[Observium] How to filter only fibre network ports in an alert for link down?

Hi,

I want to create an alert for network ports that are down, but only associate the alert with fibre ports in our network infrastructure. I didn't find something like "ifPortType = fibre" or similar i can use.

I could go with the interface speed but  there could also be 1GBit fibre ports.

How can i solve this?

Best,

Thomas