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Optical Loss: Principles and Applications
Published in John G. Webster, Halit Eren, Measurement, Instrumentation, and Sensors Handbook, 2017
M.M. Rad, Halit Eren, Martin Maier
The OTDR equipment launches a series of short light pulses into the fiber and measures the backscattered light. A general schematic of an OTDR device is presented in Figure 53.9. The reflected signal arrives at the transmitter with a delay proportional to the corresponding relative distance with respect to the transmitter. The backreflected signals are decoupled from the fiber by means of a beam splitter and circulators installed inside the OTDR. The OTDR trace then gives the impulse response of the link under the test, that is, a plot of the power versus distance. OTDR is an optoelectronic device, which provides a full characterization of the fiber link under test.
Installation and Testing
Published in Lynne D. Green, Fiber Optic COMMUNICATIONS, 2019
An OTDR can be used to locate fiber faults from either end of a link, since the OTDR contains its own transmitter and receiver. To improve distance resolution, it is desirable to use the OTDR from the end nearest the break. The OTDR can also be used to check connector and splice losses. These measurements, when compared to the link loss budget, are useful in troubleshooting. The OTDR is useful both for those links with no power arriving at the receiver and those with insufficient received power.
Principles of Optical Time-Domain Reflectometry (OTDR) for Distributed Sensing
Published in Arthur H. Hartog, An Introduction to Distributed Optical Fibre Sensors, 2017
The concept of the OTDR was demonstrated in 1976 by Barnoski and Jensen [1] and almost simultaneously by Personick [2], who also provided an expression for the signal levels that are received in such systems. The OTDR was initially used in optical telecommunications and fibre quality assurance to measure uniformity and to check the attenuation profile of optical fibres for installation defects or quality control.
Calibration of Optical Fiber Time Domain Reflectometers in Accordance with IEC 61746-1:2009
Published in NCSLI Measure, 2018
Samuel C. K. Ko, Terry Hau Wah Lai
Optical time domain reflectometers (OTDR) are widely used in testing, installation and maintenance of optical communication networks. An OTDR launches a series of high speed pulses into a fiber network and measures the amplitude and the delay of reflected or backscattered signals to locate events or faults along a fiber link. The Telecommunications Industry Association standard TIA/EIA-455-226 [1] lists three methods of calibrating the distance indication of an OTDR. These are the “External Source Method”, the “Concatenated Fiber Method” and the “Recirculating Delay Line Method”. The calibration of OTDR with the use of external source method has been demonstrated in [2]. Based on the recirculating delay line method, the SCL has developed a calibration method for OTDR and the procedure is demonstrated in this paper. All the measurement standards used in this calibration are made by Swiss Federal Institute for Metrology (METAS) and provided with calibration certificates. The calibration measurements are traceable to METAS. The artifacts, include the distance calibration artifact, the attenuation calibration artifact and the reflectance calibration artifacts with reflectances of −10 dB, −20 dB, −30 dB, −40 dB, and −50 dB. The structure of this article is as follows. Section 3 details the measurement setup and techniques. Section 4 presents the measurement uncertainties of the tests. A conclusion is given in Section 5.
Distributed fiber optics sensors for civil engineering infrastructure sensing
Published in Journal of Structural Integrity and Maintenance, 2018
Early in the 1970s, soon after the breakthrough of low-loss silica optical fibers, the backscattering effect was investigated in detail (Kapron, Maurer, & Teter, 1972; Lines, 1984; Smith, 1972). Scattering effects were used to characterize loss and defective properties along the fiber (Barnoski & Jensen, 1976), resulting in the invention of OTDR (Optical Time Domain Reflectometry). At present, OTDR has been employed widely in fiber communication technology to measure fiber length and attenuation. Shortly after the development of OTDR, other light scattering effects, including Raman scattering and Brillouin scattering, were also recognized to be adopted for various distributed sensing applications, which is the main topic of this paper.