44
3 Rotatable-Polarisation Terahertz Time-Domain Spectroscopy of Anisotropic Media
by stretching a metal wires over a frame, or they can be fabricated on a substrate by
photolithography processes [9].
3.1.2.2 Methods of Terahertz Polarimetry
Static or continuously rotatable WGPs may be used to determine the polarisation
state of THz radiation [6, 10, 11], without requiring the direct detection of orthogonal
components of the THz electric field using a polarisation-resolved detector. Terahertz
polarimetry methods using static WGPs [10, 11] often make use of a geometry such
as that shown in Fig. 3.1. The generated THz radiation is passed through an initial
WGP (WGP 1 in Fig. 3.1) to define a linear polarisation state for the THz pulse
incident on the sample, i.e. along the y axis in Fig. 3.1. WGP 3 is used to project
the THz polarisation state back for efficient detection. After propagation through
the sample, a second WGP is placed in the beam, typically at angles of ±45
◦ to
WGP 3. Then either the polarisation state of the THz radiation incident on WGP 2
can be reconstructed, or optical properties of the sample under investigation can be
obtained, from a number of different time-domain projections obtained with WGP 2
oriented at different angles [11, 12].
A similar method of THz polarimetry replaces the static WGP 2 in Fig. 3.1 with a
WGP rotated at a constant frequency, demonstrated at ω ∼ 80 Hz in reference [6]. In
Sample
WGP1
WGP2
(at ± 45
o )
WGP3
Input
radiation
Polarisation
state
Fig. 3.1 Schematic configuration of a polarisation-sensitive detection method utilising static wiregrid polarisers
3 Rotatable-Polarisation Terahertz Time-Domain Spectroscopy of Anisotropic Media
by stretching a metal wires over a frame, or they can be fabricated on a substrate by
photolithography processes [9].
3.1.2.2 Methods of Terahertz Polarimetry
Static or continuously rotatable WGPs may be used to determine the polarisation
state of THz radiation [6, 10, 11], without requiring the direct detection of orthogonal
components of the THz electric field using a polarisation-resolved detector. Terahertz
polarimetry methods using static WGPs [10, 11] often make use of a geometry such
as that shown in Fig. 3.1. The generated THz radiation is passed through an initial
WGP (WGP 1 in Fig. 3.1) to define a linear polarisation state for the THz pulse
incident on the sample, i.e. along the y axis in Fig. 3.1. WGP 3 is used to project
the THz polarisation state back for efficient detection. After propagation through
the sample, a second WGP is placed in the beam, typically at angles of ±45
◦ to
WGP 3. Then either the polarisation state of the THz radiation incident on WGP 2
can be reconstructed, or optical properties of the sample under investigation can be
obtained, from a number of different time-domain projections obtained with WGP 2
oriented at different angles [11, 12].
A similar method of THz polarimetry replaces the static WGP 2 in Fig. 3.1 with a
WGP rotated at a constant frequency, demonstrated at ω ∼ 80 Hz in reference [6]. In
Sample
WGP1
WGP2
(at ± 45
o )
WGP3
Input
radiation
Polarisation
state
Fig. 3.1 Schematic configuration of a polarisation-sensitive detection method utilising static wiregrid polarisers