As you can see, component companies are toward the left of the value chain. What I like is that these vendors are at least one step removed from the systems vendors, whose technologies may or may not become obsolete. It could happen. Either way, component makers sell products to everyone. That doesn't mean there isn't risk of product or technology obsolescence for component vendors, though the diversified vendors are in a pretty strong position.
Lasers are a basic component.
A laser generates the optical signal. When thinking about components, which get very technical, remember that all these parts are designed to send, manage, and receive signals. That's the Holy Grail, though I think it's a ways off. Optical to electrical to optical transitions, which optical switches often have to make, are costly and hard to manage. Fiber optics is a very complex field, and it is very hard to just run out and build a duplicate business.