Reflectometric measurements of optical fibers

Reflectometric measurements are made using reflectometers (OTDR Optical Time Domain Reflectometer). Reflectometers, used in the construction and operation of fiber-optic networks, allow to make: junctures attenuation measurement, reflectance (reflectance connectors), visualization of the distribution attenuation along the cable on the reflectometer screen or in print OTDR measurement documentation. Analysis of measurements also allows for precise location of cable faults - the location of the failure. The averaging of measurements shall be measured bi-directional.

With the platform EXFO FTB-1, FTB-200, equipped with inserts reflectometric OTDR we make the measurements:

• measurements classic "linear"

• FTTx network analysis

• locating the place of the failure or problem

FTB-1 platform

FTB-200 plaftorm

Reflectometer ODTR measurement is based on sending to the measured fiber pulses with selected width and a predetermined wavelength and the detection of their part, which is reflected. Based on the input parameters OTDR draws graphs of optical power (or more precisely its decline) as a function of distance. The whole is given on a logarithmic scale.

The basic values, measured by the reflectometer are:

- The distance - that is the distance between events

- Losses on connectors

- Attenuation fiber unit

- Reflection (reflectance)

Sample reflectometer curve

The reflectometric measurement results

Measurement of polarization mode dispersion and chromatic dispersion.

An important transmission parameter, which performs the measurement and analysis of ENERGO-TEL is the bandwidth, the value of which is determined by the dispersion. In the he single-mode fibers we can distinguish polarization mode dispersion  (PMD) and chromatic dispersion (CD).

Measurement of polarization mode dispersion  (PMD) and chromatic dispersion (CD) is made to the qualification tests for fiber optic systems work with data rates of 10 Gb/s.  These measurements are made on the basis of a platform EXFO FTB-500 equipped with specialized modules.

EXFO FTB 500 platform

In the PMD measurements performed by ENERGO-TEL with the FTB-5500B module, interferometric method is used. It allows to perform the measurements on the lines with optical amplifiers.

Measurement of chromatic dispersion offered by ENERGO-TEL using FTB-5800 module is one of the most precise solutions. This method is characterized by a high degree of accuracy, high repeatability, and a small deviation. These features are possible to achieve with a very high-resolution measurement of 950 data points (the most commonly used measurement methods offer a resolution of up to 100 points).

PSE-Operator for testing optical fiber overhead requires methods above.

Optical power measurements

Optical power measurements allow determining whether the conditions to ensure proper operation of the transmission devices are fulfilled. They are made in order to define the level of the optical signal and loss of signal in fiber optic trunks.
These measurements can be divided into:

• measurements of the devices (transmitter power and receiver sensitivity)
• measurements of optical tracks parameters and their elements (fiber attenuation of track sections, connectors attenuation, attenuation assembled fiber optic line)
• measurements of the resulting  fiber optic lines cooperating with devices (power at the output of the track).

These measurements are made based on  EXFO sets of measures.