The Simple Guide of Optical Transceiver

The word we now often refer to optical module is transceiver. It is a compound of transmitter and receiver, which is a smart combine. Because it vividly expresses the key function of the device, transmitting and receiving signal. Therefore, a transceiver is basically a transmitter and receiver in a small package and serves as an important sub system in fiber optic communication networks.
Structure and Operational Principle
There are several key components in a common transceiver. It’s TOSA, ROSA, laser driver chip, limiting amplifier chip and PCB. This components usually hides in a small package with one or two fiber optic connector at one hand including a release latch and an electrical PCB edge connector at the other. The TOSA(Transmitter Optical Sub-assembly) consists of a laser diode, optical interface, monitor photodiode, metal housing, and electrical interface. The ROSA (Receiver Optical Sub-assembly) consists of a photodiode, optical interface, metal housing, and electrical interface.
Look at how a common transceiver works. First, the electrical signal imported through PCB (Printed Circuit Board) from a motherboard is converted into the optical signal with the help of a laser diode and laser driver chip, and through TOSA the optical signal couples into an optical fiber cable. Meanwhile, the optical signal received through optical interface is converted by ROSA into the electrical signal, then exports by limiting amplifier to the motherboard over the PCB edge connector.
Short Story of Development
It probably not be over 30 years after the first transceiver was invented, but this tiny device has experienced updating every few years, which has taken many experts’ heart and soul. Generally speaking, the pace of technology progress always faster than we can imagine. But as for transceiver, no matter how far and how deep it will go and develop, the tendency of transceiver’s evolution always focus on data speed enhancing, miniaturization, longer distance, compaction, cost-effectiveness, lower dissipation and hot-plugging. In the following chart of different generation of transceivers, you may find how transceiver develop and update over the years.
Application
As an important sub system of communication network industry, transceivers can found where high speed computer network and high-bandwidth data communications need, such as base stations, servers, data centers and so on. Specifically, Ethernet switches, routers, firewalls and network interface cards, fiber converter are most application scenarios.
Standardization
No matter old GBIC or the latest QSFP-DD, they are ‘standardized’ by multi-source agreements(MSA). It is an agreement between multiple manufacturers to make products which are compatible across vendors. This is a very important agreement for many transceiver market participator. Besides strictly defining the operating characteristic of transceivers that compliant vendor can make produce, most importantly, it establishes a competitive market for interoperable products, allowing third party vendor participating in the market. Thus, transceivers may be purchased from any of the multiple sources in the open market, just like 10Gtek.
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How to clean the Optical Transceiver

by http://www.fiber-mart.com

We have always emphasized that proper fiber cleaning of connector end-face is very important to ensure the performance of the whole fiber systems. In fact, optical transceiver module is no exception as the contamination of the optical port of a transceiver will also lead to network failure. However, many people overlook the importance of optical transceiver cleaning or do not clean it in a proper way. This is why I want to talk this topic today.
When to Clean?
As we know, the connector end-face of fiber jumper is always recommended to clean before connection. But the optical port of the optical transceiver should not need frequent cleaning unless there is a problem because they have less risk of being contaminated compared to jumper. In general, if you have cleaned your connectors, but still experience low-power output from an optical transceiver or a fault signal from your equipment, you should clean the optical port of the transceiver.
How to Clean
The best way to clean the optical port of a transceiver is to use the air duster (also called clean dry air) to blow away small dust particles. In addition, lint-free stick/swab is also required for dry cleaning. The detailed cleaning procedure is shown as below:
Remove the dust cap from the optical transceiver.
Use an air duster to remove any dirt or particles.
Insert a lint-free stick of the appropriate size (2.5 mm or 1.25 mm) and turn clockwise. Dry cleaning is recommended here. Thus, Don’t use alcohol-based cleaning sticks.
Repeat steps 2 and 3 if necessary.
Remove the lint-free stick and reinsert the dust cap to the transceiver. Always keep the dust cap inserted in the transceiver when not in use.
Place the transceiver on a clean and static-free area, such as an antistatic mat.
Optical ports of transceivers also require proper cleaning to ensure the fiber transmission performance. It is recommended to clean the transceiver port when there is an error on port. Dry cleaning is recommended to use with air duster and lint-free. Moreover, cross contamination should be avoided by always using cleaned jumper.

Which SFP Fiber Cable Should I Choose for My Optical Transceiver?

by http://www.fiber-mart.com

SFP fiber cable and fiber optic transceiver have become more and more important in fiber optic data transmission, especially in data transmission between the switches and equipment. But with so many different kinds of SFP fiber cables available in the market, which one is suitable for may optical transceiers? This article may on this issue to provide some solutions. Before starting this topic, it is necessary for us to review the basic knowledge of the fiber optic transceiver and fiber optic cable.
Fiber Optic Transceiver Overview
Fiber Optic Transceiver is a self-contained component that can both transmit and receive. Usually, it is inserted in devices such as switches, routers or network interface cards which provide one or more transceiver module slot. There are many optical transceivers types, such as SFP+ transceiver, X2 transceiver, XENPAK transceiver, XFP transceiver, SFP (Mini GBIC) transceiver, GBIC transceiver and so on.
Fiber Optic Patch Cable Overview
Fiber optic patch cable, also known as fiber jumper or fiber optic patch cord. It is composed of a fiber optic cable terminated with different connectors on the ends. Fiber optic patch cables are used in two major application areas: computer work station to outlet and patch panels or optical cross connect distribution center. According to fiber cable mode, cable structure or connector types etc., fiber patch cable can be divided into different types.
1.Single-mode and Multimode SFP fiber Cable
According cable mode, patch cables can be divided into single-mode and multimode fiber patch cable. The word mode means the transmitting mode of the fiber optic light in the fiber optic cable core. Single-mode patch cables are with 9/125 fiber glass and are yellow jacket color, while multimode patch cables are with OM1 62.5/125 or OM2 50/125 fiber glass and are orange color. In addition, there is 10G OM3 and OM4 multimode patch cables which cable jacket are usually aqua.
2.Simplex and Duplex SFP fiber Cable
Simplex fiber patch cable is consist of single fiber core, while duplex fiber patch cable is consist of two fiber cores and can be either singlemode or multimode. Additionally, there is also ribbon fan-out cable assembly (ie. one end is ribbon fiber with multi fibers and one ribbon fiber connector such as MTP connector (12 fibers), the other end is multi simplex fiber cables with connectors such as ST, SC, LC, etc.).
3.LC, SC, ST, FC, MT-RJ, E2000, MU and MPO/MTP Patch Cable
Fiber optic patch cable can be also classified by the types of fiber optic connector. For example, LC fiber optic patch cable is named as it is with LC connector. Similarly, there are SC, ST, FC, MT-RJ, E2000, MU and MPO/MTP fiber optic patch cables. What’s more, there are PC, UPC, APC type fiber patch cords, which are differentiated from the polish of fiber connectors.
Which SFP fiber Cable Should I Choose for My Fiber Optic Transceivers?
Now, I will take the Cisco fiber optic transceiver as an example to discuss this topic. For example, we need to choose a right patch cable to connect Cisco fiber optic transceiver SFP-10G-SR and X2-10GB-SR. Which patch cable to use? According to “Cisco 10-Gigabit Ethernet Transceiver Modules Compatibility Matrix”, we may know that SFP-10G-SR is the 10GBASE-SR SFP+ transceiver module for MMF, 850-nm wavelength, LC duplex connector. And X2-10GB-SR is the 10GBASE-SR X2 transceiver module for MMF, 850-nm wavelength, SC duplex connector. Obviously, this two knids of optica trancseivers are both for MMF, so we should choose a multimode patch cable. Besides, we know X2-10GB-SR is designed for SC duplex connector and the SFP-10G-SR is designed for duplex LC connector, so we should use a patch cable with SC-LC duplex connector.

Direct Attach Cable(DAC) VS Active Optical Cables(AOC)

As one kind of optical transceiver assembly, Active Optical Cables (AOC) and Direct Attach Cables (DAC) are a alteration of optical transceiver, they are used to connect switches with one another when creating a stack or switches to routers or servers.

A Direct Attach Cable (DAC) can be produced as passive or active. As the passive DAC has no active components, it offers a direct electrical connection between corresponding cable ends. This method can also be completed by an active DAC, which is considered active because there are extra electronics embedded inside the connectors. Therefore it helps to advance signal quality, offering a longer cable distance. The DAC is a fixed assembly that can be bought in several lengths for short distances of up to 15 Meter.They are suitable for short distances, making them ideal for highly cost-effective networking connectivity within a rack and between adjacent racks.

AOC cable is always active. It has two types of connectors combined with fixed optical fibers with a similar function as optical transceivers. In respond to the demand for a higher data bandwidth, active optical cable (AOC cable) has came into being to satisfy different cloud computing applications. Active optical cable is a term used to describe a cable that mates with standard electrical interfaces. The electrical-to-optical conversion on the cable ends is adopted to enhance the transmission speed and distance of the cable without sacrificing compatibility of standard electrical interfaces.

Both DAC and AOC have their particular advantage and disadvantage.

Growth of fiber technology, someone may believe that copper technology is obsolete. This is not accurate for direct attach copper cables. Indeed, a direct attach copper cable still has its advantages:

With the growth of copper cable technology, in Today’s market,DAC can support higher data rates than old copper interfaces—from 4Gbps to 100Gbps per channel.  reduce the overall power consumption and heat dissipation, which help network operators save cost.DAC cables are similar and hot swappable just like fiber optic modules. Supporting such multiple protocols from Gigabit to 100G Ethernet,Direct Attach Cables (DAC) are a cost effective solution compared to optical transceivers.

DAC cables have the potential to Another factor is that DAC cable is robust and does not need patch panels or additional cables when connected to devices, as is the case with an optical module. The modules on both ends make them sturdy and reliable as well as space-saving.

dac

Though there are a few disadvantages of using direct attach cables: One of it is that direct attach (DAC) copper cables are more thick and massive than AOC cables, making it difficult to be managed. Additionally, since the electrical signals are used, direct attach copper cables are susceptible to the effects of electromagnetic interference (EMI), such as unwanted responses, degradation, or complete system failure.

AOC provides more advantages, such as lighter weight, high performance, low power consumption, low interconnection loss, EMI immunity and flexibility.

AOC

AOCs are a substitute to optical transceivers which exclude the detachable interface between transceiver modules and optical cables. It offers a number of advantages over direct attach copper (DAC) cables. due to its material, AOC weighs less than a DAC cable. optical fiber uses light signals, AOC is immune to electromagnetic interference. the disadvantage of AOC is that it may be a slight more expensive for customers.

Whatever believe it or not, Nothing can be perfect, so do the DAC cables. Although they can save space and cost for data center managers, the drawbacks still exist. As the main element of DAC cable is copper, it is heavy and bulky. the more important, if DAC cables are deployed in high volume, the cable diameter and cable stiffness are another problem that should be considered. In this case, active optical cables (AOC cables) seem to be a better choice, for they are made of thinner and more pliable optical cable.

Fiber-Mart supplies various kinds of high speed interconnect DAC & AOC cable assemblies including 10G SFP+ Cables, 40G QSFP+ Cables, and 120G CXP AOC Cables. All of our cables can meet the ever growing need to cost-effectively deliver more bandwidth, and can be customized to meet different requirements. For more information,pls visit www.fibermart.com. if you have any requirements , pls not hesitate to contact with us service@fiber-mart.com