There has been a lot of technological progress, but the sector remains a niche one. Many new THz sources have been built and improved, including coherent source

There has been a lot of technological progress, but the sector remains a niche one. Many new THz sources have been built and improved, including coherent sources like the QCLs mentioned. Microantennas may play a big role in the future, and now there are technologies to build them. Optics and detection have also improved. THz equipment still remains expensive, demanding, fragile, and scientific, although much improved from 15 years ago and with many more people working in this field. It's even being considered for 6G communications by some [1] [2] but I do not think this is realistic given the state of technology and optical technologies will probably 'win' [1] https://opg.optica.org/abstract.cfm?uri=OFC-2022-M3C.6 https://opg.optica.org/abstract.cfm?uri=OFC-2022-M3C.6 [2] https://en.wikipedia.org/wiki/6G_(network) https://en.wikipedia.org/wiki/6G_(network)