Comparison of differences between single-mode dual fiber and single-mode single fiber in optical module

　　There are significant differences between single-mode dual fiber and single-mode single fiber in optical modules in several aspects. Here is a detailed comparison of the two:

　　Physical structure

　　Single-mode single fiber: Two-way communication using a single fiber, that is, sending and receiving operations simultaneously on the same fiber. This usually requires the use of special transceivers (such as BiDi transceivers) and wavelength division multiplexing (WDM) technology to achieve two-way communication.

　　Single-mode dual fiber: Two fibers are used for sending and receiving data, one for sending data (TX port) and the other for receiving data (RX port). The two fibers are relatively independent and can be tranSMitted in both directions simultaneously, but do not require complex wavelength division multiplexing technology.

　　Transmission method

　　Single-mode single fiber: Simultaneous transmission of signals in two directions through a single fiber, usually through wavelength division multiplexing technology implementation, that is, the transmission of optical signals of different wavelengths in the same fiber. Common wavelength division multiplexing technologies include coarse wavelength division multiplexing (CWDM) and dense wavelength division multiplexing (DWDM).

　　Single-mode dual fiber: Each fiber is only responsible for signal transmission in one direction, one fiber is used to send the signal, and the other fiber is used to receive the signal. This method is relatively simple and does not require complex wavelength division multiplexing technology.

　　III. Transmission distance

　　Single-mode single fiber: can usually support long-distance transmission, such as 10 kilometers, 40 kilometers or even more. The specific distance depends on the wavelength division multiplexing technology used and the quality of the fiber. In long-distance transmission, using a single fiber can reduce the cost and complexity of fiber laying.

　　Single-mode dual-fiber: It can also support long-distance transmission, but in general, the transmission distance of dual-fiber systems is comparable to that of single-fiber systems. In some cases, dual-fiber systems may be easier to implement because no complex wavelength division multiplexing technology is required.

　　IV. Cost

　　Single-mode single fiber: The initial cost is higher due to the use of special BiDi transceivers and wavelength division multiplexing technology. However, in the long run, the overall cost may be reduced due to the reduction in the number of fibers. Maintenance costs are also relatively high due to the need to ensure the proper operation of wavelength division multiplexing technology.

　　Single-mode dual fiber: The initial cost is lower because standard single-mode fiber and transceivers are used. But in the long run, the overall cost may increase due to the need to lay two fibers. However, maintenance costs are relatively low because the system is relatively simple and easy to maintain.

　　Application scenarios

　　Single-mode single fiber: suitable for occasions that require long-distance transmission and limited fiber resources, such as interconnection between data centers, metropolitan area networks, wide area networks, etc. It can save fiber resources and reduce wiring complexity.

　　Single-mode dual fiber: suitable for short-distance data communication requirements or applications that require high reliability and simple maintenance, such as enterprise intranets, campus networks, industrial control networks, etc.

　　VI. Technical complexity

　　Single-mode single fiber: The technical complexity is high, the wavelength division multiplexing technology is required, and the requirements for equipment and installation personnel are high. Professional training and experience are required to ensure the correct installation and maintenance of the system.

　　Single-mode dual fiber: Low technical complexity, using standard fiber optics and transceivers, installation and maintenance are relatively simple. Low requirements for installers, easy to use.

　　VII. Compatibility

　　Single-mode single fiber: requires the use of specific BiDi transceivers and wavelength division multiplexing devices, with relatively low compatibility. There are currently some standard BiDi transceivers on the market, but the selection range is relatively small.

　　Single-mode dual fiber: highly compatible, can use standard single-mode fiber and transceiver, wide selection. Compliant with international standards such as IEEE 802.3.

　　In summary, there are significant differences between single-mode dual-fiber and single-mode single-fiber in terms of physical structure, transmission mode, transmission distance, cost, application scenarios, technical complexity and compatibility. When choosing, it needs to be comprehensively considered according to specific application needs and budgets.