-
The external modulator is optically passive
In external modulation, an external device is incorporated to modulate the intensity or phase of the light source. Figure 1: Laser diode used for direct modulation. 3 Laser modulation ofers an alternative method for light detection and ranging (LIDAR) measurements with benefits of lower danger of eye damage and higher sensitivity. ve chirp free, high data rate, long-link length optical communication. The beam may be carried over free space, or propagated through an optical waveguide (optical fibre). Depending on the parameter of a light beam which is manipulated, modulators may be categorized into amplitude modulators. An external modulator restrains the light, functioning like an electrically activated shutter. It acts as the “translator” between the electronic and photonic worlds.