We study the propagation of linear waves and solitons in an array of optical waveguides with an embedded defect created by a pair of waveguides with gain and loss satisfying the socalled parity-time (PT ) symmetry condition. We demonstrate that in the case of small soliton amplitudes, the linear theory describes the scattering of solitons with a good accuracy. We find that the incident high-amp...

We will give an overview of our recent work on fibre-optic hvo-photon fluorescence endoscopy devices. The main component of these devices is a singlefibre coupler which acts as a low passfilter. The first device involves a lem-basedprobe head and the second includes a prism-basedprobe head. It has been well-known that two-photon fluorescence imaging systems offer distinct advantages over conven...

A fiber-based multimodal imaging system that combines multiphoton microscopy (MPM) with Fourier domain optical coherence microscopy (OCM) is reported. The system uses a fiber-based femtosecond laser, a fiber coupler, and a double-clad fiber (DCF) device. The fiber laser has a central wavelength of 1.04 μm and bandwidth of 29 nm. Longer excitation wavelength is used to increase penetration depth...

The efficiency of evanescent coupling between a silica optical fiber taper and a silicon photonic crystal waveguide is studied. A high-reflectivity mirror on the end of the photonic crystal waveguide is used to recollect, in the backward-propagating fiber mode, the optical power that is initially coupled into the photonic crystal waveguide. An outcoupled power in the backward-propagating fiber ...

We demonstrate that a nonlinear directional coupler with special bending of waveguide axes can be used for all-optical switching of polychromatic light with a very broad spectrum covering all of the visible region. The bandwidth of the suggested device is enhanced five times compared with conventional couplers. Our results suggest novel opportunities for the creation of all-optical logical gate...

We report the development of on-chip optical components designed to improve the out-coupling of double-metal terahertz (THz) frequency quantum cascade lasers (QCLs). A visible reshaping of the optical beam is achieved, independent of the precise waveguide configuration, by direct incorporation of cyclic-olefin copolymer (COC) dielectric optical fibers onto the QCL facet. A major improvement is ...

Since the photoacoustic effect relies only on the absorbed optical energy, the back-reflected photons from samples in optical-resolution photoacoustic microscopy are usually discarded. By employing a 2 x 2 single-mode fiber optical coupler in a laser-scanning optical-resolution photoacoustic microscope for delivering the illuminating laser light and collecting the back reflected photons, a fibe...