Hard to tell but they are likely couplers for light from the lasers and electrical interconnects you can sort of see some grating at the ends. The 4x ones are likely for 4x laser assemblies like in QSFP (Quad) or for cases where you want to TX rx over multiple fibers.

The bright cubes are the laser chips that are bonded on top of the quartz, since native silicon lasers aren't practical.

That whole illustration looks like a bunch of chips in a wafer maybe with testing and monitoring patterns included.

Looks like some other stuff like modulators in the top right of the square. Maybe a test run for process control?

Edit: yeah the cubes are definitely laser dies, fig 2 shows the process. The patterns are the couplers and such to get the light in without losses and at the right direction.