This! The biggest cost is in the opto-electric transition parts. The mechanical alignment needs to be precise, it needs to have a laser, a laser driver (most l

This! The biggest cost is in the opto-electric transition parts. The mechanical alignment needs to be precise, it needs to have a laser, a laser driver (most likely VCSEL), and a photodiode with a transimpedance amplifier. It's expensive because these parts cannot be integrated with the electronic chips easily. They are also bulky. There are initatives to use crappy alignment optics and plastic optical fiber (POF) for short reach Ethernet [1] though these aren't commercially available. They don't aim for data center or consumer market but automotive and aerospace . [1] https://kd.tech/product/evb9315-sfp-optical-demo/ https://kd.tech/product/evb9315-sfp-optical-demo/