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Is FGB Fiber Optic Reflector Still Relevant?

What is the  FGB Reflector?
Fiber Bragg Grating (FBG) Reflectors are installed at an ONU to reflect 1650nm signals from an OTDR for line testing purposes from the OLT, while the working bands of the PON are transmitted normally.

When the reflected signal has low loss, the circuit is functioning properly, when the loss is significant, the circuit has an issue, and when no signal is returned, the optical circuit is broken.

Offer SC or LC connector types in a female to male adapter configuration or in a pigtail configuration.

The adapter configuration works similarly to an attenuator and can be added to any existing connector.

The pigtail configuration has the FBG inside the ferrule and can be made into an assembly or spliced.

Customized reflect wavelengths available upon request.
FBG Reflector can be used in FTTX fiber trouble-shooting monitoring. The OTDR and FBG Reflector combination can detect and locate fiber faults in minutes.

Features of FBG Reflector:
The FBG fiber grating reflector is a wavelength selective reflector, which is usually installed at the front end of the ONU of the optical network to achieve accurate and fast detection of the end-to-end attenuation of the optical link. Compared with thin-film reflectors, fiber grating reflectors have the following characteristics:

1. The FBG reflector creates high reflectivity at the PON end, which will not affect the communication
The fiber grating reflector uses fiber grating to reflect nearly 100% of the test light pulse sent by the OTDR on the OLT side of the optical link terminal, and the wavelengths that do not meet the conditions pass through the fiber optic reflector normally with a small attenuation.

When the OTDR detects that the reflected detection signal exists, the optical fiber connection at the user end is normal. If the reflection value is very low or there is no reflection, it indicates that the fiber at the user end is damaged or broken. It can make online rapid detection of optical fiber lines without affecting the normal communication of other communication signals.

2. High stability and reliability of FBG reflector
The fiber grating reflector uses the light sensitivity of the fiber material to write the fiber grating on the fiber core. The optical fiber goes through the ceramic ferrule and the grating area is partially encapsulated inside the ceramic ferrule. The fiber grating will not be affected during the insertion and removal of the fiber optic reflector and it will not be affected by dirt, so it has high reliability.

3. The FBG reflector and the adapter structure are easy to connect.
Fiber optic reflectors are available in SC type and LC type. They interact with regular adapters. It is very convenient to use them.

With the widespread implementation of fiber-to-the-home FTTH projects, the number of users involved in optical networks continues to increase. How to quickly and accurately detect optical network faults is particularly important for the maintenance of optical networks.

By installing the fiber optic reflector at the optical fiber connection end, the maintenance efficiency of the FTTH network is improved and the cost is lower. FBG Fiber optic reflector is an ideal choice for optical fiber line monitoring and can be widely used in FTTX network, PON network, central computer room reflectivity test, communication system link detection, etc.

How do FBG reflectors work? (Passive Optical Network)

How Can Fiber Reflector Be Used in PON Network Link Monitoring?
In the PON (passive optical network) network, especially in the complex point-to-multipoint PON ODN (optical distribution network) topology environment, the rapid detection and diagnosis of optical fiber faults have become challenging work.

Although optical time-domain reflectometer (OTDR) tools are widely used at present, OTDR detection is sometimes not particularly sensitive to the attenuation of optical signals at the ends of some ODN branch fibers or ONU fibers.

Installing a low-cost wavelength-selective optical fiber reflector on the ONU side is often used at present, through which accurate detection of the end-to-end attenuation of the optical link can be achieved.

The working principle of fiber grating reflectors
The test light pulse sent by the OTDR is mainly reflected with a reflectivity of nearly 100% by using the fiber grating, while the working wavelength of a normal passive optical network (PON) system passes through the reflector with little attenuation because it does not satisfy the Bragg condition of the fiber grating.

The main function of this is to accurately calculate the return loss value of the reflection event at the end of each ONU branch by detecting the existence of the reflected OTDR test signal and the intensity of the optical signal. Thus, it tells whether the optical link from the OLT side to the ONU side is normal. In this way, real-time monitoring of fault points and fast and accurate diagnosis is realized.

By flexibly deploying the position of the fiber grating reflector and identifying different ODN sections, the detection and location of the ODN fault point and the cause analysis can be quickly realized, which can reduce the fault processing time and improve the test efficiency and maintenance quality.

In the first-level splitting scenario, through the optical fiber reflector installed on the ONU side, if the return loss of the reflector of a certain fiber branch of the home increases significantly compared with the return loss value of the health file, it indicates that there is a problem with the optical fiber link of this branch. If all the fiber branches installed with fiber reflectors have obvious return loss at the same time, it indicates that the main fiber is faulty.

In the secondary optical splitting scenario, the difference between return losses can also be used to accurately locate whether the attenuation fault has occurred in the distribution fiber segment or the home fiber segment. Whether it is a first-level or second-level splitting scenario, since the reflection peak will drop sharply at the end of the OTDR test curve, the return loss value of the longest branch link in the ODN network may not be accurately measured and it is necessary to measure the fiber reflection. The change of the reflector level can be used as the basis for fault measurement and diagnosis.

Fiber optic reflectors can also be added where deployment is required. For example, install FBG before the distribution fiber to the home (FTTH)/into the building (FTTB) and then use the OTDR to test. Compare the test data with the benchmark data, to judge indoor/outdoor optical fiber faults.

Technical Parameter

How to customize FGB Reflector?
Heyoptics provides all about FBG reflectors, If you're searching for additional amazing FBG reflectors, visit our online shop or get in touch with us for even more options! We will provide better solutions if you need more sizes Contact sales@heyoptics.ca