Squint-Free Fourier-Optical RF Beamforming Using a SHB Crystal as an Imaging Detector

From spectral holeburning memory to spatial-spectral microwave signal processing

“…The availability of a large number of accessible ions at each frequency enables high signal dynamic range. These attributes coupled with spatial and angular multiplexing capabilities [16] make S2 materials an attractive medium for high volume storage and processing applications. The frequency selectivity or resolution of an S2 material is limited to the material's homogeneous linewidth, δω h .…”

“…Initial demonstrations were typically in the MHz regime, and some were later extended to the processing or creation of GHz signals [4][5][6][7]. In 2002, the concept of using S2 materials to process microwave signals by storing the correlation of microwave signals in the S2 material and then reading out the result through a scan of the absorption profile was introduced [8] The first proposed application was correlative radar processing [9], but subsequent applications included spectral analysis [10][11][12][13], noise lidar [14], time-integrating correlators [15], squint-free imagers [16], radar direction finding [17], and analog to digital conversion [18] This paper gives a historical perspective of the advancement from spectral holeburning as a potential memory device to the currently operating and field tested broadband (over 20 GHz) spatial spectral microwave spectrum analyzers.…”

A direction finding method for spatial optical beam-forming network based on sparse Bayesian learning

“…To solve this problem, the application of optical technology to microwave array antennas has been studied for years [1][2][3][4][5][6][7][8][9][10][11]. One of the most powerful approaches is a spatial optical processing method, B Liu-li Wu wll_me1991@163.com 1 Department of Electronic Science and Engineering, National University of Defense Technology, Changsha 410073, Hunan, People's Republic of China which was originally proposed by Keopf [1].…”

“…One of the most powerful approaches is a spatial optical processing method, B Liu-li Wu wll_me1991@163.com 1 Department of Electronic Science and Engineering, National University of Defense Technology, Changsha 410073, Hunan, People's Republic of China which was originally proposed by Keopf [1]. This method implements the division, interconnection and combination of light spatially and thus has advantage in terms of bandwidth, circuit complexity and processing speed over conventional techniques [2][3][4][5][6][7][8][9][10]. A typical application of this method is a beam-forming network which is called spatial optical beamforming network (SOBFN) [4,5].…”

Investigation on group delay ripple effects and the hybrid approach for optical beamforming

“…Usually, Butler matrix [42] or Rotman lens [7] are used. The Fourier lens [43][44][45] has been widely utilized until recently for the same purpose. This is the most straightforward way to form multiple beams and support a large size array.…”