Imaging represents the most direct and pervasive method by which individuals can obtain, record, and transmit information. In the contemporary era, in which a single mobile phone is ubiquitous, the traditional method of imaging is not a foreign concept to the general public. In the conventional imaging process, the light source illuminates the object, the reflected light of the object carries the information of the object into the array detector, and the array detector responds and generates an image. The term "ghost imaging" is derived from the fact that in this imaging system, the object to be imaged and the surface array detector are positioned in two distinct ways. The light emitted by the illuminated object is not incident on the array detector; rather, it is collected by the single-pixel detector, which is not spatial-resolved. Furthermore, the light incident on the array detector never directly interacts with the object. The fundamental principle underlying ghost imaging is the second-order correlation of the light source. The second-order correlation of the light source is reflected in the joint measurements of the two detectors, which means that the image of the object can only be reconstructed by the joint measurements of the two detectors and not by either of the two detectors individually.

Silicon (Si) is one of the most popular semiconductors and is used extensively in the fields of energy, photoelectronic imaging, and remote sensing owing to its abundant reserves, low cost, and compatibility with standard complementary metal-oxide-semiconductor (CMOS) technology. To meet current needs, crystalline Si with high absorption coefficients across a broad range of wavelengths and sub-bandgap photon sensitivity is required, which can potentially fulfill the rising demand for higher photovoltaic conversion efficiency in solar cells, as well as elevated photoelectric conversion efficiency in photodetectors.

Fourier transform photoacoustic spectroscopy is a spectral analysis method that integrates the broadband advantages of Fourier transform spectroscopy with the high sensitivity, background-free nature, and wavelength-independent characteristics of the photoacoustic effect. Due to its high sensitivity and versatility, Fourier transform photoacoustic spectroscopy has become a crucial tool for both qualitative and quantitative gas analysis, significantly enhancing scientific research and practical applications. In recent years, Fourier transform photoacoustic spectroscopy has garnered extensive attention from the academic community, resulting in numerous in-depth studies. However, most current research efforts have been concentrated on combining Fourier transform spectroscopy with non-resonant photoacoustic detection modules, with relatively limited exploration of its integration with resonant photoacoustic detection modules. Furthermore, research on broadband measurement, simultaneous multi-component gas detection, and full-spectrum analysis remains underdeveloped.

The optical helico-conical beams (HCBs) can be generated from a product of helical and conical phase function, which leads to a spiral intensity distribution at the focal plane when experiencing a Fourier transform. Recently, the propagation characteristics and fabrication methods of HCBs were reported. However, most of the existing manipulating work has limited flexibility. In addition, the fine structures of optical fields represented by optical vortex arrays have not been further studied in the field of helico-conical beams.