According to a paper published in ACS Applied Electronic Materials recently, a collaborated research group of HFIPS successfully developed an active terahertz phase modulator of NdGaO3(NGO) single crystals which were appropriate candidate for the THz phase modulator.
Finding appropriate materials to shape the terahertz (THz) wave is not only highly desired, but also a challenge that limits the engineering application of terahertz technology.
In this research, scientists found that NdGaO3 crystals showed distinct terahertz phase shifts. When the temperature of NGO single crystals increased from 100 to 400 K, the THz phase shift would reach ～94°.
In addition, the terahertz phase shift of the NGO crystal was sensitive to the crystal orientation. Phase shifts for each crystal orientation showed a linearly proportional relationship.
With the help of optical control, the team achieved active modulation of the terahertz phase: the laser illumination could efficiently caused a noticeable terahertz shift. Terahertz shift～ 78° with good manipulation stability could be achieved with 20 J/cm2 light fluence. By changing the light fluence, the multi-state terahertz phase shift can be achieved.
Their sensitivity, and stability of the NGO crystals were expected to have a great technological impact and offer prospects for their applications in THz optics, according to the team.
Figure a) Schematic diagram of THz modulation experiment. b) Phase shift as a function of terahertz frequency and light switch. (Image by XU Jinyi)