Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spatial light modulation at the nanosecond scale with an atomically thin
  reflector   Techniques to mold the flow of light on subwavelength scales enable
fundamentally new optical systems and device applications. The realization of
programmable, active optical systems with fast, tunable components is among the
outstanding challenges in the field. Here, we experimentally demonstrate a
few-pixel beam steering device based on electrostatic gate control of excitons
in an atomically thin semiconductor with strong light-matter interactions. By
combining the high reflectivity of a MoSe$_2$ monolayer with a graphene
split-gate geometry, we shape the wavefront phase profile to achieve
continuously tunable beam deflection with a range of 10{\deg}, two-dimensional
beam steering, and switching times down to 1.6 nanoseconds. Our approach opens
the door for a new class of atomically thin optical systems, such as rapidly
switchable beam arrays and quantum metasurfaces operating at their fundamental
thickness limit.

1
The categories of this paper are: cs
18
The categories of this paper are: econ
29
The categories of this paper are: funct-an
8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn
25
The categories of this paper are: patt-sol
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
6
The categories of this paper are: astro-ph
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
7
The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
26
The categories of this paper are: bayes-an
31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat