Unveiling the intricacies of nonlinear third-harmonic generation within a hyperstructure

In this paper, the propagation characteristics of fundamental and third harmonic waves within the designed hyperstructure are examined using the transfer matrix method. At the same time, the efficiency of third harmonic generation is quantified. The transfer matrix method provides a framework that takes into account the interference phenomena and multiple reflections occurring within each layer, thereby facilitating a precise emulation of the generation and propagation dynamics of the harmonic wave field within the hyperstructure. Moreover, the conspicuous phenomenon of strong field localization, coupled with the lower group delay observed at the edges of the photonic band gap, confers an augmented response time on the process of third harmonic conversion. Consequently, electromagnetic waves situated in close proximity to the band-gap edge experience a heightened conversion efficiency. Comparatively, when juxtaposed against those designed in the other works hinged on conventional quasiphase matching techniques and endowed with similar lengths, the distinctive advantages offered by layered periodic structures manifest in their propensity to establish more precise phase matching conditions and yield higher conversion efficiencies. The crucial role played by third harmonic generation in advancing optical imaging, spectroscopy, biomedical applications, and laser technology is due to its distinct optical characteristics and energy conversion capabilities.