The Review of Laser Engineering

Preface to Terahertz Wave Optoelectronics

Kiyomi SAKAI

2005 Volume 33 Issue 12 Pages 812-813
Published: December 15, 2005
Released on J-STAGE: March 26, 2014

DOIhttps://doi.org/10.2184/lsj.33.812

JOURNAL FREE ACCESS

Download PDF (297K)
Future Prospect of Terahertz Technology

Masayoshi TONOUCHI

2005 Volume 33 Issue 12 Pages 814-818
Published: December 15, 2005
Released on J-STAGE: March 26, 2014

DOIhttps://doi.org/10.2184/lsj.33.814

JOURNAL FREE ACCESS

Show abstractHide abstract

Terahertz (THz) technology is becoming increasingly important in both science and technology. THz timedomain spectroscopy (THz-TDS) and THz quantum cascade lasers (QCLs) provide a powerful tool to explore the nature of various kinds of materials for a low energy excitation and ultrafast dynamics; the THz imaging is expected to be applicable to security, factory testing and so on. Thus THz-TDS and QCLs have triggered the research field of THz-technology-based basic research and application research. In addition to those activities, the development of ultrafast devices and logic circuits in the fields of THz photonics and THz electronics has accelerated the growth of the THz research field such as THz wireless communication, THz network system, ultrafast ADCs and so on. This paper reviews the future prospect of such THz-technology-based research fields.

View full abstract

Download PDF (4102K)
Generation and Applications of High-Power Terahertz Waves

Ken SUTO

2005 Volume 33 Issue 12 Pages 819-825
Published: December 15, 2005
Released on J-STAGE: March 26, 2014

DOIhttps://doi.org/10.2184/lsj.33.819

JOURNAL FREE ACCESS

Show abstractHide abstract

Inter- and intramolecular vibrations of biomolecules, originating from weak bonds such as hydrogen bonds or van der Waals' force, are known to exist in teraher tzrange. Therefore, tunable sources of coherent terahertz wave can be used for selective excitation of vibrational modes and stimulation of chemical reactions, as well as for recognition of molecules. Two systems for high-power terahertz wave generation are introduced. They are based on difference-frequency generation in Ga Pcrystal. A high-resolution OPO-source system enables measurement of fine structures in spectra, even those resulting from defects in molecules. A conventional Cr: Forsterite-source system is simple, but provides sufficient resolution for measurement at room temperature. Operation principles and construction of the instruments are described in details. Spectrometers which employ these terahertz wave generators were applied to measure absorption spectra of biomolecules. The results demonstrate superiority of these spectrometers in comparison to FTIR and TDS, in range, resolution and sensitivity.

View full abstract

Download PDF (3171K)
Status of Free-Electron Lasers in Terahertz Frequency Range

Makoto ASAKAWA

2005 Volume 33 Issue 12 Pages 826-830
Published: December 15, 2005
Released on J-STAGE: March 26, 2014

DOIhttps://doi.org/10.2184/lsj.33.826

JOURNAL FREE ACCESS

Show abstractHide abstract

This article reviews the status of Free-Electron Lasers (FELs) working in the terahertz frequency range. At this time, three operating FEL facilities exist that are able to supply powerful and tunable terahertz radiation for various application programs. This article describes the performance of FELs in these facilities and also presents novel radiation sources based on synchrotron radiation. Recent progress in accelerator technology, particularly in the energy recovering linac and electron beam compression technology, opens up the possibility of a terahertz radiation source that produces terahertz waves with MW peak power and KW average power.

View full abstract

Download PDF (998K)
Generation of Terahertz-Waves Using Uni-Traveling-Carrier Photodiodes and Its Applications

Hiroshi ITO

2005 Volume 33 Issue 12 Pages 831-836
Published: December 15, 2005
Released on J-STAGE: March 26, 2014

DOIhttps://doi.org/10.2184/lsj.33.831

JOURNAL FREE ACCESS

Show abstractHide abstract

Photonic generation of millimeter- and sub-millimeter-waves up to THz range using uni-traveling-carrier photodiodes (UTC-PDs) is described. The UTC-PD utilizes only electrons as the active carriers and this unique feature is the key to achieving excellent high-speed and high-output characteristics simultaneously. The obtained performance includes record output powers of over 20mW at 100GHz and more than 10μW at 1 THz. Promising applications, such as fiber radio communications systems, imaging systems, local signal supply for radio telescope, and measurement systems, are also overviewed.

View full abstract

Download PDF (7315K)
Development of a Nondestructive Inspection System for Detection of Illicit Drugs Hidden in Envelopes

Takayuki SHIBUYA, Masahiro YAMASHITA, Yuichi OGAWA, Chiko OTANI, Kodo ...

2005 Volume 33 Issue 12 Pages 837-842
Published: December 15, 2005
Released on J-STAGE: March 26, 2014

DOIhttps://doi.org/10.2184/lsj.33.837

JOURNAL FREE ACCESS

Show abstractHide abstract

At present, there is no established technique to detect illicit drugs concealed in mail envelopes in a nondestructive way. Therefore, such mail easily passes through the domestic post or even over the international borders. We studied the nondestructive detection of chemicals (including illicit drugs) hidden in envelopes, and developed an effective inspection system using terahertz waves in a two-step procedure: First, scattering of the terahertz waves is an indicator of the presence of powders in the envelope; second, the identification of the chemicals is done by spectral fingerprinting. Furthermore, we applied the diffuse reflectance spectroscopy for the case of thicker targets and tested whether powders can be identified using spectra obtained in diffuse reflection.

View full abstract

Download PDF (8584K)
Terahertz Time-Domain Attenuated Total Reflection Spectroscopy in Amino-Acid Solution

Masaya NAGAI, Koichiro TANAKA

2005 Volume 33 Issue 12 Pages 843-847
Published: December 15, 2005
Released on J-STAGE: March 26, 2014

DOIhttps://doi.org/10.2184/lsj.33.843

JOURNAL FREE ACCESS

Show abstractHide abstract

We review the terahertz time domain spectroscopy in biomolecules using ultrashort optical pulses, which allows us to obtain the complex dielectric function of the sample directly. We measured the temperature dependence of terahertz spectra in dry arginine crystals, and discussed unharmonicity in intermolecule interaction. We also demonstrated the time-domain attenuated total reflection measurement in a diluted arginine solution, which is sensitive to small change in refractive index in a strong absorption medium, such as water. By the analysis with considering local field, it is clear that there was intermolecular action between amino acid molecules and water molecules. This technique will open to the field of terahertz spectroscopy in hydrated biomolecules.

View full abstract

Download PDF (1063K)
Analysis of the Industrial Materials by THz Spectroscopy

Naoto NAGAI

2005 Volume 33 Issue 12 Pages 848-854
Published: December 15, 2005
Released on J-STAGE: March 26, 2014

DOIhttps://doi.org/10.2184/lsj.33.848

JOURNAL FREE ACCESS

Show abstractHide abstract

This paper shows some results on the characterization of the industrial materials by THz spectroscopy. The applications for bio-materials, dielectric thin films, polymers, nanocomposites, and semiconductors were discussed.

View full abstract

Download PDF (1270K)
Laser THz Emission Microscope for LSI Failure Analysis

Masatsugu YAMASHITA, Kiyoshi NIKAWA, Masayoshi TONOUCHI, Chiko OTANI, ...

2005 Volume 33 Issue 12 Pages 855-859
Published: December 15, 2005
Released on J-STAGE: March 26, 2014

DOIhttps://doi.org/10.2184/lsj.33.855

JOURNAL FREE ACCESS

Show abstractHide abstract

Inspection and failure analysis of large-scale integrated circuits (LSI) have become a critical issue, as there is an increasing demand for quality and reliability in LSIs. Recently, we have proposed a laser THz emission microscope (LTEM) for inspecting electrical failures in LSIs, which detects the THz emission from LSIs by scanning them with femtosecond laser pulses. We successfully obtained the THz emission image of MOSFETs without bias voltage. We also measured MOSFETs in which the connection lines from the electrodes to the p-n junctions were interrupted, and found that the polarity of the temporal waveform of the THz emission from the pn junction in damaged MOSFETs has the opposite sign compared to that in normal MOSFETs. This result indicates that the LTEM can be used for the inspection of MOSFETs without bias voltage, which is attractive for the testing of semiconductor devices during the manufacturing process.

View full abstract

Download PDF (7122K)
Magneto-Optical Spectroscopy of Semiconductors Using Terahertz Quantum Cascade Lasers

Junichiro KONO

2005 Volume 33 Issue 12 Pages 860-862
Published: December 15, 2005
Released on J-STAGE: March 26, 2014

DOIhttps://doi.org/10.2184/lsj.33.860

JOURNAL FREE ACCESS

Show abstractHide abstract

We have used quantum-cascadlea sers operating at 4.7THz, 3.5THz, and 2.3THz to perform THz magnetoopticals tudies of semiconductors. We observedc yclotronr esonance in In As and In Sb quantumw ellsf rom liquid-heliumt emperaturesto room temperature. This representst he first spectroscopica pplicationof THz quantum-cascadela sers. Results showt hat these compact lasers are convenient and reliable sources with adequatep ower and stability for this type of far-infraredm agneto-opticaslt udyo fsolids. Their compactness promisesi nterestingf uture applicationsi nsolid-states pectroscopy. As an example, the developmento fan ultracompacot ptically-detected THz resonances pectroscopys ystemwill be described.

View full abstract

Download PDF (3233K)
Measurement of Transient Temperature Using Mach-Zehnder Interferometer Employing Polarization Maintaining Fiber

Norimasa SAKURAI, Changsu KIM, Kouji AZUMA, Yasufumi MORIMOTO, Katsuno ...

2005 Volume 33 Issue 12 Pages 863-867
Published: December 15, 2005
Released on J-STAGE: March 26, 2014

DOIhttps://doi.org/10.2184/lsj.33.863

JOURNAL FREE ACCESS

Show abstractHide abstract

A new system on transient temperature measurement with a Mach-Zehnder interferometer employing Polarization Maintaining Fibers (PMF) has been successfully developed. Two PMF fibers, one as the reference arm that avoids externally added disturbances and another as the sensor arm that monitors temperature change, are employed. When temperature changes, the length and phase constant of the sensor arm changes, resulting in a phase difference at the mixing point of two optical waves after passing through both arms, forming interference fringes of concentric circles that move quickly in a radial direction. This system enables us to measure the transient state of temperature change with a resolution of (6/1000)°C and time resolution of 0.1 s.

View full abstract

Download PDF (3697K)
Imaging of Defect Density Distribution in Compound Semiconductors Using Femotosecond Laser Pump-Probe Measurements

Kohei HORIUCHI, Shinya KAMATA, Yasutaka FUJII, Fumihiko KANNARI

2005 Volume 33 Issue 12 Pages 868-872
Published: December 15, 2005
Released on J-STAGE: March 26, 2014

DOIhttps://doi.org/10.2184/lsj.33.868

JOURNAL FREE ACCESS

Show abstractHide abstract

Transient reflectivity measurements following ultrafast laser excitation reveal that the decay time of photoexcited carriers in semiconductor materials decreases as defect density increases due to recombination through deep impurity levels. We demonstrated microscopic imaging of defect density distributions for compound semiconductors (semi-insulator GaAs, epitaxially lateral overgrown In GaP, and GaN) with high sensitivity by plotting reflectivity at a fixed time after the pump pulse, which corresponds to carrier lifetime.

View full abstract

Download PDF (8154K)

Register with J-STAGE for free!