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Innovation application: Telecommunications Optical Fiber Nonlinearity Coefficient Measurements

Title Telecommunications Optical Fiber Nonlinearity Coefficient Measurements
Abstract

Telecommunications SiO2 optical fiber is one of the key element in high data rate transmission systems. Mainly it is related with very low signal losses compared with other transmission media. However increasing transmission distance and accordingly transmitted signal power in these types of fiber causes nonlinear refractve index dependence on a light intensity. This property is characterized by optical fiber nonlinearity coefficient. This parameter for various type and manufacturer fibers differs, furthermore not always is given in technical documentation. However it is very important to anticipate nonlinearity caused signal distortions and choose accordingly the most appropriate fiber for particular application in communication systems.

Keywords telecommunications optical fiber, measurements, nonlinearity coefficient
Authors Andis Supe
Jurģis Poriņš
Department (13100) Telekomunikāciju institūts
Statistical Classification of Economic Activities, NACE 2 Telecommunications
Description of the technology

Non-linearity coefficient measurements are based on Four Wave Mixing (FWM) initiation in the fiber under test. This is achieved using two lasers that radiate so called pump and signal components which are then coupled simultaneously in the fiber under test.

Measurement principal scheme is given in figure 1. Laser output power levels are set so that there is only one FWM newly created component at the output of the fiber under test. Polarization controllers PC-1 and PC-2 ensures matching of the polarization states to increase FWM efficiency.

Fig. 1. Figure 1. Non-linearity coefficient measurement scheme.

Fig. 2. Optical signal spectra at the output of fiber under test.

Output of the fiber under test is connected to optical spectrum analyzer (OSA) which measures signal spectral changes depending on the signal laser wavelength (figure 2.). Next, the optical spectrum measurement data is used to calculate the optical fiber under test nonlinearity coefficient.

Applications Optical fiber non-linearity coefficient control measurements are needed to verify compliance with manufacturer given parameter as well as to estimate fiber application possibilities both for transmission systems construction needs and special non-linear optics-based signal processing applications (multiplexing, demultiplexing, amplification, regeneration etc.)
Advantages

This optical fiber non-linearity coefficient measurement scheme is easy configurable and therefore suitable for very different optical fiber measurements used in transmission systems. Moreover FWM process is not only signal power dependent because it is also affected by the state of light polarization that is under control in the proposed measurement scheme.

Technology Readiness Level Technology validated in laboratory
Partnership offer • Collaboration contracts with telecommunication operators or optical equipment manufacturers.
Number
  • LV-14296
ID 42
Contact information Linda Šufriča, e-mail: inovacijas@rtu.lv; phone.: 28442736