2024 SFP Transceivers Buying Guide

 People commonly use SFP transceivers to connect network devices and cables. With the increasing range of applications, many 1G SFP transceivers are available. However, choosing the right 1G SFP modules for your specific requirements can be difficult.

If you are considering upgrading your switches and are unsure how to select the right 1G SFP optical modules, this blog aims to provide practical guidance. It will assist you in choosing an optical module that offers a combination of high compatibility and cost-effectiveness.

7 Factors to Choose 1G SFP Transceivers

SFP Network Technology

1G SFP transceivers are available in a range of models, each designed to cater to different networking technologies. These SFP module types are tailored to specific networking standards and can be classified as Ethernet SFP, FC SFP, SDH SFP/SONET SFP, or PON SFP.

Ethernet SFP modules are extensively utilized in enterprise networks for high-speed data transfer between switches, routers, and other networking equipment.

FC SFPs are designed for fiber channel storage in data centers and are commonly used in enterprise Storage Area Networks (SANs).

SONET/SDH SFPs are popular in telecom systems for their high-speed, long-distance data transfer. They can support different transmission rates and reach distances, making them flexible and ideal for various network topologies.

PON SFPs are specifically designed for various fiber-based (FTTx) access networks, making them ideal for delivering exceptional video, voice, and data services to both residential and commercial environments.

SFP Network Technology

Transmission Medium

1G SFP module types are available to support both single-mode and multimode fiber (Fiber SFP), as well as twisted-pair copper cables such as Cat5e, Cat6 and Cat6a (Copper SFP). If the endpoints are close enough (for example, less than 100m), it‘s wise to use copper SFP modules. However, when the distance is significant or there is a need to prevent cross-talk between cables, opting for fiber SFPs is a better choice. Commonly, the 1G SFP EXZ module supports up to 160km transmission via single-mode fiber.

Fiber SFP vs Copper SFP

Wavelength

In fiber optics, make sure you use the right wavelengths on each side, otherwise, the transmission will fail. For 1G dual fiber SFP, 850nm, 1310nm, and 1550nm are the most used wavelengths, while 1G BIDI module‘s wavelength includes TX1310/RX1550nm, TX1550/RX1310nm, TX1490/RX1550nm, TX1550/RX1490nm, TX1310nm/Rx1490nm and TX1490nm/Rx1310nm. Note that, both 1G dual and BIDI fiber modules should be used in pairs. Dual fiber SFP modules must have the same wavelengths at each point, while BiDi SFPs use the opposite wavelength together.

Working Temperature

The operating temperature range is a critical consideration, especially in environments with extreme temperature variations. Industrial 1G SFP modules are designed to withstand wider temperature ranges, typically from -40°C to 85°C, while commercial-grade modules are suitable for standard temperature ranges of 0°C to 70°C. Assess the environmental conditions where the 1G SFP transceivers will be deployed and choose the appropriate temperature range accordingly.

Compatibility

Compatibility issues can lead to connectivity problems and impact overall network performance. The compatibility of SFP is determined by the inclusion of specific brands and models of equipment. To verify device compatibility, you can refer to the SFP compatibility matrix available on the official website of the equipment brand or consult your vendors for assistance.

HTF provides multiple brands of compatible transceiver modules, some of the main-stream brands are Cisco, HP, Juniper, Brocade, Dell, Extreme, H3C, Arista, Huawei, Intel, IBM, Netgear, Ciena, D-Link, Avago, F5 Networks, Avaya, Alcatel-Lucent, Aruba Networks, Allied Telesis, SMC Networks, TRENDnet, etc.

DOM Support

Opting for high-quality SFP modules is essential for reliable and efficient network operations. Consider features such as Digital Optical Monitoring (DOM), which provides real-time monitoring of optical parameters like power levels, temperature, and signal quality. Investing in quality modules with advanced monitoring capabilities can help in proactive network management and troubleshooting.

Price & Budget

Compare prices from different vendors to get a sense of the market range for 1000Base SFP modules. Keep in mind that excessively low-priced modules may indicate lower quality or compatibility issues, while excessively high-priced modules may not necessarily offer significant added value. Look for a balance between cost and quality.

In addition to comparing 1G SFP transceiver prices from various manufacturers, it‘s essential to explore if there are more cost-effective alternatives available. For instance, if you require an end-to-end connection between two switches within the same rack and the distance is short, you might consider using a high-speed cable that eliminates the need for additional fiber cables.

Conclusion

This guide provides practical tips on factors to consider, such as SFP network technology, medium support, wavelength, working temperature, compatibility and DOM support to help you make an informed decision. You could click the article How Many Types of SFP Transceivers Do You Know? to get more information. If you are still facing difficulties in purchasing 1G SFP transceivers. Please feel free to reach out to our sales expert through the chatbox or send us an email at ivy@htfuture.com.

Application of the Coherent Optical Communication

 Coherent Optical Communication， It is an advanced and complex optical transmission system suitable for longer distance, higher capacity information transmission. In the long-distance transmission of optical fibers, EDFAs (Erbium-Doped Fiber Amplifiers) are generally used for every 80km span.

With coherent optical communication, long-distance transmission is much easier. Moreover, coherent optical communication can be transformed directly with the existing optical fiber and cable, whose cost is controllable.

Coherent optical communication can be used to upgrade the existing backbone network WDM system, and can also be used in 5G mid-backhaul scenarios. Even metro FTTx fiber access has begun to study the introduction of coherent optical communication. At present, the most heated discussion of coherent optical communication focuses on the “data center interconnection”(DCI) scenario.

DCI has a strong demand for long-distance coherent optical modules. Especially this year, the country vigorously promotes channeling more computing resources from the eastern areas to the less developed western regions, which has a great stimulating effect on the coherent optical communication market.

Conclusion:
All in all, the return and popularization of coherent optical communication technology are conducive to further tapping the performance potential of optical communication, increasing the limit bandwidth, and reducing deployment costs. At present, the research on coherent optical communication technology is still in progress. The problems of a complex process, large volume, and high power consumption of coherent optical modules have not been completely solved. There is still a lot of room for technological innovation in each key link of coherent optical communication.

HTF can help you design coherent 400G/200G/100G DWDM/OTN solution, DWDM Single lamda 100G/200G/400G Dual fiber/Single fiber Ultra long distance transmission.

Other Supporting Technologies for Coherent Optical Communication

 The performance of coherent optical communication is powerful, but the system is very complex and it’s hard to make the technology happen.

In order to realize the practical application of coherent optical communication, it is necessary to rely on the following technologies:

Polarization PreservingTechnology
Coherent detection requires that the polarization directions of the signal light and the local oscillator light are the same in coherent optical communication, that is, the electric vector directions of the two must be the same, so as to obtain the high sensitivity that coherent reception can provide.

Because, in this case, only the projection of the signal light electric vector in the direction of the local oscillator light electric vector can really contribute to the intermediate frequency signal current generated by the mixing. In order to ensure high sensitivity, it is necessary to take lightwave polarization stabilization measures. There are two main methods currently:

First, the “polarization-maintaining fiber” is used to keep the polarization state of the light wave unchanged during the transmission process. (Ordinary single-mode fiber will change the polarization state of the light wave due to factors such as mechanical vibration or temperature change of the fiber.)

Second, use ordinary single-mode fiber, but use polarization diversity technology at the receiving end.

Frequency Stabilization Technology
The frequency stability of semiconductor lasers is very important In coherent optical communication. The frequency of the laser is very sensitive to changes in operating temperature and current. If the frequency of the laser drifts with different operating conditions, it will affect the IF current, thereby increasing the bit error rate.

Spectrum Compression Technology
The spectral width of the light source also matters in coherent optical communication. Only by ensuring the narrow linewidth of the light wave, can the influence of the quantum amplitude modulation and frequency modulation noise of the semiconductor laser on the sensitivity of the receiver be overcome. Besides, the narrower the line width, the smaller the phase noise caused by the phase drift. In order to meet the requirements of coherent optical communication on the spectral width of the light source, spectral width compression technology is usually adopted.

HTF can help you design coherent 400G/200G/100G DWDM/OTN solution, DWDM Single lamda 100G/200G/400G Dual fiber/Single fiber Ultra long distance transmission.

Technical Principles of Coherent Optical Communication

 As mentioned earlier, coherent optical communication mainly utilizes two key technologies, namely coherent modulation and heterodyne detection. Let’s first look at coherent modulation on the optical transmitter side. In the backward IM-DD (Intensity Modulation-Direct Detection) system, only intensity (amplitude) modulation can be used to modulate the light wave by changing the laser intensity through current to generate 0 and 1.

Direct modulation

Direct modulation is very simple, but it’s with a weak ability and many problems. However, in a coherent optical communication system, in addition to amplitude modulation of light, external modulation can also be used to perform frequency modulation or phase modulation, such as PSK, QPSK, and QAM. Additional modulation methods not only increase the information-carrying capacity (a single symbol can represent more bits) but also are suitable for flexible engineering applications.

The following is a schematic diagram of an external modulation:

Optical Transmitter (Coherent Modulation)

As shown in the figure, at the transmitting end, the external modulation method is adopted, and the IQ modulator based on the Mach-Zehnder modulator (MZM) is used to realize the high-order modulation format, and the signal is modulated on the optical carrier, and sent out.

It is the key link when entering the receiving end. First, a laser signal generated by local oscillation (local oscillator light) is used to mix with the input signal light in an optical mixer to obtain an intermediate frequency signal whose frequency, phase, and amplitude change according to the same rules as the signal light.

Optical receiver (heterodyne detection)

An enlarged version of the optical receiver structure

In a coherent optical communication system, the size of the output photocurrent after coherent mixing is proportional to the product of the signal optical power and the local oscillator optical power. Since the power of the local oscillator light is much higher than the power of the signal light, the output photocurrent is greatly increased, and the detection sensitivity is also improved.

In other words,non-coherent optical communication uses a lot of amplifiers to continuously relay and amplify the signal during the transmission process, while the essence of coherent optical communication is to mix and amplify the weak arriving signal directly at the receiving end.

After mixing, detection is performed with a balanced receiver. Coherent optical communication can be divided into heterodyne detection, intradyne detection, and homodyne detection according to the relationship between the frequency of the local oscillator optical signal and the signal optical frequency.

Classifications of coherent optical communication

In the coherent optical communication of heterodyne detection, the intermediate frequency signal is obtained by the photoelectric detector. The second demodulation is also required before it can be converted into a baseband signal. Homodyne and intradyne detection bring less noise and reduce the power overhead of subsequent digital signal processing and the requirements for related devices, so they are most commonly used. In homodyne detection coherent optical communication, the optical signal is directly converted into a baseband signal after passing through a photoelectric detector without secondary demodulation. However, it requires that the frequency of the local oscillator light and the signal light frequency be strictly matched, and the phase locking of the local oscillator light and the signal light is required.

Next, is the digital signal processing(DSP) link of great importance.

Digital Signal Processing(DSP)

Distortion occurs when an optical signal is transmitted in a fiber optic link. DCP technology takes advantage of the easy-handle characteristic of digital signals to combat and compensate for distortion, and reduce the impact of distortion on the system bit error rate. It has created the digital era of optical communication systems and become an important support for coherent optical communication technology. DSP technology can be not only applied to receivers, but also to transmitters.

As shown below:

digital signal processing(DSP) technologyDSP technology

Digital to analogue and analogue to digital

As can be seen from the above figure, DSP technology performs various signal compensation processing, such as chromatic dispersion compensation and polarization mode dispersion compensation (PMD).

Various Compensation and Estimation of DSP

The traditional non-coherent optical communication performs dispersion compensation and other functions through optical path compensation devices, whose compensation effect is far inferior to that of the DSP. The introduction of DSP technology simplifies the system design, saves cost, and eliminates the original dispersion compensation module (DCM) or dispersion compensation fiber in the system, which makes the link design of long-distance transmission simpler. With the development of DSP, more algorithms and functions are added continuously, such as nonlinear compensation technology and multi-code modulation and demodulation technology.

After DSP processing, the final electrical signal is output. Next, we review the whole process through a case of 100G coherent transmission.

The specific process is as follows:

1. After digital signal processing and digital-to-analog conversion, the 112Gbps signal stream, after entering the optical transmitter, undergoes “serial-parallel” conversion and becomes 4 channels of 28Gbps signals;

2. The signal emitted by the laser becomes an optical signal polarized in two vertical directions of x and y through the polarization beam splitter;

3. Through the high-order modulator composed of the MZM modulator, QPSK high-order modulation is performed on the optical signal in the x and y polarization directions;

4. The modulated polarized light signal is combined with an optical fiber through a polarization combiner for transmission;

5. After receiving the signal, the receiving end separates the signal into two vertical polarization directions of X and Y;

6. Through coherent detection and reception, the X and Y vertically polarized signals become current/voltage signals;

7. Through ADC conversion, the current and voltage signals are turned into digital code streams such as 0101…;

8. Through digital signal processing, the interference factors such as dispersion, noise, and nonlinearity are removed, and the 112Gbps telecommunication number stream is restored, and it’s the end.

HTF can help you design coherent 400G/200G/100G DWDM/OTN solution, DWDM Single lamda 100G/200G/400G Dual fiber/Single fiber Ultra long distance transmission.