Disable XFP laser in JUNOS

Unfortunately JUNOS doesn’t provide a built-in command to disable laser on XFP ports.  If you have to shutdown the laser anyway, you can do this in the “pfe shell” with the command test xfp <index> laser off:
adm@MX80> start shell pfe network tfeb0

TFEB platform (1000Mhz MPC 8544 processor, 1024MB memory, 512KB flash)

TAZ-TBB-0(MX80 vty)# test xfp
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