Hi,
your issue is wrong coding of the 1G SFP. It states to the EX4600 that it is an Fibre channel SFP which of obviously not supported on an ethernet switch.
Even that Juniper doesn't support the 3rd party optics I have used both CWDM, DWDM, bidi and other type of optics which Juniper doesn't officially sell - and they have worked every time, as long as the coding states the right optic type (speed and type ethernet).
But bottom line, you need another optic which has it's eeprom reporting back as a 1G ethernet SFP.