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What is an optical module?

What is an optical module? An optical module is a component in the fiber optic communication link, with fiber optic being the main component of fiber optic communication. Before discussing optical modules, let's first talk about fiber optics. Fiber optics have ultra-wide bandwidth, with the frequency of light carrier being around 200 THz, which is hundreds of thousands of times higher than microwave carrier, making it almost an unlimited bandwidth. Fiber optics also have ultra-low loss, for example, the 112G XSR electrical signal in the optical module over a distance of approximately 150mm incurs a 22dB loss. A loss of 22dB means that 99.3% of the energy is consumed. If the same 112G signal is transmitted through the fiber optic cable, with a loss of 0.2dB/km, the signal would incur a 22dB loss over a distance of 110km. The difference between transmitting the signal electrically over 150mm and transmitting the signal through the fiber optic cable over 110km is quite significant. Therefore, fiber optic is considered to have almost zero loss. Fiber optics are made from thin strands of glass and are sold at a very low cost, typically only a few cents per kilometer, making it almost zero cost compared to copper cables. The signal that fiber optics transmit is "light", which is an electromagnetic wave with energy, specifically kinetic energy. Light can be transmitted in fiber optics at an ultra-low cost. However, due to the fact that light cannot be stationary, it is difficult to implement low-cost signal exchange, storage, and computation. To handle the massive amount of information transmission and exchange, signal conversion between light and electricity is necessary. The solution to achieving low-cost conversion is standardization. For example, USB is a standardized interface, and the Type C data cable for mobile phones can be purchased inexpensively because of standardization.


The optical module is the standardized conversion interface between electrical and optical signals. Since we need to convert the optical signal to the electrical signal and vice versa, from the perspective of light, this is reception and transmission respectively. The reception of light in the optical module is accomplished by the ROSA, while the transmission of light is accomplished by the TOSA. XINXIN GEM provides full-bandwidth (1250~1650 nm) TOSA and ROSA, as well as TO Can package of different wavelengths.


Since the optical module is typically required to handle both reception and transmission, it is also called an optical transceiver module. Since standardization is aimed at reducing costs, the interfaces for light and electricity need to be standardized with appropriate sizes. The external dimensions of the electrical signal also need to be standardized. The entire module's external appearance and other aspects need to be defined clearly to maximize cost reduction.


Many information in the optical module require criterion and detection. Therefore, the management channel's registers are also standardized. The meaning of each bit in which register needs to be clearly defined.


The optical module is designed to transmit signals, and aspects related to signal transmission such as encoding format, amplitude, phase, and signal quality are also defined for interoperability. Aspects related to the light signal need to be matched with the performance of the fiber optic cable and the requirements of the application scenario. In the industry, a relatively low-cost approach needs to be identified to classify wavelength-related information and unify requirements for similar products.


The core essence of the optical module is "interoperability", low cost, and standardization. However, some products may depart from this idea and become customized and non-standardized. There are two reasons for this: First, the industrial scale of the subdivision area is not large enough. For example, in the backbone network coherent module, a large percentage of them cannot be completely interoperable between multiple manufacturers. Compared to the market size of several million/billion for the access network, the total market size of some coherent optical modules is only tens of thousands or hundreds of thousands. There are not many manufacturers capable of producing coherent optical modules, and it may require lengthy discussions in the industry to achieve complete interoperability. The second reason is the competition between industries. If the products made by Manufacturer

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