Pixelated Micropolarizer Array Based on Carbon Nanotube Films

A micropolarizer array (MPA) that can be integrated into a scientific camera is proposed as a real-time polarimeter that is capable of extracting the polarization parameters. The MPA is based on highly aligned carbon nanotube (CNT) films inspired by their typical anisotropy and selectivity for light propagation over a wide spectral range. The MPA contains a dual-tier CNT pixel plane with 0° and 45° orientations. The thickness of the dual-tier structure of the CNT-based MPA is limited to less than 2 μm with a pixel size of 7.45 μm × 7.45 μm. The degree of polarization of the CNT-MPA reached 93% at a 632 nm wavelength. The specific designs in structure and semiconductor fabrication procedures are described. Compared with customary MPAs, CNT-based MPA holds great potential in decreasing the cross-talk risk associated with lower film thickness and can be extended to a wide spectral range.

Polarization-sensitive optical coherence tomography imaging of the anterior mouse eye

Polarization-sensitive optical coherence tomography (PS-OCT) enables noninvasive, high-resolution imaging of tissue polarization properties. In the anterior segments of human eyes, PS-OCT allows the visualization of birefringent and depolarizing structures. We present the use of PS-OCT for imaging the murine anterior eye. Using a spectral domain PS-OCT setup operating in the 840-nm regime, we performed in vivo volumetric imaging in anesthetized C57BL/6 mice. The polarization properties of murine anterior eye structures largely replicated those known from human PS-OCT imagery, suggesting that the mouse eye may also serve as a model system under polarization contrast. However, dissimilarities were found in the depolarizing structure of the iris which, as we confirmed in postmortem histological sections, were caused by anatomical differences between both species. In addition to the imaging of tissues in the anterior chamber and the iridocorneal angle, we demonstrate longitudinal PS-OCT imaging of the murine anterior segment during mydriasis as well as birefringence imaging of corneal pathology in an aged mouse.

Polarization dependence suppression of optical fiber grating sensor in a π-shifted Sagnac loop interferometer

In the sensing applications of optical fiber grating, it is necessary to reduce the transmission-type polarization dependence to isolate the sensing parameter. It is experimentally shown that the polarization-dependent spectrum of acousto-optic long-period fiber grating sensors can be suppressed in the transmission port of a π-shifted Sagnac loop interferometer. General expressions for the transmittance and reflectance are derived for transmission-type, reflection-type, and partially reflecting/transmitting-type polarization-dependent optical devices. The compensation of polarization dependence through the counter propagation in the Sagnac loop interferometer is quantitatively measured for a commercial in-line polarizer and an acousto-optic long-period fiber grating sensor.