Alejandra Lopez-Santiago

Faraday rotation in magnetite-polymethylmethacrylate core-shell nanocomposites with high optical quality

Wavelength dependent Faraday rotation measured at room temperature in a polymer containing varying concentrations of crosslinked magnetite core poly(3-methyl)methacrylate (PMMA) shell nanocomposite particles is reported. The magnitude of the FR in these composites appears to be strongly dependent on the concentration of the particles, the wavelength of measurement, and the size and shape of the nanoparticles. Comparison of the figure of merit of 2.1° in these core-shell nanocomposites to that of 4.2° for yttrium iron garnet at 980 nm indicates that these nanocomposites may find applications in various magnetic and magneto-optic sensors and devices.

Cobalt ferrite nanoparticles polymer composites based all-optical magnetometer

A method has been developed to prepare cobalt ferrite particle core polymer shell nanoparticles. These engineered nanoparticles can be further embedded into a polymer host matrix to develop highly transparent polymer based magneto-optic materials. A proof-of-principle all-optical magnetometer has been constructed based on the cobalt ferrite core polymer shell based nanocomposite material. A noise equivalent magnetic field sensitivity of 50nT/√Hz was observed using a 3μT 500Hz control magnetic field.

Effect of modular diffraction gratings on absorption in P3HT:PCBM layers

Various gratings with 700 nm feature spacings are patterned on the reverse side of organic solar cell active layers to increase the path length and constrain light to the cell through total internal reflection. The absorption enhancement is studied for 15, 40, and 120 nm active layers. We were able to confine 9% of the incident light over the wavelength range of 400-650 nm, with thinner gratings having a greater enhancement potential. The measurement setup utilizing an integrating sphere to fully characterize scattered or diffracted light is also fully described.

Polarization independent and low loss laser written polysiloxane interconnect building blocks

Single-mode polysiloxane based waveguides and directional couplers, key optical interconnect building blocks, were fabricated using direct laser writing. Key performance parameters include polarization independent propagation loss of 0.23 dB/cm and a possible wafer scale fabrication.

New materials for magneto optic in-fiber and waveguide isolators

We report recent advances in new magneto optic materials including novel colorless magnetic ionic liquids and magnetic nanoparticle-core polymer-shell nanocomposites for non-reciprocal in-fiber and waveguide operation for isolation and circulation.

Magnetic and magneto optic properties of substituted polythiophenes

We report on our recent observation of magnetic and magneto optic properties of regioregular substituted polythiophenes. The relevance of existing mechanisms within the classical limit in cognizance of our recent magnetic and MO measurements on a set of π-conjugated polymer is also discussed.

Faraday Rotation Measurements on Thin Films of Regioregular Alkyl Substituted Polythiophene

Faraday rotation has been measured in thin films of regioregular alkyl substituted polythiophene derivatives in their pristine state. These results could lead to a new frontier of conjugated polymer research.