achieve this, they have realized wavelength multiplexed fiber optic systems that can be used for simultaneous communication and detection in both standard single mode (9/125 μm) and standard multimode (62.5 / 125 μm) fiber optic systems.

FIG. 1A shows a configuration used for implementing a simultaneous optical fiber communication and detection system. The system configuration comprises a single or multi-mode fiber link 1 with a standard 3 dB at each end (50% separation) and 2 at the transmitting and receiving ends.
2.times.2 type fiber couplers 3a and 3b are provided to enable multiplexing and demultiplexing of two wavelengths, respectively. Since the responsiveness of the InGaAs detecting means 2b of the communication channel needs to be very small at the detection wavelength, selection of the detection wavelength is important. Therefore, the communication channel 2a was selected to function at a wavelength of 1300 nm, and the detection channel 4a was selected to function at 633 nm or 850 nm. As a result, the Si detector 4b used in the detection channel does not respond to the communication signal of 1300 nm, so that the interference between the channels is reduced.

FIG. 2B is a diagram when the vibration disturbance is applied to the short portion of the fiber link.
Shows the results obtained by the detection means shown in FIG. Oscillating disturbance was applied to a small portion (5 cm) of the fiber link using a cantilever beam device. The fibers are simply taped longitudinally along the direction of beam travel. Typical sensor responses are shown in FIG. 2 (a) for a 28km single mode (SM) link and in FIG. 2 (c) for a 53km multi-mode (MM) fiber link. As can be seen, the signal is of very good quality. In addition, fast Fourier transform (FFT) (FIG. 2)
b and 2d) show that the natural frequency of the beam is １８18 Hz in both links.

Simultaneous and non-interfering communication and detection has been successfully realized at a communication data rate of 50 Mb / s over SM fiber optic links, as well as a 500 MHz analog communication channel bandwidth system using detection wavelengths of 633 nm and 850 nm. .

Although the technology has proven itself to be effective in protecting optical fiber communication cables, it has significant limitations that limit its practical appeal. It is impossible to precisely measure the perturbation position of the fiber. To overcome this critical limitation, our International Application No. PCT / AU99 / 01028 discloses a disturbance localization methodology and technique in a fiber optic detection system. The technique uses a transmissive count in a two-ended fiber element affected by the same event.
er-propagating) by measuring the time delay or time difference of the optical signal. In the new device, as shown in FIG. 3 (3), continuous wave (CW) optical signals S and S1 are preferably transmitted simultaneously from a single light source to both ends of a detection optical fiber 1 or a group of fibers, and are synchronized by a synchronous photo detector. Detected at the same time. The pulsing of the optical signal is not essential, although some devices use it. Any detection parameter P that causes a change in the countercurrent signal affects both signals equally, but the affected countercurrent signal must continue to propagate through the rest of the fiber to each photodetector. ,
A time delay or a time difference occurs between the detection signals. The time delay is directly proportional to the location of the detection event on the fiber. Thus, if a time delay or time difference is detected or measured, the location of the event can be measured. At the same time, if a detection mechanism with both capabilities is realized, the detection events (ie, distortion, vibration, acoustic emission,
Sudden changes in temperature, etc.) can be quantified and / or identified. Further, a light-insensitive fiber delay line L may be connected at one or both ends to the detection fiber to provide additional delay between the transmitted countercurrent signals and to form a non-sensitive lead fiber.

The technique allows for the location of dynamic and instantaneous events in virtually any distributed fiber optic detection system, and its transmissive countercurrent technology does not involve the limitations and complexity of OTDRs.

The system has the following advantages. • Works with virtually any existing type of transmission dispersive fiber optic sensor that allows the detection, quantification, localization and localization of dynamic and instantaneous events at any location on the fiber. -Transmits all optical signals and power to the detection means and performs its function in a transmissive configuration that does not require signal averaging. • Measure the location of events through a time delay measured between the countercurrent optical signals affected by a common disturbance. Thus, position analysis is limited and determined by the speed of the data acquisition system. -Can work with pulsing techniques but does not require laser pulsing.

With respect to the foregoing advantages, a feasible configuration for inspecting disturbances and measuring position of a fiber optic communication cable by utilizing an inactive (dark) fiber of the cable as shown in FIG. Proposed. However, according to the opinions of the industry, there is a strong demand for testing of live fibers under certain circumstances.

A simple solution to this requirement would be to use the wavelength multiplexing scheme shown in FIG. However, the use of a 3 dB coupler involves a minimum of 6 dB of additional optical loss, which strongly impacts the optical power limit of most communication systems. Ultimately, it would be desirable to improve the technique of modal detection and localization of optical devices that can minimize optical power loss in communication systems. Similarly, if the device also minimizes the optical power loss of the detection system, devising and configuring a communication node or coupling bypass element for the detection signal to extend the detection fiber length beyond one communication node. Becomes possible. This is particularly useful for networks having a ring topology.

[0030]

[Problems to be solved by the invention]

It is an object of the present invention to provide an optical waveguide system configured to protect a fiber from unauthorized data interference and interception while minimizing optical power loss of communication and detection signals in existing optical fiber communication system links. And

[0031]

[Means for Solving the Problems]

The present invention is an optical waveguide communication link, wherein the waveguide transmits a signal from one position to another position, and a data transmitting unit transmits a data signal of a first wavelength to the waveguide.
Data receiving means for receiving the data signal from the waveguide; detection signal transmitting means for transmitting a detection signal of a second wavelength different from the first wavelength to the waveguide; Detection signal detection means for detecting the detection signal after passing through, and substantially all of the data signal are transmitted to the data reception means without significant loss and without containing an important component of the detection signal. And the signal at the first wavelength is transmitted to the detection signal detection means such that substantially all of the detection signal is transmitted to the detection signal detection means without significant loss and without significant components of the data signal. A link comprising the waveguide, the data receiving means, and a signal separating means provided between the detection signal detecting means so as to be separated from the two wavelengths of the detecting signal; provide.

As described above, according to the present invention, the detection signal and the communication signal are transmitted to one waveguide,
Transmitted to the waveguide, and then the system separates the individual wavelength components of the detection signal and the data signal for transmission to each of the data receiving means and the detection signal detecting means, such that the two signals are substantially mixed with each other. And is received with minimal optical power loss. Thus, the sensitivity of the transmitted data signal and the detection signal is significantly improved, which allows for proper data communication and proper detection of any attempt at unauthorized interference of the waveguide to intercept data from the waveguide. It becomes possible.

In a preferred aspect of the present invention, the signal separating means is a wavelength multiplexing / demultiplexing waveguide coupler.

According to a preferred aspect of the present invention, the data signal from the waveguide and the detection signal from the detection signal transmitting unit combine the signal for transmission to the waveguide. Receiving by a wavelength multiplexing / demultiplexing coupler.

Minimizing optical power loss by using wavelength multiplexing / demultiplexing (WDM) waveguide elements to combine or separate individual wavelength components of communication and detection signals in the same optical fiber Can be For example, a typical 2x2 coupler separates the transmitted light into two substantially equal signals in each direction (50% / 50% power separation), and a WDM coupler is effectively very small loss (typically Extract or incorporate a particular wavelength.

In one embodiment of the present invention, the detection signal transmitting means and the detection signal detecting means are provided at the one position and the other position, respectively.

However, in another aspect, both the detection signal transmitting means and the detection signal detecting means are provided at one or the other of the one position or the other position, and the data signal is transmitted by the signal separating means. And a reflection means for reflecting the detection signal through the waveguide after the detection signal is separated from the detection signal.

Preferably, the reflection means is a reflection mirror.

In one embodiment, the detection signal transmitting means transmits a counter-current detection signal to the waveguide, propagates the counter-current detection signal through the waveguide in opposite directions, and detects a perturbation in both counter-current detection signals. It is characterized by a countercurrent detection signal transmitting means capable of measuring the position of any disturbance of the waveguide by the time difference at which the event is detected.

Preferably, there is provided processing means for processing the detection signal, measuring a parameter change in the signal, and identifying a disturbance of the waveguide indicating an irregular interference with the waveguide. It is characterized by the following.

In one embodiment of the present invention, the communication link has a plurality of communication nodes, at least one node has the data transmission means, and a second node has the data reception means and another data transmission means. And the third node has at least another data receiving means, and the waveguide connects each node such that the detection signal passes through the waveguide from the first node to the third node. It is characterized by having.

[0042] In yet another aspect, the waveguide is a continuous loop having a plurality of communication nodes installed along the loop, at least one of the loops including the detection signal transmitting means, A loop having the detection signal detection means is formed.

Preferably, signal coupling means for transmitting a data signal from data transmission means of one node to data reception means of another node is provided.

The invention also provides an optical waveguide communication link, comprising: a waveguide for transmitting a signal from one location to another; data transmission means for transmitting a data signal to the waveguide; A first wavelength multiplexing / multiplexing device coupled to the waveguide and having a first output arm and a second output arm;
A demultiplexing waveguide element, detection signal transmitting means for transmitting a detection signal having a wavelength different from the wavelength of the data signal to the waveguide for transmission to the waveguide together with the data signal, A data receiving means coupled to the first output arm for receiving the data signal from the waveguide element; and a detection signal detecting means coupled to the second output arm for detecting the detection signal from the waveguide element. Attributable to a link that is characterized by

Preferably, the waveguide element is a waveguide multiplexing / demultiplexing coupler.

Preferably, a second waveguide element is separated from the first waveguide element and connected to the waveguide, and the second waveguide element transmits the data signal and the detection signal to the waveguide. Having a first input arm coupled to said data transmission means for transmission to a second waveguide element for transmission to a waveguide, and a second input arm coupled to said detection signal transmission means; It is characterized.

Preferably, the second waveguide element is connected to the waveguide by an output arm that receives both the data signal and the detection signal from the second waveguide element.

Preferably, a first waveguide element is coupled to the waveguide by the input arm such that both the detection signal and the data signal are transmitted to the first waveguide element via the input arm. It is characterized by having.

Preferably, the first waveguide element is a first wavelength multiplexing / demultiplexing (WDM) coupler having the input arm and first and second output arms.

Preferably, the second waveguide element is a second wavelength multiplexing / demultiplexing (WDM) coupler having a first input arm, a second input arm, and the output arm. .

Preferably, the waveguide is an optical fiber. The optical fiber may be a single mode fiber or a multimode fiber.

In one embodiment, the second output arm of the first WDM coupler outputs the detection signal to the WD.
A second input arm of the second WDM coupler is connected to an auxiliary coupler having first and second auxiliary input arms;
A first auxiliary input arm is connected to the detection signal transmission means, a second auxiliary input arm is connected to the detection signal detection means, and the detection signal reflected from the reflection means is transmitted to the first detection means.
After passing through a WDM coupler, reaches a second input arm via a second WDM coupler, reaches a second auxiliary arm via an auxiliary coupler, and reaches the detection signal detecting means. .

A preferred aspect of the invention is a method of protecting an active fiber in a fiber optic communication link from unauthorized interference and interception of data, comprising: providing a light source of a detection system having a different wavelength than the light source of the communication system; Providing a (single or multi-mode) wavelength multiplexed waveguide optical splitter or coupler that efficiently couples detection and communication signals into a single waveguide; light from the wavelength multiplexed waveguide optical splitter or coupler; And transmit the detection and communication signals, while the detection wavelength and waveguide characteristics, among others, satisfy the requirements of the modal detection and position measurement technique described above without affecting the communication signals (single or single). Multi-mode) Silica waveguide is provided. ・ Detection and communication signal are output to two outputs while minimizing optical power loss of communication and detection signal. Providing a split or separate (single or multi-mode) wavelength demultiplexing waveguide optical splitter or coupler at the tube port for detecting the detection signal and, if necessary, the countercurrent detection signal affected by the same parameters And providing a detection means for measuring a time delay or time difference to measure the position of the detection event.

A separate silica waveguide is preferably provided at one or both ends to preferably constitute a blind lead waveguide and, where applicable, to provide additional delay between the transmitted countercurrent signals. It is connected to the first silica waveguide.

In another aspect, the detection wavelength output port of the wavelength demultiplexing waveguide coupler is terminated with a reflection mirror to perform the detection technique in a reflection mode. Similarly, a mirrored waveguide can be coupled to a detection wavelength output port of a wavelength demultiplexing waveguide coupler.

If only detection technology is used, preferably the detection means comprises: a photodetector for receiving electromagnetic waves transmitted or reflected from the detection signal in the silica waveguide; and a signal for recording the detection event. And a processing means for analyzing the

If the position measurement technique is used together with the detection technique, preferably the detection means comprises: a first and a second photodetector simultaneously receiving countercurrent signals in a silica waveguide; Processing means for receiving the signal from the two photodetectors, analyzing the signal to record a second event, measuring the time delay or time difference between the countercurrent signals to determine the location of the detected event. It is characterized by the following.

In a preferred embodiment, the silica waveguide is a detection wavelength multimode fiber,
The lead waveguide is a single mode fiber having a detection wavelength.

In a preferred embodiment, but not by way of limitation, the distributed detection technique is characterized in that it is based on a modal technique using welding of insensitive single mode fiber to insensitive multimode fiber.

In another preferred embodiment, a countercurrent signaling system is used to determine the location of the event, and suitable optics are provided at one or both ends of the system for detecting the signal. I do.

In a preferred embodiment, the wavelength multiplexing / demultiplexing (WDM) coupler is a 2 × 1 WD
It is an M coupler. In other embodiments, they are of the form 2 × 2, 3 ×
It is a suitable multi-port device such as a type 1 or 4 × 2 type.

In a preferred embodiment, all the optical fibers and the fiber elements are connected by welding. In another aspect, the optical fibers and fiber elements are connected in any suitable or suitable manner, such as by mechanical bonding, connecting leads, and through adapters.

In other embodiments, the WDM coupler may be replaced with any of a wavelength filtering, tuning, combining, demultiplexing or guiding device.

In another aspect, a plurality of WDM couplers are used in a ring topology network to configure a coupling bypass element for a detection signal to extend a detection fiber beyond one communication node.

Preferably, the waveguide is provided with at least one optical fiber and / or at least one optical fiber element. In some aspects of the invention, the waveguide is characterized by merely comprising an optical fiber without additional components. However, the optical fiber may have passive or active elements. In addition, the optical fiber has a detecting element, which responds to a change in a desired parameter in an application environment, and also affects the characteristic or property of the detected electromagnetic wave propagating in the waveguide, thereby changing the parameter. May be an element indicating

Preferably, a suitable CW or pulse signal or multiple wavelength sources, or multiple light sources may be used. In a preferred embodiment, without limitation, coherent laser diodes for CW or pulse may be used to provide the optical signal. In other configurations, multiple light sources of the same or different wavelengths may be used to emit a detection signal or detection signals. In other embodiments, the detection and data transmission means may be combined into one transmission means.

A preferred embodiment of the present invention is characterized in that all fibers, low cost optical devices are used in combination with laser diodes, light emitting diodes, photodetectors, couplers, WDM couplers, isolators, and filters.

In a preferred embodiment of the invention, any suitable light source, coupler and photodetector device is used in the detection and position measurement system. In a preferred embodiment, the required property of the light source is that the light is transmitted and propagated in a single mode waveguide.
For position measurement, light propagating in the single mode waveguide remains single mode while traveling the entire length of the single mode waveguide. Once light is transmitted from a single mode fiber to a multimode fiber, multiple modes are induced,
Multimode fibers are sensitive to various parameters. Also, once light is returned from the multi-mode fiber to the single-mode fiber, only the single mode is maintained and travels to the optics of the system. Desensitization of the lead-in / lead-out fiber and position measurement of the sensor are performed in this way. In practice, single mode fibers are made long enough to attenuate all cladding modes to improve the signal to noise ratio. The preferred embodiment applies to both traveling directions of the countercurrent signal.

A nondestructive inspection can be performed by utilizing the characteristics and characteristics of the electromagnetic wave propagating through the waveguide sensor. Thus, the sensors are not necessarily damaged or destroyed to inspect and measure the desired parameters.

In another embodiment, the multimode fiber is replaced by two single mode fibers and a coupler, and the detection is performed on the principle of phase interference.

In the method, according to a preferred embodiment of the present invention, an electromagnetic wave having a detection wavelength is transmitted from a light source such as a pigtail laser diode, a fiber laser or a light emitting diode to a (single or multi-mode) optical waveguide such as an optical fiber. And propagates through the optical waveguide. The optical waveguide is welded or (permanently or temporarily) coupled to one output arm of a wavelength multiplexed (single or multi-mode) optical splitter or coupler for the optical waveguide. Then, when the electromagnetic wave reaches the coupler, it is branched to the output waveguide arm of the coupler. At the same time, the electromagnetic wave at the communication wavelength is pigtailed
A light source such as a laser diode, a fiber laser, or a light emitting diode is branched to another (single or multi-mode) optical waveguide such as an optical fiber, and propagates through the optical waveguide. The optical waveguide is welded or (permanently or temporarily) coupled to the second output arm of the wavelength multiplexed (single or multimode) optical splitter or coupler for the optical waveguide. Then, when the electromagnetic wave reaches the coupler, it is branched to the output waveguide arm of the coupler similarly to the detection signal. Thus, the wavelength multiplexing coupler efficiently couples the detection and communication signals to one output waveguide arm. If a wavelength multiplexing coupler with two output arms is used, the unused arms are broken or terminated to avoid reflection. The output arm of the wavelength multiplexing coupler is either directly welded (permanently or temporarily) to the main waveguide transmission link (single or multi-mode for communication signals and multi-mode for detection signals) or connected (permanently or temporarily). You. Both communication and detection signals propagate the full length of the waveguide without interfering with each other until they reach the other end of the link. The main waveguide is welded or connected (permanently or temporarily) to the input arm of the wavelength demultiplexing coupler. Then, when the signal reaches the coupler, it is effectively separated and split into two separate output arms of the coupler. The output arm of the wavelength demultiplexing coupler is terminated by a suitable photodetector. Appropriate electronics, processing mechanisms and algorithms process the signal from the photodetector to obtain the desired information.

In a preferred aspect, the WDM coupler is a 2 × 1 WDM coupler. In another aspect, these are suitable multi-port devices, such as 2 × 2, 3 × 1, 4 × 2, etc.

In another aspect, a plurality of WDM couplers form a coupling bypass element for a detection signal to extend the detection fiber beyond one communication node.

In another embodiment, all optical fibers and fiber elements are connected by welding. In another aspect, the optical fibers and fiber elements are connected in any suitable or suitable manner, such as by mechanical bonding, connecting leads, and through adapters.

In another aspect, the output port for the detection wavelength of the WDM coupler is terminated with a reflection mirror to perform the detection technique in a reflection mode. Similarly, a mirrored fiber can be coupled to the output port of a WDM coupler.

In another aspect, a transmit countercurrent signal method for determining the location of an event is employed, wherein a suitable optical device is provided at one or both ends of the system for detecting the signal.

In other embodiments, the WDM coupler may be replaced with any of a wavelength filtering, tuning, combining, demultiplexing or guiding device.

Preferably, the optical and electrical devices of the device are characterized by utilizing noise suppression techniques.

Preferably, the optical and electrical components are located in one device control box with optical fiber input / output ports.

Optical, electronic, acousto-optical, magneto-optical, and / or combined optical devices may be used in the system.

[0081]

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention are disclosed by way of example with reference to the following drawings.
FIG. 1 shows an integrated optical fiber detection and communication system using modal detection technology,
2a, 2b, 2c and 2d are graphs showing the results of the detection device shown in FIG. 1 when an oscillating disturbance is applied to a small portion of the fiber link, and FIG. 3 shows an event in an optical fiber detection system. FIG. 4 shows the basic principle of the waveguide transmitted countercurrent signal method for measuring the position of the optical fiber, and FIG. 4 shows a coupled optical fiber detection / communication using the mode type detection technology constituted by the technology of FIG. 3 and the position measurement performance of disturbance. The device is shown in FIG.
FIG. 6 illustrates a general embodiment of the present invention for a transmission detector operating in a single mode optical fiber telecommunication link, and FIG. 6 shows a general embodiment of the present invention for a reflective detector operating in a single mode optical fiber telecommunication link. FIG. 7 is a diagram illustrating an embodiment, FIG. 7 is a diagram illustrating a general embodiment of the present invention for a two-ended counter-current detection and position measurement device functioning in a single-mode optical fiber telecommunication link, and FIG. FIG. 9 illustrates a general embodiment of the present invention for a one-sided counter-current sensing and locating device functioning in a mode fiber optic telecommunications link, and FIG. 9 relates to a transmission type sensing device functioning in a multi-mode fiber optic telecommunications link. FIG. 2 illustrates another general embodiment of the present invention.
0 is a diagram illustrating another general embodiment of the present invention for a reflective detection device functioning in a multi-mode fiber optic telecommunications link, and FIG. 11 is a two-ended countercurrent type working in a multi-mode fiber optic telecommunications link. FIG. 12 illustrates another general embodiment of the present invention for a sensing and locating device, and FIG. 12 shows another embodiment of the present invention for a one-sided countercurrent sensing and locating device functioning in a multimode fiber optic telecommunications link. FIG. 13 is a diagram showing a general embodiment, and FIG. 13 shows a single mode optical fiber / three-node / point-to-point network device using a plurality of WDM couplers and a detection signal for extending a detection fiber beyond one communication node. FIG. 14 is a view showing still another general embodiment of the present invention constituting the connection bypass element of FIG. Still another embodiment of the present invention, wherein a plurality of WDM couplers are used in a fiber optic, three-node, point-to-point network device, and a connection bypass element for a detection signal is configured to extend a detection fiber beyond one communication node. FIG. 15 is a diagram illustrating a general embodiment, wherein FIG. 15 uses a transmissive detector and multiple WDM couplers in a fiber optic ring topology network, and provides a detection signal for extending the detection fiber across all ring topology networks. FIG. 16 is a view showing still another general embodiment of the present invention which constitutes a connection bypass element. FIG. 16 shows a detection method using a countercurrent type detection / position identification apparatus and a plurality of WDM couplers in an optical fiber ring topology network apparatus. Extend fiber across all ring topology networks Is a diagram showing still another general embodiment of the present invention which constitutes a coupling bypass element for a plurality of detection signals.

The preferred embodiments of the present invention will be described without limitation with reference to the drawings. The drawings and the following embodiments are depicted in the most general form possible to avoid confusion. Even if not specifically described or illustrated in the following embodiments and drawings, the following configurations are appropriately used and are not intentionally omitted. • Distributed detection technology is based on modal technology using welding of insensitive single mode fiber to sensitive multimode fiber. • Permeable countercurrent signaling is used for event localization, and appropriate optics are used to detect and process signals at one or both ends of the system, as appropriate. -An additional silica waveguide is provided at one or both ends of the main silica waveguide to form a blind lead waveguide and, where applicable, to provide additional delay between transmitted countercurrent signals. It is connected to a waveguide communication link. • Any suitable light source, coupler and photodetector combination is used in the sensor and position measurement system. In a preferred embodiment, the optical property required for the light source is that light be transmitted and propagated into a single mode waveguide. For position measurement,
Light propagating in a single mode fiber must remain single mode while propagating through the single mode fiber. Once light is transmitted from a single mode fiber to a multimode fiber, multiple modes are induced,
Multimode fibers are sensitive to various parameters. Also, once light is returned from multimode to single mode, only single mode is boosted and propagates to the optics of the system. Sensitivity suppression of the lead-in / lead-out fiber and position measurement of the sensor are performed in this way. In practice, a single mode fiber is made long enough that all cladding modes are attenuated to improve the signal to noise ratio.
This preferred embodiment applies for both traveling directions of the transmitted countercurrent optical signal in which the technique is used. -The use of the properties and properties of the electromagnetic waves propagating through the waveguide sensor allows for inspection in a non-destructive manner. Thus, the sensors are not necessarily damaged, crushed or destroyed to check and localize desired parameters. • All fiber, low cost optics are used with laser diodes, light emitting diodes, photodetectors, couplers, WDM couplers, isolators and filters. The wavelength multiplexing / demultiplexing (WDM) coupler is a 2x1 WDM coupler, and in other embodiments, any suitable multiport device such as 2x2, 3x1, 4x2, etc. May be. -The optical fiber and the optical device are connected by welding. In other embodiments, the optical fiber and the optical device are connected by any suitable or suitable technique, such as a mechanical connection, a connecting lead, and a through adapter.

FIG. 1 shows the configuration used for operation of the simultaneous optical fiber communication and detection system. The system configuration includes two ends 2a and 4a on the transmitting device side and two ends 2b on the receiving device side.
And 4b for the multiplexing and demultiplexing of the two wavelengths, a standard 3 dB (separation rate 50
%) A single or multimode fiber link 1 provided with 2 × 2 type fiber couplers 3a and 3b at both ends. In on the communication channel
Since the response of the GaAs detector 2b needs to be very small at the detection wavelength, selection of the detection wavelength is important. For this reason, the communication channel was selected to function at 1300 nm and the detection channel was selected to function at 633 nm or 850 nm. Since the Si detection device 4b used in the detection channel did not respond to the communication signal of 1300 nm, the interference between the channels became small.

Our International Application Nos. PCT / AU95 / 00568 and PCT / AU99
/ 01028 is incorporated herein by this reference number.

FIGS. 2 a to 2 d show the results of the detection device shown in FIG. 1 when a vibration disturbance is applied to a short part of the fiber link using a cantilever beam device. The fibers are simply taped longitudinally along the beam length. The results are shown for a 28 km single mode (SM) link and a 53 km multi-mode (MM) fiber link. As can be seen, the signal is of very good quality.
In addition, the fast Fourier transform (FFT) has an inherent frequency of the beam of ~ 1 at both ends.
It clearly shows that the frequency is 8 Hz.

FIG. 3 illustrates the basic principle of waveguide through countercurrent signaling for locating events in a fiber optic detection system. The technique relies on measuring the time delay or time difference between transmitted countercurrent optical signals affected by the same event in a two-ended fiber element. In this novel device, a continuous wave (CW) optical signal is preferably transmitted simultaneously from a single light source to both ends of a detection optical fiber or group of fibers and detected simultaneously by a synchronous photodetector. Any detection parameter that changes the countercurrent signal will affect both signals as well. However, the affected countercurrent signal must continue to propagate through the rest of the fiber to each photodetector, causing a time delay or time difference between the detected signals. The time delay is directly proportional to the location of the detection event from port 1 along the length of the fiber according to the following equation:

Point of disturbance _Port1 = {d _x − (νΔt)} / 2 (1)

Here, d _x is the total length of the optical fiber link, Δt is the time delay or time difference between the detection signals, ν is the light speed in vacuum (3 × 10 ⁸ m / s), c is the effective reflection of the optical fiber. This is the optical signal speed represented by c / n _fiber where the coefficient is n _fiber .

Similarly, the disturbance position from port 2 is given by the following equation.

Point of disturbance _Port2 = {d _x + (νΔt)} / 2 (2)

Thus, if a time delay or time difference is detected and measured, the location of the event can be determined. At the same time, if conflicting detection mechanisms are employed, the detection event (ie, distortion,
Vibrations, acoustic emissions, temperature changes, etc.) are quantified and / or identified. Also, a light-insensitive fiber delay line may be coupled at one or both ends to the detection fiber to provide additional delay between the transmitted countercurrent signals and form a blind lead fiber. This helps in designing the technology into a production system.

It is interesting that the results do not need to know the length of the various sensitive and insensitive fiber regions of the system, only the total length d _{x of the} fiber link. This information can be obtained at the project design and installation stage or at OTDR
It is easily obtained in a pre-installation stage by the use of. And once you know the full length,
And if the time delay Δt is measured by the system, then using equation 1 or 2 to determine the location of the detected event is straightforward.

FIG. 4 shows a coupled optical fiber detection / communication device utilizing the modal detection technique and the disturbance position measurement performance configured by the technique of FIG. In practical use of the technology,
It is desirable that the transmission positions of the transmitted countercurrent signals are physically the same. One way in which this can be easily accomplished is by utilizing multiple fiber cables that make up a one-sided system. In this embodiment, two fibers 2 and 3, one in single mode and the other in multimode, span the target specific area (within sleeve 4) (
It is necessary to construct a modal intrusion sensor (for event detection and localization) and one single mode fiber 1 is used as the communication fiber. A perturbation P somewhere in the multimode fiber sleeve 4 produces two countercurrent perturbation signals. The position of the disturbance is measured by measuring the arrival time difference of the signal to the end of the link on the transmitting device side.

FIG. 5 is a diagram illustrating a general embodiment of the present invention for a transmission-type detection device that functions in a single-mode fiber optic telecommunications link. Referring to FIG. 5, in accordance with a preferred embodiment of the present invention, a coherent laser beam having a detection wavelength of 980 nm is transmitted from a pigtailed laser diode having an optional integrated isolator 40 to 98.
The light is transmitted to the 0 nm single mode optical fiber 6a and propagates through the optical fiber 6a. The optical fiber 6a is welded at 57 to one of the input arms 6b of the 980/1550 nm single mode optical fiber wavelength multiplex coupler 30. Then, when the light of the detection wavelength reaches the coupler 30, it is branched to the output arm 5a of the coupler 30. At the same time, a laser beam having a communication wavelength of 1550 nm is transmitted from a pigtail type laser diode having an arbitrary integrated isolator 20 to a 1550 nm single mode optical fiber 7a, and propagates through the optical fiber 7a. The optical fiber 7a is a 980/1550 nm single mode optical fiber wavelength multiplexing coupler 3
0 is welded to the second input arm 7b at 50. Then, when the light of the communication wavelength reaches the coupler 30, it is branched to the output arm 5a of the coupler 30 in the same manner as the detection signal. Therefore, the wavelength multiplexing coupler 30 efficiently couples both the detection and the communication signal to one output arm 5a of the coupler. The output arm 5a of the wavelength multiplexing coupler 30 is directly welded at 52 to the main 1550nm single mode fiber optic transmission link 1000. Both communication and detection signals propagate the entire length of the 1550 nm single mode optical fiber transmission link 1000 without interfering with each other up to the other end of the link 1000. The 1550 nm single mode fiber optic transmission link 1000 is welded at 54 to the input arm 5 b of the 980/1550 nm single mode fiber optic wavelength demultiplexing coupler 32 at the coupler 32.
Are separated and branched into two separate output arms 6c and 7c. The detection signal output arm 6c of 980 nm of the wavelength demultiplexing coupler 32 is a pigtail type InGaAs.
s is welded at 58 to a 980 nm single mode fiber 6d connected to the detector 42. Similarly, the 1550 nm communication signal output arm 7c of the wavelength demultiplexing coupler 32 is connected to the pigtail type InGaAs detector 22 by a 155
It is welded at 56 to the 0 nm single mode fiber 7d. And
Appropriate electronics, signal processing techniques, and algorithms process the signal from the photodetector to obtain the desired information.

FIG. 6 is a diagram illustrating a general embodiment of the present invention for a reflective detection device that functions in a single mode fiber optic telecommunications link. In the embodiment of FIG.
According to a preferred configuration of the present invention, a coherent laser beam having a detection wavelength of 980 nm is transmitted from a pigtailed laser diode having an optional integrated isolator
The light is transmitted to the 80 nm single mode optical fiber 6a and propagates through the optical fiber 6a. The optical fiber 6a is welded at 60 to one input arm 4e of the 980 nm single mode coupler 44. Then, when the light of the detection wavelength reaches the coupler 44, it is branched to the output arm 6g of the coupler 44. If a wavelength multiplexing coupler with two output arms is used, the unused arms are broken or terminated to avoid reflections. Then, the light of the detection wavelength propagates through the optical fiber 6g. The optical fiber 6g is welded at 62 to one input arm 6b of one of the 980 / 1550nm single mode optical fiber wavelength multiplexing couplers 30. Then, when the light of the detection wavelength reaches the coupler 30, it is branched to the output arm 5a of the coupler 30. At the same time, a laser beam having a communication wavelength of 1550 nm is emitted from an arbitrary integrated isolator 2.
The light is transmitted from the pigtail type laser diode having 0 to the 1550 nm single mode optical fiber 7a and propagates through the optical fiber 7a. The optical fiber 7a is connected to the second input arm 7 of the 980/1550 nm single mode wavelength multiplexing coupler 44.
b is welded at 50. Then, when the light of the communication wavelength reaches the coupler 30, it is branched to the output arm 5a of the coupler 30 in the same manner as the detection signal. Therefore,
The wavelength multiplexing coupler 30 efficiently couples the detection and communication signals to one output arm 5a of the coupler. The output arm 5a of the wavelength multiplexing coupler 30 has a main 1550 nm
It is directly welded at 52 to the single mode fiber optic transmission link 1000. Both communication and detection signals propagate the entire length of the 1550 nm single mode optical fiber transmission link without interfering with each other up to the other end of the link 1000. The 1550 nm single mode optical fiber transmission link 1000 is 980 /
It is welded at 54 to the input arm 5b of the 1550 nm single mode optical fiber wavelength demultiplexing coupler 32. Then, when the signal reaches the coupler 30, it is effectively split and split into two separate output arms 6c and 7c of the coupler 32. The 1550 nm communication signal output arm 7 c of the wavelength demultiplexing coupler 32 is welded at 56 to a 1550 nm single mode fiber 7 d connected to the pigtailed InGaAs detector 22. 980 of wavelength demultiplexing coupler 32
The nm detection signal output arm 6c is welded at 64 to a 980nm single mode fiber 6h terminating at a reflective mirror 46. Thus, the detection signal is reflected in opposite directions along the fibers 6h, 6c, 5b, 1000, 5a, 6b and 6g. The detection signal is 1550nm single mode optical fiber transmission link 1.
000 twice, effectively doubling the sensitivity. Output arm 6f of coupler 44
Is welded at 66 to a 980 nm single mode fiber 6d connected to a pigtailed InGaAs detector. Then, appropriate electronics, signal processing methods and algorithms process the signal from the photodetector to obtain desired information.

FIG. 7 is a diagram illustrating another general embodiment of the present invention for a two-ended counter-current sensing and locating device functioning in a single-mode fiber optic telecommunications link in accordance with the technique of FIG. The 980 nm countercurrent detection system 300 converts the detection signal to 155
Used to transmit in the opposite direction of the 0 nm single mode fiber optic transmission link 1000, the system 300 is suitably a second 980 nm countercurrent detection system 320 that transmits the detection signal in the opposite direction of the 1550 nm single mode fiber optic transmission link 1000. Synchronize with the time. Any disturbance P that causes a change in the counter-current detection signal at link 1000 will affect both signals as well. However, the affected convection signal must continue to propagate through the remainder of the fiber to each of the photodetectors in systems 300 and 320, resulting in a time delay or time difference between the detected signals. As mentioned earlier, the time difference is directly proportional to the location of the detected event in the fiber. The time synchronization between the systems 300 and 320 is important in measuring the time difference between the countercurrent signals.

FIG. 8 is a diagram illustrating another general embodiment of the present invention for a one-sided counter-current sensing and locating device functioning in a single-mode fiber optic telecommunications link in accordance with the technique of FIG. The one-end 980 nm counter-current detection system 350 includes two counter-current detections on a 1550 nm single-mode fiber optic transmission link 1000 that is welded 74 at 74 to another optical fiber (single or multi-mode) of the same or similar cable 1200. Used to transmit, propagate, and test signals simultaneously. Any disturbance P that causes a change in the counter-current detection signal of the link 1000 and / or 1200 will affect both signals as well. However, the affected convection signal must continue to propagate through the rest of the fiber to each photodetector of system 350, resulting in a time delay or time difference between the detected signals. As mentioned earlier, the time difference is directly proportional to the location of the detection event on the fiber. System 3
The time synchronization between 00 and 320 is important in measuring the time difference between countercurrent signals.

FIG. 9 is a diagram illustrating another embodiment of the present invention relating to a transmissive detector operating in a multimode fiber optic telecommunications link. Referring to FIG. 9, in accordance with another preferred embodiment of the present invention, a coherent laser beam with a detection wavelength of 1310 nm is transmitted from a pigtailed laser diode with an optional integrated isolator 41 to 13.
The light is transmitted to the 10 nm single mode optical fiber 8a and propagates through the optical fiber 8a. Optical fiber 6a is welded at 84 to one input arm 8b of 850/1310 nm multimode wavelength multiplexing coupler. When the light of the detection wavelength reaches the coupler 34, the light is branched to the output arm 5c of the coupler 34. At the same time, a laser beam having a communication wavelength of 850 nm is transmitted from a pigtail type laser diode having an optional integrated isolator 20 to an 850 nm multimode optical fiber 9.
a and propagates through the optical fiber 9a. The optical fiber 9a is 850/13
Second input arm 9b of 10 nm multimode optical fiber wavelength multiplexing coupler 34
Are welded at 80. Then, when the light of the communication wavelength reaches the coupler 34, it is branched to the output arm 5c of the coupler 34 in the same manner as the detection signal. Accordingly, the wavelength multiplexing coupler 34 efficiently couples the detection and communication signals to one output arm 5c of the coupler. The output arm 5c of the wavelength multiplexing coupler 34 is directly welded at 81 to the main multimode fiber optic transmission link 1500. Both communication and detection signals propagate the entire length of the multi-mode fiber optic transmission link 1500 without interfering with each other up to the other end of the link 1500. The multimode fiber optic transmission link 1500 is welded at 82 to the input arm 5d of the 850/1310 nm multimode fiber optic wavelength demultiplexing coupler. Then, when the signal reaches the coupler 36, the two separate output arms 8 of the coupler 36
c and 9c are efficiently separated and branched. 1310 of wavelength demultiplexing coupler 36
The nm detection signal output arm 8c is welded at 88 to a 1310 nm single mode fiber 8d connected to the pigtailed InGaAs detector 43. Similarly, the 850 nm communication signal output arm 98c of the wavelength demultiplexing coupler 36 is welded at 83 to the multimode fiber 9d connected or inserted into the pigtail Si detector 27. Then, appropriate electronics, signal processing methods and algorithms process the signal from the photodetector to obtain desired information.

FIG. 10 shows another embodiment of the present invention relating to a reflective sensing device functioning in a multimode fiber optic telecommunications link. In the embodiment of FIG. 10, according to another preferred configuration of the present invention, a coherent laser beam having a detection wavelength of 1310 nm is transmitted from a pigtailed laser diode having an optional integrated isolator 41 to 13.
The light is transmitted to the 10 nm single mode optical fiber 8a and propagates through the optical fiber 8a. The optical fiber 8a is connected to one input arm 8e of the single mode coupler 45 by 8
6 is welded. Then, when the light of the detection wavelength reaches the coupler 45, it is branched to the output arm 8g of the coupler 45. If a coupler with two output arms is used, the unused arms are broken or terminated to avoid reflection. The light of the detection wavelength propagates through the optical fiber 8. 8g of optical fiber is 850/13
One input arm 8b of 10 nm multimode optical fiber wavelength multiplexing coupler 34
At 87. When the light having the detection wavelength reaches the coupler 34, the light is branched to the output arm 5c of the coupler 34 in the same manner as the detection signal. If a wavelength multiplexing coupler with two output arms is used, the unused arms are broken or terminated to avoid reflection. At the same time, laser light having a communication wavelength of 850 nm is transmitted from the pigtail type laser diode having an arbitrary integrated isolator 25 to the multimode optical fiber 9a, and propagates through the optical fiber 9a. The optical fiber 9a is a 850 / 1310nm multimode optical fiber wavelength multiplexing coupler 3.
4 is welded at 80 to the second input arm 9b. Then, when the light of the communication wavelength reaches the coupler 34, it is branched to the output arm 5c of the coupler 34 in the same manner as the detection signal. Accordingly, the wavelength multiplexing coupler 34 efficiently couples the detection and communication signals to one output arm 5c of the coupler. The output arm 5c of the wavelength multiplexing coupler 34 is directly welded at 81 to the main multimode fiber optic transmission link 1500. Both communication and detection signals propagate the entire length of the multi-mode fiber optic transmission link 1500 without interfering with each other up to the other end of the link 1500. The multimode fiber optic transmission link 1500 is welded at 82 to the input arm 5d of the 850/1310 nm multimode fiber optic wavelength demultiplexing coupler. When the signal reaches the coupler 36, the signal of the coupler 36
It is effectively separated and branched into two separate output arms 8c and 9c. The 1310 nm communication signal output arm 8c of the wavelength demultiplexing coupler 36 is welded at 83 to a multimode fiber 9d connected to a pigtail or receptacle Si detector 27. The 1310 nm communication signal output arm 9 c of the wavelength demultiplexing coupler 36 is welded 88 to a 1310 nm single or multimode fiber 8 h terminating at a reflective mirror 47. Therefore, the detection signal is reflected in opposite directions along the fibers 8h, 8c, 5d, 1500, 5c, 8b, and 9g, and is branched to the arm 8f via the coupler 45. The detection signal propagates twice through the 1550 nm single-mode fiber optic transmission link 1500, effectively doubling the sensitivity. The output arm 8f of the coupler 45 is welded at 89 to a 980 nm single mode fiber 8d connected to the pigtailed InGaAs detector 42. Then, appropriate electronics, signal processing methods and algorithms process the signal from the photodetector to obtain desired information.

FIG. 11 is a diagram illustrating another general embodiment of the present invention for a two-ended counter-current sensing and locating device functioning in a multi-mode fiber optic telecommunications link in accordance with the technique of FIG. A 1310 nm counter-current detection system 400 is used to transmit the detection signal in one direction of the main multi-mode fiber optic transmission link 1500, and the system 400 is suitably configured to detect the detection signal in the opposite direction of the main multi-mode fiber optic transmission link 1500. In time with a second 1310 nm countercurrent detection system 420 that transmits Any disturbance P that causes a change in the counter-current detection signal at link 1500 will affect both signals as well. However, the affected countercurrent signal must continue to propagate through the remainder of the fiber to the photodetectors of systems 400 and 420, resulting in a time lag or time difference between the detected signals. As mentioned earlier, the time difference is directly proportional to the location of the detection event on the fiber. Time synchronization between the systems 400 and 420 is important in determining the time difference between the countercurrent signals.

FIG. 12 is a diagram illustrating another general embodiment of the present invention relating to a one-sided counter-current sensing and locating device functioning in a multi-mode fiber optic telecommunications link in accordance with the technique of FIG. The one-sided 1310 nm counter-current detection system 450 includes two main multi-mode fiber optic transmission links 1500 that are welded 94 to other fiber (single or multi-mode) of the same or similar cable 1700. It is used to simultaneously transmit, propagate and test convection detection signals. Any disturbance P that causes a change in the countercurrent detection signal of the link 1500 and / or 1700 affects both signals as well. However, the affected countercurrent signal must continue to propagate the rest of the fiber to each photodetector of system 450, resulting in a time delay or time difference between the detected signals. As mentioned above, the time difference is directly proportional to the location of the detection event on the fiber. In this case, time synchronization of the system is possible using a normal signal acquisition system.

FIG. 13 shows a single-mode optical fiber / three-node / point-to-point network device using a plurality of WDM couplers and configuring a connection bypass element for a detection signal in order to extend a detection fiber beyond one communication node. FIG. 4 illustrates yet another general embodiment of the present invention. Referring to FIG. 13, according to a further preferred configuration of the invention, starting at the communication node 1N1, a 980 nm wavelength coherent laser beam is transmitted from a pigtailed laser diode with an optional integrated isolator 140 to a 980 nm single mode optical fiber 16a, Optical fiber 16a
Is propagated. Optical fiber 16a is welded 157 to one input arm 16b of 980 / 1550nm single mode wavelength multiplexing coupler 130. Then, when the light of the detection wavelength reaches the coupler 130, it is branched to the output arm 15a of the coupler 130. At the same time, a laser beam having a communication wavelength of 1550 nm is transmitted from the pigtail type laser diode having an arbitrary integrated isolator 120 to the 1550 nm multimode optical fiber 17a at the communication node 1 and propagates through the optical fiber 17a. The optical fiber 17a is welded at 150 to the second input arm 17b of the 980/1550 nm single mode optical fiber wavelength multiplex coupler 130. Then, when the light of the communication wavelength reaches the coupler 130, it is branched to the output arm 15a of the coupler 130 in the same manner as the detection signal. Accordingly, the wavelength multiplexing coupler 130 efficiently couples the detection and communication signals to one output arm 15a of the coupler. The output arm 15a of the wavelength multiplexing coupler 130 is a main 1550n.
m is directly welded at 152 to the single mode fiber optic transmission link 2000. The 1550 nm single-mode fiber optic transmission link 2000 without both communication and detection signals interfering with each other up to the other end of the link 2000.
Propagate the full length of 1550nm single mode optical fiber transmission link 200
0 is a 980/1550 nm single mode optical fiber wavelength demultiplexing coupler 13
The second input arm 15b is welded at 154. Then, when the signal reaches the coupler 132, the two separate output arms 16c and 17 of the coupler 132
c is efficiently separated and branched. The 1550 nm communication signal output arm 17 c of the wavelength demultiplexing coupler 132 is welded at 88 to a 1550 nm single mode fiber 17 d connected to the pigtailed InGaAs detector 122 at the communication node 2N2. Then, appropriate electronics, signal processing methods and algorithms process signals from the photodetector to obtain desired communication information. The 980 nm detection signal output arm 16c of the wavelength demultiplexing coupler 132 bypasses the communication node 2 so that the detection signal continues to propagate to the communication node 3N3 98.
It is welded at 158 to a 0 nm or 1550 nm single mode optical fiber 2001. Subsequently, the detection signal propagates through the connection bypass fiber 2001 to the welding position of the 980/1550 nm single-mode optical fiber wavelength multiplexing coupler 230 of the fiber 2001 to the input arm 116b of the coupler 230, and when the light of the detection wavelength reaches the coupler 230. , To the output arm 115a of the coupler 230. At the same time, a laser beam having a communication wavelength of 1550 nm is incident on a 1550 nm single mode optical fiber 117a from a pigtail type laser diode having an arbitrary integrated isolator 220 at the communication node 2 and propagates through the optical fiber 117a. The optical fiber 117a is welded at 250 to the second input arm 17b of the 980 / 1550nm single mode optical fiber wavelength multiplex coupler 230. Then, when the light of the communication wavelength reaches the coupler 230, the light of the
It branches into 30 output arms 115a. Thus, wavelength multiplexing coupler 230 efficiently couples the detection and communication signals to one output arm 115a of the coupler. The output arm 115a of the wavelength multiplexing coupler 230 is directly welded 252 to the main 1550nm single mode fiber optic transmission link 2002. Both communication and detection signals do not interfere with each other up to the other
It propagates the entire length of the 0 nm single mode optical fiber transmission link 2002. Fifteen
50nm single mode fiber optic transmission link 2002 is 980 / 1550n
Input arm 215b of m single mode optical fiber wavelength demultiplexing coupler 232
At 254. Then, when the signal arrives at coupler 232, it is effectively split and split into two separate output arms 116c and 117c of coupler 232. 1550 nm communication signal output arm 11 of wavelength demultiplexing coupler 232
Reference numeral 7c denotes a communication node 3 connected to the pigtail type InGaAs detector 222.
It is welded at 256 to a 550 nm single mode fiber 117d. At the same time, the detection signal output arm 116 of 980 nm of the wavelength demultiplexing coupler 232
c is welded at 258 to a 980 nm single mode fiber 116d coupled to a pigtailed InGaAs detector 242. Then, appropriate electronics, signal processing methods and algorithms process signals from the photodetector to obtain desired communication information. In this method, an end of one transmitting device 140 and an end of one detecting device 242 are used, and a detection signal is propagated through two optical fiber links 2000 and 2002. For a 980 nm detection signal, if the communication system is functioning in a multi-mode link, it is also possible to use a true multi-mode fiber instead of the single mode fibers 2000, 2001 and 2002.

FIG. 14 shows a multi-mode optical fiber / three-node / point-to-point network device using a plurality of WDM couplers and configuring a connection bypass element for a detection signal in order to extend a detection fiber beyond one communication node. FIG. 4 illustrates yet another general embodiment of the present invention. Referring to FIG. 14, according to another preferred embodiment of the present invention, a coherent laser beam having a detection wavelength of 1310 nm starting from a communication node 1 is transmitted from a pigtail type laser diode having an optional integrated isolator 141 to a 1310 nm single mode optical fiber. 18a and propagates through the optical fiber 18a. The optical fiber 18a is welded at 184 to one input arm 18b of an 850/1310 nm multimode optical fiber multiplexing coupler 134. When the light of the detection wavelength reaches the coupler 134,
To the output arm 15c. At the same time, the communication wavelength
Laser light of 0 nm is transmitted from the pigtailed laser diode having an optional integrated isolator 125 to the multimode optical fiber 19a and propagates through the optical fiber 19a. The optical fiber 19a is welded at 180 to the second input arm 19b of the 850 / 1310nm multimode optical fiber wavelength multiplexing coupler 134. When the light having the communication wavelength reaches the coupler 134, the light is branched to the output arm 15c of the coupler 134 in the same manner as the detection signal. Thus, the wavelength multiplexing coupler 134 efficiently couples the detection and communication signals to one output arm 15c of the coupler. The output arm 15c of the wavelength multiplexing coupler 134 is directly welded 181 to the main multimode fiber optic transmission link 2150. Without both communication and detection signals interfering with each other until reaching the other end of link 2150,
It propagates the entire length of the multimode optical fiber transmission link 2150. The multimode fiber optic transmission link 2150 is welded 182 to the input arm 15d of the 850/1310 nm multimode fiber optic wavelength demultiplexing coupler 136. Then, when the signal reaches the coupler 136, it is effectively split and split into two separate output arms 18c and 19c of the coupler 136. The communication signal output arm 19c of 850 nm of the wavelength demultiplexing coupler 136 is connected to the multi-mode fiber 1 of the pigtail type or receptacle type Si detector 127 at the communication node 2.
9d is welded at 183. Then, appropriate electronics, signal processing methods and algorithms process the signal from the photodetector to obtain desired information. 1310 nm detection signal output arm 1 of wavelength demultiplexing coupler 136
8c is a multimode or 1310 nm single mode optical fiber 2160 that bypasses communication node 2 so that the detection signal continues to propagate to communication node 3.
8 is welded. Subsequently, the detection signal indicates that the fiber 2160 is 850/131.
One input arm 11 of 0 nm multimode optical fiber wavelength multiplexing coupler 234
8b through the connecting bypass fiber 2160 to the welding position 284. When the light of the detection wavelength reaches the coupler 234, the output arm 1 of the coupler 234
It branches to 15c. At the same time, a laser beam having a communication wavelength of 850 nm is transmitted from the pigtail type laser diode having an arbitrary integrated isolator 225 to the multimode optical fiber 119a at the communication node 2, and the optical fiber 119a
Is propagated. The optical fiber 119a is welded at 250 to the second input arm 119b of the 850 / 1310nm multimode optical fiber wavelength multiplexing coupler 234. Then, when the light of the communication wavelength reaches the coupler 234, it is branched to the output arm 115c of the coupler 234 in the same manner as the detection signal. Accordingly, the wavelength multiplexing coupler 234 efficiently couples the detection and communication signals to one output arm 115c of the coupler. The output arm 115c of the wavelength multiplexing coupler 234 is directly welded 281 to the main multimode fiber optic transmission link 2710. Without both communication and detection signals interfering with each other until reaching the other end of link 2710,
It propagates the entire length of the multimode optical fiber transmission link 2710. The multimode fiber optic transmission link 2710 is welded at 282 to the input arm 115d of the 850/1310 nm multimode fiber optic wavelength demultiplexing coupler 236. Then, when the signal reaches the coupler 236, it is effectively split and split into two separate output arms 118c and 119c of the coupler 236. The 850 nm communication signal output arm 119c of the wavelength demultiplexing coupler 236 is a multimode fiber 119d connected to the pigtail type Si detector 227 at the communication node 3.
At 283. Similarly, 131 of the wavelength demultiplexing coupler 236
The 0 nm detection signal output arm 118c is a pigtail type InGaAs detector 24.
Multimode or 1310 nm single mode fiber 118 coupled to 3
d is welded at 288. Then, appropriate electronics, signal processing methods and algorithms process signals from the photodetector to obtain desired communication information. In this method, one transmitting device 141 side end and one detecting device 2
Only the end on the 43 side is used, and the detection signal is propagated through two optical fiber links 2150 and 2170.

FIG. 15 shows a book forming a connection bypass element for a detection signal in order to extend a detection fiber across all ring topology networks using a transmission type detection device and a plurality of WDM couplers in an optical fiber ring topology network. FIG. 4 illustrates yet another general embodiment of the invention. In this configuration, ring topology network (RTN) nodes 500, 502, 504, 506, 508 and 5
10 (single or multi-mode) fiber optic links 600, 602, 60
4, 606, 608 and 610 through appropriate WDM couplers 550, 552, 5
54, 556, 558, 560, 562, 564, 566, 568, 570 and 572. On the other hand, the detection signal is transmitted from a pigtailed laser diode with an optional integrated isolator 520 to the network fiber
04, 606, 608 and 610, suitable WDM couplers 550, 552,
The signal is detected by the same logical sequence of 554, 556, 558, 560, 562, 564, 566, 568, 570 and 572 and the (single or multi-mode) coupled bypass fibers 650, 652, 654, 656 and 658. Sent until received at 540. The advantage of this embodiment is that only the end on the one transmitting device 520 side and the end on the one detecting device 540 side are used, while the detecting fiber is extended over all ring topology networks.

FIG. 16 shows an optical fiber ring topology network device using a countercurrent type detection / position measurement device and a plurality of WDM couplers, and a plurality of signal detection signals for extending a detection fiber over all ring topology networks. FIG. 9 is a view showing still another general embodiment of the present invention constituting a connection bypass element. In this configuration, ring topology network (RTN) nodes 700, 702, 704,
706, 708 and 710 are fiber optic links (single or multi-mode).
Via 00, 802, 804, 806, 808 and 810, suitable WDM couplers 750, 752, 754, 756, 758, 760, 762, 764, 766,
They are connected by a logical sequence of 768, 770 and 772. On the other hand, the convection detection system 720 can be connected to the appropriate W through network fibers 800, 802, 804, 806, 808, and 810, as detailed with respect to the other figures.
DM couplers 750, 752, 754, 756, 758, 760, 762, 764
, 766, 768, 770, and 772 and the coupled bypass fibers 850, 852, 854, 856, and 858 (single or multi-mode) receive the signal at the tuned detector of the countercurrent detection system 720. The counter-current detection signal is transmitted at the same time. An advantage of this embodiment is that only one device control box with individual fiber optic input / output ports is used, and that the detection fibers are extended across the entire ring topology network.

Communication using fiber optics has a number of attractive properties and advantages over conventional communication devices, the effects of which have been demonstrated over the past two decades. The value provided by these systems has simultaneously been demonstrated in real-time, with the ability to inspect the integrity of the cable, along with any structures or objects to which the cable is attached or attached. This attractive and useful property increases the technical demand.

By way of example, but not exhaustively, the following example illustrates an application in which a combined communication and detection (duplex) system is utilized.

[0108] Any fiber optic communication system that needs to be inspected and detected for intrusion, unauthorized interference and interception of information from fiber optics such as:

Single Mode or Multi Mode Information Technology (IT) Networks and Links Single Mode Local Area Network (LAN) Multi Mode Local Area Network (LAN) Single Mode Wide Area Network (WAN) Multi Mode Wide Area Network (WAN) Short Range Telecommunications Long-distance telecommunications Private fiber optic links and networks Public fiber optic links and networks Commercial fiber optic links and networks Military fiber optic links and networks Defense fiber optic links and networks Embassy fiber optics Links & Networks Industrial Fiber Optic Links & Networks Financial Institution Fiber Optic Links And networks Any optical fiber communication system used for the following detection application technologies:-Public telecommunications-Private telecommunications-Information industry networks-National security-Personal security-Industrial security-Strengthening laws・ Intelligence operations ・ Physical perimeter security ・ Intrusion detection and localization ・ Pipeline maintenance ・ Pipeline interference detection and localization ・ Pipeline leak detection and localization ・ Public Road Authorities-Private Road Searching-Railway Authorities and Traffic Control Operators-Road Traffic Operators All fiber optic detection systems used for telecommunications, including:-Public telecommunications-Private telecommunications-Information industry networks-National Security ・ personal security ・ industrial security ・ strengthening of law ・ intelligence ・ physical perimeter security ・Intrusion detection and localization ・ Pipeline maintenance inspection ・ Pipeline interference detection and localization ・ Pipeline leak detection and localization ・ Island and offshore buildings and construction structures maintenance inspection and design ・ Machinery Inspection and design of performance ・ Inspection of railway stock (flat spot detection) ・ Power generation and transmission companies ・ Inspection and design of institutions for petrochemical and industrial plants ・ Aerospace / aviation design and maintenance agencies ・ Public road authorities ・ Private Road search ・ Railway authorities and traffic control operators ・ Road traffic operators ・ Airline operators ・ Mining companies ・ Earthquake observation agencies ・ Marine companies

The present invention is not to be construed as limited to the particular embodiments described by way of the examples, as modifications within the spirit and scope of the invention will be readily made by those skilled in the art.

[Brief description of the drawings]

FIG. 1 Integrated optical fiber detection and communication system using modal detection technology

2A is a graph showing the result of the detection device shown in FIG. 1 when a vibration disturbance is applied to a small portion of a fiber link;

FIG. 2B is a graph showing the result of the detection device shown in FIG. 1 when the vibration disturbance is applied to a small portion of the fiber link.

2C is a graph showing the result of the detection device shown in FIG. 1 when the vibration disturbance is applied to a small portion of the fiber link.

FIG. 2D is a graph showing the result of the detection device shown in FIG. 1 when a vibration disturbance is applied to a small portion of the fiber link;

FIG. 3. Basic principle of a counter-current signal transmission method for measuring the position of an event in an optical fiber detection system.

4 is a combined optical fiber detection / communication apparatus using a modal detection technique constituted by the technique of FIG. 3 and a position measurement performance of a disturbance.

FIG. 5 illustrates a general embodiment of the present invention for a transmissive detector operating in a single mode fiber optic telecommunications link.

FIG. 6 illustrates a general embodiment of the present invention for a reflective detection device functioning in a single mode fiber optic telecommunications link.

FIG. 7 illustrates a general embodiment of the present invention for a two-ended counter-current sensing and locating device functioning in a single-mode fiber optic telecommunications link.

FIG. 8 illustrates a general embodiment of the present invention for a single-ended counter-current sensing and locating device functioning in a single-mode fiber optic telecommunications link.

FIG. 9 illustrates another general embodiment of the present invention relating to a transmission-type detection device functioning in a multi-mode fiber optic telecommunications link.

FIG. 10 illustrates another general embodiment of the present invention for a reflective detection device functioning in a multimode fiber optic telecommunications link.

FIG. 11 illustrates another general embodiment of the present invention for a two-ended, counter-current sensing and locating device functioning in a multi-mode fiber optic telecommunications link.

FIG. 12 illustrates another general embodiment of the present invention for a one-sided counter-current sensing and locating device functioning in a multi-mode fiber optic telecommunications link.

FIG. 13 is a diagram illustrating a single-mode optical fiber / three-node / point-to-point network device using a plurality of WDM couplers to configure a connection bypass element for a detection signal in order to extend a detection fiber beyond one communication node; FIG. 4 shows still another general embodiment of

FIG. 14 is a diagram illustrating a multi-mode optical fiber / three-node / point-to-point network device using a plurality of WDM couplers to configure a connection bypass element for a detection signal in order to extend a detection fiber beyond one communication node; Figure showing yet another general embodiment of

FIG. 15 is a diagram illustrating a connection bypass device for a detection signal in order to extend a detection fiber across all ring topology networks using a transmission type detection device and a plurality of WDM couplers in an optical fiber ring topology network according to the present invention. Diagram showing yet another general embodiment

FIG. 16 shows a connection bypass for a plurality of detection signals in order to extend a detection fiber across all ring topology networks by using a counter-current detection / position identification device and a plurality of WDM couplers in an optical fiber ring topology network device. FIG. 4 is a diagram showing still another general embodiment of the present invention constituting an element.

[Procedural Amendment] Submission of translation of Article 34 Amendment of the Patent Cooperation Treaty

[Submission date] November 1, 2000 (2000.11.1)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Contents of correction]

[Claims]

──────────────────────────────────────────────────続 き Continuation of front page (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, TZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CR, CU, CZ, DE, DK, DM, DZ, EE, ES, FI, GB, GD, GE, GH, GM, HR , HU, ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA , ZW

Claims (21)

[Claims] 1. An optical waveguide communication link, comprising: a waveguide for transmitting a signal from one location to another; a data transmission means for transmitting a data signal of a first wavelength to the waveguide; Data receiving means for receiving the data signal from the waveguide; detection signal transmitting means for transmitting a detection signal of a second wavelength different from the first wavelength to the waveguide; Detection signal detection means for detecting the detection signal after passing through, and substantially all of the data signal is transmitted to the data reception means without significant loss and without containing an important component of the detection signal. And the signal at the first wavelength is transmitted to the detection signal detection means such that substantially all of the detection signal is transmitted to the detection signal detection means without significant loss and without significant components of the data signal. The waveguide, the data so as to be separated from the two wavelengths of the detection signal. A link comprising: a data receiving unit; and a signal separating unit provided between the detection signal detecting unit. 2. The link according to claim 1, wherein said signal separating means is a wavelength multiplexing / demultiplexing waveguide coupler. 3. The wavelength multiplexing / demultiplexing of the data signal from the waveguide and the detection signal from the detection signal transmitting means for combining the signal for transmission to the waveguide. The link of claim 1, wherein the link is received by a coupler. 4. The link according to claim 1, wherein the detection signal transmitting means and the detection signal detecting means are provided at the one position and the other position, respectively. 5. The detection signal transmitting means and the detection signal detecting means are both provided at one or the other of the one position or the other position, and the signal separating means converts the detection signal from the data signal. 2. The link according to claim 1, further comprising a reflection means for reflecting the detection signal through the waveguide after being separated. 6. The link according to claim 5, wherein said reflection means is a reflection mirror. 7. The detection signal transmitting means transmits a counter-current detection signal to the waveguide and causes the counter-current detection signal to propagate through the waveguide in mutually opposite directions, and a perturbation detection event occurs in both counter-current detection signals. The link according to any one of claims 1 to 5, wherein the link is a counter-current detection signal transmitting means capable of measuring the position of any disturbance in the waveguide based on the detected time difference. . 8. A processing means for processing the detection signal, measuring a change in a parameter in the signal, and identifying a disturbance of the waveguide indicating an irregular interference with the waveguide. The link according to claim 1, wherein the link comprises: 9. The communication link has a plurality of communication nodes, at least one node has the data transmission means, a second node has the data reception means and another data transmission means, The three nodes have at least another data receiving means, and the waveguide connects each node so that the detection signal passes through the waveguide from the first node to the third node. The link according to claim 1, wherein: 10. The waveguide is a continuous loop having a plurality of communication nodes installed along the loop, wherein at least one of the loops includes the detection signal transmitting means and the detection signal detection. 2. A link according to claim 1, wherein the link forms a loop having means. 11. A link comprising signal coupling means for transmitting a data signal from data transmission means of one node to data reception means of another node. 12. An optical waveguide communication link, comprising: a waveguide for transmitting a signal from one location to another; data transmission means for transmitting a data signal to the waveguide; A first wavelength multiplexing / demultiplexing waveguide element having a first output arm and a second output arm, and a detection signal having a wavelength different from the wavelength of the data signal. Detection signal transmitting means for transmitting to the waveguide for transmission to the waveguide; data receiving means coupled to the first output arm for receiving the data signal from the waveguide element; A link connected to the arm and detecting signal detection means for detecting a detection signal from the waveguide element. 13. The link according to claim 12, wherein said waveguide element is a waveguide multiplexing / demultiplexing coupler. 14. A second waveguide element is coupled to said waveguide away from said first waveguide element, said second waveguide element being adapted to transmit said data signal and said detection signal to said waveguide. A first input arm coupled to said data transmitting means to be transmitted to a second waveguide element for transmission to the first input arm;
The link according to claim 12, further comprising a second input arm connected to the detection signal transmitting means. 15. The apparatus of claim 1, wherein the second waveguide element is coupled to the waveguide by an output arm that receives both the data signal and the detection signal from the second waveguide element.
Link described in 4. 16. A first waveguide element in which both the detection signal and the data signal are transmitted through an input arm to the first waveguide element.
13. The link of claim 12, wherein said link is coupled to said waveguide by said input arm for transmission to a waveguide element. 17. A first waveguide element comprising: a first waveguide element having the input arm and first and second output arms.
The link of claim 14, wherein the link is a wavelength multiplexing / demultiplexing (WDM) coupler. 18. The apparatus of claim 18, wherein the second waveguide element is a second wavelength multiplexing / demultiplexing (WDM) coupler having a first input arm, a second input arm, and the output arm. 17 described link. 19. The link according to claim 12, wherein the waveguide is an optical fiber. 20. A second output arm of the first WDM coupler is coupled to a reflection means for reflecting the detection signal through the WDM coupler to the waveguide, and a second input arm of the second WDM coupler has first and second input arms. The first auxiliary input arm is connected to the detection signal transmitting means, the second auxiliary input arm is connected to the detection signal detecting means, and the detection reflected from the reflecting means is connected to an auxiliary coupler having an auxiliary input arm. After the signal has passed through the first WDM coupler,
19. The detection signal detecting means according to claim 18, wherein the detection signal reaches the second input arm via a DM coupler, reaches the second auxiliary arm via an auxiliary coupler, and reaches the detection signal detecting means.
The mentioned link. 21. A method of protecting an active fiber in a fiber optic communication link from unauthorized interference and interception of data, comprising: providing a detection system light source having a wavelength different from the light source of the communication system; Providing a (single or multi-mode) wavelength multiplexing optical waveguide splitter or coupler that efficiently merges with the waveguide of the optical waveguide, receiving light from the wavelength multiplexing optical waveguide splitter or coupler, and transmitting the detection and communication signals. Providing a propagable (single or multi-mode) silica waveguide to split or separate the detection and communication signals into two output waveguide ports while minimizing optical power loss of the communication and detection signals (Single or multi-mode) wavelength demultiplexing optical waveguide splitter or coupler, detect the detection signal, and Wherein the measuring the occurrence of unauthorized interference with the tube.