All-dielectric miniature wideband rf receive antenna

An integrated Mach-Zehnder interferometer made of electro-optic (EO) polymers with a dimension of 3×1.2 cm was fabricated as a wideband rf receive antenna. When an electric field is applied to the interferometer arm(s) made of EO material, a phase delay is generated that results in a net imbalance in the interferometer, and thus a change in the output intensity. This output intensity change, which contains electric field strength and temporal profile information, is then read by a photodetector and processed. This antenna was tested in a μ-strip traveling wave electromagnetic cell at frequencies from 100 MHz to 1.04 GHz. The test results show the antenna had a good linear response over a 70-dB power range. The lowest possible measured $Emin$ was about 4 mV/m (or 2.1 pW/cm²) at 1-kHz resolution bandwidth with a laser power of 0.4 mW (−4 dBm) measured after the sensor. The measured E-field signal increases with increasing laser power, which indicates that significant sensitivity improvement can be easily obtained by lowering passive losses. The antenna sensitivity can be further improved by lowering the device insertion loss, optimizing the photodetector and detection circuitry, and using EO polymers with higher EO coefficients. © 2004 Society of Photo-Optical Instrumentation Engineers.