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IEC standard 61300-3-43 on the measurement of mode power distribution in multimode optical fibres has now been published and is available from the IEC website. This standard contains a description of the experimental method to characterise the mode-filling in multimode fibres. It features a normative annex which specifies a template for the required Mode Power Distribution (MPD) for the measurement of insertion loss in installed fibre links and in fibre components, such as connectors. The MPD template is also specified in ISO/IEC link testing document 14763-3, which is currently out for final voting.

Title: Fibre optic interconnecting devices and passive components - Basic test and measurement procedures - Part 3-43: Examinations and measurements - Mode transfer function measurement for fibre optic sources.

Number: IEC61300-3-43

Publication Date: 13th Feb 2006

Abstract: This part of IEC 61300 describes the method for measuring the mode transfer function (MTF) to be used in characterizing the launch conditions for measurements of attenuation and or return loss of multimode passive components, according to IEC 61300-1 and IEC 61300-3-4. The MTF may be measured at the operational wavelengths.

Available from: www.iec.ch

An example of the new MPD template in action is shown below:

On the left are MPDs, measured according to the new standard, for a variety of LED and OTDR sources. It can be seen that they fail the MPD template test.

On the right, the same sources are each connected to the same mode controller and then their MPDs are re-measured. Now, all the MPDs are very similar to each other and they also pass the template test.

For more information on the Mode Controller, and on the MPX-1 instrument used to make these measurements, please see the Products page.