Takahisa Harayama

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We show that the solution of fully nonlinear lasing equations for stadium cavities exhibits a highly directional emission pattern. This directionality can be well explained by a ray-dynamical model, where the dominant ray-escape dynamics is governed by the unstable manifolds of the unstable short periodic orbits for the stadium cavity. Investigating the(More)
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(More)
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(More)
Laser action on a single spatially chaotic wave function is obtained as a final stable state in a nonlinear dynamical model of a stadium shaped resonant cavity with an active medium. The stable single-mode lasing state corresponds to a particular metastable resonance of the cavity which wins a competition among multiple modes with positive net linear gain(More)
We propose a flower-shaped billiard in order to study the irregular parameter dependence of chaotic normal diffusion. Our model is an open system consisting of periodically distributed obstacles in the shape of a flower, and it is strongly chaotic for almost all parameter values. We compute the parameter dependent diffusion coefficient of this model from(More)
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(More)
We fabricated and investigated two confocal quasi-stadium laser diodes: one has a narrow electrode contact pattern along its cavity axis and the other has a narrow electrode contact pattern along a diamond-shaped trajectory. The lowest-order axial and ring modes were selectively excited. The resonator modes of the laser diodes were calculated using the(More)