In this research, we demonstrate array of transverse-junction (TJ) blue light-emitting-diodes (LEDs), which are specified
as a horizontal carrier flow instead of side-by-side injection, with a consequence of InxGa1-xN/GaN multiple-quantumwells
(MQWs) as the active region. The demonstrated devices were carried out by the re-growth of n-type GaN on the
sidewall of p-type GaN. Regarding the transverse carrier flow of injected carriers, these TJ-LEDs, as compared to the
control related to traditional vertical junction structure, can effectively spread injected currents more uniformly,
minimize the problem of nonuniform carrier-distribution and current crowding effect, and achieve 35% improvement of
Since the first demonstration in 1990, two-photon fluorescence microscopy (TPFM) has made a great impact on biomedical researches. With its high penetration ability, low out-of-focus photodamage, and intrinsic three-dimensional (3D) sectioning capability, TPFM has been widely applied to various medical diagnosis and genome researches. Recently, single-mode optical fibers were introduced into the TPFM systems for remote optical pulse delivery. Fiber-based TPFM has advantages including isolating the vibration from laser and electronic devices, flexible system design, and low cross-talks. It is also the first step toward an all-fiber based two-photon endoscope. However, due to serious temporal broadening when conventional Ti:sapphire based femtosecond pulses propagate through the fiber, the two-photon excitation efficiency of the fiber-optic TPFM is much lower than the conventional one. The temporal broadening effect mainly comes from group velocity dispersion (GVD) and self-phase modulation (SPM), which also leads to significant spectral broadening. To reduce the temporal broadening effect, here we present a hollow-core photonic-bandgap fiber based TPFM. By replacing the conventional single-mode fiber with the hollow core photonic bandgap fiber, the GVD and SPM effects can be greatly reduced for high intensity, ultra-short pulse delivery. Femtosecond Ti:sapphire pulses passing through the fiber with negligible GVD and SPM effects is demonstrated in this paper. Much improvement of two-photon fluorescence excitation efficiency is thus achieved with the hollow-core photonic-bandgap fiber based TPFM.