A flexible and scalable, fully software-based lock-in amplifier for nonlinear spectroscopy

We demonstrate a cost-effective, fully software-based lock-in amplifier (LIA) implemented on a commercial computer. The device is designed for application in nonlinear spectroscopy, such as transient absorption and coherent multidimensional spectroscopy, but may also be used in any other application. The performance of our device is compared to a state-of-the-art commercial LIA with nearly identical results for both devices. Advantages of our device over commercial hardwired electronic LIAs are the improved flexibility in the data analysis and the possibility of arbitrary up-scaling of the number of LIA channels.