Electrically tunable transmission type beam deflector using liquid crystal with high resolution and wide angle

Abstract: : High efficient transmission type beam deflectors which have wide angle have been widely used for various applications. Especially, continuously tunable beam deflectors have been also needed for a lot of purposes. An indium-tin-oxide (ITO), widely used for transparent electrode, was placed on the upper and lower glass substrate. The ITO layer on the lower substrate was patterned by the contact mask aligner for relatively wide input and output pad compare to main grating ITO patterns in active area. These input and output pads on the lower substrate are connected to each driving integrated circuit (IC) which have 360 channels for continuous control. A small pixel pitch of grating patterns of 6 μm, the electrode width is 3 μm with a 3 μm spacing, was developed and the maximum diffraction angle is calculated and measured at 2.541º with a wavelength of 532 nm. A minimal cell-gap of 2.5 μm was applied for the full 2 π phase modulation by using a high birefringence liquid crystal. Driving module for continuous beam steering is also developed and applied to the beam deflector system. The diffraction efficiency of about 50.9％ is observed at an angle of diffraction about 2.541°.