Abstract

High-sensitivity receiver systems with near-ideal polarization sensitivity are highly desirable for development of millimeter and submillimeter radio astronomy. Multimoded bolometers provide a unique solution to achieve such sensitivity, for which hundreds of single-mode sensors would otherwise be required. The primary concern in employing such multimoded sensors for polarimetery is the control of the polarization systematics. In this work, we examine the angular- and polarization-dependent absorption pattern of a thin resistive grid or membrane, which models an absorber used for a multimoded bolometer. The result shows that a freestanding thin resistive absorber with a surface resistivity of $\eta /2$, where $\eta$ is the impedance of free space, attains a beam pattern with equal $E$- and $H$-plane responses, leading to zero cross-polarization. For a resistive-grid absorber, the condition is met when a pair of grids is positioned orthogonal to each other and both have a resistivity of $\eta /2$. When a reflective backshort termination is employed to improve absorption efficiency, the cross-polar level can be suppressed below $-30\mathrm{dB}$ if acceptance angle of the sensor is limited to $\lesssim 60°$. The small cross-polar systematics have even-parity patterns and do not contaminate the measurements of odd-parity polarization patterns, for which many of the recent instruments for cosmic microwave background are designed. Underlying symmetry that suppresses these cross-polar systematics is discussed in detail. The estimates and formalism provided in this work offer key tools in the design consideration of the instruments using the multimoded polarimeters.

© 2014 Optical Society of America

Modeling the intensity and polarization response of planar bolometric detectors

Christopher N. Thomas, Stafford Withington, David T. Chuss, Edward J. Wollack, and S. Harvey Moseley
J. Opt. Soc. Am. A 27(5) 1219-1231 (2010)

Optical theory of partially coherent thin-film energy-absorbing structures for power detectors and imaging arrays

Stafford Withington and Christopher N. Thomas
J. Opt. Soc. Am. A 26(6) 1382-1392 (2009)

Characteristic functions describing the power absorption response of periodic structures to partially coherent fields

Christophe Craeye, Stafford Withington, and Christopher N. Thomas
J. Opt. Soc. Am. A 31(7) 1360-1368 (2014)

Optical modeling techniques for multimode horn-coupled power detectors for submillimeter and far-infrared astronomy

Christopher N. Thomas and Stafford Withington
J. Opt. Soc. Am. A 30(8) 1703-1713 (2013)

Polarization properties of a broadband multi-moded concentrator

Alan Kogut, Dale J. Fixsen, and Robert S. Hill
J. Opt. Soc. Am. A 32(6) 1040-1045 (2015)