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 demonstrate a random bit streaming system that uses a chaotic laser as its physical entropy source. By performing real-time bit manipulation for bias reduction, we were able to provide the memory of a personal computer with a constant supply of ready-to-use physical random bits at a throughput of up to 4 Gbps. We pay special attention to the end-to-end(More)
We investigated the polarization characteristics of emissions from two-dimensional microcavity laser diodes. For an unstrained single-quantum-well active layer structure, an argument based on the interband optical transition usually leads to the lasing of transverse electric (TE) rather than transverse magnetic (TM) modes. Indeed, we observed TE-polarized(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)