Q‐Han Park 교수

Using the Painlev\'e analysis, we investigate the integrability properties of a system of two coupled nonlinear Schr\"odinger equations that describe the propagation of orthogonally polarized optical waves in an isotropic medium. Besides the well-known integrable vector nonlinear Schr\"odinger equation, we show that there exists a set of equations passing the Painlev\'e test where the self and cross phase modulational terms are of different magnitude. We introduce the Hirota bilinearization and

Optical antenna is a nanoscale miniaturisation of radio or microwave antennas that is also governed by the rule of plasmonics. We introduce various types of optical antenna and make an overview of recent developments in optical antenna research. The role of local and surface plasmons in optical antenna is explained through antenna resonance and resonance conditions for specific metal structures are explicitly obtained. A strong electric field is shown to exist within a highly localised region of

The B\"acklund transformation for the three-level coupled Schr\"odinger-Maxwell equation is presented in the matrix potential formalism. By applying the B\"acklund transformation to a constant-electric-field background, we obtain a general solution for matched pulses (a pair of solitary waves) that can emit or absorb a light velocity solitary pulse but otherwise propagate with their shapes invariant. In the special case, this solution describes a steady-state pulse without emission or absorption

We use the four-loop corrections to the gravitational \ensuremath{\beta} function of the N=1 supersymmetric \ensuremath{\sigma} model to compute the on-shell effective action which is relevant up to order \ensuremath{\alpha}${\mathcal{'}}^{3}$ for string amplitudes with external graviton and dilaton fields.

4D self-dual theories are proposed to generalize 2D conformal field theory. We identify 4D self-dual gravity as well as self-dual Yang-Mills theory with 2D sigma models valued in infinite-dimensional gauge groups. It is shown that these models possess infinite-dimensional symmetries with associated algebras—“CP 1 extensions” of respective gauge algebras of 2D sigma models—which generalize the Kac-Moody algebra as well as W ∞ . We address various issues concerning 2D sigma models, twistors and sh

Discovery of low-dimensional materials has been of great interest in physics and material science. Optical permittivity is an optical fingerprint of material electronic structures, and thus it is an important parameter in the study of the properties of materials. Spectroscopic ellipsometry provides a fast, robust, and noninvasive method for obtaining the optical permittivity spectra of newly discovered materials. Atomically thin low-dimensional materials have an extremely short vertical optical

We propose a method for timing optical solitons through an intermittent injection of cw light pulses. By changing amplitude, frequency, and width of a cw light pulse, we demonstrate that a free parametric control of time shift of a soliton is possible. An analytic formula is also provided which agrees well with numerical results.

We propose a single-layer terahertz metasurface that acts as an efficient terahertz waveplate, providing phase retardation of up to 180° with a tunable operation frequency. Designed with the tight coupling of elementary resonators, our metasurface provides extraordinarily strong hyperbolicity that is closely associated with the distance between resonators, enabling both significant phase retardation and spectral tunability through mechanical deformation. The proposed concept of terahertz wavepla