Modulating VCSELs
One of the foremost applications of VCSELs is to transmit optical signals. These signals require modulation of the VCSEL to vary its emitted power. This note provides information about VCSEL modulation that may assist in the design of optical transmitters. While many of the same principles apply to analog modulation applications, this note is aimed primarily at digital applications where data is encoded as ones and zeros, corresponding to pulses of high or low power, respectively.
The VCSEL behavior defined here is based on testing and analysis, but it must be considered typical, not assured. Some data is shown here for instruction and may not be representative of VCSELs available for sale; refer to data sheets for actual limits. Finally, while described behaviors may fit many VCSELs, they are specifically applicable to ~850-nm, proton-implanted devices intended for data communications.
