Colossal Optical Anisotropy from Atomic‐Scale Modulations
Abstract
Materials with large birefringence (Δn, where n is the refractive index) are sought after for polarization control (e.g., in wave plates, polarizing beam splitters, etc.), nonlinear optics, micromanipulation, and as a platform for unconventional light–matter coupling, such as hyperbolic phonon polaritons. Layered 2D materials can feature some of the largest optical anisotropy; however, their use in most optical systems is limited because their optical axis is out of the plane of the layers and the layers are weakly attached. This work demonstrates that a bulk crystal with subtle periodic modulations in its structure—Sr9/8TiS3—is transparent and positive‐uniaxial, with extraordinary index ne = 4.5 and ordinary index no = 2.4 in the mid‐ to far‐infrared. The excess Sr, compared to stoichiometric SrTiS3, results in the formation of TiS6 trigonal‐prismatic units that break the chains of face‐sharing TiS6 octahedra in SrTiS3 into periodic blocks of five TiS6 octahedral units. The additional electrons introduced by the excess Sr form highly oriented electron clouds, which selectively boost the extraordinary index ne and result in record birefringence (Δn > 2.1 with low loss). The connection between subtle structural modulations and large changes in refractive index suggests new categories of anisotropic materials and also tunable optical materials with large refractive‐index modulation.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Sep 20, 2023
- Source ID
- 10.1002/adma.202303588
Entities
People
- Arashdeep S. Thind
- Boyang Zhao
- Bryan C Chakoumakos
- Chenghao Wan
- Graham Joe
- Guodong Ren
- Gwan Yeong Jung
- Hongyan Mei
- Huandong Chen
- Jad Salman
- Jayakanth Ravichandran
- John Cavin
- Jordan A Hachtel
- Miaofang Chi
- Mikhail A Kats
- Nick Settineri
- Rohan Mishra
- Shantanu Singh
- Shanyuan Niu
- Simon J. Teat
Organizations
- Air Force Office of Scientific Research
- Army Research Office
- Lawrence Berkeley National Laboratory
- National Science Foundation
- Oak Ridge National Laboratory
- Office of Naval Research
- University of Southern California
- University of Wisconsin–Madison
- Washington University in St. Louis