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This paper demonstrates the design of high efficiency OLEDs by incorporating micro/nano-metric structures on the surface of and inside the substrate layer of the OLEDs. The OLEDs have been designed and simulated using Lumerical FDTD simulator. We also analyze the performance of the OLEDs from various perspectives such as quantum efficiency, normalized transmitted power, intensity, and angular distribution of light. To increase light extraction from the substrate layer, various micro/nano-metric structures, made of SijN 4 , have been incorporated as light scattering structures. Single layer structures of various size, shape (plano-convex & plano-concave lenses and pillars), and period have been investigated during our simulation. Simulation results confirm higher light extraction, angular distribution, and efficiency in micro/nano-metric structures induced OLEDs, compared to traditional OLEDs. Plano-concave MLA engraved OLEDs show high out-coupling efficiency, whereas, nano-pillars engraved OLED shows consistent light distribution in a wide angular region. We strongly believe that, the proposed OLEDs will have wide range of commercial applications.

We fabricated micro-lens array on fused silica glass using femtosecond and CO2 laser. We micro-machined periodic micro-grooves on the glass surface with femtosecond laser, and polished the patterned surface with CO2 laser. We confirmed that curvature was formed on the surface by heat from the CO2 laser beam as the surface roughness was removed. Depending on the fabricated pattern size, we could fabricate micro-lens array with controlling sizes. Using such this laser fabrication technique, we have demonstrated micro-lens array with various dimension.

We observed enhanced terahertz (THz) transmission by implementing visible excitation in bi-layer graphene transferred on a metal slit which was designed for funneling THz field.

We demonstrate the design and simulation of a focused intense light beam by means of multi-layer Fresnel zone plate fabricated on the surface of and inside the core of a multi-mode optical fiber. We investigate both single layer and multi-layer Fresnel zone plate engraved intense light beam. Besides, we analyze various optical properties of the intense light beam including focusing characteristics, intensity, and beam profile at the near field and far field. Increase in the number of Fresnel zone plate layers inside the core of the optical fiber causes the increase in the intensity and focusing sharpness at the focal point of the focused intense light beam. In addition, we propose suitable fabrication technologies for forming Fresnel zone plate in the core of multi-mode optical fiber. Furthermore, we explore the potential application areas of the proposed intense light beam. We strongly believe that, the designed intense light beam would find numerous applications in a diverse field of science and technology.

This paper demonstrates the characterization of femtosecond laser filamentation in soda-lime glass. We achieved femtosecond pulse filamentation of variable height and width by focusing the femtosecond laser beam in different layers inside the sample glass. The dielectric medium immediately before the target position increases the effective numerical aperture of the objective lens that causes the elongation of focal length of the laser beam in a tiny focal spot with high power density. As a result, high aspect ratio voids are engraved inside the glass samples. Furthermore, we investigate the characteristics of the fabricated voids and their dependence on the irradiation conditions of the laser beam and associated optical setup. The height and width of the voids are controlled by varying the laser power, numerical aperture & magnification of the objective lens, and width of the dielectric medium before laser focusing position. Using high power femtosecond laser pulse filaments, we fabricated very long voids inside the glass sample, which undergoes cleaving process with uniform mechanical pressure for smooth cutting of the glass substrate.

We report on the splitting of the resonant transmission mode, due to the symmetry breaking of the structural shape, in a coupled slit structure. The finding demonstrates the important role of the shape symmetry in designing a plasmonic structure for high-efficiency transmission modulation and supports possibilities of developing new terahertz devices.

We investigated the characteristics of THz radiation from a n-type InAs wafer with a triangular array of air holes under optical excitation. The periodic array of air holes was introduced by a femtosecond laser machining technique. We observed the power enhancement of THz radiation from the InAs surface surrounded by the air holes in a frequency range.

The effects of laser drilling through silicon substrate formed by femtosecond laser on n-type MOSFET device characteristics are investigated. The tested MOSFET device structures are fabricated using the commercial 130-nm process. Through via holes and laser scanning line affect the device characteristics, such as drain current and threshold voltage, depending on the distance between the location of the drilling. The device degradation and variation along with a distance from the holes or the line are examined and the device characteristic variation is analyzed to determine the reliability of MOSFET devices against laser drilling damage.

We report huge field accumulations in rectangular aperture arrays on thin metal film by using shape resonance in THz frequency region. A large far-field transmittance enhancement is observed in the samples of various widths ranging from 10 μm to 1.8 μm which corresponds to only an order of λ/100. Theoretical calculations based on vector diffraction theory indicates 230 times field enhancement in the near-field for the 1.8 μm rectangular aperture.

Micro air cavity fiber Mach-Zehnder interferometer (MZI) was experimentally demonstrated by femtosecond laser micromachining process followed by optimal fusion-splicing. Two optical paths were provided by the cavity to result in a characteristic, wide spacing MZI spectra.

We demonstrated a compact zone plate lens on the end facet of hard polymer clad fiber (HPCF). Femto-second laser inscription technique was developed and the focusing properties of the lens were investigated.

We demonstrate a synchronized femtosecond laser pulse switching system for a rapid patterning, which is applicable to fabricate periodic photonic band gap structures. Also, we show the utility of the femtosecond laser writing of periodic patterns by fabricating the submicron patterns inside a transparent material, which is great potential for future application.

We report formation of nanoparticles and colors in the silver doped glasses produced by femtosecond laser irradiation and feasibility of multilayer three-dimensional optical recording using the photoluminescence change.

We propose one dimensional fiber end-surface grating fabricated by inscribing micro- structure on the cleaved surface of a thermally expanded core fiber with femtosecond laser pulses. For the monitoring of signals, the diffraction patterns according to the wavelength of input light were investigated.