| 摘要 |
An electro-optic, phase-only spatial light modulator is disclosed which uses an electro-optic wafer, such as lithium niobate (LiNbO3) or lead-lanthanum-zirconate-titanate (PLZT). The electro-optic wafer is sandwiched between a transparent top electrode that forms a solid ground plane and a bottom electrode that is segmented into an array of electrode pads. Voltage source circuitry for each electrode is located immediately beneath the electrode. When a voltage is applied across the electrodes, an electrostatic field is generated between the conductors, and the refractive index of the electro-optic wafer changes slightly. The spatial light modulator can also include a totally reflecting dielectric mirror on the bottom face of the electro-optic wafer and a partially reflecting dielectric mirror deposited on the top face. Together, the mirrors and wafer form an asymmetric Fabry-Perot cavity. This resonant cavity enhances the effect that the small changes in the wafer's refractive index has, resulting in phase shifts of ±½pi in the reflected light. Because the bottom electrode is segmented, a different voltage can be applied to each electrode. Thus, the refractive index, and therefore the phase of the exiting light wave, can be manipulated to vary with position. In this way, the phase of the outgoing optical wavefront is spatially modulated. The voltage source integrated circuitry for each electrode is located immediately behind the electrode pad. This integrated circuitry is fabricated on a separate silicon wafer that is later bonded to the electro-optic wafer.
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