how to drive a VCSEL?
Driving a VCSEL (or other laser diode) can be done with no IC at all. The circuit can be as simple as a bias tee:







simulate this circuit &ndash; Schematic created using CircuitLab

What the Maxim chip does is reduce cost by eliminating the inductor from the circuit, and gives a way to adjust the bias and modulation currents programmatically (with external digitally adjustable resistors). It also provides feedback features that enable building a standard fiber optic transceiver module (such as an SFP module), and a shutdown pin that would be helpful for designing a product with eye safety requirements.