Classification and Types of Optical Modules
2019-10-01
Classification by rate
In order to meet the needs of various transmission rates, optical modules with different rates are produced: FE optical module, GE optical module, 10GE optical module and 40GE optical module.
The higher the transmission rate, more complex the structure of the optical module. In order to meet the needs of different structures, various types of optical modules are produced. Huawei switches are suitable for packaging types: SFP packaging, SFP + packaging, XFP packaging, QSFP + packaging.
Classification by physical layer standard
In order to meet the requirement that data can be transmitted in different forms, different physical layer standards are defined, and optical modules supporting various standards are generated. The detailed categories are shown in the "standard types" in the table below.
Classification by mode
Optical fibers are divided into single-mode fibers and multi-mode fibers. In order to meet the requirements of different types of optical fibers, single-mode optical module and multi-mode optical module are produced.
It includes optical receiving module, optical transmitting module, optical transceiver module, optical forwarding module, etc. Transponder (optical transponder): In addition to photoelectric conversion function, it also integrates many signal processing functions, such as MUX/DEMUX, CDR, function control, performance acquisition and monitoring. Common are: 200/300 pin MSA, XENPAK, X2/XPAK and so on. The types of optical modules are mainly distinguished by their parameters and characteristics. Current classification methods include: transmission distance, rate/protocol, wavelength and other characteristics of lasers: operating temperature range, suitable transmission medium (optical fiber) type, whether there is digital diagnosis, type of lasers, type of receivers, etc.
Today, we introduce the main types of optical modules.
1).SFF
SFF is short for Small Form. Factor, Intel calls small package technology. SFF optical module is the earliest optical module product. Its main service rate is below 2.5 Gbps. Its electrical interface has two specifications: 10 pin and 20 pin. The two versions of the main data signal interface are the same. The 20pin module provides additional pins for clock signal recovery, laser surveillance and alarm surveillance in addition to data signals. SFF is smaller in size than SFP and is welded to the motherboard in the form of pins.
2).GBIC
GBIC is the abbreviation of Gigabit Interface Converter, which is a Gigabit interface converter. It is an interface device that converts Gigabit electrical signal into optical signal. GBIC is large, almost twice the volume of SFP, and is welded on PCB board by inserting pins. At present, it is basically replaced by SFP. SFP module is basically the same as GBIC in function. It is also called Mini-GBIC by some switch manufacturers.
3).SFP
SFP is short for Small Form-factor Pluggable, i.e. small package pluggable optical modules. SFP can be seen as a pluggable version of SFF. Its electrical interface is 20 pin golden. The data signal interface is basically the same as SFF module.
SFP module also provides I2C control interface, which is compatible with SFP-8472 standard optical interface diagnosis. Both SFF and SPF do not contain . They only provide a serial data interface, and put the CDR and electro-dispersion compensation outside the module, which makes it possible to have small size and small power consumption. Due to the limitation of heat dissipation, SFF/SFP can only be used for ultra-short, short and medium distance applications at 2.5 Gbps and below.
4).XFP
XFP is short for 10 Gigabit Small Form. Factor Pluggable, that is, 10G small package pluggable optical module, electrical interface is 30pin golden finger. Modules of different business types can support OC192/SMT-649.95 Gbps, 10 Gigabit FC 10.5 Gbps, G.709 10.7 Gbps, 10 Gigabit Ethernet 10.3 Gbps. Main used in need of miniaturization and low cost 10G solutions. Like SFF/SFP, XFP places the SerDes part outside the optical module in order to reduce the volume. The XFP optical transceiver has a serial 10Gbps electrical interface, called XFI, which is used to connect external SerDes devices. XFP is developed on the basis of four-channel SerDes optical transceiver modules such as XENPAK, X2, XPAK. Based on XENPAK, X2 and XPAK, XFP completely removed SerDes, which greatly reduced power consumption, volume and cost.
5).SFP+
SFP + is the same shape as SFP, and it is also the 20pin golden finger electrical interface, but the maximum rate of support is higher than SFP, reaching the same 10Gbps as XFP. Compared with XFP, SFP + has no CDR (clock data recovery) module, so SFP + has smaller volume and power consumption than XFP. SFP + generally only supports short and medium distance transmission, but it has not yet supported the SPF + module of ER (40km) and ZR (80km). SFP + is compared with XFP as follows:
6). 300pin MSA
300pin MSA is a complete optical interface module, which is characterized by large volume and encapsulated in a radiator-type metal shell to facilitate heat dissipation. These two specifications work on 16 parallel channels. The single channel electrical interface rates of 10G specifications are 622-669 MHz, which conform to OFI SFI4 and IEEE XSBI specifications. The single channel electrical interface rate of 40G module is 2.5G~3.125G, which conforms to SFI5 specification. The optical modules support SONET/SDH and 10G XSBI. According to ITU-T G.691 and G.693 standards, the transmission distance is from 600 m to 80 km.
7).XENPAK
XENPAK is a 4-channel SerDes structure, which connects to PCB through 70pin's SPF connector. Its data channel is XAUI interface. XenPAK supports all the optical interfaces defined by 802.3ae. It can provide 10.3 Gbps, 9.95 Gbps or 4*3.125 Gbps at the circuit end.
In order to reduce the cost of 300 pin MSA optical module, the electrical interface of optical module is developing in two directions: 4-channel parallel interface and 10 Gbps single-channel serial interface, which are represented by XENPAK and XFP.XENPAK is the first generation optical module for 10G ethernet. It uses 4*3.125G interface. XENPAK transits from 16-channel parallel XSBI to 4-channel XAUI. XENPAK chooses XAUI because it has fewer pins, does not need clocks, and has a speed of 3.125 G. It can be used in standard CMOS circuits immediately. And the data through the XAUI is arranged automatically, that is to say, the SerDes device automatically balances the use of four channels.
When Xenpak optical module is installed on the circuit board, it needs slotting on the circuit board, which is complex to realize and can’t achieve high-density applications.
8).XPAK/X2
Although the volume of XENPAK has been reduced a lot compared with 300pin MSA, it is still not ideal. At present, miniaturization is a trend of 10G optical module. XPAK is a direct improvement of XENPAK.
In order to meet the needs of various transmission rates, optical modules with different rates are produced: FE optical module, GE optical module, 10GE optical module and 40GE optical module.
The higher the transmission rate, more complex the structure of the optical module. In order to meet the needs of different structures, various types of optical modules are produced. Huawei switches are suitable for packaging types: SFP packaging, SFP + packaging, XFP packaging, QSFP + packaging.
Classification by physical layer standard
In order to meet the requirement that data can be transmitted in different forms, different physical layer standards are defined, and optical modules supporting various standards are generated. The detailed categories are shown in the "standard types" in the table below.
Classification by mode
Optical fibers are divided into single-mode fibers and multi-mode fibers. In order to meet the requirements of different types of optical fibers, single-mode optical module and multi-mode optical module are produced.
It includes optical receiving module, optical transmitting module, optical transceiver module, optical forwarding module, etc. Transponder (optical transponder): In addition to photoelectric conversion function, it also integrates many signal processing functions, such as MUX/DEMUX, CDR, function control, performance acquisition and monitoring. Common are: 200/300 pin MSA, XENPAK, X2/XPAK and so on. The types of optical modules are mainly distinguished by their parameters and characteristics. Current classification methods include: transmission distance, rate/protocol, wavelength and other characteristics of lasers: operating temperature range, suitable transmission medium (optical fiber) type, whether there is digital diagnosis, type of lasers, type of receivers, etc.
Today, we introduce the main types of optical modules.
1).SFF
SFF is short for Small Form. Factor, Intel calls small package technology. SFF optical module is the earliest optical module product. Its main service rate is below 2.5 Gbps. Its electrical interface has two specifications: 10 pin and 20 pin. The two versions of the main data signal interface are the same. The 20pin module provides additional pins for clock signal recovery, laser surveillance and alarm surveillance in addition to data signals. SFF is smaller in size than SFP and is welded to the motherboard in the form of pins.
2).GBIC
GBIC is the abbreviation of Gigabit Interface Converter, which is a Gigabit interface converter. It is an interface device that converts Gigabit electrical signal into optical signal. GBIC is large, almost twice the volume of SFP, and is welded on PCB board by inserting pins. At present, it is basically replaced by SFP. SFP module is basically the same as GBIC in function. It is also called Mini-GBIC by some switch manufacturers.
3).SFP
SFP is short for Small Form-factor Pluggable, i.e. small package pluggable optical modules. SFP can be seen as a pluggable version of SFF. Its electrical interface is 20 pin golden. The data signal interface is basically the same as SFF module.
SFP module also provides I2C control interface, which is compatible with SFP-8472 standard optical interface diagnosis. Both SFF and SPF do not contain . They only provide a serial data interface, and put the CDR and electro-dispersion compensation outside the module, which makes it possible to have small size and small power consumption. Due to the limitation of heat dissipation, SFF/SFP can only be used for ultra-short, short and medium distance applications at 2.5 Gbps and below.
4).XFP
XFP is short for 10 Gigabit Small Form. Factor Pluggable, that is, 10G small package pluggable optical module, electrical interface is 30pin golden finger. Modules of different business types can support OC192/SMT-649.95 Gbps, 10 Gigabit FC 10.5 Gbps, G.709 10.7 Gbps, 10 Gigabit Ethernet 10.3 Gbps. Main used in need of miniaturization and low cost 10G solutions. Like SFF/SFP, XFP places the SerDes part outside the optical module in order to reduce the volume. The XFP optical transceiver has a serial 10Gbps electrical interface, called XFI, which is used to connect external SerDes devices. XFP is developed on the basis of four-channel SerDes optical transceiver modules such as XENPAK, X2, XPAK. Based on XENPAK, X2 and XPAK, XFP completely removed SerDes, which greatly reduced power consumption, volume and cost.
5).SFP+
SFP + is the same shape as SFP, and it is also the 20pin golden finger electrical interface, but the maximum rate of support is higher than SFP, reaching the same 10Gbps as XFP. Compared with XFP, SFP + has no CDR (clock data recovery) module, so SFP + has smaller volume and power consumption than XFP. SFP + generally only supports short and medium distance transmission, but it has not yet supported the SPF + module of ER (40km) and ZR (80km). SFP + is compared with XFP as follows:
6). 300pin MSA
300pin MSA is a complete optical interface module, which is characterized by large volume and encapsulated in a radiator-type metal shell to facilitate heat dissipation. These two specifications work on 16 parallel channels. The single channel electrical interface rates of 10G specifications are 622-669 MHz, which conform to OFI SFI4 and IEEE XSBI specifications. The single channel electrical interface rate of 40G module is 2.5G~3.125G, which conforms to SFI5 specification. The optical modules support SONET/SDH and 10G XSBI. According to ITU-T G.691 and G.693 standards, the transmission distance is from 600 m to 80 km.
7).XENPAK
XENPAK is a 4-channel SerDes structure, which connects to PCB through 70pin's SPF connector. Its data channel is XAUI interface. XenPAK supports all the optical interfaces defined by 802.3ae. It can provide 10.3 Gbps, 9.95 Gbps or 4*3.125 Gbps at the circuit end.
In order to reduce the cost of 300 pin MSA optical module, the electrical interface of optical module is developing in two directions: 4-channel parallel interface and 10 Gbps single-channel serial interface, which are represented by XENPAK and XFP.XENPAK is the first generation optical module for 10G ethernet. It uses 4*3.125G interface. XENPAK transits from 16-channel parallel XSBI to 4-channel XAUI. XENPAK chooses XAUI because it has fewer pins, does not need clocks, and has a speed of 3.125 G. It can be used in standard CMOS circuits immediately. And the data through the XAUI is arranged automatically, that is to say, the SerDes device automatically balances the use of four channels.
When Xenpak optical module is installed on the circuit board, it needs slotting on the circuit board, which is complex to realize and can’t achieve high-density applications.
8).XPAK/X2
Although the volume of XENPAK has been reduced a lot compared with 300pin MSA, it is still not ideal. At present, miniaturization is a trend of 10G optical module. XPAK is a direct improvement of XENPAK.
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