The Cheater’s Guide To Choosing Fiber Optic Patch Cables

What is a fiber optic patch cable

 

Fiber optic patch cable, often called fiber optic patch cord or fiber jumper cable, is a optical cable terminated with connectors on both ends. It has two major application areas: computer work station to outlet and patch panels or optical cross connect distribution center. They are for indoor applications only.

 

Common types

 

Fiber patch cables can be divided into different types based on cable mode, cable structure, connector types, connector polishing types and cable sizes.

 

Cable Mode:

 

1. Single mode:

 

Single mode patch cables use 9/125 micron bulk cable and single mode connectors on both ends. Single mode fiber jacket is usually yellow.

 

2. Multimode:

 

Multimode patch cables use 62.5/125 micron or 50/125 micron bulk multimode fiber and are terminated with multimode connectors on both ends. Multimode fiber jacket is usually orange.

 

3. 10gig multimode:

 

10Gig multimode fibers are specially designed 50/125 micron fibers optimized for 850nm VCSEL laser based 10Gig Ethernet. They are backward compatible with existing network equipment and provide close to three times the bandwidth of traditional 62.5/125 multimode fibers. 10Gig fiber cable jacket is usually aqua.

 

Cable Structure:

 

1. Simplex patch cables:

 

Simplex patch cable has one fiber and one connector on each end.

 

2. Duplex patch cables:

 

Duplex patch cable has two fibers and two connectors on each end. Each fiber is marked “A” or “B” or different colored connector boots are used to mark polarity.

 

3. Ribbon fan-out cable assembly:

 

For ribbon fan-out cable assembly, one end is ribbon fiber and ribbon connector such as MTP connector (12 fibers), the other end are multiple fibers with connectors such as ST, SC, LC, etc.

 

Connector Types:

 

1. Same connector type:

 

This type has the same type of connector on both ends, such as ST, SC, LC, FC, etc.

 

2. Hybrid:

 

This type has different connectors on each end. One end can be SC and the other end can be LC, ST, FC, etc.

 

Connector Polishing Types

 

Optical connectors are designed and polished to different shapes to minimize back reflection. This is particularly important in single mode applications. Typical back reflection grades are -30dB, -40dB, -50dB and -60dB.

 

1. PC (Physical Contact): Typical back reflection is less than -40dB, for single mode and multimode applications.

 

2. UPC (Ultra Physical Contact): Typical back reflection is less than -50dB, for single mode applications.

 

3. APC (Angled Physical Contact): Typical back reflection is less than -60dB, for single mode applications.

 

Special types of patch cables

 

1. Mode conditioning patch cable

 

In some cases such as for long wave laser modules used in Gigabit Ethernet, modules need to operate for both single mode and multimode fibers, the mode conditioning fiber optic patch cables will fit for such situations.

 

By allowing the single mode laser launch to be offset away from the center of the multi mode fiber the mode conditioning fiber optic patch cable reduces the effect of such differential mode delay.These cables are usually duplex type.

 

2. Polarization maintaining patch cable

 

Polarization maintaining fiber optic cables are made with a special fiber that maintains the polarization of light waves. They are used where high stability is required, not withstanding fiber and stress movements.

 

These cables are mainly used in instrumentation, measurement and in some applications where stability is required at speeds above 10Gbps.