Millimeter Wave Coplanar Structures on InP for Electro-Optic Modulation Applications
External optical modulators are essential components in optical fiber communication systems for frequencies in excess of 10 GHz. Modulators fabricated on compound semiconductor substrates, such as gallium arsenide (GaAs) or indium phosphide (InP), normally have a phase velocity mismatch between the optical signal propagating in the optical waveguide and the modulating microwave signal applied to the conventional coplanar waveguides1. In such a case, the microwave signal travels faster than the optical signal. If the two velocities can be matched, the bandwidth of these optical modulators will be limited only by electrode microwave losses2. The velocity-match condition can be obtained by slowing down the microwave signal. Significant research has already been carried out for the optimization and characterization of slow wave structures on semi-insulating GaAs3–5.
KeywordsPhase Velocity Characteristic Impedance Gallium Arsenide Microwave Signal Slow Wave Structure
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