Category: Cables

Why Use an Active Optical Cable?

Why Use an Active Optical Cable?

active optical cable, QSFP28 to QSFP28 100gb, RoHS Compliant.
QSFP28 active optical cable

Active optical cable (AOC) is a high-performance communication cable used for short-range multi-lane communication and interconnected applications.

What is an Active Optical Cable (AOC)?

An Active Optical Cable transforms the data signal into a laser light, which is communicated over an optical fiber. The conversion of electronic data is done by an optical transceiver connector. This allows for the fiber to disconnect from the transceiver. At the transceiver’s end, Active Optical Cables bond the fiber connection, which in turn creates a cable assembly similar to a DAC cable.

Active optical cable have four functional parts.

1.  High-density QSFP+ connector allows for the cable to be plugged into a router or switch.

2. 4- Channel full duplex active optical cable transceiver is embedded inside the shell and is responsible for electrical- optical conversions, making AOCs a lower cost solution in comparison to other transceivers.

3. MPO optical connector is a permanent attachment to the shell and fiber, protecting the interface from the end users (consumers) and environmental contamination.

4. Flexible ribbon optical fiber cable

Advantages of Active Optical Cables

Active optical cable assemblies offer several potential advantages. In comparison to heavy copper cables, AOCs are lighter in weight and thinner. Therefore, they do not suffer from the length restrictions of copper cables. AOCs have longer reaching potential. Additionally, to address bandwidth issues, copper cables become bulkier and harder to manage and these cables risk more power delivery issues.

Therefore, the bulkiness and weight of copper cables make a terribly inelegant system communication solution. Copper cables may be a somewhat feasible solution for small data center clusters. However, for large clusters, the link distance and the actual layout of the cluster makes it physically challenging to manage and operate. Overall, copper cables make for a messy and complicated data center design solution.  In addition, due to the nature of electrical signals, electromagnetic interference (EMI) limits both the performance and overall reliability of copper.

Active Optical Cables were initially invented to replace this limited copper technology across data centers. AOCs are far superior in performance and their advantages are undeniable. Some super computers have completely shifted from using coper cables to AOCs. The electrical to optical conversion improves the speed and increases the distance performance of its predecessors, while still remaining compatible with standard electronic devices.

Active Optical Cable Final Thoughts

AOCs must adhere to the IEEE, IBTA and SFF standards. Since the optics are contained inside the cable, AOCs have freedom from industry standards for electrical, mechanical and thermal requirements, eliminating costly optical testing. In addition, the optics location gives AOC designers freedom to find consumers low cost materials and transceiver designs. Compared to copper cables, this makes AOCs a much more cost effective solution.  In fact, a TMC active optical cable is currently one of the lowest priced optical interconnect available. Generally, they are about half the price of costly optical transceivers. Furthermore, if the network equipment utilized is properly designed, reconfiguration of AOCs are quite simple and easy. Also, AOCs are lightweight in comparison to its predecessors, making data centers physically easier to manage.

Summary of AOC Advantages

The main advantages of using AOCs over other communication cables solutions are:

– Improved performance

– Lighter weight

– Reduced bulkiness: Thinner and longer reach

– Higher bandwidth

– Immune to EMI

– Improved flexibility

– Lower power consumption

– Low interconnection loss

– Lower Bit Error Rate (BER)

The Importance of Shielded Cables

The Importance of Shielded Cables

Importance of using shielded cables
Twisted-pair cable with symbols. Foil shielded cable.

Shielded Cables

Shielded cables are electrical cables that contain insulating conductors encased in a standard conductive layer. The shield can be made from strands of braided copper (or a similar metal), a spiral copper tape, or some other conducting polymer. The importance of shielded cables cannot be stressed enough.

Shielded cables are usually thicker and more rigid than unshielded cables. They also require greater care when working with them. Shielded cables are most often found in industrial settings and installations where other nearby equipment is likely to generate electromagnetic interference (EMI).

Unshielded, twisted cables do not have internal shielding to reduce EMI. Instead, they are designed to cancel out EMI by employing a twisted pair of wires. These cables are lightweight and thin, making them best suited for indoor use in an office setting for a LAN or similar network cable systems. They are also less expensive than industrial cables. However, they are not always a good fit for industrial settings where larger amounts of power are needed or where heavy equipment will be in regular use.

What Is Shielded Cable Used For?

Shielded cables are used to protect the data being transferred through the cable from degradation by EMI exposure, which is common in data centers, industrial settings, offices, and other settings where computer technology, electrical equipment, or electronic equipment is in heavy use.

EMI is generated by an external source that affects an electrical circuit through an electrostatic coupling, conduction, or electromagnetic induction. EMI disturbance can reduce the performance of a circuit or even cease its functioning altogether. Wherever a data path exists, these effects can vary from increased error rates to a complete loss of data. Both natural and artificial (manmade) sources can generate the variable electrical currents and voltages that cause EMI. Vehicle ignitions and mobile phones are prime examples of artificial sources of EMI. Natural sources of EMI include electrical storms and the sun. EMI commonly disrupts AM radios, televisions, and mobile phones.

The shielding in shielded cable reduces the volume and intensity of the electrical noise, lowering its effect on signals and transmission while also reducing electromagnetic radiation.

Foil and Braided Shielding

Foil and braided shielded cable are the two most common types of shielded cable for industrial purposes. Foil shielding incorporates a thin sheet of either copper or aluminum. This “foil” is usually bonded to a polyester carrier to enhance the strength of the cable. Also known as “tape” shielding, this type of shielded cable provides 100% protection for the conductor wire they are wrapped around. No EMI from the environment can penetrate. However, because the foil within the cable is extremely delicate, these cables are very difficult to work with, particularly when using a connector. More often than not, a drain wire will be used rather than trying to ground the cable shield entirely.

The second method used to shield cables is braiding. Braided shielded cables employ a mesh of woven copper wires. Braided shields provide less coverage than foil shields, but are much more durable. The braid creates a low-resistance path to grounding and is much less difficult to terminate when applying the connector. Braided shielding generally will provide between 70% to 95% protection from EMI, depending on how tightly the braid is woven. Braided shields are more effective than foil shields due to the fact the copper has a higher rate of conductivity than aluminum and because they are less prone to internal damage. Braided shield cables are heavier and more expensive than tape shields, as they are more durable and offer better performance.

Depending on the work environment, one type of cable may be preferable to the others. Certain workplaces require foil shielded cable only, while others may require braided mesh shielded cable. Other workplaces demand a mix of cable types. Coil spiral cables should be used where cables will be flexed and moved frequently. In areas where a cable may not be moved often but will be exposed to pressure or impact, braided cables are often the best. In environments where the cable can be expected to go undisturbed by workers, machines, or other factors, foil shielding may be appropriate.

In all cases, shielded cables must be properly grounded to ensure the safety of workers and equipment.