摘要:
A laser Doppler velocimeter in which laser light whose frequency changes continuously at least for a fixed time duration is branched into at least two beams, and the at least two branched beams are respectively transmitted by at least one pair of optical fibers having an optical path difference therebetween, and are focused onto a region to be measured by at least one focusing device. The scattered light of the laser beams focused in the region to be measured are received by a light-receiving device via at least one incident device. At least one Doppler shift frequency in the region to be measured is calculated on the basis of the frequency of a signal of the scattered light received by the light-receiving device, the optical path difference, and a rate of change of the frequency of the laser light. The flow velocity and the direction of the flow velocity are calculated from the calculated Doppler shift frequency.
摘要:
A compact voltage sensor with stable characteristics is provided. A measuring beam that is incident from an optical fiber is branched into first and second modulation-inducing waveguides of a wave branching/combining section within an optical integrated circuit. Phase changes of opposite sign are induced in the measuring beams propagating within the first and second modulation waveguides by applying voltages of mutually opposite sign to modulation-inducing electrodes, to induce a phase difference between the two. By reflecting the measuring beams from a reflective surface, propagating them back in the opposite direction within the first and second modulation waveguides, and passing them through the optical intensity modulation section again, thus applying a further phase modulation thereto, the phase difference between the measuring beams proceeding in the opposite direction within the first and second modulation waveguides can be made to be substantially twice the phase difference of the measuring beams before they are reflected by the reflective surface. The sensor also has a function to protect a sensor section thereof from dielectric breakdown caused by the accidental input of a high voltage.
摘要:
An electromagnetic field intensity measuring apparatus capable of measuring an electromagnetic field intensity accurately and sensitively without affection by any disturbance, including a measuring light generating section for emitting a measuring light containing first and second polarized light components which are orthogonal to each other and slightly different in frequency from each other; an optical input polarization-maintaining fiber for receiving one of the first and second polarized light components in the direction of X-axis polarization and the other polarized light component in the direction of Y-axis polarization, the optical input polarization-maintaining fiber conducting the measuring light to the electromagnetic field measuring place; a sensor section disposed in the electromagnetic field measuring place, the sensor section receiving the measuring light from the optical input polarization-maintaining fiber and modulating the phase of the incident measuring light depending on the electromagnetic field intensity; and an optical output polarization-maintaining fiber for receiving one of the first and second polarized light components from the sensor section in the direction of X-axis polarization and the other polarized light component in the direction of Y-axis polarization, the optical output polarization-maintaining fiber conducting the measuring light outside the electromagnetic field measuring place. The phase difference between the first and second polarized light components contained in the measuring light from the optical output polarization-maintaining fiber is detected to determine the electromagnetic field intensity.
摘要:
An apparatus measures the intensity of an electric field with a compact sensor equipped with a light modulater of a Mach-zender interferometer type and a condenser-type antenna. The sensor modulates coherent measuring lights propagated through branched two optical paths according to the voltage induced on the surfaces of plates of a condenser-type antenna of the sensor. The modulated lights are merged and interfered with each other and result in merged light different in intensity from the original measuring light. A waveguide-type optical integrated circuit formed in the sensor calculates the intensity of the merged light having the intensity dependent on the intensity of the magnetic field.
摘要:
An electromagnetic field intensity measuring apparatus comprises a sensor located in the electromagnetic field measuring place for receiving the measuring light from the optical fiber, the sensor being adapted to modulate the measuring light entering the sensor depending on the intensity of the electromagnetic field, the modulated light being then re-applied to the optical fiber; a polarization rotating device located between the measuring light generating device and the optical fiber, the polarization rotation device being operative to cause the polarized wavefront of the measuring light passed therethrough to rotate a given angle in the direction of passage; and a polarization beam splitter disposed between the measuring light generating device and the polarization rotating device, the polarization beam splitter being operative to permit only the measuring light from said measuring light generating device to pass through said polarization beam splitter and also to reflect the modulated measuring light inputted through the polarization rotating device in a predetermined direction. The electromagnetic field intensity in the measuring place can be calculated, based on the amplitude of the measuring light reflected by the polarization beam splitter.
摘要:
A light-emitting device includes a light-emitting diode, a red light-emitting phosphor layer, a yellow light-emitting phosphor layer, and a blue light-emitting phosphor layer. These layers are stacked in the stacking sequence of the yellow, blue, and red phosphor layers in order of increasing distance from the LED. The stacking sequence of the yellow and blue phosphor layers is first determined in such a manner that these layers do not interact with each other. The stacking sequence of the red and yellow phosphor layers and the stacking sequence of the red and blue phosphor layers are determined by the discriminant D. This determination of the stacking sequence suppresses a reduction in the conversion efficiency of the phosphors due to concentration quenching, improving the emission efficiency of the light-emitting device.
摘要:
A light-emitting device includes a light-emitting diode, a red light-emitting phosphor layer, a yellow light-emitting phosphor layer, and a blue light-emitting phosphor layer. These layers are stacked in the stacking sequence of the yellow, blue, and red phosphor layers in order of increasing distance from the LED. The stacking sequence of the yellow and blue phosphor layers is first determined in such a manner that these layers do not interact with each other. The stacking sequence of the red and yellow phosphor layers and the stacking sequence of the red and blue phosphor layers are determined by the discriminant D. This determination of the stacking sequence suppresses a reduction in the conversion efficiency of the phosphors due to concentration quenching, improving the emission efficiency of the light-emitting device.
摘要:
An optical-optical modulator (10) has a substrate (1) made of Zcut-LiNbO.sub.3 and a Ti-diffused waveguide (2) thereon. The waveguide (2) is separated into two branches which merge later into one again and constitute the Mach-Zehnder interferometer. A pair of electrodes (3a, 3b) for phase modulation is formed on a modulation part (A) which is in the middle of the waveguide (2). A CdS.sub.x Te.sub.1-x photoelectric conversion film (6) is formed directly contacting the pair of electrodes (3a, 3b). The photoelectric film (6) is manufactured by oblique vapor deposition utilizing CdS and CdTe as two vapor deposition sources. When the photoelectric conversion film 6 receives a control light (Lc), the film (6) generates voltage. The generated voltage is applied to the pair of electrodes (3a, 3b) and becomes a modulation signal of the carrier light (La).
摘要:
An optical fiber laser, according to the present invention, has an optical fiber including a core to which a rare earth element is added and a clad disposed around the core, and also has an excitation light source for emitting excitation light incident on a side of the optical fiber. The optical fiber has a corrugated shape on the outer circumference of the clad along the longitudinal direction thereof; and the optical fiber is wound in a spiral form and is bundled in such a way that adjacent sides of the clad are brought into contact with one another.
摘要:
A device for stabilizing a modulation operation of an optical modulator is provided, the optical modulator having an optical waveguide provided on a substrate and an electrode provided so as to correspond to the optical waveguide, modulating light inputted to the optical waveguide by a voltage corresponding to a physical amount to be measured which is inputted to the electrode, and outputting the modulated light. The device includes: an optical detecting device for outputting signal corresponding to intensity of light outputted from the optical modulator; a control signal outputting device for, on the basis of the output signal of the optical detecting device, outputting a control signal which compensates a phase bias fluctuation of the optical modulator; a light source device for outputting control light corresponding to the control signal; and a voltage applying device, provided in contact with the electrode of the optical modulator, for applying voltage corresponding to the control light to the electrode. Accordingly, the light source device illuminates to the voltage applying device a control light corresponding to a driving signal which negatively feeds back a phase bias fluctuation signal. In this way, the voltage applying device applies a voltage which is set so as to offset variation in phase bias fluctuation in accordance with bias fluctuation, and the phase bias fluctuation is offset.