Linear and nonlinear directional couplers are currently used in fiber optics communications. They may also play a role in multiphoton approaches to quantum information processing if accurate control is obtained over the phases and polarizations of the signals at the output of the coupler. With this motivation, the constants of motion of the coupler equation are used to obtain an explicit analyt...

We report the realization of a three-path Mach-Zehnder interferometer using single-mode fibers and two integrated 3 x 3 fiber couplers. We observed enhanced phase sensitivity, as compared with two-path interferometers, with a visibility of the interference pattern of more than 97%. This interferometer has an analog in two-photon interferometry, and we believe it to be the first nontrivial examp...

The effect of cross-phase modulation (CPM) on the soliton switching in fiber nonlinear couplers is analyzed by studying the evolution of the soliton parameters at different values of the ratio sigma between the CPM and self-phase modulation contributions. It is shown that the CPM effect may sufficiently modify the switching characteristics, and perfect switching is always achieved for sigma ? 1...

We designed and manufactured two single-mode fiber-to-chip three-dimensional (3D) edge couplers with taper semi-cone structures on a 3.5 µm silicon device layer of silicon-on-insulator. The 3D finite-difference time-domain is used to simulate optimize the structure within 1550 nm band. simulation results reveal maximum coupling efficiency above 91.42% for TE mode. 3 dB tolerances mode in horizo...

For the first time, a non-destructive technique for spatially resolving the location and relative concentration of rare-earth dopants in an optical fiber is demonstrated. This novel technique is based on computerized tomographic detection of spontaneous emission and achieves micron-scale spatial resolution with the aid of oil-immersion imaging. In addition to elucidating interactions between th...

We report significant advances in the development of simple all-fiber, tunable acousto-optic spectral filters based on null couplers. The performance agrees well with theoretical predictions and is attributed to improved control of the coupler uniformity. Furthermore, using a double-pass arrangement, we demonstrate filter bandwidth reduction and improved sidelobe suppression of -20 dB . The dou...