Optical devices packaged in TO are commonly referred to as coaxial devices. In active optical devices, coaxial devices mainly include coaxial optical transmission devices and coaxial optical reception devices.
Coaxial optical transmission devices are mainly composed of TO-CAN, couplers, interface parts, etc. Among them, TO-CAN is the main core component. TO-CAN packaging mainly connects the laser core, backlight detection tube, and heat sink, and achieves interconnection with the outside world through bonding. TO-CAN must undergo sealing treatment. Coaxial optical receiving devices are mainly composed of TO-CAN, couplers, interface parts, etc.
TO-CAN is the main core component. TO-CAN coaxial package: Its outer shell is usually cylindrical, and it integrates detectors (PIN or APD) and preamplifiers inside. It is interconnected with the outside world through bonding and must be sealed. Then connect and fix it together with metal casing, lens, tail fiber and other components. Due to its small size, it is difficult to have built-in cooling and heat dissipation, and cannot achieve high power output under high current, making it difficult to use for long-distance transmission. At present, its main application is still short-range transmission at 2.5Gbit/s and 10Gbit/s. But its cost is low and the process is simple.
Currently, coaxial devices dominate the mainstream optical device market due to their ease of manufacturing and cost advantages. The TO packaging has also made significant progress in terms of size. The conventional specifications for TO packaged devices mainly include TO56, TO46, TO52, TO38, TO85, and TO65.