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We investigated the interactions among unperturbed-basis modes in an asymmetrical-deformed optical microcavity. We found that the coupling strength is enhanced when the angular mode number difference of interacting modes equals an integer multiple of the number of the chain islands. We could explain this phenomenon by applying the theory of resonance-assisted tunneling (RAT) to our microcavity system.
Output directionality of asymmetric optical microcavities has been widely studied revealing many interesting features. Especially the tunneling emission is now attracting many interests due to the unexpected features in the semiclassical model. We found that the tunneling emission pattern in the far-field region can be reconstructed from the outside-outgoing Husimi function corresponding to the critical...
We have studied circular shell ultrasonic cavities immersed in water in both theory and experiment. Calculations show that there exist two types of modes (mainly residing in the inner cavity and in the shell, respectively) and they interact with each other via the coupling across the inner boundary. We have experimentally confirmed this by using the schlieren method.
We show that high-Q modes in a strongly deformed microcavity can be efficiently excited by free-space resonant pumping. We observed that the far-field pattern of cavity transmission is changed when a probe laser is resonant with a scar mode, which can be excited by free-space optical pumping. By measuring the difference between the pump-beam transmission in the nonresonant pumping and that in the...
We have performed boundary-element-method (BEM) simulations in a ultrasonic cavity. To confirm the accuracy of our BEM calculation, the BEM results obtained for a circular cavity were compared with the analytic solutions for the same cavity. In the simulation results, we found that the imaginary part of the resonance frequency shows different aspects from that of a corresponding optical microcavity.
We report experimental study on the evolution of the emission mechanism by using a phase-space imaging technique based on the local angular momentum conservation in emission process in a chaotic optical microcavity as the cavity deformation corresponding to nonintegrability increases. In the regime of weak deformation, we could image the output beam being emitted tangentially from a location at a...
We employ an ultrasonic acoustic cavity in which the pressure field satisfies the same form of Helmholtz equation as the optical field in an optical microcavity of much interest, where many interesting features of mode distributions are expected but difficult to observe directly. Mode patterns in an acoustic cavity are measured with the Schlieren method, not perturbing the mode distributions at all...
We have demonstrated free-space resonant coupling with a two-dimensional deformed microcavity made of a liquid jet of ethanol doped with laser dye. The pumping efficiency was obtained from the measurement of threshold pump power. We have achieved a thousand-fold enhancement in the pumping efficiency.
We have measured pumping efficiency experimentally in a deformed microcavity laser. We observed a tenfold enhancement in the pumping efficiency via chaos-assisted nonresonant optical pumping at properly chosen pumping angle and position. When the pump wavelength was scanned at the optimal pumping angle and position in a manner of excitation spectroscopy, we observed an additional hundredfold enhancement...
We have developed a new surface boundary profiling technique based on forward shadow diffraction that satisfies both requirements of high-precision and applicability for soft columnar objects and have measured the boundary shape of a microscopic liquid jet two-dimensional microcavity with it. We established a reciprocal relation between the forwardly-projected width of an opaque object and the angular...
Tenfold enhancement in the pumping efficiency has been observed at a properly chosen pumping angle and a position in chaos-assissted nonresonant optical pumping of a deformed microcavity laser. The pumping efficiency distribution resembles the output emission intensity distribution of the deformed microcavity, consistent with the concept of the time-reversal ray tracing.
We have found that the angular width between two adjacent local minima on the forward diffraction pattern of an opaque convex object is inversely proportional to the projection width of the object in that diffraction direction. Based on this finding we have developed a nondestructive two-dimensional surface mapping technique with a 20-nm resolution.
We have demonstrated an efficient nonresonant optical pumping scheme for high-Q scar modes in a two-dimensional quadrupole-deformed microlaser. We could obtain the dependence of pumping efficiency on the pumping angle from the cavity-modified fluorescence and from the measurement of threshold pump, which is inversely proportional to the pumping efficiency. Up to three-fold enhancement in the pumping...
The characteristics of quasi-bound states of a highly deformed microcavity were investigated in both theory and experiment. Five distinct mode groups were observed with cavity quality factors different by several orders of magnitude in the range of 104 - 106. Consistently they had quite different intracavity mode distributions. However, their far-field emission patterns were found to be almost identical,...
It is crucial to know how to determine the direction of far-field emission in deformed microcavities. We review the recent advances on this issue focusing on our works. To realize a microlaser with extremely large Q value, the so-called whispering gallery mode (WGM) in the dielectric cavity with spherical or cylindrical boundary has been extensively investigated. The WGM is a mode generated from the...
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