Free Space
Free Space Optics (FSO) is a packaging technology that uses more traditional optical subcomponents to create, receive and transmit optical paths using the principles of geometric optics. The key components of an FSO system are the transmitting laser and receiving photodetector, but they also utilise a number of additional functional optical devices, such as reflectors, lenses, isolators, splitters and combiners.
The transmitter and receiver are typically packaged in a hermetically sealed TO can, and the challenge for FSO packaging is then to assemble and align all components in a three-dimensional space. This requires very high precision fixturing, tight processes and skilled operators, but it is a mature technology that is widely used today.