ABSTRACT
We demonstrate a novel technique to determine the size of Mie scatterers with high sensitivity. Our technique is based on spectral domain optical coherence tomography measurements of the dispersion that is induced by the scattering process. We use both Mie scattering predictions and dispersion measurements of phantoms to show that the scattering dispersion is very sensitive to small changes in the size and/or refractive index of the scatterer. We also show the light scattered from a single sphere is, in some cases, non-minimum phase, and therefore the phase of the scattered light is independent of the intensity. Phase dispersion measurements may have application to distinguishing the size and refractive index of scattering particles in biological tissue samples.
ABSTRACT
We have theoretically and experimentally investigated an optical fiber with circular polarization modes on one end and linear polarization modes on the other end. We call this fiber a polarization-transforming fiber because the local modes, or polarization states they represent, are converted from linear to circular, and visa versa, in the fiber. We have developed and implemented a postdraw process for making polarization-transforming fiber samples 30 mm long with losses less than 1 dB and a polarization-mode conversion from circular to linear greater than 20 dB. Also, we have modeled and measured the dependence on wavelength and temperature of polarization-transforming fiber samples. The measured normalized wavelength dependence of a sample fiber 30 mm long was approximately 1.4 x 10(-4) nm(-1), and the measured normalized temperature dependence was approximately 6 x 10(-4) degrees C(-1). These values are better in some cases than values for conventional high-birefringent fiber quarter-wave plates.
