Acoustic energy harvesting and modeling from distributed feedback quantum cascade laser based sensor system

This study analyzes acoustic energy harvesting from a distributed feedback quantum cascade laser (DFB-QCL)-based sensor system. The system integrates a DFB-QCL as an optical excitation source and a custom-designed photoacoustic resonator to generate and detect acoustic waves. A Cockcroft–Walton voltage multiplier (CWVM) converts the resulting electrical signal into direct current voltage. Capacitor tests for the VM are conducted under open-circuit and loaded conditions. Considering voltage conversion efficiency, mean voltage, and ripple, 22 µF capacitors are selected as optimal and used in all subsequent analyses. Experiments with up to four-stage VMs are conducted using ten load resistances. The fourth-stage VM delivers 6.4 mW of mean power under a 10 kΩ load, with an energy efficiency of 26.7%. These findings indicate the system's potential to power self-sufficient sensor networks and low-power electronic devices, especially in remote or inaccessible environments. A mathematical model is developed to describe the relationship between acoustic input, load resistance, and VM output. The model reflects the nonlinear characteristics derived from the time-domain analysis of the VM circuit and is constructed from experimental data. Its accuracy is validated using the mean squared error (MSE), root mean squared error (RMSE), and coefficient of determination (R2) metrics, yielding low error rates with R2 values ranging from 0.972 to 0.991. Mean voltage and power outputs are fitted by power series functions of load resistance, achieving goodness of fit above 99%. The high level of agreement between the fitted and modeled results demonstrates the model's reliability in representing stage-dependent system behavior.