Metal Free Interchangeable Connectors

Metal dust contamination is a significant reliability issue for high power connectors.

Behaviour of connectors at high power

Connectors have been found to sporadically fail in transmission systems which operate over about 100 mW (+20 dBm). Detailed studies have found metal particle contamination in every case. Such failure may take some time to occur.

The metal dust generally comes from wear particles caused when connectors are mated using a metal alignment sleeve in the through connector. Other dust contamination should be covered by normal cleaning procedures. A special termination cleaning kit may be required.

Choosing metal free connectors

So to improve the reliability of high power systems, it is recommended to minimise the incidence of metal wear particles on connector tips. This implies that both ferrules and alignment sleeves must not be made of metal.

The recommendation particularly applies to test instruments, since they are usually the last item to be in contact with a connector. Unfortunately, many instruments (particularly power meters) use a metal interface adapter. Often this is anodised aluminium, which creates the worst number of wear particles and will almost certainly result in connector contamination.

To avoid this problem, Kingfisher instruments are commonly supplied with ceramic (eg metal-free) interchangeable connector adaptors (SC, FC, and ST).

Optical Safety Standards

The relevant international laser safety standard is usually AS / NZS IEC 60825-2:2011 ‘Safety of laser products Part 2: Safety of optical fibre communications systems (OFCS)’ Specifically Annex D, table D.1

Equivalent USA standards are administered by the FDA (Food & Drug Administration) under 21CFR1040.10

There are two safety classes directly relevant to Kingfisher Test Equipment:

Our infra-red test sources are all Class 1, and our VFL sources are Class 2. This means they are eye safe, with or without a microscope.

Class 2 devices are visible, so the "eye aversion" or "blink" response will cause the user to look away before eye damage is caused, allowing a higher safe level.

Power meters don't emit light, but safety precautions need to be used relevant to the maximum light level that could be emitted from the fiber.