Fiber optic connector grades

05.01.2024 | Good fiber optic connectors have low attenuation and high return loss. But what exactly is “good“? IEC 61753-1 specifies performance grades for fiber optic connectors.

IEC 61753-1 and the European issue EN IEC 61753-1 specify performance grades for attenuation and return loss. For attenuation grades letters from A to D are used and for return loss grades numbers ranging from 1 to 4. Not all grades are finalized yet, some are still for further studies.

Attenuation	Connectors for singlemode fibers Attenuation at 1310 nm, 1550 nm and 1625 nm
Grade A	for further studies
Grade B	max. 0.12 dB average value max. 0.25 dB limit for min. 97% of all connectio
Grade C	>max. 0.25 dB average value max. 0.5 dB limit for min. 97% of all connections
Grade D	max. 0.5 dB average value max. 1.0 dB limit for min. 97% of all connections

Return loss	Connectors for singlemode fibers Return loss at 1310 nm, 1550 nm and 1625 nm
Grade 1	min. 60 dB plugged-in and min. 55 dB unplugged
Grade 2	min. 45 dB
Grade 3	min. 35 dB
Grade 4	min. 26 dB

Attenuation	Connectors for multimode fibers Attenuation at 850 nm
Grade A_m	for further studies
Grade B_m	max. 0.3 dB average value max. 0.6 dB limit for min. 97% of all connection
Grade C_m	max. 0.5 dB average value max. 1.0 dB limit for min. 97% of all connections
Grade D_m	for further studies

Return loss	Connectors for multimode fibers
Grade 1_m	for further studies
Grade 2_m	min. 20 dB

Caption: Performance grades of randomly mated fiber optic connectors as specified by IEC 61753-1:2018. Testing singlemode connectors at 1625 nm are optional for enterprise applications but mandatory for carrier applications. Performance grades of field-installable singlemode connectors are still under discussion.

Author:

Dirk Traeger

Technical Solutions Manager DataVoice