---------------------------------------------------------------------- Report of Referee A -- LP18648/Yeo ---------------------------------------------------------------------- This manuscript aims at generating high-brightness bunched light with intensity modulation on the nanosecond timescale. The authors realize random interference of laser light using cascaded asymmetric Mach–Zehnder interferometers and report the generation of high-brightness bunched light. In contrast to the widely used rotating ground-glass approach, the present scheme exploits the temporal degree of freedom, thereby suppressing scattering and, in principle, reducing losses. Using a fiber-based cascaded interferometric setup, the authors successfully demonstrate the generation of high-brightness bunched light. The experimental results are clearly presented. This work represents a clear experimental advance in techniques for generating bunched light. In particular, the use of cascaded asymmetric Mach–Zehnder interferometers while suppressing scattering and achieving high brightness is noteworthy. The proposed method is relatively simple in design, and the experimental results are convincing. On the other hand, from a physical standpoint, the level of conceptual novelty appears limited. The generation of bunched light via random interference is already a well-established mechanism. The present work can therefore be regarded primarily as a technical implementation of this mechanism using an interferometric architecture. While the reported results are experimentally significant, it is difficult to conclude that the manuscript introduces new physical concepts, deeper understanding, or fundamentally new interpretations regarding optical statistics or correlation physics. The standard for publication in Physical Review Letters generally requires a physical breakthrough or conceptual advance beyond incremental technical improvement. Although the technical execution of this work is strong, its physical impact may not fully meet that threshold. Major Comment Clarification of Physical Novelty The central mechanism of this study (generation of bunching through random interference of coherent light) is based on well-established principles. The authors should clarify more explicitly whether the present approach provides physical insight beyond an implementation-level improvement over existing methods such as rotating ground-glass schemes. In particular, it would be important to delineate whether the proposed configuration leads to new physics, or whether its contribution is primarily technical in nature. At present, the manuscript does not demonstrate access to previously unattainable statistical regimes or fundamentally new photon-correlation behavior. The suppression of scattering and enhancement of brightness represent meaningful engineering progress, but the underlying photon statistics remain governed by established interference physics. Applied Relevance and Claimed Bottlenecks In the abstract, the authors state that existing photon-bunching light sources have failed to realize some application proposals due to either excessively short coherence times or insufficient brightness. However, the paper does not provide sufficient discussion in the introduction or discussion sections to substantiate that these factors actually constitute the primary bottlenecks for sensing applications. Furthermore, the abstract mentions potential applications such as clock synchronization and non-line-of-sight imaging. However, no specific references or quantitative performance analysis are provided. Historical Context and Literature Coverage Photon-bunching research spans several decades, with substantial foundational work carried out in the 20th century. The manuscript cites relatively few of these earlier studies. Given the long history of intensity-correlation research, a more comprehensive discussion of prior work would help clarify the technical and conceptual position of the present study. In summary, this study demonstrates technically important advance. However, in terms of conceptual novelty and broad physical impact, it does not appear to fully satisfy the typical criteria for publication in Physical Review Letters. I therefore do not recommend publication in this journal. That said, the work exhibits practical significance, and it would constitute a valuable contribution to a specialized journal such as Physical Review Applied.