Assuming the device detects and you get the SFP basic information on the right hand panel?
Are you wanting to know when there is a link loss or just some degredation of the power? Link loss will be detected and can be alerted using this existing collection rule - it works on all the SFP interfaces on my Mikrotiks:
For example:
If the sensor has a limit defined and captured (there isn’t on my Mikrotiks it seems) these two existing rules from the collection will flag it - it’s more common for temperatures:
If you want to make your own limits, you can use the sensors_current information something like this to make a custom alert: