Table 1 is a summary of the most common materials used for the NEOS acousto-optic modulators. For the visible region and near infrared region the common modulators are made from dense flint glass, tellurium oxide, chalcogenide glass or fused quartz. At the infered region, germanium is the only commercially available modulator material with a relatively high figure of merit. Lithium niobate, and gallium phosphide are used for high frequency signal processing devices. Once the acousto-optic material is selected, it is optically polished, and a lithium niobate transducer is metal vacuum bonded to the modulator medium.
Metal bonding provides a much better acoustic coupling than epoxy bonding.
NEOS used only high quality metal bonds. Then the transducer is lapped to the fundamental resonant frequency such as 80MHz. The RF drive usually consists of an RF oscillator, an amplitude modulator with an interface which accepts input modulation, and an RF amplifier which drives the AO modulator. The acousto-optic modulator is used to shutter the laser beam on and off by an external digital TTL signal. The TTL signal allows for easy interface to a computer.