Optical Modulators

Optical modulators vary the amplitude and phase of a light beam; e.g., from a laser or by sound waves. In optical modulation, not only is the phase and amplitude of a beam of light changed, but optical modulators such as a fiber modulator can alter the frequency and direction of the light beam as well.

There are several types of optical modulators. A fiber optic modulator system is used for modulating high power optical carriers to increase the optical power from the modulator without exceeding the optical power damage threshold imposed by the modulator. The low loss and large intrinsic bandwidth of a fiber modulator make them invaluable for the transmission of information at RF frequencies. There are two main types of nonlinear optical modulators, which include the electro-optic modulator and the acousto-optic modulator. The electro-optic modulator is an instrument used to reveal the electro-optic effect that alters a beam of light. This alteration may be by way of changing its amplitude, frequency, phase, or direction. It is possible for modulation bandwidths to move into the gigahertz range using a laser modulator. The electro-optic modulator is used to affect the beam of light using a static electric field. This is an example of nonlinear optics, which is also seen in acousto-optic and fiber optic modulator, by which the refractive index of light is affected. An acousto-optic modulator can utilize the acousto-optic effect of sound waves on light, resulting in the light being diffracted and shifted in frequency. This optic modulator involves the use of a transducer that is secured to a piece of glass. As the electrical current causes the transducer to vibrate, the glass starts to create sound waves within. As a consequence, the light entering will have its index of refraction changed. Acousto-optic modulators are much faster in their function than regular mirrors in varying the amplitude and phase of a beam of light. However when comparing optical modulators, the fastest modulation is carried out by the electro-optic modulator.

Optical modulators are common in many industries such as the chemical, electrical, and telecommunications industries. Optical modulators are also utilized by the Navy and Air Force. Optical modulators can also be used in spectroscopy and in digital telecommunication systems to increase a signal.

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