Fourier transform study of the complex electric field induced on axially heterostructured nanowires

: We present in this work a study of the effect of Raman enhancement on axially heterostructured semiconductor nanowires (NWs). The investigation is motivated by the recent detection of a Raman signal enhancement effect at the heterojunction (HJ) of axially heterostructured NWs. Semiconductor NWs offer very interesting properties as compared to their bulk counterparts, making them the building blocks of future optoelectronic nanodevices. The use of HJs turns out to be essential for a great variety of devices. As a result, understanding the optical properties of heterostructured NWs is a fundamental step for their possible application on future technologies. In order to unveil the underlying physics of the light/NW interaction, the complex-valued electromagnetic (EM) field distribution induced inside heterostructured NWs under light exposure is studied. The use of the Fourier transform is presented as a key tool in order to ascertain the different components of the EM field generated inside the NW. The results show the presence of two components: one associated with the incident light beam and a second one which appears as a consequence of the presence of the axial HJ. This second component explains the emergence of the Raman enhancement effect as a result of the interaction of the incident beam with the dielectric discontinuity associated with the HJ.