Synthesized complex-frequency waves for optical sensing and superimaging

Abstract

Both optical sensing and superimaging are based on light-matter interactions. Optical sensing plays an important role for material identification, whereas superimaging is a distinctive technique that can image features at the sub-diffraction resolution. Benefiting from the advancement of nanofabrication over the past decades, these two technologies have experienced rapid development and hold significant potential across various fields, encompassing environmental monitoring, food safety, nanolithography and high-resolution microscopy. However, the intrinsic losses severely weaken the signals of optical sensing and limit resolution and quality of superimaging, hindering their widespread applications. Synthesized complex-frequency waves (CFWs) is a novel method for loss compensation via coherent combination of multiple real-frequency responses. Compared to the other solutions such as gain materials and low-loss materials, the synthesized CFW method can be universally applied to different application scenarios without additional experimental challenges and costs, facilitating the investigation of light-matter interactions. This thesis is devoted to studying the physical mechanism and mathematical principles of the synthesized CFW method, as well as exploring its practical applications in optical sensing and superimaging. An in-depth analysis is presented to understand the synthesized CFW method and offer a complete process for improving the synthesized CFW method to mitigate the negative impact of non-ideal conditions of actual data. The CFW enhancements of molecular infrared sensing are experimentally demonstrated in different phase. The subwavelength images of a microwave superlens are restored by applying the synthesized CFW method. This thesis provides a practical solution to overcome the intrinsic losses for sensing and imaging applications.