Singlemode fiber and multimode fiber different and selection method(2)

The application of fiber optics is being gradually extended from the trunk or the computer room to the desktop and residential users, which means that more and more users who do not understand the characteristics of the fiber have come into contact with the fiber optic system. Therefore, when designing fiber link systems and selecting products, full consideration should be given to the current and future application requirements of the system, use of compatible systems and products, the greatest possible ease of maintenance and management, and adaptation to the ever-changing field conditions and user installation requirements.


1. Can a fiber optic connector be terminated directly on a 250 μm fiber?  


Loose sleeve fiber optic cable contains bare fiber with an outer diameter of 250 μm, which is very small and fragile. It is unable to fix the fiber and is not enough to support the weight of the fiber optic connector and is very insecure. The connector is terminated directly on the fiber optic cable. At a minimum, a 900 μm tight jacket is required to wrap around the 250 μm fiber to protect the fiber and support the connector.

2. Can the FC connector be connected directly to the SC connector?

Yes, this is just a different connection method for two different types of connectors.
If you need to connect them, you must select a mixed adapter and use the FC/SC adapter to connect the FC connector and the SC connector at both ends. This method requires that the connectors should all be flat ground. If you absolutely need to connect APC connectors, you must use a second method to prevent damage.

The second method is to use a hybrid jumper and two connection adapters. Hybrid patch cords use different types of fiber connectors at both ends. These connectors will connect to the place where you need to connect. In this way, you can use a universal adapter to connect the system in the patch panel, but bring the system budget to budget. The increase in the number of connector pairs.

3. The fixed connection of optical fibers includes mechanical optical fiber connection and thermal welding. What are the selection principles for mechanical optical fiber connection and thermal welding?

Mechanical fiber optic connection, commonly known as fiber optic cold connection, refers to an optical fiber connection method in which a single or multi-fiber optical fiber is permanently connected through a simple connection tool and a mechanical connection technology without the need of a thermal fusion bonding machine. In general, mechanical splices should be used in place of thermal fusion when splices are made at a small number of cores dispersed at multiple locations.

Mechanical fiber optic connection technology is often used in engineering practices such as line repairs and small-scale applications in special occasions. In recent years, with the large-scale deployment of fiber-to-the-desktop and fiber-to-the-home (FTTH), it has been recognized that mechanical fiber optic connection is an important means of fiber optic connection.

For fiber-to-the-desktop and fiber-to-the-home applications with a large number of users and geographically dispersed features, when the scale of the users reaches a certain level, the construction complexity and construction personnel and fusion splicer cannot meet the time requirements for users to open services. Because of the simple operation, short training cycle, and low equipment investment, the mechanical fiber connection method provides the most cost-effective solution for optical fiber connection for large-scale deployment of optical fibers. For example, in the high corridors, narrow spaces, insufficient lighting, inconvenient on-site power and other occasions, mechanical fiber optic connection provides a convenient, practical, fast and high-performance optical fiber continuation means for design, construction and maintenance personnel.


 4. What is the difference between fiber optic splice enclosure requirements and fiber optic splice closures used in telecom operators’ outdoor lines in fiber-to-the-home systems?

First of all, in the fiber-to-the-home system, it is necessary to reserve the position of the optical splitter installation and termination, accommodation, and protection of the jumper to and from the optical splitter in the joint box according to actual needs. Because the actual situation is that the optical splitter may be located in the cable joint box, optical cable transfer box, wiring box, ODF and other facilities, and in which the optical cable termination and distribution.

Secondly, for residential quarters, the optical fiber cable splice box is installed in a buried manner. Therefore, the optical cable splice box has higher requirements for buried performance.

In addition, in the fiber-to-the-home project, it may be necessary to consider the entry and exit of a large number of small-core optical cables.

Don’t Tell Us Connector Cleaning Does not Matter!


A high-performance fiber optic network requires low attenuation and low reflectance values to obtain the necessary bit error rate level. Unfortunately, all it takes is one contaminated or damaged connector to slow down or disrupt a transmission system.

In the images below, see how cleaning connectors significantly reduces insertion loss and reflectance and the effects of cross contamination.

Cleaning Makes a Difference!

These two dirty connectors are not an uncommon thing! We mated them ‘as is’ and tested for insertion loss and reflectance.

We then cleaned the connectors with a dry one-click cleaner, mated them again, and ran the same test. Connector images and results have improved dramatically.

Contamination from a Dirty Test Lead

Below is a clean connector – one end of your link where you’ll connect your test cord for optical loss testing.

This could be a test lead that someone carries around in their test equipment bag or tool kit. The technician may have lost the dust cap or even wiped it on their shirt. They plug that test lead in and mate it to your clean connector.

Ouch! See what your clean, undamaged connector looks like now? Cross-contaminated by the dirty test lead!

It is important to recognize the difference between contaminants and end face damage. To do so requires a good inspection scope with the digital video ones being the safest and most versatile. Inspecting and cleaning both ferrules and adapters is essential as cross contamination from one dirty plug can contaminate its mating plug.

Singlemode fiber and multimode fiber different and selection method(1)

1.What is singlemode and multimode fiber? What is the difference between them?

The concept of single-mode and multi-mode is to classify fibers according to the propagation mode—the concept of multi-mode fiber and single-mode fiber propagation mode. We know that light is an extremely high-frequency (3×1014Hz) electromagnetic wave. When it propagates in an optical fiber, it is found from theories of wave optics, electromagnetic fields, and Maxwell equations.

When the fiber core has a geometric dimension much larger than the wavelength of the light, the light will propagate in the fiber in dozens or even hundreds of propagation modes, such as TMmn mode, TEmn mode, HEmn mode, etc. (where m, n=0, 1, 2, 3, …).

Among them, the HE11 mode is called the basic mode, and the rest are all called high-order modes.

Multimode fiber

When the fiber’s geometric size (mainly the core diameter d1) is far greater than the wavelength of light (about 1μm), there will be dozens or even hundreds of propagation modes in the fiber. Different propagation modes have different propagation speeds and phases, resulting in delays and widening light pulses after long-distance transmission. This phenomenon is called the modal dispersion of the fiber (also called inter-modal dispersion).

Mode dispersion can narrow the bandwidth of multimode fiber and reduce its transmission capacity. Therefore, multimode fiber is only suitable for smaller-capacity fiber communication.

The refractive index distribution of a multimode fiber is mostly a parabolic distribution, ie, a graded index profile. Its core diameter is about 50μm.


Single Mode Fiber

When the fiber’s geometry (mainly the core diameter) can be similar to the wavelength of light, if the core diameter d1 is in the range of 5~10μm, the fiber only allows one mode (base mode HE11) to propagate in it, and all other high-order modes are all cut off. This kind of fiber is called single-mode fiber.
Since it only has one mode to propagate and avoids the problem of mode dispersion, single-mode fiber has a very wide bandwidth and is particularly suitable for large-capacity optical fiber communications. Therefore, in order to achieve single-mode transmission, the parameters of the fiber must satisfy certain conditions. Through formulae calculations, for a fiber with NA=0.12, single-mode transmission above λ=1.3 μm, the radius of the fiber core should be ≤ 4.2 μm, ie its core diameter d1 ≤ 8.4 μm.
Because the core diameter of a singlemode fiber is very small, more stringent requirements are imposed on its manufacturing process.

2.What are the advantages of using optical fiber?

1) The passband of the fiber is very wide and the theory can reach 30T.
2) The length of non-relay support is up to tens to hundreds of kilometers, and the copper wire is only a few hundred meters.
3) Not affected by electromagnetic fields and electromagnetic radiation.
4) Light weight and small size.
5) Optical fiber communication is not powered, and the use of safety can be used in flammable, volatile and other places.
6) The use of a wide range of ambient temperatures.
7) Long service life.

图片2 to choose the optical cable?

In addition to selecting the number of optical fiber cores and optical fibers, the optical cable must be selected according to the use environment of the optical cable to select the structure of the optical cable and the outer sheath.

1) Optical cable for outdoor use When loosely buried, it is better to use loose-sheathed cable. When overhead, a loose PE cable with a black PE sheath with two or more ribs can be used.
2) Optical fiber cables used in buildings should use tight-fitting optical cables and pay attention to their fire-retardant, toxic and smoke characteristics. The type of flame-retardant but smoke (Plenum) or flammable and non-toxic type (LSZH) can be used in the pipeline or in forced ventilation. The type of flame-retardant, non-toxic and non-smoking (Riser) should be used in the exposed environment.
3) When vertical or horizontal cabling is installed in a building, it can be used when using tight-fit optical cable, distribution optical cable or branch optical cable that are common in the building.
4) Select single-mode and multi-mode optical cables based on network applications and optical cable application parameters. Usually, indoor and short-distance applications use multimode optical cables, while outdoor and long-distance applications use single-mode optical cables.

4.In the connection of optical fibers, how to choose different applications of fixed connection and active connection?

The active connection of the fiber is achieved through a fiber optic connector. An active connection point in the optical link is a clear split interface. In the choice of active connection and fixed connection, the advantages of fixed connection are reflected in lower cost, light loss, but less flexibility, and the active connection is the opposite. When designing the network, it is necessary to flexibly select the use of activities and fixed connections according to the entire link situation to ensure flexibility and stability, so as to give full play to their respective advantages. The active connection interface is an important test, maintenance, and change interface. The active connection is relatively easy to find the fault point in the link than the fixed connection, which increases the convenience of replacement of the faulty device, thereby improving system maintenance and reducing maintenance costs.


5.Fibers are getting closer to user terminals. What do you need to pay attention to when it comes to the meaning of “fiber to the desktop” and system design?

“Fiber-to-the-desktop” in the application of the horizontal subsystem, and the relationship between copper and copper cable is complementary and indispensable. Optical fiber has its unique advantages, such as long transmission distance, stable transmission, free from electromagnetic interference, high support bandwidth, and no electromagnetic leakage. These characteristics make the optical fiber play an irreplaceable role in some specific environments:
1) If the information point transmission distance is greater than 100m, if you choose to use copper cable. Replicators must be added or network equipment and weak rooms must be added to increase costs and hidden troubles. Using fiber can easily solve this problem.
2) There are a large number of sources of electromagnetic interference in specific work environments (such as factories, hospitals, air-conditioning rooms, power equipment rooms, etc.), and optical fibers can be operated stably without electromagnetic interference in these environments.
3) There is no electromagnetic leakage in the fiber. It is very difficult to detect the signal transmitted in the fiber. It is a good choice for places where the security level is relatively high (such as military, R&D, auditing, government, etc.).
4) The environment with high demand for bandwidth has reached more than 1G. Optical fiber is a good choice.

There are many differences between single-mode fiber and multi-mode fiber, and the selection method is not the same. Let’s talk about it today. For more details, please keep an eye on Singlemode fiber and multimode fiber different and selection method(2).

Difference Between Composite and Component Adapters

by Fiber-MART.COM

When it comes to audio-visual cables that are used for video products within the market, there are two types that exist: composite and component. Although both of them are similar in many ways, such that they both use RCA connectors, there are also some key differences to be mindful of that will affect the type of cables that you plan to use, and, hence, the adapters that you will purchase. The type of device you use will also affect your choice because they are better suited to work with one type of adapter over the other.
Number of Connectors & Their Color
A composite adapter will come with three connectors: one yellow cable that is entirely responsible for analog video transmission, and two cables (red and white) that are dedicated to carrying the audio signal; left channel for the red cable and the right channel for the white cable. The video that you see on the device is a linear combination of hue, saturation, and luminance. You will see these kinds of connections being used in older TVs.
A component adapter is different in that there are five connectors: three colored cables (usually red, blue, and green) that are responsible for transmitting the video signal, with the other two used to carry the audio signal (usually red and white). This type of connection is supported by modern electronic devices. For both adapters, there is not a drastic difference in sound quality.
Make sure to read the instructions when you are determining which cable corresponds to what function – some manufacturers will design the cables differently and use an unconventional coloring schematic. This might explain why the picture on your device is not displaying properly, and this assumes that neither the device or cables are damaged.
Image Transmission
As previously stated, the composite adapter will take in the image data that is encoded within a single channel. All of the video comes entirely from the single yellow cable. In the case of the component adapter, it takes in three separate signals from separate channels: Y (Brightness, or the luminance of the screen), PR (difference between red and luminance) and PB (difference between blue and luminance), which is known in consumer electronics as YPBPR.
In terms of the quality of the image on the screen, composite will only carry a resolution of 480i; 576i for the highest quality models. However, these are older standards and the component cables have since improved on the resolution of the picture, and they are able to optimally display high-definition images at 1080p or higher. The only real limitation on resolution comes down to the capabilities of the device presenting the video image.
Even though the differences may appear to be slight, people are opting for component adapters because the technology used for composite adapters is dying out. They were used for older devices that do not support component video technology.
The only real drawback with component video is that signals are transmitted through waveforms, in comparison to DVI and HDMI cables that transmit clearer signals for both audio and video through binary code. This means that they are susceptible to interference from nearby equipment.
That’s not to say that component adapters are not heavily used, but, eventually, they will be phased out in favor of adapters and cables that transmit all their signals digitally. At the same time, it will be a few years before they start being phased out, so there is no need to worry about using outdated technology. Plus, component video technology still provides high-quality footage!

Introduction of SM to MM Media Converters

What is SM to MM Media Converter?

Enterprise networks often require conversion from MM to SM fiber, which supports longer distances than MM fiber. Mode conversion is typically required when lower cost legacy equipment uses MM ports but connectivity is required to SM equipment, a building has MM equipment, while the connection to the service provider is SM, and MM equipment is in a campus building but SM fiber is used between buildings.

SM to MM Media Converters are Fiber-to-Fiber Media Converters used to conduct the transparent conversion between singlemode and multimode fiber for applications where media conversion required between multimode segments separated by long distances. Fiber-Mart provides various type of singlemode to multimode media converters, which fulfill the conversion at 850/1310nm or 850/1310/1550nm wavelengths and transmission distance up to 120 km. In addition, these Fiber-to-Fiber media converters also support transmission between dual fiber and simplex fiber.


Why use SM to MM fiber converters?

From the aspect of photoelectric conversion, the use of fiber converters greatly reduces the cost of fiber-to-the-home. What effect does it have on the conversion between singlemode-multimode, simplex-duplex, and different wavelengths? The following examples will illustrate the important role of fiber converters in these applications.

As we all know, when the distance between two connection points in a network system is long, we need to use singlemode fiber optic cables to transmit optical signals to ensure the normal transmission of signals. Therefore, many network service providers use singlemode fiber optic cables for transmission. Optical signals, and many devices in data centers or enterprise networks are multimode fiber ports. At this time, a device is required to achieve single mode-multimode conversion of optical signals. Campus network is such a common application. The equipment in the campus building is usually a multimode fiber port, and the connection between buildings is usually a single mode fiber optic cable. The singlemode multimode conversion function of the fiber converter has been fully implemented at this time.


Select SM to MM fiber converter considerations?

Whether the serial fiber converter is easy to use, especially whether the networking is simple, needs to be examined from the following aspects:

1, single fiber, double fiber optional. Sometimes the optical fiber used in serial optical fiber networking is a certain optical fiber core that is distributed in the same optical cable that contains multi-core optical fibers. Obviously, using a single optical fiber core can save one optical fiber core compared to dual-core optical fibers.

2, volume and power consumption. In a complex optical fiber network, a large number of optical fiber converters are used. Therefore, the use of a small-sized optical fiber converter can greatly reduce the size of the cabinet, and a product with a low power consumption can reduce the size and cost of the power supply.

3, the versatility of the software. Is nothing to do with RS-232/RS-485 communication software, does not require settings, and is a true zero delay.

4, the versatility of single mode, multimode fiber. In many cases, serial optical fiber networking uses prefabricated fiber-optic cables, such as those used in Ethernet fiber-optic networks, and may be used for both long-distance single-mode fibers and near-distance multimode fibers.



Optical fiber converters are cost-effective solutions for expanding networks such as single-mode-multi-mode, simplex-duplex, and switching between different wavelengths, and increasing optical fiber capacity. They have wide applications in optical networks. Fiber-Mart provides various types of single mode to multimode media converters, which fulfill the conversion at 850/1310nm or 850/1310/1550nm wavelengths and transmission distance up to 120 km.

How to use an optical attenuator to test the sensitivity of a fiber optic transceiver?

Do you know how to use an optical attenuator to test the sensitivity of a fiber optic transceiver?In order to maximize the performance of our fiber optic transceivers, welcome to join our Fiber-Mart editors to see how to learn this skill.

Do you know how to use an optical attenuator to test the sensitivity of a fiber optic transceiver?In order to maximize the performance of our fiber optic transceivers, welcome to join our Fiber-Mart editors to see how to learn this skill. When the optical input power is within a certain range, the optical fiber receiver has the best performance. But how can we determine if the fiber optic transceiver will provide the best performance at the lowest optical input power? One commonly used method is to use an optical attenuator such as a diaphragm attenuator. Usually only two values are needed to complete the test. The process includes the following three steps.


1.Use a power meter to measure the optical output power of the fiber optic transmitter. Remember that industry standards define the optical input power of transmitters and receivers for specific network standards. If you are testing a 100BASE-FX transceiver,use a 100BASE-FX transmitter and the transmitter’s optical output power should be within the manufacturer’s data sheet.

2.Connect the transmitter to the receiver and verify it is operating at the maximum optical output power available from the transmitter. You need to test the receiver with the minimum optical input power that the receiver can accept, while the receiver still provides the best performance. To do this, you need to obtain the lowest light input power value from the manufacturer’s data sheet.


3.Calculate the level of attenuation required for the test. For example, the transmitter’s optical output power is -17 dBm, and the receiver’s minimum optical power level is -33 dBm. The difference between them is 16 dB. You can use a 16 dB bulkhead attenuator at the input of the receiver and retest the receiver. If the receiver still works, it is within specification.

Note: Light loss is not considered in the above example. Assuming the transmitter is located 10 kilometers from the receiver and the loss of the entire fiber link (including the interconnect) is 6 dB, then a 10 dB bulkhead attenuator should be used instead of 16 dB for your test.


The optical attenuator is a very important passive optical fiber device. It can attenuate the optical signal energy according to the user’s requirements. It can also be used to test the sensitivity of optical fiber transceivers. Fiber-Mart offers a full range of optical attenuators that bring convenience to users of optical communications.Any questions welcome to communicate with us:

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