I PAPER Special Issue on Optical Fiber Sensors Improving Design Method for Sensitivity and Frequency Response ofE-Field Sensor Using a Mach-Zehnder Interferometer

SUMMARY Thedesign method forsensitivity andfrequency re-sponse of anelectric fieldsensorusinga Mach-Zehnder interferometer (anoptical E-field sensor) hasbeendeveloped inorderto measure elec-tromagnetic environments and the performance of measuring facili-ties.Thedesigns of theoptical modulator, sensorelements, andsensi-tivity wereanalyzed theoretically by usingan accurate equivalent cir-cuitof thesensor. Thenanactual sensorwasfabricated, andits charac-teristics of thesensorwereevaluated experimentally. Theresultsshow thatthedesigned sensitivity andfrequency response wereoptimal. The optical outputdeviation when thetemperature increased from0 to40'C was reduced to within 2 dB. The minimum detectableelectric field strength was 17dBIlV/m (8IlV/m), and the dynamic rangewasmore than100dB.Thefrequency response of thesensitivity wasalmostflat between 200Hz and900MHz. key words: electric field sensor, antenna measurement, optical modulator, electro-optical effect, EMC 1