전헌수 교수

Laser diode action in the blue-green has been observed from (Zn,Cd)Se quantum wells within ZnSe/Zn(S,Se) p-n heterojunctions up to 250 K. Operation is reported for two different configurations for which the GaAs substrate serves either as the n- or p-type injecting contact. In pulsed operation, output powers exceeding 0.6 W have been measured in devices prepared on both n-type and p-type GaAs epitaxial buffer layers and substrates.

Laser diode operation has been obtained from (Zn,Cd)Se/ZnSe and (Zn,Cd)Se/Zn(S,Se) quantum well structures in the blue and the green. The devices, prepared on p- and n-type (In,Ga)As or GaAs buffer layers for lattice matching purposes to control the defect density, have been operated at near-room-temperature conditions and briefly at room temperature with uncoated end facets. Quasi-continuous wave operation has been obtained at T=77 K.

We report on studies of optically pumped laser action in (Zn,Cd)Se/ZnSe multiple quantum well structures prepared by molecular beam epitaxy on lattice-matched bulk (Ga,In)As substrates. Room-temperature lasing under pulsed excitation with threshold pump intensity at I≊500 kW/cm2 has been achieved, together with high repetition ‘‘quasi-continuous’’ mode operation at temperatures so far up to 100 K.

Recently, topologically engineered photonic structures have garnered significant attention, as their eigenstates may offer a new insight on photon manipulation and an unconventional route for nanophotonic devices with unprecedented functionalities and robustness. Herein, we present lasing actions at all hierarchical eigenstates that can exist in a topologically designed single two-dimensional (2D) photonic crystal (PhC) platform: 2D bulk, one-dimensional edge, and zero-dimensional corner states.

Following the proof-of-concept experiment in the unit structure level, photonic crystal (PhC) phosphors-structurally engineered phosphor materials based on the nanophotonics principles-are integrated with a blue light-emitting diode (LED) chip to demonstrate a compact and efficient white light source. Red- or green-emitting CdSe-based colloidal quantum dots (CQDs) are coated on a Si₃ N₄ thin-film grating to fabricate PhC phosphors. The underlying PhC structure is designed s

pn junction characteristics and LED action in ZnSe-based multilayers grown by molecular beam epitaxy is demonstrated. In particular, we show that (Zn,Cd)Se/ZnSe/Zn(S,Se) structures containing (Zn,Cd)Se quantum wells, grown on p-type GaAs epilayers, and designed with a heavily doped n+-ZnSe top contact layer may be appropriate for display device applications in the blue-green portion of the spectrum.

Laser action in the blue-green at room temperature has been achieved in pulsed optically pumped (Zn,Cd)Se/ZnSe multiple quantum well structures at threshold intensities Ith≊30 kW/cm2. Continuous-wave operation in a II-VI semiconductor laser has also been demonstrated for the first time, here above 100 K. The role of excitons is found to be of importance in defining the lasing mechanism up to room temperature in these quasi-two-dimensional wide-gap heterostructures.

Abstract A single‐mode laser operation from a solution‐processed halide perovskite alloy system, CH(NH 2 ) 2 Pb(I 1− x Br x ) 3 (0 ≤ x ≤ 1), is reported. Despite its simplicity, the solution process results in halide perovskite alloy films of smooth and uniform surface morphology that exhibits characteristics of bandgap engineering, where t he bandgap and thus emission wavelength can be tuned (from near‐infrared to green) by controlling the anion composition ratio x . A set of thin films of the

A nano-engineered phosphor structure that produces enhanced fluorescence is reported. Two kinds of polymer materials with different refractive indices are spin-coated alternately to realize a one-dimensional (1D) photonic crystal (PC) phosphor platform, in which CdSe/ZnS core-shell quantum dots (QDs) were embedded as a fluorescence agent. The 1D PC phosphor structure is designed to match the pump photon energy with one of the photonic band-edges (PBEs), where the photon group velocity becomes ze

Surface emitting laser operation at room temperature at λ=496 nm by ps pulsed optical injection has been demonstrated in a II–VI separate confinement heterostructure containing three 80 Å thick (Zn,Cd)Se quantum wells (QW). The vertical cavity was formed by low loss, dielectric, distributed Bragg mirrors, yielding a quality factor for the structure of approximately Q≊2000. The room-temperature threshold excitation corresponds to an absorbed optical energy density of 1.4 μJ/cm2 or, equivalently,

Optically activated silk bio-ink is used to realize a physically transient distributed feedback laser. By water-washing and recoating, a fresh single-use laser can be easily obtained. Along with reliable lasing, a chemosensing application to detect a toxic acid vapor is presented. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or ty

We developed a laser interference lithography (LIL) system for fabrication of period-chirped gratings, which would be useful for sophisticated optical components. Despite its simplicity, the developed LIL system, based on a Lloyd's mirror interferometer with a cylindrically concave mirror, can generate chirped gratings, yet over a large area at high throughput owing to the nature of LIL. We have derived exact theoretical equations needed for system design, built the LIL system, and subsequently

Abstract We proposed and demonstrated a modified GaN light‐emitting diode (LED) structure. The structure was made by integrating angled sidewalls to an otherwise conventional LED structure. Various GaN sidewall angles were obtained by adjusting etch conditions and the etched surface roughness was ∼2 nm. Near‐field emission patterns indicated that the angled sidewalls efficiently deflect photons that are initially guided laterally within the GaN epilayer into the off‐surface direction. For sidewa

High-power diode lasers with low-vertical divergence and high-fiber coupling efficiency were developed for GaAs-based 980-nm pump lasers and InP-based 1550-nm Fabry-Perot and distributed-feedback (DFB) lasers. Narrow divergence at 980 nm was made possible by a large optical-mode waveguide design, with full-width at half-maximum (FWHM) far-field angles of 11.7/spl deg//spl times/17.8/spl deg/ and coupling efficiency of 80% into a cleaved single-mode fiber (SMF). A vertical taper processing techni