SFP-10G-SR vs. SFP-10G-LR

 With the development of technology, from the original GBIC, XENPAK, X2 to the current SFP28, QSFP2 optical modules are used in different application scenarios. However, based on the market analysis, the 10G SFP+ optical modules are still the most in demand, especially SFP-10G-SR and SFP-10G-LR.

SFP-10G-SR and SFP-10G-LR have different wavelengths, transmission distances, fiber types and laser types：

Module	SFP-10G-SR	SFP-10G-LR
Wavelength	850nm	1310nm
Transmission Distance	300m	10km
Fiber Type	MMF	SMF
Laser Type	VCSEL	DFB
DOM	Support	Support

SFP-10G-SR optical module, where SR means short range (Short Range), the center wavelength is 850nm, it can be used with 62.5/125um multimode fiber and 50/125um multimode fiber, and its transmission distance will be affected by the fiber type, as follows (refer to IEEE Standard 802.3)

Data Rate	Fiber Type	Model Bandwidth @850nm (MHz-km)	Distance Range(m)
9.83-11.3Gb/s	62.5/125um MMF	160	26
9.83-11.3Gb/s	62.5/125um MMF	200	33
9.83-11.3Gb/s	50/125um MMF	400	66
9.83-11.3Gb/s	50/125um MMF	500	82
9.83-11.3Gb/s	50/125um MMF	2000	100

SFP-10G-LR optical module, where LR refers to the long range (Long Range), the center wavelength is 1310nm, it is used with 9/125um single-mode fiber, and the effective transmission is 2km to 10km.

Applications of SFP-10G-SR & SFP-10G-LR
Comparison of the characteristics of the two modules shows that the advantages and applications are as follows: SFP-10G-SR optical module has the characteristics of miniaturization and low power consumption. The TOSA laser used is a VCSEL laser, and the cost is low. The short transmission distance is suitable for short-distance application scenarios, such as enterprises, hospitals and data centers. SFP-10G-LR optical module has the characteristics of miniaturization, low power consumption and long transmission distance. It is suitable for medium and long-distance application scenarios, such as campus, industrial districts, and operator customers, big data centers, etc.

When using these two types of optical modules with optical fibers, should be paid attention to the fact that single-mode optical fibers cannot be inserted into multi-mode optical modules, because the divergence angle of the optical signal sent by the multi-mode optical module is large, while the aperture of single-mode optical fibers is small. Too little light enters the fiber to travel long distances. Meanwhile, it is not recommended to multi-mode optical fiber into the single-mode optical module, because although the light emitted by the single-mode optical module can all enter the optical fiber, it is transmitted in multi-mode mode in the optical fiber, and the dispersion is large, so it can only be transmitted over a short distance. And in this case, the optical power of the receiving end will increase, which will cause the optical power over"" of the receiving end. Therefore, it is not recommended to use multi-mode optical fibers with single-mode optical modules.

What's Optical Protection?

 Optical protection means that once the optical fiber cable is broken, but the communication network won’t be interrupted.

 

OLP optical line protection is a functional device used in optical fiber communication to automatically switch between the main and backup optical paths. It can monitor the optical signal status of the main and backup links in real time. When the optical cable of the main link fails, the system automatically switches to the backup link. transmission, protect the system from running normally, and improve system stability.

Optical line protection can realize functions such as optical power monitoring, automatic switching of optical paths, and network management. In the optical communication network, OLP monitors the optical power on the working fiber and the standby fiber in real time. When the optical power value on the current working fiber is detected to be lower than the set switching threshold, it will issue a warning prompt and automatically switch to the standby fiber, thereby Realize the protection of the optical transmission system. OLP can simply and economically form protection schemes for various channels and trunk lines, and can also protect various networks that require optical path switching, so as to form a non-blocking, high-reliability, safe, flexible, and disaster-resistant optical communications network.

Features
⦁ Automatic Instantaneous Switching
⦁ Real-time Monitoring of Luminous Power
⦁ Reduce Various Losses Caused by Network Node Failures
⦁ Increase the Reliability of Transmission Network
⦁ Improve the Service Quality of Operation
⦁ Main Route and Backup Route can be Scheduled Arbitrarily

Applications
⦁ Backbone Network
⦁ 5G Base Station Fronthaul
⦁ Government and Enterprise Backbone Network
⦁ Banking and Finance Network, etc

 

OBP Optical bypass protection is an intelligent system that is applied in the field of optical fiber communication and can automatically bypass faulty network nodes. The system automatically recognizes the power supply status and optical signal output status of network nodes. The faulty network nodes can be avoided, so as to avoid all-blocking obstacles in the network nodes and maintain the normal connection of the system.

 

Features
⦁ High Security
⦁ Transmitting Signals Transparently
⦁ Automatic Switching without Blocking
⦁ Effectively Respond to Power-off and Light-Emitting Faults

 

Applications
⦁ Local Network Base Station
⦁ Local Network Transmission Station
⦁ Network Room
⦁ Others

What Are the Key Components of Optical Transceiver Module?

 The function of optical transceiver module is to perform photoelectric conversion, and its internal TOSA, ROSA and BOSA are the key components to realize the photoelectric conversion function. The optical device is composed of transmitter and receiver to complete the optical-electrical or electrical-optical conversion of optical signals.

The interior is composed of optical devices, functional circuits and optical interfaces. The optical device is the main component of the optical transceiver module.

The optical devices used for optical signal conversion are called TOSA and ROSA.

TOSA (Transmitting Optical Sub-Assembly) mainly completes the conversion of electrical signals into optical signals. With the light source (semiconductor light-emitting diode or laser diode) as the core, LD chip, monitor photodiode (MD) and other components are packaged in a TO coaxial package or butterfly package, which constitutes TOSA.

In TOSA, laser diode is the most commonly used semiconductor emitting device for optical transceiver modules. Threshold current (Ith) and slope efficiency (S) are the two main parameters. In order to make the LD work quickly, a DC bias current slightly greater than the threshold current must be provided to the LD, that is, the laser is emitted only when the forward current exceeds the threshold current.

ROSA (Resceiving Optical Sub-Assembly) optical receiving assembly, in the high data rate optical fiber module, PIN or APD photodiode and TIA are usually assembled in a sealed metal casing to form an optical receiving assembly.

The figure below is the schematic diagram of the optical module ROSA, which is composed of a photodetector (PIN/APD), a TIA pre-amplifier, and a limiting amplifier.

Photodetector, the main device of ROSA, is mainly used to convert optical signals into electronic signals through the photoelectric effect. The common photodetectors in optical communications are PIN photodiodes and avalanche photodiodes (APDs). APDs are high-sensitivity photodetectors that use the avalanche multiplication effect to double the photocurrent. Compared with PIN photodiode, the receiving sensitivity of APD can be improved by 6~10dB.

The weak signal current generated by the photodetector is converted into a signal voltage of sufficient magnitude by the preamplifier TIA, and then output. TIA is actually a voltage converter, which converts electro-optic current into voltage.

At this time, the voltage signal output by the TIA is still an analog signal, which needs to be converted into a digital signal before the signal processing circuit can recognize it. The function of the Poster Amplifier behind the TIA is to convert signals of different amplitudes into digital signals with the same amplitude.

After introducing TOSA and ROSA, let's take a look at what is BOSA?
With the development of process level technology, the modules can be made smaller. TOSA and ROSA integrate the transmission and reception of light (LD and PIN/APD) through the coaxial coupling process, plus splitters, optical fibers and other components, called BOSA (Bi-Directional Optical Sub-Assembly).

Nowadays, the high-speed optical transceiver module integrates high-performance DSP at the receiving end, and its performance in terms of dispersion and noise processing is really good.

Application Scenarios of CFP Transceiver Modules

 CFP optical transceiver modules are mainly used in switches, routers, converters, OTN optical transmission platforms and other equipment for line-side optical transmission of 100G wavelength division systems. Compared with other forms of line-side optical modules, It has good OSNR performance, sensitivity, dispersion tolerance, and DGD tolerance. At the same time, CFP coherent optical modules using wavelength division multiplexing technology are widely used in 100G metropolitan area networks to meet their high-capacity and long-distance requirements.

100G Multi-channel DWDM Transmission Network
Since 100G is more susceptible to dispersion, it is necessary to dispersion and improve optical power. First, a 100GHz DWDM multiplexer is used to combine all 100Gs, and then the dispersion compensation and amplification of the whole combination are performed. This architecture supports "pay-as-you-grow" service providers. Existing legacy 10G channels can be seamlessly swapped with 100G services when bandwidth is exhausted. The rest of the same components can even be reused to extend the data rate to 2.4Tb/s.

This solution requires 24 color CFP optical transceiver modules and a 48-channel 100GHz DWDM multiplexer. First, all 100G lines are multiplexed together, and then only one dispersion compensation and amplification is required. Obviously, such a network structure can provide higher density at a reasonable cost, and has the ability to flexibly reuse the existing infrastructure.

100G Distance Extension Solution
SFP + OEO Optical amplification repeaters can be used in conjunction with switches to achieve distance extension. After the 100G output signal of the switch is converted into a DWDM signal, it can realize longer distance transmission. This solution eliminates the distance limitation problem by using CFP coherent optical transceiver modules to connect the output signal to the line fiber to achieve longer distance signal transmission.

The above architecture achieves longer-distance signal transmission by adding MTP branch cables and WDM SFP + OEO converters, 6-channel dual-fiber DWDM dense wavelength division multiplexers and 8-channel dual-fiber CWDM coarse wavelength division multiplexers. The role of OEO is to convert conventional SR wavelengths to DWDM wavelengths. Therefore, the 100G CFP coherent optical module is an effective solution for building a 2500km long-distance DWDM network.