## Comparison of Single Mode and Multimode Index Fibres

Comparison of Single-Mode Index Fibres and Multimode Index Fibres→

S.No. Single Mode Index Fibre Multimode Index Fibre
1. In single mode index fibre, the diameter of the core is very small and is of the same order as the wavelength of light to be propagated. It is in the range $5\mu m - 10 \mu m$. The Cladding diameter is about $125 \mu m$. In multimode index fibre, the diameter of the core is large. It is in the range $30\mu m - 100 \mu m$. The Cladding diameter is in the range $125 \mu m - 500 \mu m$.
2. The difference in refractive indices of the core and cladding material is very small. The difference in the refractive indices of the core and the cladding materials is large.
3. In single-mode fibre, only a single mode is propagated. In multi-mode fibre, a large number of modes can be propagated.
4. Single mod fibre does require a much more sophisticated light source in order to launch enough light into the tiny core. Multi-mode fibre does not require any sophisticated light source.
5. Single-mode fibre is more expensive but more effective. Multimode fibre is less expensive.
6. The acceptance angle and the size of the acceptance cone of single-mode fibre are small. The acceptance angle and the size of the acceptance cone of multimode fibre are large.
7. The numerical aperture of single-mode fibre is small. The numerical aperture of multimode fibre is large.
8. Single-mode fibre has a very high information-carrying capability. Multimode fibre has low information carrying capability.
9. Single-mode fibre is used when sort distance communication is required. It is used for long-distance communication.
10. Model dispersion in single-mode fibre is almost nil. Model dispersion in multimode fibre is the dominant source of dispersion.
11. Material dispersion in single-mode fibre is low. Material dispersion in multimode fibre is large.
12. When a transmission has a very large bandwidth, single-mode fibre is used Example: Under Sea Cables. When the system bandwidth requirement is low, multimode fibres are used Example: Datalink