## 1 Introduction
### Aim and Scope  
Currently, there is no specific comparative review regarding the performance of these fiber optic cables based on DAS measurement and the desired output within the scope of relevant geophysics exploration. Hence, the primary objective of this review is to provide a comparative overview of the relative performance and evaluation of SMF and MMF in geophysics exploration based on VSP, reservoir monitoring, and microseismic event detection in terms of ML processing. Accordingly, this review presents a comparison of SMF and MMF in terms of acquisition factors like spatial resolution, cable deployment method, and measurement result particularly tailored to the applications. The advantages and limitations of using SMF and MMF for subsurface imaging in DAS measurement are also highlighted, as each cable type has certain advantages. The pertinent information regarding their comparative performance will help in the selection of suitable fiber optic cables for deployment in DAS data acquisition for future geophysics exploration research. The combined deployment of SMF and MMF cable for subsurface imaging is also reviewed to distinguish the utility of each cable when deployed in the same fiber optic cables. This review also aims to enhance the application of SMF and MMF in geophysics exploration when DAS data acquisition is applied for each type of fiber optic cable using an ML algorithm, as it provides the best choice in terms of improving prediction, minimizing error, and generating a high-accuracy model for geophysics exploration.  
This paper comprehensively reviews the application of fiber optic cables in DAS paradigms, assessing their effectiveness and potential for subsurface imaging over conventional geophysics exploration methods such as seismic and VSP geophone applications. The literature forming the foundation of this review was selected based on a search of various geoscience and electrical engineering academic databases, such as Geoscience World, Society of Exploration Geophysics journal, and IEEE Xplore. Accordingly, we used specific keywords, which include SMF, MMF, and specific applications in geophysics. Based on the literature search conducted for this review paper, most of the SMF and MMF geophysics applications are DAS VSP or fiber optic cables deployed along the wellbore instead of surface DAS. Therefore, most of the reviewed papers discuss DAS VSP. The innovation of enhancing the fiber optic cable data efficiency of these DAS data processing frameworks through an ML approach is also reviewed. This review also present the conclusions of our comparative study, as well as possible routes for the future development of optimized DAS data for various applications in geophysics exploration.  
Other types of fiber optic cables, like Few-Mode Fiber (FMF), are also applicable as a sensing medium in optical fiber sensing [18]. FMF cable has the advantage of having a higher nonlinear threshold level, as well as a higher capture fraction for scattered light [11]. However, FMF can have larger splicing loss compared to SMF, which can negatively impact its performance and might cause coupling between modes, which can degrade its performance in DAS systems, although it can be useful for other applications [19]. The selection of these two fiber optic cable types stems from the fact that SMF is the most utilized in DAS acquisition, whereas MMF has lower consumed costs associated with its devices and components that are installed during acquisition; furthermore, the coupling light input of MMF requires less stringent tolerances, corresponding to its distributed temperature sensing (DTS) ability [12].