A single-sheet backlight unit (BLU) for dual-sided LCD is designed and demonstrated in this paper. The proposed BLU is comprised only a sheet of lightguide plate (LGP) that is patterned with novel buried inverse-trapezoidal (BIT) microstructures as light output couplers only on the top surface of the LGP. The LGP can light extracting to both the front and back side of the LGP with vertically, therefore, the LGP can act as a dual-sided planar light source for dual-sided LCD solely. Due to its single-sheet nature, the thickness of the BLU is only about 500 µm. The proposed BLU has the potential to reduce thickness, weight, and cost of dual-sided LCD.