• Title/Summary/Keyword: microcavities

Search Result 16, Processing Time 0.027 seconds

Spectral Behaviors of Unidirectional Lasing from Various Semiconductor Square Ring Microcavities

  • Moon, Hee-Jong;Hyun, Kyung-Sook;Lim, Changhwan
    • Journal of the Korean Physical Society
    • /
    • v.73 no.10
    • /
    • pp.1506-1511
    • /
    • 2018
  • Spectral behaviors of lasing from semiconductor square ring microcavities with structures for unidirectional laser oscillation were investigated. When a tapered structure was introduced, the lasing envelope shifted to a shorter wavelength region. Statistical estimate of the additional loss caused by the tapered structure was carried out by analyzing spectral data from many sets of cavities with various sizes. When a saw-edged structure was introduced, the unidirectional lasing functioned well but no apparent spectral shift was observed due to negligible additional loss.

Observation of Strong Coupling between Cavity Photon and Exciton in GaN Micro-rod

  • Gong, Su-Hyun;Ko, Suk-Min;Cho, Yong-Hoon
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • 2014.02a
    • /
    • pp.297.2-297.2
    • /
    • 2014
  • Strong exciton-photon coupling in microcavities have generated an intense research effort since quasiparticles called exciton polaritons are produced and shows interesting phenomena. Most of studies have been done with GaAs based microcavities at cryogenic temperature. Recently, GaN material which has large exciton binding energy and oscillator strength has much attention because strong coupling between photon and exciton could be realized at room temperature. However, fabrication of high quality microcavity using GaN is challengeable due to the large mismatch between the lattice and the thermal expansion coefficient in GaN based distributed Bragg mirror. Here, we observed strong coupling regime of exciton-photon in GaN micro-rods which were grown by metalorganic vapour phase epitaxy (MOCVD) on Si substrate. Owing to the hexagonal cross-section of micro-rod, whispering gallery modes of photon are naturally formed and could be coupled with exciton in GaN. Using angle-resolved micro-photoluminescence measurement, exciton polariton dispersion curves were directly observed from GaN micro-rod. We expect room temperature exciton polariton condensation could be realized in high quality GaN micro-rod.

  • PDF

Bow-tie Mode Lasing in a Grooved Rectangular Semiconductor Microcavity

  • Moon, Hee-Jong;Hyun, Kyung-Sook
    • Journal of the Optical Society of Korea
    • /
    • v.16 no.2
    • /
    • pp.162-165
    • /
    • 2012
  • Bow-tie modes were proposed in a grooved rectangular resonator and their lasing characteristics were investigated in semiconductor microcavities. The observed spacing between two adjacent lasing peaks from the grooved cavity was reduced compared to that of 4-bounce whispering gallery modes (WGMs) from the same-sized simple rectangular cavity due to increased round-trip path length of the bow-tie modes. The lasing spectra of bow-tie modes obtained from two adjacent corners showed highly correlated patterns while those of 4-bounce WGMs did not.

Tafoni Patterns on Tuff Slopes in Gogulsa Temple, Gyeongju and Its Microstructural Properties (경주 골굴사 응회암 사면의 타포니 분포 특성과 미세구조)

  • Choo, Chang-Oh;Lee, Jin-Kook
    • The Journal of Engineering Geology
    • /
    • v.32 no.3
    • /
    • pp.339-350
    • /
    • 2022
  • There are a variety of types in tafoni formed in Miocene tuff from Golgulsa, Gyeongju. Tuff bearing tafoni was quite weathered, composed of quartz, feldspars, micas, vermiculite, chlorite, smectite, and analcite. In the early stage of the tafoni development, tafoni preferentially formed from cavities where volcanic breccias were removed or from microcavities where microcrystals were chemically altered. Small tafoni grew into large one by merging each other. The orientation of tafoni is inversely arranged to slopes, with slight inclination toward the inner cavity. Height, width, and depth of tafoni are closely interrelated: the correlation coefficients are 0.839 (width-height), 0.900 (width-depth), and 0.856 (height-depth), respectively. Removal of walls between tafoni resulted in lenticular or crescent forms, and small tafoni laterally combined to large tafoni. Large tafoni is weak because of high porosity and low strength compared to normal slope. Therefore, systematic monitoring for slope strength, pore proportion and volume, and growth of cavity needs to secure the slope stability where tafoni in Golgulsa is widespread.

Study of nano patterning rheology in hot embossing process (핫엠보싱 공정에서의 미세 패턴 성형에 관한 연구)

  • Kim, H.;Kim, K.S.;Kim, H.Y.;Kim, B.H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
    • /
    • 2003.10a
    • /
    • pp.371-376
    • /
    • 2003
  • The hot embossing process has been mentioned as one of major nanoreplication techniques. This is due to its simple process, low cost, high replication fidelity and relatively high throughput. As the initial step of quantitating the embossing process, simple parametric study about embossing time have been carried out using high-resolution masters which patterned by the DRIE process and laser machining. Under the various embossing time, the viscous flow of thin PMMA films into microcavities during Compression force has been investigated. Also, a study about simulating the viscous flow during embossing process has planned and continuum scale FDM analysis was applied on this simulation. With currently available test data and condition, simple FDM analysis using FLOW3D was made attempt to match simulation and experiment.

  • PDF

Quantitative rheology of polymers in high resolution structuring (미세성형공정에서의 폴리머 레올로지의 정량화)

  • Kim, Byeong-Hee;Kim, Heon-Young;Ki, Ho;Kim, Kwang-Soon;Kang, Shin-Ill
    • Proceedings of the KSME Conference
    • /
    • 2003.04a
    • /
    • pp.1036-1042
    • /
    • 2003
  • The hot embossing process has been mentioned as one of major nanoreplication techniques. This is due to its simple process, low cost, high replication fidelity and relatively high throughput. As the initial step of quantitating the embossing process , simple parametric study about embossing time have been carried out using high-resolution masters which patterned by the DRIE process and laser machining. Under the various embossing time, the viscous flow of thin PMMA films into microcavities during compression force has been investigated. Also, a study about simulating the viscous flow during embossing process has planned and continuum scale FDM analysis was applied on this simulation. With currently available test data and condition, simple FDM analysis using FLOW3D was made attempt to match simulation and experiment.

  • PDF