title: Ultrathin broadband nearly perfect absorber with symmetrical coherent illumination.
abstract: As highlighted by recent articles [Phys. Rev. Lett. 105, 053901 (2010) and Science 331, 889-892 (2011)], the coherent control of narrowband perfect absorption in intrinsic silicon slab has attracted much attention. In this paper, we demonstrate that broadband coherent perfect absorber (CPA) can be achieved by heavily doping an ultrathin silicon film. Two distinct perfect absorption regimes are derived with extremely broad and moderately narrow bandwidth under symmetrical coherent illumination. The large enhancement of bandwidth may open up new avenues for broadband applications. Subsequently, interferometric method is used to control the absorption coherently with extremely large contrast between the maximum and minimum absorptance. Compared with the results in literatures, the thin film CPAs proposed here show much more flexibility in both operation frequency and bandwidth.
authors.affiliation: State Key Laboratory of Optical Technologies for Microfabrication, Institute of Optics and Electronics, Chinese Academy of Science, P.O.box 350, Chengdu 610209, China.
authors.forename: Mingbo
authors.initials: M
authors.lastname: Pu
authors.forename: Qin
authors.initials: Q
authors.lastname: Feng
authors.forename: Min
authors.initials: M
authors.lastname: Wang
authors.forename: Chenggang
authors.initials: C
authors.lastname: Hu
authors.forename: Cheng
authors.initials: C
authors.lastname: Huang
authors.forename: Xiaoliang
authors.initials: X
authors.lastname: Ma
authors.forename: Zeyu
authors.initials: Z
authors.lastname: Zhao
authors.forename: Changtao
authors.initials: C
authors.lastname: Wang
authors.forename: Xiangang
authors.initials: X
authors.lastname: Luo
mesh_terms: D000042:Absorption; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008027:Light; D008029:Lighting / Q000295:instrumentation*; D008567:Membranes, Artificial; D012825:Silicon / Q000737:chemistry*; D020349:Surface Plasmon Resonance / Q000295:instrumentation*
chemical_list: D008567:Membranes, Artificial; D012825:Silicon