Common knowledge of optical modules and optical interfaces

What is GBIC?

GBIC is an abbreviation of Giga Bitrate Interface Converter, which is an interface device for converting gigabit electrical signals into optical signals.The GBIC can be designed for hot swapping.GBIC is an interchangeable product that meets international standards.Gigabit switches designed with GBIC interface occupies a large market share in the market due to flexible interchangeability.

What is SFP?

SFP is an abbreviation of SMALL FORM PLUGGABLE, which can be simply understood as an upgraded version of GBIC.SFP modules are half the size of GBIC modules and can be configured with more than twice the number of ports on the same panel.The other functions of the SFP module are basically the same as the GBIC.Some switch manufacturers call the SFP module a miniaturized GBIC (MINI-GBIC).Future optical modules must support hot plugging, which means that they can be connected or disconnected from devices without cutting off power.Because the optical module is hot-plugged, network managers can upgrade and extend the system without shutting down the network, with little impact on online users.Hotplug also simplifies overall maintenance and allows end users to better manage their transceiver modules.At the same time, because of this heat exchange performance, the module enables network managers to plan the overall transmission and transmission costs, link distances, and all network topologies according to the requirements of network upgrades, without having to replace all the system boards.The optical modules that support this hot plugging currently have GBIC and SFP, because the size of SFP and SFF is about the same, it can be directly inserted in the circuit board, which saves space and time in packaging, and has a wide range of applications.Therefore, its future development is worth expecting and may even threaten the market of SFF.

What is SFF?

The SFF(Small Form Factor) compact optical module adopts advanced precision optical and circuit integration technology and is only half the size of the ordinary duplex SC(1X9) fiber optic transceiver module.It can double the number of optical ports in the same space, increase the line port density and reduce the system cost per port.In addition, the small package module of SFF adopts kt-rj interface similar to copper wire network, the same size as common copper wire interface of computer network, which is conducive to the transition of existing copper-cable-based network equipment to higher-rate optical fiber network to meet the rapid growth of network bandwidth demand.

Network connection device interface type

BNC interface

BNC interface refers to coaxial cable interface. BNC interface is used for 75 euro coaxial cable connection, providing two channels for receiving (RX) and sending (TX), and it is used for connection of non-balanced signals.

Optical fiber interface

Fiber optic interface is the physical interface used to connect fiber optic cables.There are usually SC, ST, LC, FC and other types.For a 10base-f connection, the connector is usually of type ST, and the other end of the FC is connected to a fiber optic cable rack.FC is the abbreviation of FerruleConnector. Its external reinforcement is metal sleeve and fastening is screw buckle.ST interface is usually used for 10base-f.SC interface is usually used for 100base-fx and GBIC.LC is usually used for SFP.

RJ – 45 interface

The rj-45 interface is the most commonly used Ethernet interface.Rj-45 is a common name for modular jacks or plugs with 8 positions (8 pins) as defined by the international connector standard, standardized by IEC(60)603-7.

RS – 232 interface

Rs-232-c interface (also known as EIA rs-232-c) is the most commonly used serial communication interface.It was developed in 1970 by the American electronics industry association (EIA) in collaboration with bell systems, modem manufacturers and computer terminal manufacturers for serial communication standards.Its full name is ”technical standard for serial binary data exchange interface between data terminal devices (DTE) and data communication devices (DCE)”.The standard specifies the use of a 25-pin DB25 connector, specifying the signal content of each pin of the connector and the level of various signals.

RJ – 11 interface

The RJ-11 interface is what we call the phone line interface.RJ-11 is the generic name for the connector developed by Western Electric.Its shape is defined as a 6-pin connector.Its shape is defined as a 6-pin connector.Formerly known as WExW, the x here stands for “active”, contact or needle injection.For example, WE6W has all six contacts, Numbers 1 through 6, WE4W interface only USES 4 pins, the outermost two contacts (1 and 6) do not use, WE2W only USES the middle two pins (i.e., phone line interface).

CWDM and DWDM

With the rapid growth of Internet IP data service, the demand for transmission line bandwidth is increasing.Although DWDM(dense wavelength division multiplexing) technology is the most effective method to solve line bandwidth expansion, CWDM (coarse wavelength division multiplexing) technology has advantages over DWDM in system cost, maintainability and other aspects.

CWDM and DWDM are both wavelength division multiplexing technologies, which can combine the light of different wavelengths into a single core fiber and transmit them together.ainability and other aspects.

The latest ITU standard of CWDM is g.695, which provides 18 wavelength channels with an interval of 20nm from 1271nm to 1611nm. Considering the influence of water peak of ordinary g. 652 fiber, 16 channels are generally used.Because of the large channel spacing, the combined wave separators and lasers are cheaper than DWDM devices.

DWDM channel intervals are 0.4nm, 0.8nm, 1.6nm and other different intervals as required, which are small and require additional wavelength control devices. Therefore, devices based on DWDM technology are more expensive than those based on CWDM technology.

PIN photodiode is a layer of lightly doped n-type materials, known as the I(Intrinsic) layer, between highly doped p-type and n-type semiconductors.Because it is lightly doped, the electron concentration is very low. After diffusion, a very wide depletion layer is formed, which can improve its response speed and conversion efficiency.APD is a photodiode with gain. When the sensitivity of optical receiver is higher, APD is helpful to extend the transmission distance of the system.