the way to Test a Fiber Optic Transceiver?

by Fiber-MART.COM

When optical transceiver was first deployed, verifying the performance of it was straightforward. The entire network was installed and owned by a single company, and if the system worked, extensive testing of the subcomponents was unnecessary. Today, however, most optical networks use components that may come from a variety of suppliers. Therefore, to test the compatibility and interoperability of each fiber optic transceiver becomes particularly important. How to test a fiber optic transceiver? This article may give you the answer.

 

As we all know, basically, a fiber optical transceiver consists of a transmitter and a receiver. When a transmitter through a fiber to connect with a receiver but the system doesn’t achieve your desired bit-error-ratio (BER), is the transmitter at fault? Or, is it the receiver? Perhaps both are faulty. A low-quality transmitter can compensate for by a low-quality receiver (and vice versa). Thus, specifications should guarantee that any receiver will interoperate with a worst-case transmitter, and any transmitter will provide a signal with sufficient quality such that it will interoperate with a worst-case receiver.

 

Precisely defining worst case is often a complicated task. If a receiver needs a minimum level of power to achieve the system BER target, then that level will dictate the minimum allowed output power of the transmitter. If the receiver can only tolerate a certain level of jitter, this will be used to define the maximum acceptable jitter from the transmitter. In general, there are four basic steps in testing an optical transceiver, as shown in the following picture, which mainly includes the transmitter testing and receiver testing.

 

Transmitter Testing

Transmitter parameters may include wavelength and shape of the output waveform while the receiver may specify tolerance to jitter and bandwidth. There are two steps to test a transmitter:

Transmitter Testing1. The input signal used to test the transmitter must be good enough. Measurements of jitter and an eye mask test must be performed to confirm the quality using electrical measurements. An eye mask test is the common method to view the transmitter waveform and provides a wealth of information about overall transmitter performance.

 

Transmitter Testing2. The optical output of the transmitter must be tested using several optical quality metrics such as a mask test, OMA (optical modulation amplitude), and Extinction Ratio.

 

Receiver Testing

To test a receiver, there are also two steps:

Receiver Testing3. Unlike testing the transmitter, where one must ensure that the input signal is of good enough quality, testing the receiver involves sending in a signal that is of poor enough quality. To do this, a stressed eye representing the worst case signal shall be created. This is an optical signal, and must be calibrated using jitter and optical power measurements.

 

4. Finally, testing the electrical output of the receiver must be performed. Three basic categories of tests must be performed:

 

A mask test, which ensures a large enough eye opening. The mask test is usually accompanied by a BER (bit error ratio) depth.Receiver Testing

Jitter budget test, which tests for the amount of certain types of jitter.

Jitter tracking and tolerance, which tests the ability of the internal clock recovery circuit to track jitter within its loop bandwidth.

 

In summary, testing a fiber optic transceiver is a complicated job, but it is an indispensable step to ensure its performance. Basic eye-mask test is an effective way to test a transmitter and is still widely used today. To test a receiver seems more complex and requires more testing methods. Fiberstore provides all kinds of transceivers, which can be compatible with many brands, such as Cisco, HP, IBM, Arista, Brocade, DELL, Juniper etc. In Fiberstore, each fiber optic transceiver has been tested to ensure our customers to receive the optics with superior quality. For more information about the transceivers or compatible performance test, please visit www.fiber-mart.com or contact us over sales@fiber-mart.com.

A Quick Guide To Fiber Optic Power Meter

When you install and terminate fiber optic cables, you always have to test them. A test should be conducted for each fiber optic cable plant for three main areas: continuity, loss, and power. And optical power meters are part of the toolbox essentials to do this. There are general-purpose power meters, semi-automated ones, as well as power meters optimized for certain types of networks, such as FTTx or LAN/WAN architectures. It’s all a matter of choosing the right gear for the need.

Here is a quick guide to fiber optic power meters and how they work.

 

Optical power meters are commonly used to measure absolute light power in dBm. For dBm measurement of light transmission power, proper calibration is essential. A fiber optic power meter is also used with an optical light source for measuring loss or relative power level in dB. To calculate the power loss, optic power meter is first connected directly to an optical transmission device through a fiber optic pigtail, and the signal power is measured. Then the measurements are taken at the remote end of the fiber cable.

 

Fiber optic power meter detects the average power of a continuous beam of light in an optical fiber network, tests the signal power of laser or light emitting diode (LED) sources. Light dispersion can occur at many points in a network due to faults or misalignments; the power meter analyzes the high-powered beams of long-distance single-mode fibers and the low-power multibeams of short-distance multimode fibers.

 

Important specifications for fiber optic power meters include wavelength range, optical power range, power resolution, and power accuracy. Some devices are rack-mounted or hand held. Others are designed for use atop a bench or desktop. Power meters that interface to computers are also available.

 

The fiber optic power meter is a special light meter that measures how much light is coming out of the end of the fiber optic cable. The power meter needs to be able to measure the light at the proper wavelength and over the appropriate power range. Most power meters used in datacom networks are designed to work at 850nm and 1300nn. Power levels are modest, in the range of –15 to –35dBm for multimode links, 0 to –40dBm for single mode links. Power meters generally can be adapted to a variety of connector styles such as SC, ST, FC, SMA, LC, MU, etc.

 

Generally, multimode fiber is tested with LEDs at both 850nm and 1300nm and single mode fiber is tested with lasers at 1310nm and 1550nm. The test source will typically be a LED for multimode fiber unless the fiber is being used for Gigabit Ethernet or other high-speed networks that use laser sources. LEDs can be used to test single mode fibers less than 5000 meters long, while a laser should be used for long single mode fibers.

 

Most fiber optic power meters are calibrated in linear units such as milliwatts or microwatts. They may also provide measurements in decibels referenced to one milliwatt or microwatt of optical power. Typically, fiber optic power meters include a removable adaptor for connections to other devices. By measuring average time instead of peak power, power meters remain sensitive to the duty cycle of digital pulse input streams.

 

Use fiber optic power meter and other useful fiber optic tool kits to ensure that your fiber optic system will operate smoothly.

How 5G Wireless Goes Hand in Hand With Fiber Optics

Wireless networks are getting better all the time. The most recent development is 5G, which stands for fifth generation, and it will cover a wide range of devices. It will cover fixed network infrastructure as well as mobile which makes people wonder if it will eliminate the need for fiber cables. It is actually quite the opposite. 5G will depend on fiber in order to be fully functional.

Why 5G Wireless Relies on Fiber Optics for Internet Connectivity

Fiber Allows for Increased Speed

5G promised increased speed and even though many people are accustomed to wireless networks, wireless infrastructures actually rely on a huge net of fiber optic cables. Even though it is available as wireless technology, about 90% of it is actually traveled via wireline fiber. If 5G actually plans on delivering what it promises, then fiber optic wires are the only way this can get done because it is the top choice for many mediums when looking towards the future.

Fiber Allows for Better Performance

In addition to the faster speed promise, there is also a goal of better performance. In order to meet this goal, there will need to be even more fiber used all over the globe. There needs to be a solid foundation in order to accomplish the availability and coverage. The idea is that there will be more smaller sites instead of a few large ones because it will allow for more users to utilize the capabilities in an area. Copper or air options will not be able to sustain this so fiber optic is the most viable option.

Fiber is Cost Effective

The last reason that 5G will rely on fiber is that it is very cost effective. Because of its affordability and how long it lasts before it needs to be replaced, it is the best all around option. More companies will be able to utilize it which will result in more people having access to 5G.

Fiber is the only option for 5G when you look at all of these factors. As you can see, fiber optic cables and the 5G network go hand in hand.

Raman-off gain 10dB FM-RA Series Raman Amplifier

Raman-off gain 10dB FM-RA Series Raman Amplifier

Raman-off gain 10dB FM-RA Series Raman Amplifier is high power Raman Amplifier which is used in low noise, Long span or high speed Optical Transmission system. Using transmission fiber as the gain medium to form distributed to enlarge, reduce system noise and will get best gain and noise index mix the our EDFA product.

Each Pump output power can be adjustable independently which is suitable for a variety network applications and to enlarge the bandwidth.

"Intelligent network management system. Perfectly network interface: Ethernet, RS-485 and RS-232 network，and the open network management interface ensure the connectivity with all other network management system. "

Features

• Gain: 10dB
• Connectors: SC/UPC, SC/APC, FC/UPC, FC/APC, LC/UPC, LC/APC, ST/UPC and ST/APC connectors are available
• 1U 19” rack mount structure for easy installation
• Redundancy hot swap power: 110V/220V mixed with 48V
• Distributed low-noise amplification
• Easy control and operate: Dual CPU process control Loops and the upper Interface respectively
• Perfect network Management interface: Ethernet RS-485 and RS232
• SNMP Network management Or provide SNMP Mib
• Single channel, DWDM or C+L band is available
• Intelligent temperature control system: power consumption and hot Radiation reduce 30% than common products
• Pump polarization-Independent design
• Compatible with Bellcore GR-1312-CORE
• High stability and reliability
• 10 years of operation life
• 3 years warranty
• OEM is available

Application

• SDH, ATM telecom long distance optical Transmission
• Analog digital TV long distance Optical Transmission system
• Long span system
• 10G, 40G system

Specification

Parameters	Symbol	Min	Typ	Max	Unit
Operation Wavelength	λc	1525	1550	1565	nm
Pump wavelength	λp	1425	1	1505	nm
Pump output power	Po		500	1000	mW
On/OFF Gain	G	6		14	dB
Gain Flatness	FL		1		dB
Polarization Dependent Gain	PDG			0.3	dB
PMD	PMD			0.3	ps
Relative Noise Figure	NF			0	dB
Power Supply	Vps	85/170	110/220	132/264	VAC
Consumption	P			18	W
Operating Temperature	Tw	-5		60	℃
Storage Temperature	Ts	-40		80	℃
Humidity		10		85	%

Fusion Splice vs. Mechanical Splice

Fusion Splice vs. Mechanical Splice

There are four basic steps involved in fusion splice and mechanical splice. For both the two methods, the first two steps are nearly the same, and there’s a little difference for the last two steps.

 

Steps for Fusion Splice

Step 1: Fiber preparation. Fibers are prepared by stripping away all the protective coatings, such as cladding, jacket and sheath. Once only bare glass remains, the fibers are carefully cleaned--and here, cleanliness is next to godliness.

 

Step 2: Cleaving. Cleaving isnt cutting. As the word implies, it’s scoring the fiber using a cleaver and pulling or flexing it until it breaks. The cleaved end must be mirror-smooth and perpendicular to the fiber axis to obtain a proper splice.

 

 

 

Step 3: Fusing the fibers. Fusion, in turn, consists of two steps: aligning and heating. Alignment can be fixed or three-dimensional, manual or automatic, and is normally accomplished with the aid of a viewer that magnifies or enhances the images of the fiber ends, so that they can be properly positioned. Common magnifying devices are video cameras, viewing scopes and optical power meters. Aligning the fibers means perfectly matching up their two ends, so that light can pass from one fiber to the other with a minimum of loss, reflection or distortion. Once the fibers are aligned, they are fused or burned together by generating a high-voltage electric arc that melts the fiber tips, which are then pushed or fed together.

 

 

 

Step 4: Protecting the fiber. Protecting the fiber from bending and tensile forces will ensure the splice not break during normal handling. A typical fusion splice has a tensile strength between 0.5 and 1.5 lbs and will not break during normal handling but it still requires protection from excessive bending and pulling forces. Using heat shrink tubing, silicone gel and/or mechanical crimp protectors will keep the splice protected from outside elements and breakage.

 

 

 

Steps for Mechanical Splice

 

As previously mentioned, the differences between the two lie in the last two steps. Thus, the step 3 and step 4 for mechanical splices are described below.

 

Step 1 and 2: see the process for fusion splice.

 

Step 3: Mechanically join the fibers. There is no heat used in this method. Simply position the fiber ends together inside the mechanical splice unit. The index matching gel inside the mechanical splice apparatus will help couple the light from one fiber end to the other. Older apparatus will have an epoxy rather than the index matching gel holding the cores together.

 

Step 4: Protect the fiber. The completed mechanical splice provides its own protection for the splice.

 

Fusion Splice vs. Mechanical Splice: Which to Choose?

 

The typical reason for choosing one method over the other lies on the cost and performance.

 

Cost

 

Fusion splice typically has a higher initial investment due to the investment required to add a fusion splicing machine to your toolkit, but it offers a lower variable cost per fusion splice: $0.50 to $1.50 per splice.

 

Mechanical splice doesn’t require a large upfront investment in tools, but it has a higher variable cost at $10 to $30 per splice. The more splicing you do, the less cost-efficient mechanical splice will be due to its high variable cost per termination.

 

Performance

 

With mechanical splice, the typical insertion loss (IL) is higher—between 0.2 dB and 0.75 dB. This is because the two fibers are simply aligned and not physically joined. (Insertion loss is the loss of signal power resulting from the insertion of a splice in optical fiber.)

 

Fusion splice offers lower insertion loss and better performance, because fusion splice provides a continuous connection between two fibers. The typical loss in fusion splice is < 0.1 dB, providing better protection against cable failure and weak signals.

 

Conclusion

 

Overall, the advantages of fusion splice are primarily lower loss and better reflectance performance. It is in these areas that it surpasses mechanical splice. Many telecommunications and CATV companies invest in fusion splice for their long haul single-mode networks, but will still use mechanical splice for shorter, local cable runs. Since analog video signals require minimal reflection for optimal performance, fusion splice is preferred for this application as well. The LAN industry has the choice of either method, as signal loss and reflection are minor concerns for most LAN applications.