How a modulator works.
No physics degree needed. Scroll, and the diagram follows along one step at a time.
Start with steady light.
A laser shines a constant beam into the chip. On its own, steady light carries no information. It's a blank page.
Split it in two.
Inside the chip, the light travels through a waveguide, a microscopic "wire" for light. The path splits into two arms. This layout is called a Mach-Zehnder modulator.
Add voltage to one arm.
One arm runs through electro-optic polymer with electrodes on either side. When voltage is applied, the polymer changes how fast light moves through it, slightly delaying that arm's light.
Recombine: bright or dark.
When the arms rejoin, light that's in step adds up (bright = 1). Light that's out of step cancels (dark = 0). Flip the voltage and you flip the bit.
Now do it billions of times a second.
Modern links use PAM4: four brightness levels instead of two, so every symbol carries two bits. Push the symbol rate high enough and one lane carries 200G or 400G.
Why the material matters.
The stronger a material reacts to voltage, the less voltage and length you need. LWLG's polymers react strongly and switch fast. That points to faster links, lower power and smaller chips than older materials. Compare the materials →