In order to get light to escape from a length of fibre optic, it has to be bent through quite a sharp angle (determined by the refractive index of the material).

Why can't fibre manufacturers formulate their materials a little more carefully, so that the fibre will break -- thus notifying the intended recipient that something is amiss -- at a rather shallower angle than that at which light is allowed to escape?

A dye could be added which will turn opaque at high temperatures, so as to thwart any attempt to prevent such breakage by softening the fibre with a blowtorch.

"0.1dB of the optical rating is enough ... to extract the data from an optical link." (quoted from the Infoguard whitepaper available from their web site (infoguard.ch)

AFAIK 0.1dB equates to a 2.3% *increase* in (optical) power levels. If what they're trying to say is that only 2.3% of the light in the fibre needs to be captured in order for this hacking technique to work, then this should be expressed as -16dB. Or am I missing something?

Regarding the hacking technique itself, I think if someone can achieve this level of physical access to your central systems, you're basically stuffed anyway! To capture the data stream you're interested in from a fibre connexion inside a carrier (such as Verizon) would require a good deal of fairly sophisticated kit (or your own fibre link to carry it to your private machine room for analysis), which would be tricky to conceal.

This technique has been around so long that I really can't remember how long, certainly two or three decades !

But then this is an appliance vendor "talking up" the need for their equipment !