Overclad fiber optic couplers are made by inserting the uncoated portions of a plurality of optical fibers into the bore (14) of a glass tube, collapsing the tube midregion (15) onto the fibers and stretching the central portion of the tube midregion. The present method utilizes a glass tube (10) the bore of which includes a circular portion and a recess. A plurality of optical fibers (21, 22) are sequentially inserted into the tube by threading the coated end into the circular bore portion until the uncoated portion of fiber (23, 24) is centered in the tube. The uncoated portion of fiber is then transferred laterally into the bore (14) recess. After all fibers have been threaded into the circular bore portion and transferred to the recess, a filler fiber (28) is inserted into the circular bore portion. The resultant coupler exhibits low excess loss.

Method of making fiber optic couplers

An electric field sensor comprising an input optical, an incoming waveguide (5) formed on a substrate (4), two branched waveguides (6) branched from the waveguide (5) on the substrate (4) and having refractive indexes variable depending upon the intensity of the applied electric field; an output wave guide (7) joined with the waveguides (6) on the substrate (4); and a shield member (8) provided near the guides (6) to shield part of the waveguide (6) from electric fields. A reflecting mirror (16) may be formed on the substrate (4) so as to reflect light from the guides (6). The substrate (4) may be formed of a ferroelectric substance, in which the respective regions of the two waveguides (6) are polarized in opposite directions.

Electric field sensor

An overclad fiber optic coupler is formed from a coupler preform including a glass tube having a longitudinal aperture. The aperture is formed of a plurality of similarly shaped side walls, each of which includes a longitudinally extending, inwardly projecting protrusions. The region between each two adjacent protrusions constitutes a corner region. Disposed within the aperture are at least a portion of each of a plurality of glass optical fibers, one fiber being situated in each corner region. The midregion of the tube is collapsed onto the fibers, the protrusions maintaining the fibers in their relative positions. At least a portion of the midregion is stretched to reduce the tube midregion diameter.

Method of making fiber optic coupler with longitudinal protrusions

PURPOSE:To eliminate the influence of an optical cable which is extended round by providing a deflector, optical crystal, and an analyzer. CONSTITUTION:The light from a light source 1 is guided to the optical modulator of the part of an antenna 8 by a multi-mode fiber 12 and its output is guided to a receiver 16 by a fiber 12. In this case, no single-mode fiber is used, so tolerance to bending stress, etc., is obtained. The optical modulator which uses the optical crystal 9 extract a linear polarized wave component having a 45 deg. angle to the optical axis of the crystal 9 from an unmodulated signal and outputs an optically modulated signal which is modulated according to the intensity of an electric field applied to the crystal 9. At this time, the part of the optical modulator is integrated at the antenna part 8, so the specific linear polarized wave component is extracted and then the shape of the elliptic polarized light of the unmodulated signal entering the optical modulator is constant or varied at random. Therefore, the antenna 8 which uses the fiber 12 for the transmission of light signals between the light source 1 and antenna 8 is realized and not influenced by the laying-round state of the optical cable.

Electric field antenna using optical crystal

PURPOSE:To set vacuum suction force small and to reduce the noise and the electric power consumption of a vacuum suction system by using both electrostatic attracting force and vacuum suction force for separating the front end of transfer paper from a photoreceptor. CONSTITUTION:The front end part of the transfer paper S moving in contact with the photoreceptor 1 passes by the opposite part of a transfer electrostatic charger 2 and when it almost reaches the opposite position to the slit opening 4a of a suction positioning cylinder 4, a voltage with the opposite polarity to the charged polarity of the transfer paper is applied from a power source 12 to a cylinder member 3. Therefore, the front end of the transfer paper is separated and sucked to the cylinder member 3 by the electrostatic attracting force of the cylinder member 3 and the internal negative pressure of the cylinder 4. Then, the voltage applied to the cylinder member 3 is changed to the same polarity as the charged polarity within, for example, the >=10mm. range of the transfer-paper front end after the separation starts. The switching of voltage application timing and applied polarity is controlled by a controller 13. Thus, the suction force is set small and the noise and power consumption are reduced.

Transferring and separating device

PURPOSE:To eliminate the effect of a resonance phenomenon by a method wherein, when a BSO or BGO single crystal is Z-cut and the work size measures l length X w(mm.) width within a surface perpendicular to a Z-direction, it is set to[(1/l )+(1/w )] > 0.68(1/mm.). CONSTITUTION:So called standard pulse waveform, having a rise time 1musec and a fall time 40musec, is often used in a high-voltage application field, but in order to measure a standard pulse waveform by a sensor, a resonance frequency is needed to be at least 500kHz or more. It order to obtain a photo application voltage sensor having a high resonance frequency of 500kHz or more, and when a BSO crystal is Z-cut to measure l length X w(mm.) width within a surface perpendicular to a Z-direction, it may be set to[(1/l )+(1/w )] >0.68(1/mm.), and this eliminates the effect of a resonance phenomenon due to a surface slip.

Voltage sensor under photo application

PURPOSE:To improve coupling efficiency and reliability by reducing the outside diameter of the end part of the photo detecting part of a guide fiber and forming the end to spherical shape in the photo coupling device in which a light emitting diode and an optical fiber are coupled by way of an optcial guide fiber. CONSTITUTION:An optical guide fiber 11 of a diameter larger than that of an optical fiber 13 is provided between the light emitting part 8 of a light emitting diode 7 and optical fiber 13 and is connected to the optical fiber 13 by means of a connector 12. The end part of said optical fiber 11 opposing to the light emitting part 8 is made smaller in outside diameter and is formed to the shape which has the optical radius determined by the diameter of the light emitting part 8 and the refractive index, etc. of the core 15 and clad 16 at said end. In the case where the end part of the optical guide fiber is not reduced, the radius of the sphere at the end must be made larger than the radius of the guide fiber and therefore it does not become optimum radius. Hence, the above-mentioned method improves the coupling efficiency and improves reliability as well becuase of the absence of any moving parts such as lenses.

Photo coupling device

PURPOSE:To ensure the high-accuracy measurement of wide-ranging voltages with a detecting circuit itself provided with voltage division function by utilizing part of the side face range of a single crystal board on which no electrode is provided for the impression of the voltage to be measured as light passage. CONSTITUTION:The electrodes 5a and 5b to which the voltage to be measured is impressed are formed only in part of the side face of a single erystal board 4, and part of a side face range at which no electrode is provided is utilized as the passage of the light beam 6. The voltage between plates at the light beam passage range 7 becomes lower than those at electrodes 5a and 5b, i.e. the voltage to be measured, and the voltage to be measured is impressed to the range 7 after divided and measured in terms of the intensity of passing output light beam 6. Thereby, a high linearlity can be obtained in measuring even high voltage is impressed directly and the required quantity of parts can be reduced from conventional level.

Light-applying voltage detecting device

PURPOSE:To stabilize sensor sensitivity influenced by the coiling of optical fiber by stabilizing fluctuations of light power by using multi-mode optical fiber for a transmission line and then by interposing a sensor composed of an electrooptical crystal, a wavelength plate and an analyzer, inbetween on the line. CONSTITUTION:Light emitting diode 1 as a light source and photodetector 2 from a PIN photodiode or avalanche photodiode are connected together by multi-mode optical fiber 3 as a transmission line. On the line leading to this optical fiber 3, sensor 4 is equipped, and in this sensor 4, lens 4a, polarizer 4b, electrooptical crystal 4a made of bismuth silicon oxide, etc., wavelength plate 4d, analyzer 4e, and lens 4a are disposed successively in the light traveling direction. Photodetector 2 is provided with amplifier 5. Consequently, fluctuations of light power from the light source are stabilized and the variation in sensitivity of the sensor due to the cooling of the optical fiber can be suppressed.

Voltageeelectric field measuring instrument by means of light

PURPOSE:To stabilize and surely measure the voltage and electric current by connecting with multimode type optical fiber a crystal having a light source quite similar to circular polarized light and an electrooptical effect or an element and a sensor having a faraday effect. CONSTITUTION:A light passge connecting an electrooptical crystal or a faraday element 4 through a light source quite similar to circular polarized light, a lens 10 and a polarizer 3 are formed using a multimode type optical fiber 12. At the same time, a photopassage is formed connecting the afore-mentioned crystal or the element 4 with a sensor 7 through the intermediary of an analyzer 5 and a lens 11, using a multimode type optical fiber 12. Under this constitution, it is possible to avoid a change in the polarized light characteristics due to the bending of optical fiber, etc. and measure voltage and electric current in a stable and sure manner.

Hamazaki Yuuji

Papers

Voltage sensor under photo application

Photo coupling device

Light-applying voltage detecting device

Voltageeelectric field measuring instrument by means of light

Voltage*current measurement device by light beam