Alvaro Casas Bedoya

Multicore, tapered optical fiber for nonlinear pulse reshaping and saturable absorption.

We present a new method to create a coupled waveguide array via tapering a seven-core telecommunications fiber. The fiber based waveguide array is demonstrated to exhibit the novel physics associated with coupled waveguide arrays, such as discrete diffraction and discrete self-focusing. The saturable absorber characteristics of the device are characterized and an autocorrelation measurement reveals significant single-pass pulse reshaping.

In situ optofluidic control of reconfigurable photonic crystal cavities

The mobile nature of fluids is fully exploited in planar photonic crystals to not only tune and reconfigure in situ optical microcavities, in a continuous and reversible manner, but also to create “a posteriori” spatially programmable cavities. Both the amount of liquid and the location of the selectively infiltrated area can be accurately controlled either mechanically, using a microfiber manipulator, or optically, using a laser-controlled evaporation and recondensation scheme. The wide applicability is illustrated by tuning a cavity resonance over 50 nm, adjusting the frequency splitting of an originally degenerate cavity mode, and by freely moving a liquid-induced cavity through dragging a microdroplet.

Measuring the dispersive properties of liquids using a microinterferometer

Using a single-beam, compact interferometer, we measure the refractive index of liquids in the near IR. This highly compact device relies on a silica capillary with a 50 μm inner diameter: it uses a minimal volume of test liquid, isolates the liquid from the humid atmosphere, has broadband operation, and is inherently mechanically stable. These characteristics, in combination with straightforward data acquisition, make it particularly well-suited for measuring the optical properties in the near IR of a wide range of liquids. Using this refractometer, we measure the refractive index of high-index liquids that are expected to be hydroscopic. The accuracy of the refractometer (±0.1%) is demonstrated through measuring the indices of air and pure water. We show that the hydroscopic behavior of the probed liquids has little influence on their optical properties in the near IR.

Phase-sensitive tomography of the joint spectral amplitude of photon pair sources

We present a novel measurement technique to perform full phase-sensitive tomography on the joint spectrum of photon pair sources, using stimulated four-wave mixing and phase-sensitive amplification. Applying this method to an integrated silicon nanowire source with a frequency chirped pump laser, we are able to observe a corresponding phase change in the spectral amplitude that would otherwise be hidden in standard intensity measurements. With a highly nonlinear fiber source, we show that phase-sensitive measurements have superior sensitivity to small spectral features when compared to intensity measurements. This technique enables more complete characterization of photon pair sources based on nonlinear photonics.

Nonlinear Loss Engineering in a Silicon-Chalcogenide Hybrid Optical Waveguide

We fabricated a nonlinear loss engineered silicon-chalcogenide hybrid waveguide and experimentally demonstrated TPA reduction.Additionally, we showed a five-fold improvement in the figure of merit compared to standard silicon nanowire.

Humidity sensor based on a microfluidic infiltrated silicon photonic crystal waveguide

We fabricated a relative humidity sensor based on a selectively infiltrated photonic crystal. We demonstrate how the reversible hydroscopic behavior of the embedded liquid into the air micropores impacts the photonic crystal waveguide cut-off frequency.

Multi-core, tapered fiber for nonlinear pulse reshaping

We present a new method to create a coupled waveguide array via tapering a multi-core telecommunications fiber. This device exhibits the novel physics associated with coupled waveguide arrays: Discrete self-focusing and nonlinear pulse chopping.

Characterization New CO2 Laser Universidad del Valle Cali Colombia

The new CO2 laser constructed in Cali Colombia was characterized. Include power vs. pressure, for a constant voltage and constant pressure, spectrum visible for mixture, stability of the power, wavelength measurement, polarization, and mixture optimization.