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We discuss the role of physical fluctuations in physical random bit generators focusing on the practical limits of generation rates. First we present a brief review of existing random bit generators, their mechanisms and performance characteristics. Then we discuss in detail random bit generation by chaotic lasers. It has recently been shown that bit sequences which passed statistical tests of randomness...
In this paper, we discuss about the design of the trapezoidal acceleration input which does not excite the mechanical vibration modes. We first obtain the spectrum of the trapezoidal acceleration input analytically, and the frequencies where the spectrum becomes zero are obtained. Since the zero spectrum frequencies are the function of the ramp-up and ramp-down time, they can be determined so as to...
The Sagnac effect in rotating microcavities is studied theoretically and numerically. The frequency splitting due to the Sagnac effect occurs as a threshold-like phenomenon for the angular velocity in a rotating microcavity. Above the threshold, the eigenfunctions of a rotating microcavity become rotating waves while they are standing waves below the threshold.
We fabricated Monza-shaped semiconductor microcavity lasers and evaluated their far-field characteristics. From the ray dynamical point of view, the Monza-shaped cavity belongs to a special class of fully chaotic cavities; its phase space is decomposed into two independent chaotic components, which yield two different emission patterns. In the present paper, we discuss which ensemble of ray trajectories...
The Sagnac effect in rotating microcavities is studied theoretically and numerically. The frequency shift due to the Sagnac effect occurs as a threshold-like phenomenon for the angular velocity in a rotating microcavity. Above the threshold, the eigenfunctions of a rotating microcavity become rotating waves while they are standing waves below the threshold.
We found alternate oscillations in AlGaAs/GaAs single-quantum-well (SQW) quasi-stadium laser diodes (QSLD). The alternate oscillations in QSLD can be well explained by the interactions of two different cavity modes due to the geometrical symmetry of QSLD. We also showed the alternate oscillation frequencies are inversely proportional to the amplitudes of two different cavity modes.
We found alternate oscillations in AlGaAs/GaAs single-quantum-well (SQW) quasi-stadium laser diodes (QSLD). The alternate oscillations in QSLD can be well explained by the interactions of two different cavity modes due to the geometrical symmetry of QSLD. Unlike the alternate oscillations in semiconductor ring lasers that need the waveguides to extract the light signals, the alternate oscillation...
We report a demonstration of lasing in a two-dimensional (2D) microcavity which is a semiconductor diode structure with a stadium shape finely formed by reactive-ion-etching technique and pumped by electric current injection. The laser exhibits output over a wide angle, although the fundamental lasing modes have highly complex wave structures which do not correspond to any simple set of rays inside...
We study the effect of rotation on resonances of an optical cavity in an accelerated frame of reference. We show that, even when the resonant modes of an optical cavity are wave-chaotic, degenerate resonant frequency of those modes split into different frequencies due to the rotation of the cavity. The frequency difference is proportional to the rotation rate, although the splitting resonant modes...
We study light emission from a stadium-shaped optical cavity by ray and wave descriptions. A remarkable ray-wave correspondence is revealed by investigating phase space distributions that describe how the light is transmitted outside the cavity.
In order to demonstrate controlling directional emissions corresponding to the ring trajectory modes by using external optical injection, we fabricate the AlGaAs/GaAs single-quantum-well tandem quasi-stadium laser diodes consist of the front slave and the rear master laser diodes. The geometry of the laser cavities have been defined by using a lithography system and a reactive-ion-etching technique...
We fabricated quasi-stadium laser diode which has a 'window' on the top of cavity by ion-etching technique to epitaxial wafer and demonstrated to observe direct lasing mode observation. In the carrier poor region, bright line can recognize. On the other hands, in the rich carrier region, lasing pattern was recognized as dark line. Both lines well fit extended Fox-Li simulation. From these results,...
We fabricated and tested multi-electrode quasi-stadium laser diodes having GaAs/AlGaAs GRIN-SCH-SQW structures. Axis and ring mode switching was achieved under CW operation for output powers up to 15 mW by selecting the electrode used.
We present locking of two modes in GaAs/AlGaAs single-quantum-well quasi-stadium laser diodes and unidirectional emission from InGaAsP multiple-quantum-well quasi-stadium laser diodes
We report the Sagnac effect in resonant microcavities. The Sagnac effect is the phase and frequency difference between two counter propagating laser beams in a rotating ring resonator, and has been studied for a long time. It forms the basis for the optical gyroscopes, such as ring laser gyroscope or fiber optic gyroscopes. Conventional theoretical approach for the Sagnac effect has been derived from...
In two-dimensional microcavity lasers, as a way to extract highly directional emission, it has been proposed to deform the cavity shape smoothly from perfect circularity. As a result, rays start to exhibit a variety of dynamics from integrable to strongly chaotic, which is tunable by the deformation. The ray picture has been providing a simple and intuitive method to explain experimental observations...
Mode switching operation of multi-electrode strained InGaAsP multiple-quantum-well quasi-stadium laser diodes is reported. Far-field patterns exhibit highly directional emission along the laser cavity axis for current injection at the axis electrode and highly directional emission at angles plusmn19deg from the cavity axis for current injection at the ring electrode
We investigate the lasing characteristics of oval-resonator laser diodes made of AlGaAs/GaAs quantum wells both experimentally and theoretically. The resonator shapes are various oval geometries, thereby probing chaotic and mixed classical dynamics. The far field pattern shows a pronounced fine structure that strongly depends on the cavity shape
We fabricated the AlGaAs/GaAs 3QW quasi-stadium laser diodes with two-electrodes and succeeded in controlling directional laser emission by applying different currents to each electrode. We showed the ratio of laser emission with two different directions is proportional to the ratio of currents injected into two electrodes. These devices are applicable for beam switching and splitting
We demonstrate mode switching in tandem quasi-stadium laser diodes. Switching is achieved by optical injection between lasing in the cavity axis and the closed ring trajectory of a quasi-stadium laser resonator.
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