Question
Can the WLD laser diode driver be externally modulated with an analog signal, if so what would be the bandwidth?
Answer
Yes, the WLD can be modulated by an external analog signal. In constant current mode the modulation bandwidth is 2 MHz.
The WLD3343 features a very fast rise time of 460 nsec, so waveforms with higher-order frequency components (such as square waves) can also be used to modulate the laser. The fall time is 320 nsec. The WLD33ND rise time is 100 nsec, and fall time is 200 nsec.
The laser can also be modulated in constant power mode. The modulation bandwidth in constant power mode will depend primarily on the frequency response of the photodiode; in our experience the constant power modulation bandwidth is lower than the constant current mode bandwidth.