Bachelor of Science, Korea Advanced Institute Of Science (2005)
Doctor of Philosophy, Korea Advanced Institute Of Science (2011)
The use of wrinkling provides a generic route to stretchable metamaterials, with unprecedented terahertz tunability. The wrinkled metamaterial can be stretched reversibly up to 52.5%; the structural integrity can be maintained during at least 100 stretching/relaxing cycles. Importantly, the wrinkling of meta-atoms offers a deterministic way to achieve controlled broadening of electrical resonance.
View details for DOI 10.1002/adma.201200419
View details for Web of Science ID 000305943900004
View details for PubMedID 22688807
We demonstrate one-dimensional nanobeam photonic bandedge lasers with InGaAsP quantum wells at room temperature from the lowest dielectric band of photonic crystal nanobeam waveguides. The incident optical power at threshold is 0.6 mW (effectively ~18 ?W). To confirm the lasing from the dielectric bandedge, the polarization and the photoluminescent spectra are taken from nanobeams of varying lattice constants. The observed shift of the lasing wavelength agrees well with the computational prediction.
View details for Web of Science ID 000298322000042
View details for PubMedID 22109430
We investigate high-Q, small mode volume photonic crystal nanobeam cavities using a curved, tapered optical microfiber loop. The strength of the coupling between the cavity and the microfiber loop is shown to depend on the contact position on the nanobeam, angle between the nanobeam and the microfiber, and polarization of the light in the fiber. The results are compared to a resonant scattering measurement.
View details for Web of Science ID 000283679200002
View details for PubMedID 20940950
A photonic crystal microresonator is proposed in this study that is relocatable in two dimensions. A wavelength-scale resonator with high Q-factor (26,000) and high collection efficiency (80%) is formed and repositioned by simply placing and relocating a curved-microfiber to a new position on the surface of a two-dimensional square lattice photonic crystal slab. The formation of the resonator was confirmed by observing lasing of resonators. Infrared microscope images showed that the lasing site is two-dimensionally relocated in-situ. Spectral tuning was demonstrated by modifying the curvature of the microfiber. Functionalities, such as the two-dimensional relocation, spectral tuning and efficient extraction, which the curved-microfiber coupling offers, may provide an alternative way of coupling with a single quantum dot.
View details for Web of Science ID 000268399500082
View details for PubMedID 19654705
A wavelength-scale cavity is generated by printing a carbonaceous nano-block on a photonic-crystal waveguide. The nanometer-size carbonaceous block is grown at a pre-determined region by the electron-beam-induced deposition method. The wavelength-scale photonic-crystal cavity operates as a single mode laser, near 1550 nm with threshold of approximately 100 microW at room temperature. Finite-difference time-domain computations show that a high-quality-factor cavity mode is defined around the nano-block with resonant wavelength slightly longer than the dispersion-edge of the photonic-crystal waveguide. Measured near-field images exhibit photon distribution well-localized in the proximity of the printed nano-block. Linearly-polarized emission along the vertical direction is also observed.
View details for Web of Science ID 000265108900099
View details for PubMedID 19365508
We propose and demonstrate a scheme that enables spectral tuning of a photonic crystal high-quality resonant mode, in steps finer than 0.2 nm, via electron beam induced deposition of carbonaceous nano-dots. The position and size of a nano-dot with a diameter of <100 nm are controlled to an accuracy on the order of nanometers. The possibility of selective modal tuning is also demonstrated by placing nano-dots at locations pre-determined by theoretical computation. The lasing threshold of a photonic crystal mode tends to increase when a nano-dot is grown at the point of strong electric field, showing the absorptive nature of the nano-dot.
View details for Web of Science ID 000257563900064
View details for PubMedID 18575552
We propose and demonstrate evanescently-decoupled, solid-angle-optimized distributed Bragg reflectors (DBRs) for AlGaInP light-emitting diodes (LEDs). The thickness of each DBR layer is tuned to the wavelength slightly longer than the emission peak of the active medium in order to maximize the radiated power integrated over the top surface. In addition, to increase the horizontal radiation through the side facets, the glancing-angle reflectivity at the AlInP/AlAs interface is improved by employing an AlAs layer thicker than the attenuation length of the evanescent field. With the improved DBR, the integrated output power of AlGaInP LEDs is enhanced by a factor of 1.9 in comparison to those of LEDs with conventional DBRs. Additional 1.25-fold enhancement is observed by incorporating an square-lattice hole array (a=1200nm) into the top GaP surface by a conventional photolithography.
View details for Web of Science ID 000255663000007
View details for PubMedID 18545303