Supplemental Material for
Observation of Spin Hall Effect in Photon Tunneling via
Weak Measurements
Xinxing Zhou1, Xiaohui Ling2, Zhiyou Zhang2, Hailu Luo1,* and Shuangchun Wen1
1
Laboratory for Spin Photonics, College of Physics and Microelectronic Science, Hunan University,
Changsha 410082, China
2
SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology, Shenzhen
University, Shenzhen 518060, China
* hailuluo@hnu.edu.cn
Contents:
(1) The initial shifts of spin Hall effect in photon tunneling
(2) Determining the size of waist radius
(3) Confirming the actual thickness of tunneling barrier
(4) The comparative experiment using only index matching fluid
(1) The initial shifts of spin Hall effect in photon tunneling
From Eqs. (6) and (7) of the main text, we can get the initial transverse shifts of spin Hall effect
(SHE) in photon tunneling. Figure S1 shows the transverse displacements changing with the incident
angle  i in the cases of H and V polarizations. We can see that the initial displacements are
restricted to a few tens of nanometers. It should be noted that the incident angle is fixed to 45 in the
potential barrier structure (in the main text). Under this condition, the initial shifts are fixed values
which only change with the thickness of potential barrier.
Fig. S1. The initial transverse shifts of photonic SHE in photon tunneling under the conditions of H
and V polarizations [(a) and (b)].
(2) Determining the size of waist radius
To obtain the accurate weak measurement experimental results, we first need to determine the
waist radius when the light beam passes through the focus lens L1. Because the distance between the
initial waist position of laser and the position of first lens L1 can greatly affect the focused waist
radius. This focused waist radius is an important reference parameter in the following experiment.
Using the ABCD law and the CCD, we can initially obtain the focused waist radius w0
27  m . In
order to make the result credible, we reexamine this result by measuring the transverse shifts induced
by the photonic SHE when a light beam reflected on an air-prism (BK7 glass) interface. Here the
polarized states are chosen as H and V and we measure the transverse displacements three times
for making the results repeatable. The experimental results, shown in Fig. S2, are in good agreement
with the theoretical cures.
Fig. S2. (a) and (b) denote the experimental results for determining the focused waist radius in the case
of H and V polarizations. Here the lines are theoretical values with waist radius w0
27  m . The
circle, square, and triangle show the experimental results.
(3) Confirming the actual thickness of tunneling barrier
Before observing the photonic SHE in photon tunneling structure, we should confirm the actual
thickness of the metal potential barrier. Here we similarly consider using the weak measurements for
detecting photonic SHE induced transverse shifts to judge the accurate thickness of the potential
barrier. We carried out the experiments for three different areas of the tunneling sample and the
incident polarized states are
H and V . The experimental results are described in Fig. S3 and we
find that the actual thickness of metal potential barrier are about 9nm, 12nm, and 16nm. Then, using
the parameter fit, we can observe the photonic SHE in this photon tunneling structure.
Fig. S3. The experimental results for determining the accurate thickness of tunneling potential barrier
in the case of H (left column) and V (right column) polarizations. The lines denote the theoretical
values. The circle, square, and triangle represent the experimental results.
(4) The comparative experiment for using only index matching fluid
In order to make the results more dependable, we need to carry out the comparative experiment
when the two BK7 prisms are put together using only the index matching fluid (without coating the Au
film). From the experimental results (shown in Fig. S4), we can clearly see that the shifts of field
centroid is nearly to zero, which indicates that there is no spin-dependent splitting in this condition.
Fig. S4. The comparative experimental results in the case of two BK7 prisms are put together without
coating the Au film. (a) and (b) show the amplified displacements when the incident beam is
horizontal and vertical polarizations. The solid lines describe the theoretical shifts in the case of
without coating the Au film. The dash lines show the comparative theoretical shifts with 12 nm
thickness Au film. Circle, square, and triangle denote the experimental results under the condition of
without coating the Au film.