Abstract-In this paper we propose a digital beamformer utilizing the radar integrator method of detection. In the receive mode the digitized radar returns weights are allocate on the such a way that the first pulse reflect a SUM pattern and the subsequent three pulses reflect DIFFERENCE pattern. The pulses on DIFFERENCE pattern are added to each other and the net signal subtracted from signal received in SUM pattern. This results in very narrow beam which shows narrow spatial resolution. The schematic is presented and the results are shown.
We report on experiments with deformed polymer microlasers that have a low refractive index and exhibit unidirectional light emission. We demonstrate that the highly directional emission is due to transport of light rays along the unstable manifold of the chaotic saddle in phase space. Experiments, ray-tracing simulations, and mode calculations show very good agreement.The physics of optical microcavities is a topical research field for more than one decade [1]. Microcavities [2,3] confine photons for a long time τ due to total internal reflection at the boundary of the cavity. These so-called whispering-gallery modes (WGMs) have high quality factors Q = ωτ , where ω is the resonance frequency. The in-plane light emission from an ideal circular-shaped microlaser is isotropic due to the rotational symmetry. To overcome this disadvantage microcavities with deformed boundaries have been fabricated leading to significantly improved emission patterns [4][5][6][7][8]. Even unidirectional emission is possible, which has been demonstrated for several shapes, e.g., the spiral [9-11], cavities with holes [12,13], the limaçon [14][15][16][17][18][19][20], the circle with a point scatterer [21], and the notched ellipse [22,23].The ray dynamics inside a deformed microcavity is (partially) chaotic, i.e., neighboring ray trajectories deviate from each other exponentially fast. Because of this, deformed microdisks have attracted attention as models for studying ray-wave correspondence in open systems [5]. This is analog to the study of quantum-classical correspondence in the field of quantum chaos [24]. In open chaotic systems the long-time behavior of trajectories is governed by the chaotic saddle (or chaotic repeller for noninvertible dynamical systems) and its unstable manifold [25,26]. The chaotic saddle is the set of points in phase space that never visits the leaky region both in forward and backward time evolution. The unstable manifold of a chaotic saddle is the set of points that converges to the saddle in backward time evolution. This unstable manifold therefore describes how trajectories, after a transient time, escape from the open chaotic system. It has been shown both theoretically and experimentally that this kind of unstable manifold in chaotic microcavities determines the far-field pattern of all high-Q modes [7,27]. As a consequence, the high-Q modes in such a cavity have very similar far-field patterns. This useful property has been termed universal far-field pat- *
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