Recent theoretical and experimental advances have shed light on the existence of so-called `perfectly transmitting' wavefronts with transmission coefficients close to 1 in strongly backscattering random media. These perfectly transmitting eigen-wavefronts can be synthesized by spatial amplitude and phase modulation. Here, we consider the problem of transmission enhancement using phase-only modulated wavefronts. We develop physically realizable iterative and non-iterative algorithms for increasing the transmission through such random media using backscatter analysis. We theoretically show that, despite the phase-only modulation constraint, the non-iterative algorithms will achieve at least about 25$π$% or about 78.5% transmission assuming there is at least one perfectly transmitting eigen-wavefront and that the singular vectors of the transmission matrix obey a maximum entropy principle so that they are isotropically random.
We numerically analyze the limits of phase-only modulated transmission in 2-D with fully spectrally accurate simulators and provide rigorous numerical evidence confirming our theoretical prediction in random media with periodic boundary conditions that is composed of hundreds of thousands of non-absorbing scatterers. We show via numerical simulations that the iterative algorithms we have developed converge rapidly, yielding highly transmitting wavefronts using relatively few measurements of the backscatter field. Specifically, the best performing iterative algorithm yields approx 70% transmission using just 15-20 measurements in the regime where the non-iterative algorithms yield approximately 78.5% transmission but require measuring the entire modal reflection matrix.
Making the unmodulated pyramid wavefront sensor smart II. First on-sky demonstration of extreme adaptive optics with deep learning
Leiden Observatory, Leiden University（莱顿大学莱顿天文台）；Center for Computational Astrophysics, Flatiron Institute（弗拉铁隆研究所计算天体物理中心）；Wyant College of Optical Sciences, The University of Arizona（亚利桑那大学怀恩特光学科学学院）；Subaru Telescope, National Observatory of Japan, National Institutes of Natural Sciences（日本自然科学研究机构国立天文台昴星团望远镜）；Astrobiology Center, National Institutes of Natural Sciences（日本自然科学研究机构天体生物学中心）；Northrop Grumman Corporation（诺斯罗普·格鲁曼公司）；Draper Laboratory（德雷珀实验室）；Starfire Optical Range（星火光学靶场）
