Jinhang Cho

Continuous wave operation of a spiral-shaped microcavity laser

We report a continuous wave laser output of a spiral-shaped InGaAs microcavity laser. When the boundary of the cavity is selectively pumped by current injection with a dc current, the laser generates a directional emission around the notch. We investigate the characteristics of the cw laser operation and observe whispering gallery type modes, whose Q factor is about 7000.

Terahertz beat frequency generation from two-mode lasing operation of coupled microdisk laser

We propose a coupled microdisk laser as a compact and tunable laser source for the generation of a coherent continuous-wave terahertz radiation by photomixing. Using the Schrödinger-Bloch model including the nonlinear effect of active medium, we find single-mode and two-mode lasings depending on the pumping strength. We explain the transitions of lasing modes in terms of resonant modes that are the solutions of the Schrödinger-Bloch model without active medium and nonlinear interaction. In particular, a two-mode lasing is shown to generate a terahertz oscillating frequency originating from the light beating of two nearly degenerated resonant modes with different symmetries.

Light emission of a scarlike mode with assistance of quasiperiodicity

In an elliptic In{sub x}Ga{sub 1-x}AsP microcavity laser, various scarlike modes are experimentally observed. Below the lasing threshold, a bouncing-ball, a triangle, a double, and a triple bow-tie mode spontaneously emit. Above the threshold, a bow-tie scarlike mode lases alone. Our numerical analysis reveals that the bow-tie scarlike mode is not caused by regular islands in phase space due to the Goos-Haenchen shift, but by unstable periodic orbits and that the light emission is assisted by a quasiperiodic orbit.

Unidirectional resonance modes supported by secondary islands in a microcavity comprised of two half-ellipses

We propose a simple and robust mechanism to achieve unidirectional emission in a microcavity comprised of two half-ellipses. The microcavity has two geometrical parameters, two eccentricities, which permit a control of the directional emissions. For the microcavity with two small eccentricities, the positions of secondary islands near primary islands in the survival probability distributions determine the directionality of emissions. We obtain the optimized values of the eccentricities for unidirectional emission.

Outer resonances and effective potential analogy in two-dimensional dielectric cavities

Abstract Outer resonances are studied as one type of quasinormal modes in two-dimensional dielectric cavities with refractive index n > 1 . The outer resonances can be verified as the resonances which survive only outside the cavity in the small opening limit of the dielectric disk. We have confirmed that the outer resonances universally exist in deformed cavities irrespective of the geometry of cavity and they split into nearly degenerate states in slightly deformed cavity. Also we have introduced an extended interpretation of the effective potential analogy for the outer resonances. Since most outer resonances in the dielectric cavities have quite high leakages, they would affect to the broad background in the density of states. But, for TE polarization case, relatively low-leaky outer resonances exist and it presents the possibility that they can interact with the inner resonances.

Oscillatory Lasing Modes In a Coupled Circular Microcavity

We have numerically investigated oscillatory lasing modes in a coupled circular microcavity laser by solving the Schrodinger-Bloch equation with a nonlinear interaction between the light field and the lasing medium. Uniform pumping in the lasing process generates some special patterns as stationary ones, and the patterns are repeatedly shown during the lasing process. In this case, the patterns may be interpreted as linear combinations of the nearly degenerate modes in which the classical trajectory inside the cavity encounter the boundary of the cavity with a nearly critical angle. The numerical results are posted with a brief physical analysis.