How do I know if my transceiver is single-mode or multimode？

Single-mode vs multimode SFP Transmission Distance

The core is the central and innermost layer of fiber. A size distinction exists between single-mode and multimode fiber cores. Multimode fiber has a wider fiber core, generally 50um for OM2/OM3/OM4/OM5 fiber and 62.5um for OM1 fiber. However, the core diameter in a single-mode fiber is quite small. 9um is common; 7um and 5um are also available.

Light passes through a thinner core with fewer reflections, which leads to a lower attenuation value. This means SMF against MMF can carry a higher bandwidth at a longer distance to maintain acceptable signal levels.

Accordingly, MM SFP is generally used for short-distance transmission while SM SFP is mostly applied in medium to long-range transmission environments. More specifically, a value is assigned on SFP to evaluate the max transmission distance within the signal stability range. MM SFP has the max reach option of 100m, 150m, 300m, 500m, etc. SMF SFP is common in 2km, 10km, 40km, 80km, 120km, etc.

Single-mode vs multimode SFP Wavelength

850nm is the typical central wavelength of MMF SFP, deployed in short-reach transmission. Single-mode fiber imposes more harsh requirements on the optics used. 1310nm and 1550nm are two common wavelengths on the SM SFP modules for long-haul transmission.

1310nm is a special wavelength, that adapts to both multimode and single-mode usage. Some SFPs using a wavelength of 1310nm support both multimode and single-mode fiber. For example, the HXSX-FL1R2C-1 10G SFP+ with a wavelength of 1310nm supports up to 10km link over OS2 SMF or up to 500m links via OM3 MMF.

SFP Single Mode vs Multimode –

PARAMETER	SM SFP	MM SFP
Abbreviation for	Single Mode SFP	Multimode SFP
Distance Supported	Can Support Greater distance than MM Fiber. SM Fiber can support distance value as high as 80 km or even 120 km	Used for short distance transmission reaching 100 m and 500 m
Cost	SM SFP is costly	MM SFP is cheaper than SM SFP
Core Size	Single-mode fiber has a smaller core (9 micron)	Multi-mode fiber has a broader core (62.5 and 50 micron)
Wavelength supported	works mainly in 1310nm and 1550nm wavelength	Works mainly in 850nm wavelength
Preferential usage	Used inside LAN for Switch ,Router and Server connectivity inside Building or Data Center	Required on WAN connectivity like Service provider Handoff to office/Data Center or connectivity between offices.
Colour schema	The colour coded bale clasp and colour arrow on label are generally blue, yellow or purple. And the colour of compatible fiber optic patch cord is yellow.	Their colour coded bale clasp and colour arrow on label are black and the used fiber optic patch cord is usually orange.