Terahertz Sensors for Industrial Automation

Tuesday, July 29, 2014

SPIE Leaders, Community Speak Out To Support Photonics R&D



Comment period provides opportunity for advocacy of new photonics manufacturing capability
Leaders of SPIE, the international society for optics and photonics, have been among those speaking out for the value of light-based technologies through the National Photonics Initiative, including in response to a request for information on a proposal for new manufacturing institutes. A photonics institute for manufacturing innovation would help ensure community safety, generate new high-value jobs, and drive economic growth, society leaders say.
A request for information on possible new manufacturing institutes focused on light-based technologies has offered a valuable opportunity for the community to speak out on how the development of new photonics-based applications benefit the economy and society, say leaders of SPIE, the international society for optics and photonics.
A comment period closed last week for a U.S. Department of Defense (DoD) Request for Information (RFI) to gather input to use in scoping focus areas for future Institutes for Manufacturing Innovation (IMI).
“We have received very positive comments in recent meetings in Washington, D.C., on the response from the photonics community. Individuals’ comments are very powerful, and taken together become an even stronger voice of advocacy for photonics,” said SPIE CEO Eugene Arthurs. “We are pleased that the National Photonics Initiative (NPI) once again has been able to help focus and amplify the efforts of individuals from all segments of the industry.”
The NPI, a collaborative alliance seeking to raise awareness of photonics and drive U.S. funding and investment in key photonics-driven fields, was launched in the wake of shrinking federal budgets for research, and on the recommendation of a 2012 National Academies’ report on optics and photonics. SPIE and The Optical Society (OSA) are Founding Sponsors, and the American Physical Society (APS), the IEEE Photonics Society, and the Laser Institute of America (LIA) are Sponsors of the coalition.
Arthurs noted that the NPI’s advocacy efforts in the U.S. resemble similar initiatives in other regions of the world that have been highly successful in promoting optics and photonics and resulting in important funding opportunities.
In the European Union, efforts by Photonics21, which represents industry and research groups and not-for-profit societies including SPIE, have helped secure photonics a place among six Key Enabling Technologies that receive priority funding for R&D. Previously, photonics had been one of 37 Technology Platforms, with less favored funding.
China, Japan, Germany, Singapore, and Belgium are among countries that have invested heavily in national photonics technology institutes, centers of excellence, and similar initiatives, and gained leadership positions in targeted markets as a result.
In Taiwan, R&D strategy has helped create annual export levels in photonics of around US$80B, more than US$3,500 per resident.
A photonics IMI would ensure defense technology leadership for the future while generating and securing jobs and innovation to drive economic growth, SPIE leaders said.
“To maintain a competitive edge requires a healthy symbiosis of science and technology with manufacturing,” Arthurs said. “This is vital to sustenance and progress for both. Knowledge diffusion, from research to manufacturing and from manufacturing to research, is crucial for ongoing innovation that results in tangible economic or social outcomes.”
“Photonics is an enabling technology used in communications, computing, healthcare, transportation, energy, and entertainment, and plays a vital part in our security and defense capabilities” said SPIE Vice President Robert Lieberman, who serves on the NPI steering committee. “For example, optical sensors, from UV through IR to terahertz, have myriad uses in the ongoing quest for the security of our communities. Sensors have multiple uses in everyday life, such as diagnosing disease, ensuring food safety, monitoring health, and ensuring safety on our streets and highways.”
Economic benefits of innovation fund more than 70% of R&D in the United States, he said, but “without the economic benefits from manufacturing, this funding withers.”
More than 300 people signed up for a webinar organized by the NPI about how to respond to the RFI, and SPIE submitted a letter emphasizing the economic impact of photonics.
In advance of the RFI, SPIE and other NPI partners presented white papers on a national photonics prototyping and advanced manufacturing facility to the Office of Science and Technology Policy and DoD officials. The NPI has also been active in promoting biophotonics, environmental sensors, and high-power laser technologies among federal policy makers in Washington, D.C.
About SPIE
SPIE is the international society for optics and photonics, a not-for-profit organization founded in 1955 to advance light-based technologies. The Society serves nearly 256,000 constituents from approximately 155 countries, offering conferences, continuing education, books, journals, and a digital library in support of interdisciplinary information exchange, professional networking, and patent precedent. SPIE provided more than $3.2M in support of education and outreach programs in 2013.
SOURCE: SPIE

Abstract-Visualization of ferroelectric domains in a hydrogen-bonded molecular crystal using emission of terahertz radiation



Using a terahertz-radiation imaging, visualizations of ferroelectric domains were made in a room-temperature organic ferroelectric, croconic acid. In as-grown crystals, observed are ferroelectricdomains with sizes larger than 50-m square, which are separated by both 180° and tail-to-taildomain walls (DWs). By applying an electric field along  axis (the polarization direction), a pair of 180° DWs is generated and an each 180° DW oppositely propagates along  axis, resulting in a single domain. By cyclic applications of electric fields, a pair of 180° DWs repeatedly emerges, while no tail-to-tail DWs appear. We discuss the usefulness of the terahertz-radiation imaging as well as the observed unique DW dynamics.

Abstract-Peculiar Bi-ion dynamics in Na1/2Bi1/2TiO3 from terahertz and microwave dielectric spectroscopy



Dynamics of the main dielectric anomaly in Na1/2Bi1/2TiO3 (NBT) was studied by time-domain THz and microwave spectroscopy, using also previously published data and their new overall fits. Above the dielectric maximum temperature Tm ~ 600 K, the response consists of coupled sub-THz oscillator and a relaxation mode, assigned to strongly anharmonic Bi-ion vibrations and hopping, whose slowing down explains the paraelectric-like permittivity increase to Tm. Below Tm, the main relaxation continues slowing down and additional relaxation, assigned to quasi-Debye losses, appears in the 10^11 Hz range. The oscillator hardens on cooling and takes over the whole oscillator strength. The permittivity decrease below Tm is caused by the reduced strength of the relaxations due to dominance of the rhombohedral phase within the coexistence region with the tetragonal phase. The anharmonic dynamics of Bi is supported by previous structural studies. NBT represents a hybrid between standard and relaxor ferroelectric behaviour.

Monday, July 28, 2014

Abstract-Plasmonic corrugated cylinder–cone terahertz probe



Haizi Yao and Shuncong Zhong  »View Author Affiliations

JOSA A, Vol. 31, Issue 8, pp. 1856-1860 (2014)
http://dx.doi.org/10.1364/JOSAA.31.001856

The spoof surface plasmon polariton (SPP) effect on the electromagnetic field distribution near the tip of a periodically corrugated metal cylinder–cone probe working at the terahertz regime was studied. We found that radially polarized terahertz radiation could be coupled effectively through a spoof SPP into a surface wave and propagated along the corrugated surface, resulting in more than 20× electric field enhancement near the tip of probe. Multiple resonances caused by the antenna effect were discussed in detail by finite element computation and theoretical analysis of dispersion relation for spoof SPP modes. Moreover, the key figures of merit such as the resonance frequency of the SPP can be flexibly tuned by modifying the geometry of the probe structure, making it attractive for application in an apertureless background-free terahertz near-field microscope.
© 2014 Optical Society of America

Sunday, July 27, 2014

Abstract-Intrinsic Josephson junctions in the iron-based multi-band superconductor (V2Sr4O6)Fe2As2



In layered superconductors, Josephson junctions may be formed within the unit cell123 as a result of sufficiently low inter-layer coupling. These intrinsic Josephson junction (iJJ) systems4 have attracted considerable interest for their application potential in quantum computing as well as efficient sources of THz radiation, closing the famous ‘THz gap’5. So far, iJJ have been demonstrated in single-band, copper-based high-Tc superconductors, mainly in Bi–Sr–Ca–Cu–O (refs 678). Here we report clear experimental evidence for iJJ behaviour in the iron-based superconductor (V2Sr4O6)Fe2As2. The intrinsic junctions are identified by periodic oscillations of the flux-flow voltage on increasing a well-aligned in-plane magnetic field9. The periodicity is explained by commensurability effects between the Josephson vortex lattice and the crystal structure, which is a hallmark signature of Josephson vortices confined into iJJ stacks1011. This finding adds the pnictide (V2Sr4O6)Fe2As2 to the copper-based iJJ materials of interest for Josephson junction applications. In particular, novel devices based on multi-band Josephson coupling may be realized.