The IEC released in March a noteworthy standard, the IEC 61282-9, that discusses measurement methods: Fibre optic communication system design guides – Part 9: Guidance on polarization dispersion measurements and theory. It is well-known that PMD is an important type of dispersion (the other one being chromatic dispersion) that distorts signals by increasing their duration, and that it can lead to bit errors in extreme cases. Therefore, PMD limits how fast and how far a signal can travel.
The IEC 61282-9 standard defines important concepts, such as differential group delay (DGD), birefringence, etc. It also provides guidelines on implementing various PMD measurement methods, such as traditional interferometric method (TINTY), generic interferometric method (GINTY), Stokes parameter evaluation, etc.
More interestingly, it defines for the first time the “wavelength scanning OTDR and SOP analysis method”, which is one of the few methods that allows for single-ended analysis, i.e., a dispersion tester where the light source and the detector are found in a single box (see figure 1). The benefits of single-ended analysis are numerous: a single technician is required versus two for the dual-ended solution, reduced operational expenses, and greater ease of use.
Figure 1: Single-ended versus dual-ended approaches.
The FTB-5700 is currently the only commercial single-ended dispersion tester on the market based on the “wavelength scanning OTDR and SOP analysis method”. To find out more, please consult the FTB-5700 product page.