Modeling resonant energy absorption of finite laser pulses in a doped porous dielectric slab

We present a model to calculate the resonant energy absorption of a laser with finite number of pulses impinging on a doped porous dielectric slab. Analytical reflection R and transmission T coefficients are first derived as a function of 0 < α ≤ 1 to account for porosity with α = 1 denotes a perfect ideal slab, which are verified using an electromagnetic solver. Based on the Drude model with resonant line due to impurities, we calculate the resonant energy absorption as a function of doping concentration, quality factor of the resonant line, porosity, length of the slab, and laser pulse length. It is important to note that simulating the combined effects of these parameters is challenging using existing models. The energy absorption efficiency is maximized for a certain degree of doping concentration at a given pulse length and also for a certain pulse length at a given doping concentration. At small doping concentration, the absorption efficiency increases with smaller α (high porosity) and the trend is reversed at larger α (low porosity). Dimensionless parameters are constructed, allowing the calculated results to be applicable over a wide range of frequencies and pulse durations. Thus, this model serves as a useful tool to characterize the amount of energy absorption due to these combined effects, which are important for many applications in plasmonics, optoelectronics, high power microwaves breakdown, and organic materials. Some possible experiments are suggested for future verification of the model.