Demonstration of a reef knot microfiber resonator.

We propose a new way to realize a microfiber optical resonator by implementing the topology of a reef knot using two microfibers. We describe how this structure, which includes 4 ports and can serve as an add-drop filter, can be fabricated. Resonances in an all-silica reef knot are measured and good fits are obtained from a simple resonator model.

Observation of a nonlinear microfiber resonator.

Measurements of the intensity transfer function of a silica microfiber resonator are shown to follow a wide variety of hysteresis cycles, depending on the cavity detuning and the scanning frequency of the range of input powers. We attribute these observations to a nonlinear phase shift of thermal origin and provide a simple model that reproduces well our measurements. The response time is found to be around 0.

All-fiber add-drop filters based on microfiber knot resonators.

We demonstrate an all-fiber add-drop filter composed of a microfiber knot (working as a resonator) and a fiber taper (working as a dropping fiber). The dropping taper can be either parallel or perpendicular to the input port of the filter. A quality factor (Q factor) of 13,000 is obtained from a parallel-coupling 308 microm diameter microknot add-drop filter with a free spectral range (FSR) of 1.

Modeling rare-earth doped microfiber ring lasers.

We propose a compact laser configuration based on resonating both the pump and signal light along a microfiber ring doped with active ions. We estimate the minimum Q-factor to obtain lasing and find that values already demonstrated in passive microfiber rings will be sufficient. We model the performance of this device in steady state using rate equations and show that pump resonance can significantly reduce the threshold and increase the quantum efficiency, especially for rings made of materials with weak active ion absorption.

Ultra-large bandwidth hollow-core guiding in all-silica Bragg fibers with nano-supports.

We demonstrate a new class of hollow-core Bragg fibers that are composed of concentric cylindrical silica rings separated by nanoscale support bridges. We theoretically predict and experimentally observe hollow-core confinement over an octave frequency range. The bandwidth of bandgap guiding in this new class of Bragg fibers exceeds that of other hollow-core fibers reported in the literature.

Side pumping of double-clad photonic crystal fibers.

Side pumping of double-clad photonic crystal fibers is experimentally demonstrated. Optical access to the multimode cladding is obtained by collapsing the airholes over a short length of fiber while leaving the inner single-mode core undisturbed. Coupling efficiencies greater than 90% are obtained.

Investigation of microdeformation-induced attenuation spectra in a photonic crystal fiber.

We investigate both theoretically and experimentally the induced spectral attenuation in an all-silica photonic crystal fiber subjected to periodic axial microdeformations. The induced attenuation spectra show discrete attenuation peaks with a spectral position that is dependent on the period of the induced deformation. The peaks are assumed to be the result of mode coupling between the fundamental mode and a highly lossy higher-order mode.