Application Of Terahertz Spectroscopy Research Articles

Terahertz TDS signal de-noising using wavelet shrinkage

The field of terahertz (THz) science and technology has achieved significant progress over the last decades. Research interest focuses on THz spectroscopy and imaging. The signal-to-noise ratio (SNR) of the THz system is of great importance in the application of THz spectroscopy and imaging. In this letter, the wavelet de-noising technology is used to improve SNR and increase the speed of the THz time-domain spectroscopy system by reducing the repeating times.

Application of Terahertz Spectroscopy and Imaging

We examined the feasibility of Terahertz time-domain spectroscopy (THz-TDS) using a 4-mm-thick quartz crystal to extract the angle of rotation of THz radiation polarization induced by a two-color laser in air plasma. We also used the THz-TDS technique to identify explosives and melamine in mixtures. In addition, we presented a new opto-mechanical scanner for security applications using the method of passive THz imaging

Terahertz response of acoustically driven optical phonons

The manipulation of TO-phonon polaritons and the terahertz (THz) light field associated with them by means of an ultra-sound acoustic wave is proposed and illustrated by calculating the TO-phonon-mediated THz response of acoustically-pumped CuCl and TlCl crystals. We show the high-contrast acoustically-induced change of the THz reflectivity alongside with multiple THz Bragg replicas, which are associated with the infrared-active TO-phonon resonance driven by the ultrasonic wave. The effect, which stems from phonon anharmonicity, refers to an operating acoustic intensity I_ac ~ 1-100 kW/cm^2 and frequency nu_ac ~ 0.1 - 1 GHz, with possible applications in THz spectroscopy.

Linearly tapered slotline antenna array for quasi‐optical molecular spectroscopy

AbstractIn this article, a novel design of a millimeter‐wave antenna array consisting of linearly tapered slotline antenna elements is presented. The antenna array was designed for the frequency range from 50 to 600 GHz. A numerical model of the antenna array was developed in CST microwave studio. To optimize the antenna model, a novel real‐coded genetic algorithm was proposed. The optimized antenna was fabricated from a low‐loss dielectric substrate ARLON CuClad 217, and its parameters were experimentally verified. The antenna was designed for quasi‐optical terahertz spectroscopy applications. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1043–1046, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25110

Characterization of continuous-wave terahertz sources: laser mixing versus backward-wave oscillators

The tunable, continuous-wave terahertz (THz) radiation generated by mixing of two near-infrared laser lines in an antenna-coupled photomixer is compared with the monochromatic beam of backward-wave oscillators. The electromagnetic radiation of the different THz sources is characterized with respect to intensity, linewidth, degree of linear polarization, angular characteristic, beam quality, and M(2) value. The results are discussed with respect to applications in THz spectroscopy and imaging.

Integrated diffractive terahertz elements

Femtosecond laser machining with high-energy pulses is used for fabrication of diffractive elements in LiNbO3 crystalline samples. This permits terahertz generation, frequency dispersion, detection, and analysis within a single integrated platform that is well suited for applications in terahertz spectroscopy or signal processing.

Terahertz polariton propagation in patterned materials.

Generation and control of pulsed terahertz-frequency radiation have received extensive attention, with applications in terahertz spectroscopy, imaging and ultrahigh-bandwidth electro-optic signal processing. Terahertz 'polaritonics', in which terahertz lattice waves called phonon-polaritons are generated, manipulated and visualized with femtosecond optical pulses, offers prospects for an integrated solid-state platform for terahertz signal generation and guidance. Here, we extend terahertz polaritonics methods to patterned structures. We demonstrate femtosecond laser fabrication of polaritonic waveguide structures in lithium tantalate and lithium niobate crystals, and illustrate polariton focusing into, and propagation within, the fabricated waveguide structures. We also demonstrate a 90 degrees turn within a structure consisting of two waveguides and a reflecting face, as well as a structure consisting of splitting and recombining elements that can be used as a terahertz Mach-Zehnder interferometer. The structures permit integrated terahertz signal generation, propagation through waveguide-based devices, and readout within a single solid-state platform.

Free-space coherent broadband terahertz time-domainspectroscopy

This paper reports on a free-space broadband terahertz (THz)spectroscopy technique with frequency ranging from 30 GHz to over 40 THz. Ahistorical review is given on the development of THz spectroscopy and itsunique features. We focus on a time-domain detection technique usingfree-space electro-optic sampling. This broadband THz spectroscopy techniqueopens the door to many interesting applications. We present some recentdevelopments in applications of THz spectroscopy, including characterizationof the optical properties of materials, study of the dynamics of phonon andphotocarriers and THz imaging. This THz time-domain technique continues toattract interest in both fundamental research and real-world applications.