Introduction
Based on the number of fibre cores, we can classify fibre optic patch cords into simplex fibre optic and duplex fibre optic, as shown in the picture. A simplex fibre optic usually consists of only one fibre and one connector, which means that the signal can only be sent in one direction, e.g. the signal can be transmitted from A to B via a simplex fibre, but cannot be transmitted from B to A in the reverse direction. A duplex fibre optic is composed of two fibres and two connectors, which enables the signal to be transmitted in the reverse direction, e.g. the signal can be transmitted from A to B as well as from B to A.
Comparison of Simplex Fibre Optic and Duplex Fibre Optic
Ⅰ Different optical sources
1. Simplex fibre optic: solid-state laser.
2. Duplex fibre optic: light-emitting diodes (LED).
Ⅱ Different number of fibre cores
1. Simplex: There is only one fibre core in simplex fibre.
2. Duplex: Duplex fibre integrates two simplex fibres, i.e. two fibre cores.
Ⅲ Different performance
1. Simplex: Simplex fibre has higher transmission rates, higher capacity, longer transmission distance; but the cost is also higher because it requires a laser source .
2. Duplex: The overall performance of duplex fibre is not as good as simplex fibre for its lower transmission speed and shorter distance, but the cost is relatively low.
Ⅳ Different operating principle
1. Duplex: transmitting and receiving on two fibres respectively, working on the same wavelength, generally 850, 1310 or 1550.
2. Simplex: transmitting and receiving on the same fibre; optical modules used in pairs because the fibre operates on different wave bands for transmission and reception. For example, if 1310 is used at one end, 1550 must be used at the other; or if 1310 is used at one end, 1490 must be used at the other.
Conclusion
From a production point of view, the distinction between simplex and duplex is merely between one and two fibres while the production process is exactly the same. In terms of access solutions, simplex or duplex cables are used depending on the link method. The use of simplex cables is referred to as a single-fibre bi-directional circuit, for example using a single fibre with a 1310nm wavelength to transmit the uplink signal and a 1550 wavelength to transmit the downlink signal. The use of duplex cables is referred to as a two-fibre dual circuit, using two fibres to transmit the uplink and downlink models respectively. Apart from this, there is a single-fibre three-loop solution, all based on different access schemes to determine the number of cores.