This is quite a cool paper. I haven't read the full thing yet, but any talk of displays is EXTREMELY premature. This isn't even one pixel- it's steerable in only one direction. In order to steer in two directions, you'd need to stack up hundreds of these. That would give you a pixel... one that's at least a millimeter wide, or 10x wider than a color block on the screen I'm typing this into. Certainly it would be incredibly expensive to make an entire display out of this.

It's even pretty premature for lidar- for safety reasons lidar is in the infrared, usually around 1 micron wavelength, which makes a big difference in terms of manufacturability and price. One of the biggest problems for solid state lidar is the beamwidth, which can be a couple degrees or even >10 degrees in some cases. This is .17 degrees, which is a fantastic result, but still quite large compared to conventional lidar. Top end lidar has angular resolution below .1 degrees and you can integrate data over time to find edges as sharp as the beamspot, which can give you some really insane precision. If we used this system, the intense blur over the spot would require deconvolution and strongly limit precision.

Back of the envelope math: at .75 m (2.5'), .17 degrees between pixels would give you ~2.25 mm pixel pitch. Even at that distance, the blurring will be intense- the middle picture here[1] is semi-accurate. Obviously fidelity wasn't the goal and this doesn't represent the limits of the technology! Don't give up hope. Just expect to see someone demonstrate something that exceeds the requirement for fidelity before it actually gets made into a consumer product.

This paper has similar results to an MIT paper[2], but with 3x higher wavelength. Naturally, 3x higher wavelength way more than 3x harder. This device is also smaller- the MIT device is ~1 mm by .1 mm vs. ~1 mm by ~10 nm. That's mostly due to the fact that the MIT device can steer in two directions- the first direction works with phase shifters just like this device, but the second direction works by heating up the emitters so that they change size (genius).

The device here basically just pipes laser light out through the side of the wafer, which syncs up excellently with the MIT approach. MIT used very long (500 micron) antennas that have a thin-thick-thin wavy pattern[3]; at each wide part (IIRC) refraction causes light to escape at a particular angle. Changing the length of the wide parts changes the resonance of the light inside and therefor the angle light escapes at, and that's how they did beamforming. Normally this would require atomically-perfect manufacturing, but the long antenna averages errors out (although you still end up with just under 1 degree of beamwidth). With a suitable intermediate layer you might be able to plug this work into the MIT antennas and get full steering without needing to stack arrays.

This is all way better than current commercial solid state lidars, which mostly use rectangular patch antennas to project lasers. The optical properties of those systems are really bad. It's a shame there isn't more money in research like this, because it's necessary to make that final jump.

[1]:
https://en.wikipedia.org/wiki/Gaussian_blur#/media/File:Capp...

[2]: https://www.researchgate.net/publication/320235900_Coherent_...

[3]: https://spectrum.ieee.org/image/Mjc5NjU5MA.jpeg