39th Int. Conf. on Infrared, Millimeter, and THz Waves
September 14-19, 2014
The University of Arizona, Tucson, AZ
M2/D - 7. Metrology and Non-Destructive Evaluation I
Monday, September 15, 2014 11:00 am to 12:30 pm
Room: Rincon Room
Chairperson: Kodo Kawase
11:00 am 11:00 am : Micromachined Probes For Characterization Of Terahertz Devices
Presenter: Robert Weikle

The recent development of micromachined probes for on-wafer characterization of devices and circuits now permit measurements to the WR-1.0 waveguide band (0.75 -- 1.1 THz). This paper presents the probe design concept, describes methods for characterizing the probes, and applies the probes for direct on-wafer characterization of planar Schottky diodes at 1 THz. Measurements show the WR-1.0 probes exhibit an insertion loss of approximately 7 dB and a return loss greater than 15 dB over 750--1100 GHz band. This is the first demonstration of on-wafer probe measurements above 1 THz.

Author(s):
Robert Weikle - University of Virginia
Scott Barker - University of Virginia
Arthur Lichtenberger - University of Virginia
Matthew Bauwens - Dominion Microprobes
Naser Alijabbari - University of Virginia
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11:30 am 11:30 am : Lower Bound Of Sample Thickness In Terahertz Time-Domain Spectroscopy
Presenter: Withawat Withayachumnankul

Dielectric films with a thickness much less than a wavelength pose a challenge in transmission-mode terahertz time-domain spectroscopy (THz-TDS). A small signal change induced by such films is likely to be obscured by system uncertainties. In this abstract, several possible thin-film measurement procedures are carefully considered. It is found that an alternating sample and reference measurement approach is most sensitive for thin-film sensing. Importantly, a closed-form equation is developed to determine a lower bound of sample thickness as a function of the refractive index and system uncertainties. An experimental validation shows that typical THz-TDS can detect polymer films with a thickness of a few microns. The given criterion can be used to evaluate the system performance with respect to thin-film sensing.

Author(s):
Withawat Withayachumnankul - The University of Adelaide
John OíHara - Oklahoma State University
Wei Cao - Oklahoma State University
Ibraheem Al-Naib - Queenís University
Weili Zhang - Oklahoma State University
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11:45 am 11:45 am : Traceable Terahertz Power Metrology At NIST
Presenter: Malcolm White

We discuss measurement system and method for establishing traceability of terahertz (THz) power to NIST standards over a 0.75 to 2.5 THz range. In addition, we describe the performance of an electrically calibrated thermopile detector, which is used as the NIST standard for THz power measurements. Specifically, we present measurements of the reflectance and spatial uniformity of the thermopile detector.

Author(s):
Marla Dowell - NIST
Malcolm White - NIST
John Lehman - NIST
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12:00 pm 12:00 pm : Material Characterization Of Historical Parchment Using Terahertz Time-domain Spectroscopy
Presenter: Tiphaine Bardon

In this study we discuss the influence of the state of degradation, the three-dimensional fibrous structure and the presence of calcium compounds on terahertz absorption properties of historic parchment in the interval 45 -- 85 cm-1, based on the analysis of 32 archival parchment samples, with terahertz time-domain spectroscopy in transmission mode, optical microscopy and Fourier-transform infrared spectroscopy in attenuated total reflectance mode.

Author(s):
Tiphaine Bardon - UCL
Robert K. May - TeraView Ltd
Philip F. Taday - TeraView Ltd
Matija Strlic - UCL
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12:15 pm 12:15 pm : Design Considerations And Performance Metrics Of A High--Sensitivity Multi--Band Terahertz Linear Camera
Presenter: Jeremy Law

This paper reports on the design and performance of a terahertz (THz) linear camera with 50 pW/vHz noise-equivalent power (NEP). This camera is sensitive to four bands of vertically and horizontally polarized THz radiation (0.22, 0.32, 0.42, and 0.52 THz). The heart of the camera is a diode-based focal plane array (FPA) that has a 10 nV thermal noise level and 1 kV/W sensitivity across the four bands. The amplifier chain is capable of amplifying with a gain of up to 20,000, which gives the system the ability to detect signals of approximately 30--50 nV. A 12 bit analog-to-digital converter (ADC) and real--time digital signal processing provides signal recovery and processing at an application level with fast (20 kHz) frame rates.

Author(s):
Jeremy Law - Traycer
Patrick Fay - University of Notre Dame
Don Burdette - Traycer
Kubilay Sertel - The Ohio State University
Georgios C. Trichopoulos - The Ohio State University
Yi Xie - University of Notre Dame
Howard Lee Mosbacker - Traycer
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