Our findings suggest that white matter alterations are associated with the pathophysiology of OCD, and the abnormalities may be partly reversible with pharmacotherapy.

A simple method for generating a Laguerre-Gaussian (LG) mode optical vortex beam with well-determined handedness in a single-frequency solid state laser end-pumped by a ring-shaped pump beam is reported. After investigating the intensity profile and the wavefront helicity of each longitudinal mode output to understand generation of the LG mode in a Nd:YVO4 laser resonator, selection of the wavefront handedness has been achieved simply by inserting and tilting an etalon in the resonator, which breaks the propagation symmetry of the Poynting vectors with opposite helicity. Simple calculation and the experimental results are discussed for supporting this selection mechanism.

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Characterization of coherence for superfluorescent light emitted from a diode-pumped Yb-doped fiber source is reported. We have constructed a superfluorescent light source with an adjustable linewidth employing a Yb-doped fiber master oscillator and two power-amplifier stages and measured its coherence length as a function of a linewidth in a Michelson interferometer. The experimental values are in good agreement with the numerically calculated values using the given spectral intensity distribution. The results indicate that the mechanism for linewidth broadening of the fiber superfluorescent output can be attributed to inhomogeneous line broadening of an atomic transition. The prospect of the fiber superfluorescent source with a tailored coherence length will be discussed.