| 학회 | 한국재료학회 |
| 학술대회 | 2021년 가을 (11/24 ~ 11/26, 경주 라한호텔) |
| 권호 | 27권 2호 |
| 발표분야 | D. 구조 재료 분과 |
| 제목 | Acoustic Goos-Hänchen shift and Fresnel filtering effect in the hemispherical acoustic Luneburg lens |
| 초록 | The acoustic Luneberg lens with a radius R is a spherical lens whose refractive index changes as [2- (r / R)2]1/2 according to the distance r away from the center of the medium. When acoustic plane waves are incident on the lens, the waves are focused on the opposite side of the lens and this device has an aberration-free characteristic. In case of such a spherical lens, it is difficult to use a one-dimensional or two-dimensional detector-array. This problem can be solved by using a quasi-conformal mapping to convert the focus point area of a sound wave from a spherical plane to a flat plane while maintaining their physical characteristics. We studied the characteristics of the acoustic Luneburg lens of a shape of hemisphere (two dimensional: 2D) which is transformed from spherical shape using the quasi-conformal mapping and orifice type metamaterial unit cells. We designed and fabricated the 2D hemispherical acoustic Luneburg lens that is composed of the face-centered-orifice-cubic (FCOC) unit cells. We investigated the characteristics of the device with respect to the incident angle and frequency that satisfy the homogeneous medium condition of the metamaterial through the numerical simulation and the experiment. From the results of the simulation and experiment, we observed the transformed antipodal point focusing of the hemispherical Luneburg lens on the opposite flattened surface with respect to the incidence angles and frequencies of the plane waves. In particular, the effects of acoustic Goos-Hänchen shift and Fresnel filtering were observed. Acknowledgements This work was supported by grants from the National Research Foundation of Korea, funded by the Korean government (MEST) (Grants NRF-2017R1D1A1B03033936, NRF-2017R1A2B4009179, NRF-2020R1I1A1A01068135, NRF-2020R1F1A1065865). |
| 저자 | Choon Mahn Park1, Geo-Su Yim2, Kyuman Cho3, Sang Hun Lee4 |
| 소속 | 1Dong-A Univ., 2Dept. of Materials Physics, 3Busan 49315, 4South Korea |
| 키워드 | Acoustic metamaterial; conformal transformation; Luneburg lens; GRIN lens; metamaterial; optics; acoustics. |
