We report bright white-light electroluminescence (EL) from a diode structure consisting of a ZnO nanorod (NR) and a p-type conducting polymer of poly(fluorine) (PF) fabricated using a hydrothermal method. ZnO NRs are successfully grown on an organic layer of PF using a modified seeding layer. The EL spectrum shows a broad emission band covering the entire visible range from 400 to 800 nm. White-light emission is possible because the ZnO-defect-related emission from the ZnO NR/PF heterostructure is enhanced to become over thousand times stronger than that from the usual ZnO NR structure. This strong green-yellow emission associated with the ZnO defects, combined with the blue PF-related emission, results in the white-light emission. Enhancement of the ZnO-defect emission is caused by the presence of Zn(OH)(2) at the interface between the ZnO NRs and PF. Fourier transform infrared spectroscopy reveals that the absorption peaks at 3441, 3502, and 3574 cm(-1) corresponding to the OH group are formed at the ZnO NR/PF heterostructure, which confirms the enhancement of defect emission from the ZnO NR/PF heterostructure. The processing procedure revealed in this work is a convenient and low-cost way to fabricate ZnO-based white-light-emitting devices.
Nonstoichiometric
silicon carbide (SiC) bus/ring waveguide resonator
based all-optical data-format follower and inverter is demonstrated
to perform ultrafast dual-functional wavelength and data-format conversion.
The buried Si quantum dots (Si-QDs) with strong quantum confinement
effect effectively result in a significant change on the nonlinear
refractive index of 3.14 × 10–13 cm2/W, which induces a red-shift of 0.07 nm on the resonant wavelength
comb of the nonstoichiometric SiC ring waveguide resonator. By injecting
the 12 Gbit/s optical pulsed return-to-zero on–off keying (PRZ-OOK)
data stream into the ring waveguide at a notched wavelength of 1551.08
nm, the induced red-shift on resonant wavelengths allows versatile
all-optical data processing functions, including data wavelength conversion
and data format following/inversion, on the data patterns transferred
to the probe. The eye-opening diagram analysis at 12 Gbit/s reveals
that the data transferred to the probe can provide a signal-to-noise
ratio of 9.4 dB, and a receiving power penalty is degraded by 2.6
dB as compared to that of the pump data.
This paper is going to review the state-of-the-art of the high-speed 850/940-nm vertical cavity surface emitting laser (VCSEL), discussing the structural design, mode control and the related data transmission performance. InGaAs/AlGaAs multiple quantum well (MQW) was used to increase the differential gain and photon density in VCSEL. The multiple oxide layers and oxide-confined aperture were well designed in VCSEL to decrease the parasitic capacitance and generate single mode (SM) VCSEL. The maximal modulation bandwidth of 30 GHz was achieved with well-designed VCSEL structure. At the end of the paper, other applications of the near-infrared VCSELs are discussed.
InGaN ternary alloys have been studied with photoluminescence, photoluminescence excitation spectroscopy, scanning electron microscopy, and cathodoluminescence spectroscopy. The relatively large Stokes shift observed in the photoluminescence and photoluminescence excitation spectroscopy has been found to be consistent with previous results reported in the literature. By correlating our experimental findings and others reported in the literature with those of scanning electron microscopy and cathodoluminescence spectroscopy, we conclude that the physical origin of the Stokes shift in InGaN ternary alloy system is primarily due to the effects of alloy composition fluctuations. A plausible model responsible for the observed Stokes shift is proposed.
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