39th Int. Conf. on Infrared, Millimeter, and THz Waves
September 14-19, 2014
The University of Arizona, Tucson, AZ
M4/C - 13. Spectroscopy Instruments and Techniques I
Monday, September 15, 2014 4:00 pm to 5:30 pm
Room: Tucson Room
Chairperson: Enrique Castro-Camus
4:00 pm 4:00 pm : Terahertz Wave Emission From Laser-Induced Micro-Plasma
Presenter: Fabrizio Buccheri

Laser-induced plasmas with longitudinal size smaller than 100 µm are investigated as a source of broadband terahertz (THz) radiation. The angular dependent emission of the micro-plasma is measured with coherent detection, and the preferential directions of radiation are identified. The efficiency of the source increases with the numerical aperture of the laser focusing optics, allowing the measurement of THz waveforms with pump pulse energies as low as 5.5 µJ. The experimental results suggest the laser-induced micro-plasma as a promising approach to scale down the power budget for broadband terahertz spectroscopy.

Author(s):
Fabrizio Buccheri - University of Rochester
Xi-Cheng Zhang - University of Rochester
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4:30 pm 4:30 pm : Frequency-Resolved Detection Of Broadband THz Waves With Cherenkov-Phase-Matched Heterodyne EO Sampling
Presenter: Masahiko Tani

The electro-optic (EO) sampling is one of the key technologies for detection of terahertz (THz) pulsed waves and widely used in THz time domain spectroscopy (THz-TDS), as well as the photoconductive sampling. The conventional EO sampling is based on the polarization modulation of the sampling optical waves due to transient birefringence (or phase-retardation) induced by THz electric field in the EO crystal. Recently, we have reported a new electro-optic (EO) sampling scheme based on the non-collinear Cherenkov phase-matching, where the EO sampling signal is detected as the direct intensity modulation in the sampling beam without using any polarization optics. The detection scheme is based on the interference between the optical sampling wave and that generated by the sum frequency mixing (SFM) or the difference frequency mixing of the THz wave with the incident optical wave. In this "heterodyne EO sampling", each THz frequency component is detected in a direction determined by the angle-dependent wave-vector matching condition in the frequency mixing processes. By utilizing this property, we have demonstrated the frequency-resolved detection of THz waves with the Cherenkov-phase-matched heterodyne EO sampling.

Author(s):
Masahiko Tani - University of Fukui
Syougo Azuma - University of Fukui
Tomohiro Nagase - University of Fukui
Shinpei Ozawa - University of Fukui
Stefan Funkner - University of Fukui
Gudrun Niehues - University of Fukui
Atsushi Iwamae - University of Fukui
Kohji Yamamoto - University of Fukui
Takashi Furuya - University of Fukui
Elmer Estacio - University of Philippines Diliman
Michael Bakunov - University of Nizhny Novgorod
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4:45 pm 4:45 pm : Design And Characterization Of A TES Bolometer For Fourier Transform Spectroscopy In The THz Range
Presenter: Mathias Kehrt

A Transition Edge Sensor (TES) composite bolometer for Fourier Transform spectroscopy was developed. The design is based on a superconducting thermistor, SiN membrane technology and a thin film metal mesh absorber which is optimized for the spectral range from 0.1 THz to 3 THz. A prototype was built; its characterization and first application results are presented.

Author(s):
Mathias Kehrt - Physikalisch-Technische Bundesanstalt
Christian Monte - Physikalisch-Technische Bundesanstalt
Jˆrn Beyer - Physikalisch-Technische Bundesanstalt
Jˆrg Hollandt - Physikalisch-Technische Bundesanstalt
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5:00 pm 5:00 pm : Single-Shot Terahertz Magneto-Spectrometer
Presenter: Ben Spencer

A terahertz magneto-spectrometer has been developed that utilizes the spectral up-conversion technique to measure broad-bandwidth terahertz radiation pulses in a single shot. Synchronizing the laser pulses to a pulsed mini-coil 30 T magnet is enabling cyclotron resonance measurements in a range of semiconductor structures.

Author(s):
Ben Spencer - University of Manchester
Matthew Cliffe - University of Manchester
Alexander Knight-Percival - University of Manchester
William Smith - University of Manchester
Darren Graham - University of Manchester
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5:15 pm 5:15 pm : Simultaneous Measurement Of The 1st And 2nd Harmonics Of A Phase Modulated Coherent Frequency-domain THz Spectrometer
Presenter: Joseph Demers

We report on a frequency domain terahertz spectrometer with an integrated, fiber-coupled, custom manufactured lithium-niobate optical phase-modulator that operates at 783 nm. We discuss employing optical phase modulation instead of bias modulation for simultaneously measuring the 1st and 2nd harmonics of the phase modulated THz radiation. This technique allows the removal of the photomixing interference pattern and does not suffer from the same issues as our previous technique when the 0∫ and 90∫ data was recorded sequentially. Because of the phase-modulator design and optical circuit design, the new photomixing system also enjoys the benefits of common mode phase drift rejection.

Author(s):
Joseph Demers - Emcore Corporation
Bryon Kasper - Emcore Corporation
David Daughton - Lake Shore Cryotronics Inc
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