Jiu-Sheng Li

Guest Editorial TTA Special Section on Terahertz Sources and Devices

Jiu-Sheng Li

The terahertz wave is considered to have great values and plentiful applications, such as in material science, analysis of molecular spectra, information and communication technology, biology and medical science, nondestructive evaluation, and national security. High-power widely tunable terahertz sources are required in the above practical applications of terahertz technologies. A promising approach for monochromatic terahertz generation is based on second-order nonlinear optical effect, e.g. terahertz parametric oscillation and difference frequency generation due to the low cost laser pump and wide tunablity. Recently, an amount of investigation has been made to improve the efficiency, including on the nonlinear materials as well as on the phase-matching configurations. A moderate progress has been made in the terahertz generation. Therefore, the progress in terahertz sources and detectors is turning the “terahertz gap” into one of the most rapidly growing technological fields. Furthermore, high performance active devices to control and manipulate terahertz waves are highly desired to develop the terahertz science and technology. In recent years, devices based on photonic crystals, metamaterial, and plasmonic structures have been extensively investigated in the terahertz regime, which have been proved both theoretically and experimentally an effective way to transmit as well as control terahertz waves.

In the first paper, some tunable terahertz generators based on nonlinear optical frequency conversion technology, including high power and high efficiency surface-emitted TPO, DFG with organic DSTMS nonlinear crystals, and Cherenkov phase-matching in both bulk crystals were developed. A high power nanosecond pulsed terahertz wave source was realized based on intracavity surface-emitted TPO. The maximum terahertz wave output energy of 283 nJ/pulse was obtained at 1.54 THz under an intracavity 1064 nm pump energy of 59 mJ. A continuously tunable range from 0.75 THz to 2.75 THz was realized. The high energy of Cherenkov type monochromatic vity surface-emitted TPO was designed. The maximum terahertz generation was achieved to be 1.58 nJ/pulse. The tunable range of vity surface-emitted TPO was demonstrated. The maximum terahertz source was 0.1 THz to 3.2 THz. Widely tunable and monochromatic terahertz wave generation via DFG in home-made organic crystals DSTMS was achieved. A line-width around 42.7 GHz was obtained by using a double-pass OPO. The highest output energy of 85.3 nJ/pulse was achieved at 3.80 THz with pump energy of 2.47 mJ. The corresponding peak power was estimated to be 17.9 W and the photon conversion efficiency was 3.6‰.

In the second paper, terahertz functional devices were demonstrated by using artificial microstructures such as photonic crystals, metamaterial, and plasmonic structures. For terahertz modulators, two important device structures for terahertz wave modulation mechanisms were demonstrated: one was the phase-transition photonic crystals and the other was the metal-semiconductor plasmonic waveguide. Then two terahertz sensors were reported, one was terahertz microfluidic sensing based on the guided resonance effect in terahertz photonic crystals pillar array and the other was a terahertz stress sensing based on the flexible terahertz metamaterials. At last, four different terahertz microstructure magneto optical devices were demonstrated by utilizing terahertz photonic crystals and plasmonic structure with different terahertz magnetooptical materials, which have important functions of nonreciprocal transmission as a terahertz isolator and magnetically controlled terahertz wave modulation. These terahertz microstructure functional devices exhibit great promising potential in terahertz application systems.

As the guest editor of this issue, I would like to thank the authors for their contributions to this special section. I also appreciate the assistance of the editorial staffs for their great efforts on making this special section to be pressed in time.

Jiu-Sheng Li,Guest EditorChina Jiliang University Hangzhou, China

Jiu-Sheng Li received his B.S., M.S., and Ph.D. degrees from Tianjin University in 1997, 2001, and 2004, respectively. He is currently a professor with the Centre for THz Research, China Jiliang University. His research interests include devices for terahertz wave manipulation, metamaterials, and photonic crystals.

Digital Object Identifier: 10.3969/j.issn.1674-862X.2014.04.007