Non-invasive characterization of the domain boundary and structure properties of periodically poled ferroelectrics.

Shaping the ferroelectric domains as waveguide, grating, lens, and prism are key to the successful penetration of periodically-poled ferroelectrics on various wavelength conversion applications. The complicated structures are, however, difficult to be fully characterized, especially the unexpected index contrast at the anti-parallel domain boundaries are typical in the order of 10(-4) or less. An ultrahigh resolution optical coherence tomography was employed to fully characterize the domain boundary and structure properties of a periodically-poled lithium niobate (PPLN) waveguide with an axial resolution of 0.

Microstructural and microspectral characterization of a vertically aligned liquid crystal display panel.

The microstructural and microspectral characteristics of a vertically aligned liquid crystal display (VA-LCD) panel were obtained noninvasively for the first time. With 1 μm axial and 2 μm transversal resolutions, the cell gap profile beneath the patterned thin-film transistor of the VA-LCD panel can clearly be resolved. The thicknesses of the multiple thin-film layers and the embedded defects can also be unveiled.

Multipass acoustically open photoacoustic detector for trace gas measurements.

What we believe to be a novel multipass, acoustically open photoacoustic detector designed for fast-response, high-sensitivity detection of trace gases and pollutants in the atmosphere is demonstrated. The acoustic pulses generated by the absorption of the light pulses of a tunable optical parametric oscillator by target molecules are detected by an ultrasonic sensor at 40 kHz. The photoacoustic signal is enhanced by an optical multipass arrangement and by concentration of the acoustic energy to the surface of the ultrasonic sensor.