Light level of fiber cable for 1000BASE-LX/LH

Here is light level information for single mode fiber for Gigabit Ethernet port. Most of cases, it doesn't matter of how many port or vendors. Below light level indicates for GLC-LH-SM Long wavelength/long haul (1000BASE-LX/LH)

 -3 to -9.5 dBm transmit power
 -3 to -20 dBm receive sensitivity
 Wavelength 1300 nm
 

In many cases, dirty fiber or improper light-level leads, intermittent errors on the interface.

Also,  If you are looking for light level of XFP 10GigE module, check below link(from Cisco)

"Cisco XFP Modules for 10 Gigabit Ethernet and Packet-Over-Sonet Applications"

http://www.cisco.com/en/US/prod/collateral/modules/ps5455/ps6574/product_data_sheet0900aecd802a61b9.html