Means of reducing the conductor loss of a liquid crystal millimeter-wave beam former were studied. The conductor loss is caused by surface currents flowing on electrodes of the beam former for applying control voltages to the liquid crystal layers. By making the electrode thickness comparable to or thinner than the skin depth, the surface currents that flow on both sides of the electrode in opposite directions cancel each other; consequently, the conductor loss can be reduced. Simulation results proved that doing so can effectively reduce the conductor loss.
In this paper, the impacts of pump propagating direction in double-pass Erbium-doped fiber amplifier are experimentally demonstrated. The double-pass optical amplifier architecture is constructed using a fiber loop mirror that consists of a circulator to reflect the amplified signal back into the Erbium-doped fiber. The gain and noise figure performance of the double-pass optical amplifier is not affected by the direction of pump light, forward- or backward-pumped scheme. The population inversion along the Erbium-doped fiber is locked to a specific fraction due to the double-pass amplification of the signal.
A wide dynamic range CMOS image sensor based on a new active pixel structure with a pinned photodiode is proposed and evaluated with device simulations. The proposed pixel device has a linear and a logarithmic characteristics in low and high illumination region, respectively. The technique of direct detection of photodiode potential leads to a wide logarithmic response compared with the conventional linear-log wide DR image sensor with pinned photo diode.