Fiber optic modules have long been an integral and important component of the telecommunications networks. They are the key to the popularity of a compact device, high performance, fast and inexpensive network configuration changes, and many other advantages. Due to the constant improvement of transceivers on the market, there are many variants, called form factors.
In the last 10-15 years, Fiber Optical Transceivers are compact plug-in modules designed for different parameters of transmission lines and mounted in standardized electrical ports active equipment. This makes it possible to optimize costs in the design, and especially – the reconstruction of optical networks.
For example, the speed may increase the transmission distance, the increase in information transmitted through the use of wavelength division multiplexing systems (WDM, CWDM, and DWDM). Or, for example, use single switch different types of transceivers for different distance subscribers.
Emitter Type (Transmitter type)
Typically, the emitters are used as laser diodes, whose type depends on the type of fiber, as well as the required power and narrowband. They are used with a single mode (at a wavelength of 1310 nm, at least – 1550 nm) and the multimode fiber (at wavelengths 850 nm and 1300 nm) with lengths of lines from several hundred meters to several kilometers, the transmission rates of 100 Mbit /s and 1 Gbit/s. Vertically emitting lasers (VCSEL) have been developed for local optical networks.
For the transmission of optical signals, we typically use two main types of fibers: Multimode (MM) and Single mode (SM). Accordingly, the emitter and the photo detector of the optical transceiver must be designed to work with one of these two fiber types. Typically, this is reflected in their marking and technical specifications.
Features of types of fibers (eg, OM3, OM4 – multimode or DS, NZFSF, BIF – single mode) should not be taken into account. Another thing is that the damping coefficient of the chromatic dispersion coefficient wideband factor (only MM) and other parameters used fiber types must be taken into account when calculating the power budget, the total dispersion, line length, etc.
Number of optical ports
As optical transceivers uses two ports: an optical transmitter (Tx, Transmitter) and the photodetector (Rx, Receiver). Such modules are used for transmission in two different directions two fibers and one operating wavelength. In recent years, much more frequently used are single-fiber transceivers with one optical port. They work, what is called “paired”: transmission in two different directions over a single fiber is in the two working wavelengths. Transmission and reception signals are separated within the module with the integrated WDM-multiplexer.
Type optical connector (Connector type)
A variety of types of connectors can be used for connecting to the optical line. Now Ethernet networks are the most popular compact connectors’ type LC (single-fiber modules) and SC (only in single-fiber units).
Spectral line width (Maximum Spectral Width)
This rather important parameter depends on the type of radiator. The greater the spectral line width is, the larger the total chromatic dispersion in the line (Total chromatic dispersion). For communication systems in multimode fibers is prevalent intermode dispersion, so there’s often use less expensive and more broadband emitters such as FP (glc sx mmd) or VCSEL.