Linear electro‐optic effect applied to a radio astronomy correlator

Price, Nicola; Kronberg, P. P.; Iizuka, Keigo; Freundorfer, A.P.

doi:10.1029/95rs03158

Cited by 4 publications

(4 citation statements)

References 8 publications

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“…The use of electro-optical correlators is an alternative solution already implemented in embedded instruments designed for security and defense [11], and also proposed for astronomy as a Michelson correlator [12]. They allow a drastic reduction in the complexity of correlating the large amount of wideband microwave signals for large-format instruments, in contrast to microwave correlators and, moreover, avoiding expensive telescopes.…”

Section: Introductionmentioning

confidence: 99%

A Microwave Polarimeter Demonstrator for Astronomy with Near-Infra-Red Up-Conversion for Optical Correlation and Detection

Casas

Ortiz

Aja

et al. 2019

Sensors

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This paper presents a 10 to 20 GHz bandwidth microwave polarimeter demonstrator, based on the implementation of a near-infra-red frequency up-conversion stage that allows both the optical correlation, when operating as a synthesized-image interferometer, and signal detection, when operating as a direct-image instrument. The proposed idea is oriented towards the implementation of ultra-sensitive instruments presenting several dozens or even thousands of microwave receivers operating in the lowest bands of the cosmic microwave background. In this work, an electro-optical back-end module replaces the usual microwave detection stage with Mach–Zehnder modulators for the frequency up-conversion, and an optical stage for the signals correlation and detection at near-infra-red wavelengths (1550 nm). As interferometer, the instrument is able to correlate the signals of large-format instruments, while operating as a direct imaging instrument also presents advantages in terms of the possibility of implementing the optical back end by means of photonic integrated circuits to achieve reductions in cost, weight, size, and power consumption. A linearly polarized input wave, with a variable polar angle, is used as a signal source for laboratory tests. The receiver demonstrator has proved its capabilities of being used as a new microwave-photonic polarimeter for the study of the lowest bands of cosmic microwave background.

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Section: Introductionmentioning

confidence: 99%

A Microwave Polarimeter Demonstrator for Astronomy with Near-Infra-Red Up-Conversion for Optical Correlation and Detection

Casas

Ortiz

Aja

et al. 2019

Sensors

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“…Therefore, each reverse isolation will get the corresponding correlation circle. Generally speaking, the correlation coefficient of the analog correlator is required to be greater than 0.9 [22,23]. To estimate the demand of the isolation between two input signals for the correlator quickly, we can specify that the variation range of the correlator circle radius is less than 2%.…”

Section: Principle Of the Proposed Analog Correlatormentioning

confidence: 99%

A Compact Broadband Analog Complex Correlator with High Correlation Efficiency for Passive Millimeter-Wave Imaging System

Chen

et al. 2022

Electronics

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In this paper, the design, fabrication, and measurement of a compact broadband (4–8 GHz) analog complex correlator for a passive millimeter-wave imaging system are presented. To achieve high sensitivity and high integration of the imaging system, the wideband and miniaturization of the correlator are required. The correlator achieves wide bandwidth by using the add-and-square method, which is composed of a six-port circuit and a detection circuit. In order to realize the miniaturization of the correlator, the six-port circuit is realized on the chip base on the 0.15-μm gallium arsenide (GaAs) process. The influence of mismatch of the detection circuit that employs zero-bias Schottky diodes on the correlator is also analyzed to guide the design of the correlator. The measurement results of the designed chips and detector are consistent with the simulation result. Finally, a Sweep-frequency test is applied to the designed correlator, and the measurement results show that, within the frequency range of 4–8 GHz, the correlation amplitude fluctuation is less than 1.9 dB and the correlation efficiency is larger than 99%, which reveal that the correlator is suited for interferometric passive millimeter-wave imaging applications.

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“…The integration of the microwave receiver with the electrooptical correlator working as the interferometer is out of the scope of this paper and it is described in Ref. 20, which shows synthesized images characterizing the polarization of an incoming signal through the Stokes parameters.…”

Section: System Characterizationmentioning

confidence: 99%

“…18,19 When broadband input signals need to be correlated in a single channel, electro-optic correlators have shown some advantages over traditional analog ones. 20 In order to improve the sensitivity, an interferometer with very sensitive receivers and an electro-optical correlator, which allows us to obtain a synthesized image of the Stokes parameters of the CMB polarization in the near-infrared (NIR), is proposed. 21 This improvement will be possible due to a substantial increment in the number of pixels as compared to the current image telescopes, as well as a lower complexity with respect to classical correlators.…”

Section: Introductionmentioning

confidence: 99%

10- to 19.5-GHz microwave receiver of an electro-optical interferometer for radio astronomy

Aja

Fuente

Artal

et al. 2019

J. Astron. Telesc. Instrum. Syst.

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This document describes the analysis, design, and prototype test results of the microwave section of a 10-to 19.5-GHz interferometer, aimed at obtaining polarization data of cosmic microwave background (CMB) radiation from the sky. First, receiver analysis is thoroughly assessed to study the contribution of each subsystem when obtaining the Stokes parameters of an input signal. Then, the receiver design is detailed starting from the front-end module, which works at cryogenic temperature, composed of a set of passive components: feedhorn, orthomode transducer, and polarizer, together with active components, such as very low-noise amplifiers. The back-end module (BEM) is directly connected, working at room temperature for further amplification, phase switching, and correlation of the signals. Moreover, the whole frequency band is split into two sub-bands (10 to 14 GHz and 16 to 20 GHz) using a high selective diplexer in the BEM in order to reject radiofrequency interferences. Phase switches allow phase difference steps of 5.625 deg, which modulate the correlated outputs to reduce systematic effects in the postdetection signal processing. Finally, measurements of all the subsystems comprising the microwave section of the receiver as well as the characterization of the complete microwave receiver are presented. The obtained results demonstrate successful performance of the microwave receiver that, together with an electro-optical correlator and a near-infrared camera, comprises the interferometer. Moreover, synthesized images corresponding to combinations of the Stokes parameters can be obtained with the whole system.

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Linear electro‐optic effect applied to a radio astronomy correlator

Cited by 4 publications

References 8 publications

A Microwave Polarimeter Demonstrator for Astronomy with Near-Infra-Red Up-Conversion for Optical Correlation and Detection

A Microwave Polarimeter Demonstrator for Astronomy with Near-Infra-Red Up-Conversion for Optical Correlation and Detection

A Compact Broadband Analog Complex Correlator with High Correlation Efficiency for Passive Millimeter-Wave Imaging System

10- to 19.5-GHz microwave receiver of an electro-optical interferometer for radio astronomy

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