This one has been rattling around my brain for a while.  I suspect its genesis for me was when I first read about the RONJA project, although thisproject (which was featured on hackaday previously) also contributed to my fixation.

To finally put some of my thoughts to paper, so to speak, I believe the heart of this project will be a bi-di SFP fiber module, which usually operate in the 1310nm and 1490nm wavelength range (obviously I will need a matched set for a full point to point link).

This SFP optic will fire into a beam expander and collimating lens assembly, all of which will be mounted on a servo driven 3 axis gimbal for fine adjustment.  Actual traffic over the link will be passed in and out over an SFP to SFP converter, so nothing above layer 1 will be handled on the device.

For management, I plan to use an RP2040 or ESP32 with an ethernet phy.  The management IC will sniff the I2C bus on the SFP module for RSSI information and drive the servos for fine alignment.  The management IC will also drive a window defroster and possibly an LED and photodiode for rough alignment.

A significant goal of this project will be to learn how such a system will be influenced by weather in free space and how reliable it might be for a relatively low cost.  I'm not looking to break any new ground here, but if I could use such a link as a backhaul for an AREDN node or repeater linking, I'd be thrilled.