Tokin Corporation

Nippon Hoso' Kyokai

Michikazu Kondo

Yuichi Tokano

Kazuhisa Hayeiwa

Tadasu Ishikawa

Hisashi Naka

Yoshiro Sato

Yoshikazu Toba

An electric field sensor comprises a substrate 4, an incident optical waveguide 5 formed on the substrate 4, two branched optical waveguides 6 formed on the substrate 4 to be branched from the incident optical waveguide 5 and having refractive indexes, which are variable in response to an electric field intensity applied thereto, an outgoing optical waveguide 7 formed on the substrate 4 to join the branched optical waveguides 6, and an electric field shielding member 8 formed in the vicinity of a part of the branched optical waveguides 6 for shielding an electric field. The substrate 4 may be provided with a reflection mirror 16 for reflecting light beams from the branched optical waveguides 6. The substrate 4 is made of a ferroelectric material and has polarization directions reverse to each other at portions where the two branched optical waveguides 6 are formed.

Electric field sensor having sensor head with unbalanced electric field

By using an electric field sensor comprising a sensor head 100 for producing a transmitted light wave having an intensity which varies in dependence upon an intensity of an electric field applied thereto, an optical fiber 8 for delivering a light wave from a light source 1 to the sensor head 100 to make the light wave be incident thereto, an optical fiber 9 for delivering the transmitted light wave of the sensor head 100 to a photoelectric transducer 10, and a measuring unit 11 for measurement and display of an electric signal from the photoelectric transducer 10, an electromagnetic noise or an electromagnetic leaking wave is detected as variation of the light intensity by locating the sensor head 100 in the vicinity of a source of the electromagnetic noise or the leaking wave without contacting the source.

Electric field sensor

An electric field sensor comprises an electric field sensor head (3) for varying an intensity of a propagating light beam in response to an electric field intensity of an input signal received by a reception antenna (1). The electric field sensor head (3) comprises an incident optical waveguide (9), two phase-shift optical waveguides (10) having a variable refractive index which varies in response to the electric field intensity, an outgoing optical waveguide (11) and, at least one modulation electrode (12) formed in the vicinity of at least one of the two phase-shift optical waveguides (19). The electric field sensor further comprises a circuit element (2) connected between the modulation electrode (12) and the reception antenna (1). The modulation electrode (12) has a thickness not smaller than 1 .mu.m. The modulation electrode (12) may comprise a plurality of split electrodes which are split in a light propagating direction and which are capacitively coupled. The reception antenna (1) is preferably implemented by a low radiation resistance antenna.

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Sendai, Japan

Michikazu Kondo