Abstract: An external resonator type wavelength variable light source comprises a semiconductor laser 5 formed on one end face with a antireflection coating 5a, a lens 6 for converting emitted light from the end face of the semiconductor laser 5 formed with the antireflection coating 5a into collimated light, a diffraction grating 7 for selecting a wavelength of the collimated light provided through the lens 6 and diffracting the light, and a mirror for reflecting the light diffracted through the diffraction grating 7 and feeding back the light again diffracted through the diffraction grating 7 into the semiconductor laser 5 through the lens 6. A V-groove grating mirror 8 having reflecting faces with an arrangement like a grating, of a plurality of V grooves 2 each shaped like V at right angles in cross section in a base material 1 with a reflection coating 3 formed on the surface of each V groove is used as the mirror.

Abstract: A chromatic dispersion distribution measurement apparatus, comprises: a portion information obtaining unit for obtaining a portion information which specifies a portion of an optical device to be measured; a sign information obtaining unit for obtaining a sign information which indicates a correct sign to be marked on a chromatic dispersion value in the specified portion; and a sign converting unit for converting an initial sign marked on the chromatic dispersion value in the specified portion, into the correct sign in accordance with the sign information obtained by the sign information obtaining unit.

Abstract: The CPU outputs to the delay circuit 22 delay time setting signals for setting the delay time, based on input delay time data input from an external input device. The delay circuit 22 re-sets the delay time via new delay setting signals input from the CPU 24 and delays the trigger signals input from the trigger circuit 21 based on the specified delay time and outputs the resulting signals to the clock generator 23. The clock generator 23 outputs new sample start signals to the A/D sampler 3 at the input timing of the delayed trigger signals input from the delay circuit 22, thus changing the sampling start timing of interference signals in the A/D sampler.

Abstract: The DSP#A 5 specifies a read address for reading digital interference signal data stored in the buffer 4 to read the data, and executes the butterfly operation including a preset hamming windowing function coefficient to convert digital interference signal data to frequency data, then outputs the frequency data to the DSP#B 6.

Abstract: A transmitter 12 and a receiver 35 are connected to a network 20 for transferring data of moving image code as a packet between the transmitter 12 and the receiver 35. The transmitter 12 prepares a packet of moving image code from moving image data and outputs the packet to the network 20. In the receiver 35, a moving image reception section 31 receives a packet 61 input via the network 20, extracts the data bits of the moving image code sandwiched between synchronous codes from the received packet 61, and outputs the extracted bits of the moving image code to a moving image decoder 30. The moving image decoder 30 decodes the input moving image code into a digital moving image and outputs the provided digital moving image to a display 33, which then displays the input digital moving image on a display screen.

Abstract: A light source 1 is connected to a first terminal of an optical branch coupler 2, and a first optical sensor 3 is connected to a second terminal. A second optical sensor 4 is connected to a fourth terminal, and a master optical connector 7 is connected to a third terminal. While a measured optical fiber 5 is connected to the master optical connector 7, the power of light received by the first optical sensor 3 and the power of light received by the second optical sensor 4 are detected. The insertion loss and return loss of the optical fiber 5 are computed from the power values of received light detected by a measurement unit 10.

Abstract: A circuit for generating a time division multiplex signal, that hardly degrades a phase margin of a test pattern which is outputted as the time division multiplex signal. The circuit for generating a time division multiplex signal, has: a signal generator for generating a plurality of parallel signals; a phase synchronous circuit for advancing a phase of a clock signal; a divider for dividing a frequency of an output outputted from the phase synchronous circuit, for every predetermined clock number; and a time division multiplexer for time-division multiplexing the plurality of parallel signals generated by the signal generator, according to the output outputted from the phase synchronous circuit.

Abstract: An apparatus for measuring the chromatic dispersion profile of an optical fiber using two light sources 1 and 2 at least one of which is tunable in wavelength, in which two light beams of different wavelengths from said two light sources are injected into a optical fiber under test 7 and the four-wave mixing light that is generated by interaction between said light beams of different wavelengths is measured with an optical time domain reflectometer (OTDR) 9, characterized in that an optical bandpass filter 8 having a fixed central frequency is provided at a stage upstream of said optical time domain reflectometer (OTDR).

Abstract: A video distribution test system for performing simplified measurement under assumed conditions closer to the actual situation, and for performing tests for effective applications. The system includes a video packet simulator for defining different packet loss rates and simulating packet loss in video packets transmitted from the video distributing server for each packet loss rate, so as to produce defective video streams and evaluate an image quality of each defective stream, and producing a conversion table between the packet loss rate and the image quality; a pseudo-load generator for issuing pseudo-distribution requests from clients to the video distributing server; a packet quality monitor for receiving video packets from the server and calculating a packet loss rate for each client by detecting packet loss; and an image quality evaluating section for evaluating the image quality for each client based on the calculated packet loss rate and the conversion table.

Abstract: Wavelength dependent measurement is made by launching light into an object 8 to be measured and receiving transmitted light from the object 8 while continuously changing wavelengths of output light. Next, peak wavelength detection processing for detecting a wavelength at the time when loss or gain of the transmitted light from the object 8 becomes maximum based on a wavelength dependent measurement result is performed. Then, polarization dependent loss measurement processing for measuring polarization dependent loss of the object 8 is performed by measuring the transmitted light from the object 8 while launching light of a measurement wavelength detected into the object 8 and randomly changing a polarization state of the light. Further, a control circuit processes associating a wavelength dependent analysis result with a PDL measurement result, and displays its result on a display part 2.

Abstract: A PLL circuit for reducing an error in a frequency of an output signal for a reference signal and outputting the output signal with a smaller spurious output, and a control method for the PLL circuit. The PLL circuit has: a clock generator for generating and outputting a clock signal having an oscillating frequency, on the basis of a reference input signal; a phase detector for detecting a phase difference between the clock signal and an output feedback signal, and outputting a phase difference signal; a controller for controlling an oscillating frequency of an output signal on the basis of the phase difference signal; and a divider for dividing the oscillating frequency of the output signal outputted from the controller, and outputting a dividing signal having an oscillating frequency corresponding to the oscillating frequency of the clock signal, as the output feedback signal.

Abstract: A chromatic dispersion distribution measurement apparatus, comprises: a power calculation unit for calculating a power value of an input light to be input into an optical device to be measured, in order to calculate a chromatic dispersion distribution in the optical device to be measured, in accordance with an output light power of an output light from the optical device to be measured as a function of a transmission distance along the optical device to be measured; and a control unit for controlling an input light power of the input light to the optical device to be measured in accordance with the power value of the input light which is calculated by the power calculation unit.

Abstract: A chromatic dispersion distribution measurement apparatus for calculating a chromatic dispersion distribution in an optical communication path under test, includes an intensity ratio calculation unit for calculating an intensity ratio of a first light and a second light that are reflected from an optional position of the optical communication path under test and propagated to an incident end of the optical communication path under test by taking the same propagation time. A chromatic dispersion value calculation unit is provided for calculating a chromatic dispersion value in the optical communication path under test in accordance with the intensity ratio calculated by the intensity ratio calculation unit.

Abstract: In a tunable filter for launching incident light from an input side optical fiber into a diffraction grating through a condenser lens and emitting emission light from the diffraction grating through the condenser lens and outputting output light of a selected wavelength through an output side optical fiber, one optical fiber common to input and output is provided between the input side optical fiber and the output side optical fiber and the condenser lens, and also optical circulator member is provided between the input side optical fiber and the output side optical fiber and the one common optical fiber.

Abstract: An optical spectrum analyzer comprises a refractive grating which extracts a specific wavelength of light which is incident to be measured and outputs as a component light, an optical detector which measures optical intensity of the component light, a container in which the refractive grating and the optical detector are provided, a gas filling port and a gas exhaust port, for performing a replacement of air with a gas, which are provided in the container, are provided. By doing this, the optical spectrum analyzer which can measure level of the light to be measured having a specific wavelength accurately without causing the absorption of the specific wavelength by an OH group.

Abstract: A timing adjusting circuit receives a clock and a data from an outside, and outputs the delayed data to the outside. A variable delay circuit receives the data and outputting the data delayed according to a value set by a delay value setting signal A first flip-flop has a data input terminal for inputting the data output from the variable delay circuit and a clock input terminal for receiving an inverse signal of the clock being frequency divided. A second flip-flop has a data input terminal for receiving a fixed value and a clock input terminal for receiving a signal output from the first flip-flop. A counter has a counter enable input terminal for inputting a signal output from the second flip-flop, counts the clock at every plural periods, and sends an output count value as the delay value setting signal to the variable delay circuit.

Abstract: An optical part driving device for moving an optical part, comprises; a driving timing pulley, a pair of driven timing pulleys, a timing belt wound by the driving timing pulley and the driven timing pulleys and connected with the optical part between the pair of driven timing pulleys, and a pair of tension pulleys for tensing the timing belt on both sides of the driving timing pulley.

Abstract: An external cavity laser type light source including a light emitting element, a wavelength selection element for selecting a wavelength of light emitted from the light emitting element and for returning light to the light emitting element, and an optical branch element arranged between the light emitting element and the wavelength selection element. In the external cavity laser type light source, selected light sent from the wavelength selection element is branched by the optical branch element, and one branched component is taken out as output light.

Abstract: An optical fiber characteristics measuring device includes a pulse driving circuit, a first optical directional coupler, a second optical directional coupler, a third optical directional coupler, a photoelectric transducer, and a bias circuit. The frequency of the backward scattered light is detected based on the electric signal in the device.

Abstract: A semiconductor testing apparatus capable of displaying its measurement results in an easily understandable manner is provided. The apparatus comprises a display section for displaying a measurement result of a change in time of a voltage distribution on a measurement plane of a measured device and an input section for entering parameters for the display of the measurement result. When a measurement time is entered as a parameter, the display section displays the measurement result by means of a three-dimensional graph and a representation in numerals, letters or symbols of the measurement time. The graph shows along its three axes a first coordinate in a first direction on the measurement plane, a second coordinate in a second direction which is perpendicular to the first direction, and a voltage at the measurement time at a position on the measurement plane defined by the first and second coordinates.