Sparse aperture millimeter-wave imaging using optical detection and correlation techniques

Schuetz, Christopher A.; Martin, Robert; Biswas, I.; Mirotznik, Mark S.; Shi, Shouyuan; Schneider, Garrett J.; Murakowski, Janusz; Prather, Dennis W.

doi:10.1117/12.719811

Cited by 13 publications

(5 citation statements)

References 3 publications

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“…Even though the scanning architecture discussed in this manuscript does not specifically benefit from maintaining phase of the signal since it is a single-pixel scanner, a two-dimensional DAI system needs the phase information to coherently reconstruct the imagery; hence, the presented scanning architecture provides a baseline testbed for the DAI system. A onedimensional DAI approach was presented in [8]. From the success presented in that work, a two-dimensional imager is now being developed and constructed and is further discussed in [9].…”

Section: Discussionmentioning

confidence: 97%

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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

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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.

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Section: Discussionmentioning

confidence: 97%

“…In addition, using the optical upconversion methodology provides the enabling infrastructure to construct a distributed aperture imaging (DAI) system, as described in [8,9]. Upconversion inherently preserves the amplitude and phase of the detected signal.…”

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

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“…The first system to demonstrate coherent optical beamforming using a SPCL was that depicted in Fig. 4(a), which used an active source to demonstrate the line-spread function (1D) of a 1 × 4 array antenna [49]. This result was extended to a 2D sparse array, shown in Fig.…”

Section: Systems Based On the Above Formulation Have Been Undermentioning

confidence: 99%

Millimeter-Wave and Sub-THz Phased-Array Imaging Systems Based on Electro-Optic Up-Conversion and Optical Beamforming

Prather,

Murakowski,

Schuetz

et al. 2023

IEEE J. Select. Topics Quantum Electron.

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This paper presents a class of phased-array systems that function as video-rate imagers in the millimeterwave (mmW) and sub-THz bands. While the systems presented operate in the Ka-band (35 GHz) and W-band (77 and 86 GHz), the approach is scalable to the THz regime. Their operation is based on the upconversion of incident mmW and sub-THz signals to the optical domain using high-speed electro-optic modulators (EOMs) that are connected to each antenna element in a phasedarray antenna. The output optical fiber from each EOM is relayed to a fiber bundle, or optical fiber array, from which the upconverted mmW/sub-THz signals are launched into free space. Because the upconversion preserves both the temporal and spatial coherence, through a spatial phase-control loop (SPCL), the launched sideband signals re-form the beamspace of the incident mmW or sub-THz signals, but in the optical domain. At this point, a lens performs a 2D spatial Fourier transform, to produce a real-time image of the mmW or sub-THz signals from the environment on a short-wave infrared (SWIR) camera, which renders the scene at video rates. The fundamental operating principles of these systems are presented, along with the historical progress in their development, and experimental demonstrations.

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“…Since such imagers can be implemented in a planar fashion, this technique could enable high resolution imagers to be fabricated without the volumetric scaling typically encountered in traditional focal plane arrays. A prototype system based on distributed aperture techniques with optical processing of the upconverted energy has been demonstrated [4,5].…”

Section: Introductionmentioning

confidence: 99%

LiNbO 3 optical modulator for MMW sensing and imaging

et al. 2007

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We present several novel technologies for sensing millimeter-wave (mmW) radiation for imaging and spectroscopy based on photonic devices. Along these lines, in our high-sensitivity millimeter-wave (mmW) imaging system, which is based on optical upconversion, the power of mmW radiation is transferred to the sidebands on an optical carrier via an electro-optic (EO) modulator fed by a broadband horn antenna. The detection is realized by measuring the transferred optical power of the sidebands. The sensitivity of this detection system is primarily controlled by the conversion efficiency of the EO modulator at the desired mmW frequency (e.g. 95GHz). Thus, modulators are required that exhibit an ultra-broad bandwidth and small drive voltage. In this paper, we present the design, fabrication, and characteristics of LiNbO 3 traveling-wave modulator for the mmW detection system. In a traveling-wave modulator, the bandwidth is limited by the mismatch between electrical and optical propagation constants. We have developed several techniques to finely tune the propagation constant of the mmWs in the modulator and have thereby eliminated this mismatch. Further bandwidth limitations for the modulator arise from losses in the electrode conductor, the substrate and buffer layer dielectrics, and coupling between the traveling-wave mode and the substrate modes. Modulator structures are described to reduce those losses without increasing the device driving voltage. The bandwidth and conversion limits of these structures are also discussed. The mmW detection pixels using the fabricated modulators were assembled, characterized, and analyzed. A high-sensitivity W-band detection system with a low noise-equivalent temperature difference (NETD) has been demonstrated. In addition, we present ongoing work to improve coupling millimeter-wave energy to the modulator at the W-band using techniques viable for packaged devices.

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Sparse aperture millimeter-wave imaging using optical detection and correlation techniques

Cited by 13 publications

References 3 publications

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

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

Millimeter-Wave and Sub-THz Phased-Array Imaging Systems Based on Electro-Optic Up-Conversion and Optical Beamforming

LiNbO 3 optical modulator for MMW sensing and imaging

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