Connecting a coronagraph instrument to a spectrograph via a single-mode optical fiber is a promising technique for characterizing the atmospheres of exoplanets with ground and space-based telescopes. However, due to the small separation and extreme flux ratio between planets and their host stars, instrument sensitivity will be limited by residual starlight leaking into the fiber. To minimize stellar leakage, we must control the electric field at the fiber input. Implicit electric field conjugation (iEFC) is a model-independent wavefront control (WFC) technique in contrast with classical EFC, which requires a detailed optical model of the system. We present here the concept of an iEFC-based WFC algorithm to improve stellar rejection through a single-mode fiber (SMF). As opposed to image-based iEFC, which relies on minimizing intensity in a dark hole region, our approach aims to minimize the amount of residual starlight coupling into an SMF. We present broadband simulation results demonstrating a normalized intensity ≥10−10 for both fiber-based EFC and iEFC. We find that both control algorithms exhibit similar performance for the low wavefront error (WFE) case, however, iEFC outperforms EFC by ≈100x in the high WFE regime. Having no need for an optical model, this fiber-based approach offers a promising alternative to EFC for ground and space-based telescope missions, particularly in the presence of residual WFE.

中文翻译：

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通过单模光纤的隐式电场共轭


通过单模光纤将日冕仪连接到摄谱仪是一种很有前途的技术，可以通过地面和天基望远镜来表征系外行星的大气。然而，由于行星与其主恒星之间的距离较小且通量比极端，仪器灵敏度将受到泄漏到光纤中的残余星光的限制。为了最大限度地减少恒星泄漏，我们必须控制光纤输入处的电场。隐式电场共轭 (iEFC) 是一种与模型无关的波前控制 (WFC) 技术，与传统的 EFC 不同，后者需要系统的详细光学模型。我们在此提出基于 iEFC 的 WFC 算法的概念，以通过单模光纤 (SMF) 改善恒星抑制。与基于图像的 iEFC（依赖于最小化黑洞区域中的强度）相反，我们的方法旨在最小化耦合到 SMF 中的残余星光量。我们提出的宽带模拟结果表明，基于光纤的 EFC 和 iEFC 的归一化强度均≥10−10。我们发现，两种控制算法在低波前误差 (WFE) 情况下表现出相似的性能，但是，在高 WFE 情况下，iEFC 的性能优于 EFC 约 100 倍。由于不需要光学模型，这种基于光纤的方法为地面和天基望远镜任务提供了 EFC 的有前途的替代方案，特别是在存在残余 WFE 的情况下。