Antiphase dynamics and self-pulsing due to a low-frequency spatial population grating in a multimode laser

We study analytically equations that extend the Tang-Statz-deMars rate equations for a multimode Fabry-Perot laser by including the low-spatial-frequency population grating and the inhomogeneous pumping rate along the cavity axis [Quant. Semiclassic Opt. 5, L17 (1997)]. First, we prove the theorem that is the foundation of the antiphase dynamics: The total intensity transients are characterized by only one frequency, the single-mode relaxation oscillation. Second, we study the three-mode laser operation. In this context, we derive analytic expressions for the steady-state intensities, their linear stability, and the bifurcation points. We prove that strictly multimode solutions display a Hopf bifurcation leading to passive Q-switched solutions. Numerically, we have found that these time-periodic regimes may bifurcate to quasiperiodic and chaotic states and that there are many domains of bistability.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Integrated immersion lens antennas for millimeter and submillimeter wave array detectors

Two variants of an integrated lens antenna for millimeter and submillimeter-wave array receivers are analyzed. One of the variants consists of a single-chip planar array placed into a focal plane of a large immersion silicon lens. For the second case, we consider an array of multiple integrated lens antennas; each single detector is coupled to its individual immersion lens. We compare two designs of an array of TES (transition edge sensor) detectors coupled into cross-double-slot antennas at 250 GHz [1]. We define limiting parameters of the imaging array antenna configuration using a tolerance analysis, which includes beam degradation criterion for edge pixels due to aberrations in the common optical system