Highly Sensitive Magnetic Field Detection in Infrared Region With Photonic Spin Hall Effect in Silicon Waveguide Plasmonic Sensor

In this work, we propose and analyze a plasmonic sensor with a three-layer waveguide structure. We consider the transverse spin-dependent shift (SDS) of the horizontal photonic spin Hall effect (PSHE) in the waveguide at a given wavelength (1557 nm) for a TM (transverse magnetic or p-polarized) mode. The sensor structure is analyzed in two ways. First, under the normal methods, that is, angular and intensity interrogation methods, for which the results indicate that the maximum figure of merit (FOM) of 4007.0 RIU
⁻¹
is attained for an optimum thickness (
$d_{2}=51$
nm) of the gold layer and this FOM is significantly greater than the corresponding FOM (413.7 RIU
⁻¹
) reported earlier (for a 50 nm thick gold layer). Also, the average sensitivity increases from 0.0005 to 0.002°/Oe when the volume fraction of Fe
₃
O
₄
particles (
$c$
) in the magnetic fluid is increased from 1.48% to 1.93%. Correspondingly, a considerably finer value of the resolution (0.046 Oe) is obtained when the volume fraction is increased to 1.93% (compared to 0.199 Oe at 1.48%). Second way is the proposed method of PSHE, for which the analysis indicates that transverse SDS of the horizontal PSHE is the maximum for
$d_{2} = 51$
nm leads to the maximum sensitivity
$6.25 \times 10^{7}~\mu$
m/RIU for an amplified angle
$\Delta = 0.1^{\circ}$
and
$1.09 \times 10^{6}~\mu$
m/RIU for
$\Delta = 0.1$
rad in the conventional weak measurements. The corresponding finest possible resolution of magnetic field detection at 1.93% is
$1.5 \times 10^{-6}$
Oe in the conventional weak measurements for
$\Delta = 0.1^{\circ}$
and
$7.8 \times 10^{-8}$
Oe in the modified weak measurements for
$\Delta = 0.5$
rad, which are significantly finer than those existing in the related state of the art. The above resolution is also superior to those found under normal methods mentioned earlier. Furthermore, the effect of temperature (24.3 °C–60 °C) on PSHE-based magnetic field sensor’s performance is also analyzed which indicates that the proposed PSHE-based magnetic field sensor should be operated in a thermally controlled milieu.