Abstract: The invention provides an optical waveguide for enabling the reduction of a coupling loss caused by difference in the size of a mode field diameter between optical waveguide modes different in the mode field diameter and a coupling loss caused by reflection on a boundary caused by the difference of media and an optical device using it. Structure provided with a mode field diameter converter provided with an antireflection part required to reduce a coupling loss between a microoptical circuit and a single mode optical fiber is integrally produced using effective refractive index control based upon photonic crystal structure.

Abstract: A micro-spectroscopic measuring device having a structure in which a spectroscopic element made of an array of photonic crystals with defects, flow paths for introducing a sample, and light detecting elements with sensitivity to a band from near infrared to infrared are stacked.

Abstract: The present invention aims to provide a dispersion compensator which is ultra small in size and low in cost and capable of controlling dispersion compensating values, and an optical transmission system using the dispersion compensator. A dispersion property of light that propagates through defects in a photonic crystal, is used to compensate for each wavelength dispersion. A dispersion compensator comprises a dispersion-compensating-waveguide array in which a plurality of dispersion compensating waveguides having dispersion compensating values different from one another are placed, a drive unit for driving the dispersion-compensating-waveguide array, and optical fibers for inputting/outputting a light signal. Each of the dispersion compensating waveguides comprises regular waveguides and a waveguide made of defects in photonic crystal. The lengths of the waveguides made of the defects in photonic crystal are changed one by one to make dispersion compensating values different from one another.

Abstract: The invention provides an optical waveguide for enabling the reduction of a coupling loss caused by difference in the size of a mode field diameter between optical waveguide modes different in the mode field diameter and a coupling loss caused by reflection on a boundary caused by the difference of media and an optical device using it. Structure provided with a mode field diameter converter provided with an antireflection part required to reduce a coupling loss between a microoptical circuit and a single mode optical fiber is integrally produced using effective refractive index control based upon photonic crystal structure.

Abstract: A photonic crystal has a relatively simple configuration and exhibits a sufficiently large refractive index change. An optical functional device uses the photonic crystal, and a process fabricates such an optical functional device. The photonic crystal includes at least one polymer as a material and changes in refractive index by changing the temperature of the polymer to thereby control the band structure of the photonic crystal. For example, a polymer is charged into holes arranged in a two-dimensional photonic crystal and is heated using a thin-film heater or is cooled using a Peltier device. The temperature is controlled by a temperature controller.

Abstract: The present invention aims to provide a dispersion compensator which is ultra small in size and low in cost and capable of controlling dispersion compensating values, and an optical transmission system using the dispersion compensator.

Abstract: In a measuring method and a measuring apparatus which are suited for observing a dynamic physical phenomenon particularly in a microdevice, a signal for generating a physical phenomenon in a specimen is inputted to the specimen, and a signal which is caused by this dynamic physical phenomenon is detected by a probe which is close to or in contact with the specimen surface in correspondence with a signal input to the specimen on the basis of the specific time. The measuring apparatus has a scanning probe microscope with a probe (tip) which is close to or in contact with the specimen surface, a pulse voltage application control unit for applying respective pulse voltages to the specimen and probe, and a signal measuring unit for measuring a signal from the specimen detected by the probe.

Abstract: A field effect transistor and a ballistic transistor using semiconductor whiskers each having a desired diameter and formed at s desired location, a semiconductor vacuum microelectronic device using the same as electron emitting materials, a light emitting device using the same as quantum wires and the like are disclosed.

Abstract: A semiconductor light-emitting device includes a plurality of semiconductor rods, each of which has a pn junction. The semiconductor rods are formed on a semiconductor substrate such that the plurality of semiconductor rods are arranged at a distance substantially equal to an integer multiple of the wavelength of light emitted from the semiconductor rod. With such devices, various novel optical devices such as a micro-cavity laser of which the threshold current is extremely small and a coherent light-emitting device having no threshold value can be realized.

Abstract: A device structure is provided for optical modulation using a quantum interference effect in an excited state of electron-systems. The optical modulation is performed by causing the effect of modulation on the excited state of electron-systems represented by excitons to be executed on light via the state in which the light and the excited state of electron-systems represented by the excitonic polaritons are coupled.

Abstract: A device structure is provided for optical modulation using a quantum interference effect in an excited state of electron-systems. The optical modulation is performed by causing the effect of modulation on the excited state of electron-systems represented by excitons to be executed on light via the state in which the light and the excited state of electron-systems represented by the excitonic polaritons are coupled.

Abstract: An optical device having a material exhibits an optical rectification effect is disclosed. The optical device utilizes direct current polarization which is induced in the material by a control light. The induction of the direct current polarization in the material by the control light changes the refractive index and absorption spectrum of the material. This is based on the so-called electrooptic effect and Franz-Keldysh effect. The present invention provides the optical device according to which external incident light can be modulated at high speed with the control light by utilizing the change of the refractive index or the change of the absorption spectrum.

Abstract: An optical device and an optical integrated circuit which incorporate an optical switch and have a novel function. Light sources are respectively coupled to two input ends of an X-type 2.times.2 optical switch, and light receivers are respectively coupled to two output ends of the optical switch, thereby obtaining an optical device which is capable of performing both AND and OR logics. A light source is coupled to one input end of an optical switch, and a light receiver is provided at one output end from which the light emitted from the light source emerges when no electric power is supplied to the optical switch, whereby it is possible to construct a system in which, even when one terminal has a power failure, there is no hindrance to other terminals. If an optical switch is arranged such as to use driving electric power as a modulating signal, the optical switch can serve as a modulator in which the output from one output end can be employed to monitor a modulated optical signal.

Abstract: An intercalation compound obtained by intercalating a halide of sodium or an element belonging to the group IV of the periodic table such as NaBr, SiCl.sub.4, etc., in a layer crystal substance such as graphite is suitable as an optical resonator in a device for emitting coherent radiation together with an exciting energy supplying means which can radiate synchroton radiation or plasma focus X-rays, particularly in an X-ray laser for emitting X-rays having a wavelength of 10 .ANG. or less.

Abstract: An optical device utilizes a polariton substance and utilizes the absorption wavelength band of excitonic polaritons. Further, an external stimulus such as electric field, magnetic field, stress, current or electromagnetic wave (light) is continuously or intermittently given to the polariton substance, thereby to modulate light which enters the optical device. Thus, a modulating operation of ultra-high speed is possible.

Abstract: A multi-quantum well structure which is formed by laminating thin semiconductor layers is provided with means for injecting carriers in a direction which is parallel to the surface of the laminated thin semiconductor layers, whereby it is possible to obtain satisfactory changes in refractive index of the carrier injection portion. For example, if the total reflection region of an optical switch consisting of optical waveguides which cross each other is provided with a multi-quantum well structure wherein carriers are injected in a direction parallel to the surface of the well, the extinction ratio characteristics of the device can be improved.

Abstract: In a semiconductor device wherein a signal transmission in a semiconductor integrated electronic circuit is carried out partly or entirely by means of a light, the signal transmission on the light is carried out with multi-wavelength, waveguides or a photoelectric converter and an electronic integrated device are provided on a circuit board having an optical waveguide, thus providing a high performance and practical technique.

Abstract: An optical fiber having an intense polarization plane maintenability is constructed of an optical waveguide having a circular core and a circular cladding, a jacket formed on the outer circumference of the optical waveguide and having an elliptical outer circumference, and a supporting portion formed on the jacket.In order to fabricate the above-specified optical fiber, a preformed rod therefor is prepared by forming the inner wall of an silica glass tube with the jacket and the optical waveguide made of such materials as satisfy a relationship of c.sub.2 /a.gtoreq.200/(100-.gamma.)-1, wherein: letter .gamma. stands for the ellipticity of the outer circumference of the aforementioned jacket; letter c.sub.2 stands for the minor axis of an ellipse; and letter a stands for the radius of the circular optical waveguide, and by subsequently collapsing the aforementioned silica glass tube while having its internal pressure made lower than the atmospheric pressure by 1 to 20 mmH.sub.2 O.

Abstract: Herein disclosed is a branch type optical switch having three or more optical waveguides capable of being coupled to one another in a coupling region, in which is formed a refractive index changing portion for effecting the function of the branch type optical switch by changing the refractive index thereof. This optical switch has a small coupling loss and an excellent extinction ratio. Also disclosed is an intersection type optical switch having two or more optical waveguides intersecting each other. The input optical waveguide and the output waveguide are connected at their intersection by means of a bypass optical waveguide to construct the above-specified branch type optical switch in the coupling regions of the bypass optical waveguides and the input and output optical waveguides, and the bypass optical waveguide has a curved or polygonal shape. Thus, it is possible to provide a small-sized optical switch which has an excellent extinction ratio and little variability in characteristics.

Abstract: A member capable of transmitting infrared rays of 2 .mu.m or longer in wavelength, particularly of 10.6 .mu.m in wavelength, with a slight loss is provided. The member comprises a Ge-Se-Te ternary chalcogenide glass having a composition which, in a compositional diagram of the ternary chalcogenide glass falls within the region bounded by the respective straight lines connecting points A, B, C, D, and E and A in this order, which points A, B, C, D, and E indicate Ge:Se:Te molar proportions of 32:25:43, 20:6:74, 15:5:80, 15:10:75, and 22:31:47, respectively.