1 research outputs found
Terahertz Phase Shift and Its Modulation in NdGaO<sub>3</sub> Single Crystals
Finding
appropriate materials to shape the terahertz (THz) wave
is highly desired due to the increasing development of practical devices
and application systems. In this work, the THz phase shifts of four
typical oxide crystals, i.e., NdGaO3 (NGO), quartz, (LaAlO3)0.3(Sr2AlTaO6)0.35, and sapphire, have been investigated by using THz time-domain spectroscopy.
It is interesting to find that the NGO crystal is the only one that
shows a distinct phase shift. The phase shift (Δφ) of
a ∼500 μm-thick NGO crystal is almost linearly dependent
on the THz frequency and it reaches as large as ∼94° at
1.5 THz with a temperature variation from 100 to 400 K. Moreover,
the THz phase shift of NGO possesses crystal anisotropy and Δφ(100)
> Δφ(001) > Δφ(110). In addition, the
effects
of both electric field and laser illumination on the THz phase shift
in the NGO crystal have also been explored. It is found that the electric
field (∼260 V/cm) has negligible effect, while the laser illumination
can efficiently cause a noticeable THz shift and Δφ ∼
78° with good manipulation stability can be achieved with 20
J/cm2 light fluence. These findings suggest that NGO crystals
are an appropriate candidate for THz phase modulator and their sensitivity
and stability are expected to have a great technological impact and
offer prospects for their applications in THz optics