Simple, low-noise piezo driver with feed-forward for broad tuning of external cavity diode lasers

We present an inexpensive, low-noise ($<260~\mu$V$_{rms}$, 0.1~Hz - 100~kHz) design for a piezo driver suitable for frequency tuning of external-cavity diode lasers. This simple driver improves upon many commercially available drivers by incorporating circuitry to produce a `feed-forward' signal appropriate for making simultaneous adjustments to the piezo voltage and laser current, enabling dramatic improvements in mode-hop-free laser frequency tuning range. We present the theory behind our driver's operation, characterize its output noise, and demonstrate its use in absorption spectroscopy on the rubidium D$_1$ line.