Optical waveguides – Temporal optical modulation within an optical waveguide – Electro-optic
Patent
1995-03-07
1996-01-30
Ullah, Akm E.
Optical waveguides
Temporal optical modulation within an optical waveguide
Electro-optic
25022711, G02F 1035
Patent
active
054886775
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to an electric field sensor for measuring an electric field intensity of an electromagnetic wave or the like.
BACKGROUND ART
FIG. 1 shows a conventional electric field sensor. The electric field sensor comprises a sensor head 1 and an antenna 2 connected to the sensor head 1. The sensor head 1 has a substrate 3 and an optical modulator 4 attached to the substrate 3.
The optical modulator 4 comprises an incident optical waveguide 5 formed on the substrate 3, two phase-shift optical waveguides 6 which are formed on the substrate 3 to be branched from the incident optical waveguide 5 and each of which has a variable refractive index varying in response to an electric field intensity applied thereto, an outgoing optical waveguide 7 formed on the substrate 3 to join the phase-shift optical waveguides 6, and two modulation electrodes 8 formed on or in the vicinity f the phase-shift optical waveguides 6. The incident optical waveguide 5 is connected to an incident optical fiber 9. The outgoing optical waveguide 7 is connected to an outgoing optical fiber 10.
The antenna 2 has two rod antenna elements 11. The rod antenna elements 11 are connected through lead wires 12 to the modulation electrodes 8, respectively. The rod antenna elements 11 are arranged to face a direction of an electric field, in other words, to be perpendicular to the phase-shift optical waveguides 6. The rod antenna elements 11 are fixed to a package which is not illustrated in the figure.
In the conventional electric field sensor, the antenna elements face the direction of the electric field during measurement. Accordingly, a draw-out portion of the optical fiber faces a direction of measurement. This possibly results in a damage of the optical fiber.
In the conventional electric field sensor, the antenna must be arranged in various directions during measurement because of its strict directivity.
It is an object of this invention to provide an electric field sensor capable of preventing a damage of an optical fiber.
It is another object of this invention to provide an electric field sensor which need not be arranged in various directions during measurement.
DISCLOSURE OF THE INVENTION
This invention comprises a sensor head having a substrate and an optical modulator attached to the substrate, a package accommodating the sensor head, and an antenna attached to the outside of the package and connected to the optical modulator. The optical modulator comprises two phase-shift optical waveguides each of which has a variable refractive index varying in response to an electric field intensity applied thereto, and modulation electrodes formed on or in the vicinity of the phase-shift optical waveguides. The antenna has two rod antenna elements respectively connected to the modulation electrodes. The rod antenna elements extend in opposite directions with their one ends located at a center portion of the package and are arranged in parallel to the phase-shift optical waveguides.
This invention may have a structure such that the antenna comprises two film antenna elements respectively connected to the modulation electrodes and fixedly attached to a side surface of the package and that the film antenna elements extend in opposite directions with their one ends located at a center portion of the package and are arranged in parallel to the phase-shift optical waveguides.
This invention may have a structure such that the antenna comprises two film antenna elements respectively connected to the modulation electrodes and formed on the substrate in parallel to the phase-shift optical waveguides.
Furthermore, this invention comprises a sensor head having a substrate and a plurality of optical modulators attached to the substrate, and a plurality of antennas respectively connected to the optical modulators. Each of the optical modulators comprises an incident optical waveguide formed on the substrate, two phase-shift optical waveguides which are formed on the substrate to be branched from the incident optical waveguid
REFERENCES:
patent: 5008678 (1991-04-01), Herman
patent: 5021731 (1991-06-01), Saaski et al.
patent: 5210407 (1993-05-01), Ito et al.
patent: 5227715 (1993-07-01), Ito et al.
patent: 5267336 (1993-11-01), Sriram et al.
patent: 5402259 (1995-04-01), Lembo et al.
Tokin Corporation
Ullah Akm E.
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