Radiometric Millimeter-wave detection via optical upconversion and carrier suppression

Schuetz, Christopher A.; Murakowski, Janusz; Schneider, Garrett J.; Prather, Dennis W.

doi:10.1109/tmtt.2005.847106

Cited by 50 publications

(30 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As an alternative to focal plane image formation, pupil-plane image formation can also be employed [30][31][32]. In a focal plane imaging system the detectors are located after the image forming optics, while in a pupil-plane system image formation takes place in either electronics or optics (after upconversion).…”

Section: Imaging System Design Overviewmentioning

confidence: 99%

“…The latter could be solved by the use of optically generated LO using LT-GaAs THz photomixers as per-pixel LO sources [44][45][46]. Coherent optical upconversion is an approach that has been investigated actively over the recent years [32,47]. The method is an optical analog to coherent downconversion in the electrical domain.…”

Section: Coherent Up or Downconversionmentioning

confidence: 99%

See 1 more Smart Citation

Millimeter-Wave and Terahertz Imaging in Security Applications

Luukanen

Appleby

Kemp³

et al. 2012

Terahertz Spectroscopy and Imaging

View full text Add to dashboard Cite

The relatively short wavelength of mm-wave and THz radiation coupled with good transmission through many dielectric materials allows images to be formed of concealed objects. This chapter gives an overview of the detectors, their associated circuitry, and system developments over the past 10 years, focussing on personnel security screening. We will discuss the phenomenology of imaging at these wavelengths, introduce the reader to the basic architectures being used and developed for image forming instruments, show examples of systems, and also discuss the feasibility of spectroscopic THz imaging for security screening applications.

show abstract

Section: Imaging System Design Overviewmentioning

confidence: 99%

Section: Coherent Up or Downconversionmentioning

confidence: 99%

Millimeter-Wave and Terahertz Imaging in Security Applications

Luukanen

Appleby

Kemp³

et al. 2012

Terahertz Spectroscopy and Imaging

View full text Add to dashboard Cite

show abstract

“…1 and referenced in [3,4]. With this method, the mmW radiation is collected using an RF antenna and upconverted to optical frequencies using an electro-optic modulator.…”

Section: Detector Architecturementioning

confidence: 99%

“…As described in [4], use of the optical upconversion method for passive mmW detection has the potential to provide some significant advantages over traditional passive mmW detection methods, in which such applications require the use of intricate and expensive monolithic microwave integrated circuit (MMIC) components. Another advantage in using the upconversion method is that the collection bandwidth can be wider than traditional RF applications since optical modulators can be made with a band of operation of several octaves or more.…”

Section: Benefits Of Optical Upconversionmentioning

confidence: 99%

Q-Band Millimeter Wave Imaging in the Far-Field Enabled by Optical Upconversion Methodology

Samluk

Schuetz

Dillon

et al. 2011

J Infrared Milli Terahz Waves

View full text Add to dashboard Cite

Millimeter-wave (mmW) imaging has evolved to the point where it offers distinctive remote sensing capabilities in many application scenarios, such as port and harbor security, search and rescue, and navigational aids, due to its unique ability to penetrate atmospheric obscurants. Some of the applications being considered require passive imaging, imposing challenging sensitivity requirements to detect the low power levels in this spectral region. One metric used in this regard is the noise equivalent power (NEP), which quantifies the sensitivity of a detector. By utilizing a unique detector technology based on optical upconversion a low NEP value is achieved as compared to other RF methods, without the use of cryogenic cooling or low noise amplification. In addition, the overall size and weight may be reduced as compared to other imaging methodologies. As such, the construction and development of a passive mmW imaging system utilizing optical upconversion was undertaken, operating in the Q-Band to collect radiation between 33 and 50 GHz. Herein, we describe the passive mmW imager architecture and operation. Also presented are imaging results obtained using this approach as well as key imager metrics that have been experimentally validated.

show abstract

“…In previous publications [1,2], we have reported on the use of optical upconversion techniques to accomplish highsensitivity millimeter-wave detection. This detection architecture utilizes the electro-optic effect to transfer energy from an optical carrier into sidebands proportional to the millimeter-wave power incident on the modulator.…”

Section: Introductionmentioning

confidence: 99%

Noise limitations in millimeter-wave detection via optical upconversion

et al. 2005

Self Cite

View full text Add to dashboard Cite

Typical radio frequency style millimeter-wave detectors for passive millimeter-wave imaging are limited by the thermal noise floor inherent in microwave and millimeter-wave circuits. This thermal noise, or Johnson noise, can be derived from Rayleigh-Jeans approximation of Planck's blackbody radiation law and is a fundamental limit to the noise levels in such systems. For this reason low-noise amplifiers are typically used at the front end of such high sensitivity receivers to improve their noise equivalent difference temperature. However, such approaches are undesirable in high-noise environments where high signal levels could damage such amplifiers or in large pixel count arrays where the cost of amplification of each pixel becomes prohibitive. Herein, we present an alternate approach to achieving low difference temperatures, which involves upconversion to optical frequencies with subsequent filtering and square-law detection. Through this process the normal thermal noise floor limitations are not relevant as, at such high frequencies, the Rayleigh-Jean's approximation is no longer valid. In fact, the thermal noise present in the optical regime is diminished to negligible levels at room temperatures and quantum noise becomes the fundamental limit to system performance. In this paper, we present the theoretical and practical limits to reduction of noise equivalent power using optical amplifiers and relate the noise contributions of such amplifiers to the quantum noise limit.

show abstract

Radiometric Millimeter-wave detection via optical upconversion and carrier suppression

Cited by 50 publications

References 15 publications

Millimeter-Wave and Terahertz Imaging in Security Applications

Millimeter-Wave and Terahertz Imaging in Security Applications

Q-Band Millimeter Wave Imaging in the Far-Field Enabled by Optical Upconversion Methodology

Noise limitations in millimeter-wave detection via optical upconversion

Contact Info

Product

Resources

About