Abstract: An apparatus and method for accurate measurement of characteristics of optical fibers (distribution of polarization mode dispersion and distribution of magnitude of birefringence). Pulse light is inputted to a subject optical fiber, back scattered light of the pulse light from the subject optical fiber is detected by a photodetector to find a Stokes vector, and polarization mode dispersion in a longitudinal direction is measured. The apparatus comprises a light source unit for outputting the pulse light having at least three different angular frequencies, and an arithmetic operation unit for calculating the magnitude of linear polarization components and the magnitude of a circular polarization component of a polarization dispersion vector on the basis of the Stokes vector and thus calculating polarization mode dispersion.

Abstract: A wavelength monitor 10 having a Michelson interferometer (or Mach-Zehnder) optical system 11 of a spatial light type having optical input from a light source has an interference pattern generating means 12 which inclines the wavefronts of interfering beams of collimated light to generate an interference pattern in the light intensity distribution in an interference light beam planes a first slit 107 and a second slit 108 which are adjustable in position and provided in front of a first photo-detector 109 and a second photo-detector, respectively, which receive split beams of interference light, and a signal processing means 111 by which the changes in the intensity of light from the first photo-detector 109 and the second photo-detector 110 are counted and subjected to necessary arithmetic operations to output signals representing wavelength data for the input light.

Abstract: Sort operations of an input signal are performed by providing a first sort part 6 comprising one shift circuit 8 and (l?1) sort circuits 9a to 9c, and a second sort part 7 comprising one delay circuit 10, (m?1) sort circuits 11a to 11c and m shift circuits 12a to 12d in a pattern synchronous circuit 100.

Abstract: A wavelength-variable light source apparatus having a wavelength calibration function of emitted light therefrom.

Abstract: Phase-locked loop (PLL) circuits include first and second PLL stages and use fractional frequency division. In one implementation, the first stage includes a voltage-controlled oscillator (VCO) whose output is provided to both first and second fractional frequency dividers. The output of the first frequency divider is provided to a first phase comparator whose output passes through a filter so as to provide the deviation signal that controls the output frequency of the first VCO. The output of the second fractional frequency divider is received by the second PLL stage as a reference signal.

Abstract: In a data log acquisition circuit 100, the number of executed test patterns counted by a number-of-patterns counter 1, or the address of the test pattern is compared with a predetermined reference value by an identity detection circuit 2. If the number of executed test patterns or the address of the test pattern and the predetermined reference value are data for the same test pattern, an identity signal is supplied to a log mode control circuit 3. The address of the test pattern is written into a log memory 6 at timing adjusted by a timing adjustment circuit 4 correspondingly to a write address of a data log generated by a counter 5 in accordance with an established operation mode. The write address and the address of the test pattern are held temporarily by a flip-flop 9. The number of generated FAIL signals is counted and outputted by a counter 10.

Abstract: A start point time measurement section 53 measures the time at which a moving image request is input as start point time and a start point time determination section 59 determines whether the start point time is valid or invalid, and outputs only the valid start point time to a response time calculation section 52; an end point time measurement section 54 measures the time at which moving image display is started and an end point time determination section 58 determines whether the end point time measured by the end point time measurement section 54 is valid or invalid, and outputs only the valid end point time to the response time calculation section 52; and the response time calculation section 52 calculates the difference between the start point time and the end point time as the response time and an evaluation system 40 evaluates the satisfaction degree of the user at the response time and the like for monitoring and managing the response time in moving image service.

Abstract: In order to provide a multi-path monochromator capable of reducing the size of optical parts with a high resolution and a wide dynamic range, the multi-path monochromator has a lens 2 used as a first collimator for converting an incident light into a parallel light, a diffraction grating 4 for diffracting an output light outputted from the lens 2, plane mirrors 3 and 5 for reflecting a diffraction light diffracted by the diffraction grating 4 to return the diffraction light back to a same path, a parabolic mirror 7 used as a second collimator for collecting a diffraction light which is again diffracted by the diffraction grating into which a reflected light is again outputted from the plane mirror, and an output slit positioned at a focal position of the parabolic mirror 7. The parabolic mirror 7 used as the second collimator has a focal length which is longer than a focal length of the lens used as the first collimator.

Abstract: A swept-wavelength loss measuring system is provided with an arrangement including a tunable laser source that outputs light to a DUT with the wavelength being continuously varied, and outputs measuring trigger signals at arbitrary intervals, at least one optical power meter for measuring an intensity of light transmitted through the DUT in response to reception of each of the measuring trigger signals, a wavelength measuring unit for measuring a wavelength of the outputted light from the tunable laser source in response to reception of each of the measuring trigger signals, and an arithmetic operation unit carrying out an arithmetic operation of the outputs from the optical power meter and the wavelength measuring unit to output a light intensity value relative to each wavelength. The arrangement assures accuracy of the measured wavelength.

Abstract: Output light spectrum P2(?) data from an optical amplifier and input light spectrum P1(?) data of signal light are prepared, the difference between the P2(?) and a value obtained by multiplying the P1(?) by a provisional gain GT is determined (Steps S232), for the obtained spectrum data, a noise removing process such as a moving average process and the like is performed and then, a spline interpolation process is also performed, whereby ASE light spectrum P3(?) data is prepared and an ASE light level P ASE is determined (Steps S233 through S235). In addition, a noise figure-measuring device 10 calculates the number of channels of WDM light and signal light wavelengths of the respective channels based on the P1(?) or P2(?), and performs analysis to calculate a noise figure NF and the like of an appointed wavelength range around the center of each wavelength thus calculated.

Abstract: An IC measuring device constituted by a first timing generator (TG21) for outputting a pair of judgment strobe pulses (S21); a first edge detector (E21) for detecting the states of a data strobe (DCK2) at two time points within one test cycle on the basis of the pair of judgment strobe pulses (S21); a second timing generator (TG22) for outputting a pair of judgment strobe pulses (S22); a second edge detector (E22) for detecting the states of data at two time points within one test cycle on the basis of the pair of judgment strobe pulses (S22); and a judgment section (J22) for determining acceptance/rejection of the timing of the data with reference to the data strobe on the basis of the states of the data and the states of the data strobe.

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: A filter processing system making it possible to be able to set a frequency pass-band automatically and to provide the optimum filter to an input signal. A filter processing method of an output signal of an Optical Time Domain Reflectometer (OTDR) in a chromatic dispersion distribution measuring apparatus is disclosed. The filter processing method includes establishing measuring-condition parameters, generating an ideal signal waveform based on previously established chromatic dispersion values and the measuring-condition parameters, and providing correlation results between the ideal signal waveform and a filter input signal. The method also includes comparing the correlation results to a threshold value to generate a minimum chromatic dispersion value and a maximum chromatic dispersion value, and performing filter processing for the output of the OTDR based on the minimum chromatic dispersion value and the maximum chromatic dispersion value.

Abstract: A monochromator including: a concave mirror which converts incident light into parallel light and emits the parallel light, a plane diffraction grating for diffracting the parallel light emitted from the concave mirror, first reflection means which reflects first light diffracted by the plane diffraction grating and causes the diffracted light to enter the plane diffraction grating as second incident light, second reflection means which reflects second diffracted light and causes the reflected light to enter the plane diffraction grating as third incident light, and an exit slit disposed in the vicinity of a focal point such that third diffracted light is reflected by the first reflection means, to thereby enter the plane diffraction grating as fourth incident light and such that fourth diffracted light is converged at the focal point by the concave mirror, to thereby enable extraction of light having a specific wavelength.

Abstract: A monochromator comprises an optical ray input section which limits the width of optical rays input from a light source, a first concave mirror for converting the optical rays passing through the optical ray input section into parallel rays, a diffraction grating for separating the parallel rays by wavelength into diffracted rays, a second concave mirror for condensing the diffracted rays when the diffracted rays are input, an optical ray output section which limits a wavelength band width of the condensed rays, and a substrate to which the optical ray input section, the first concave mirror, the diffraction grating, the second concave mirror, and the optical ray output section are fixed. A coefficient of linear expansion of a focal length of the first concave mirror, a coefficient of linear expansion of a focal length of the second concave mirror, and a coefficient of linear expansion of a material forming the substrate in the monochromator are approximately the same.

Abstract: There is provided a wavelength tunable light source 10 in which one end surface 1a of a semiconductor laser 1 is applied anti-reflection film, a lens 6 collimates a light beam emitted from the one end surface 1a of the semiconductor laser 1 onto which the anti-reflection film is applied, and a wavelength selection portion constituted by a combination of a diffraction grating 2 and a mirror 3 selects a light beam having a desired wavelength to return the selected light to the semiconductor laser 1 to make laser oscillation. A center of rotation of the mirror 3 is provided in a position P0 where mode hopping can be suppressed when the wavelength is tuned and rotation of the mirror 3 is driven by a direct drive system by using a motor 4 having a rotation shaft 4a in the center of rotation of the mirror 3.

Abstract: A variable-wavelength light source unit for sending output light of an arbitrary wavelength selected in a variable-wavelength light source section 1 has an optical variable attenuator 2 placed on the output side of the variable-wavelength light source section and a control circuit 4 for controlling the attenuation amount of the optical variable attenuator in response to light output provided by splitting a part of the output light.

Abstract: An optical pulse ?0 from a light source section 10 is incident upon an optical fiber 1 through an optical demultiplexer section 20, and its return light is supplied to an optical/electrical processing section 30 as the light of a plurality of different wavelengths ?1 to ?n by the optical demultiplexer section 20, and is respectively converted into electrical signals. Signals of the converted return light are respectively sampled and are averaged by respective processing circuits 402 to 40n of a signal processing section 40 so as to be formed as desired measurement waveforms. In the measurement waveforms, which are the results, data for corresponding sampling points are expressed as measurement data at an identical distance in the optical fiber.

Abstract: A method is provided of setting grids and/or markers on a screen of a display unit of a measuring apparatus. First, a mode of the apparatus is changed into a mode of setting the grids and/or the markers. Then, the grid and/or the marker serving as a reference is set. Then, a plurality of grids and/or markers are set, each of which provides an arbitrary interval with respect to the grid and/or the marker serving as reference.

Abstract: To generate a noise signal corresponding to an “antinoise environmental test” of CDMA, a noise generator 1 has a noise source A 2, an amplifier A 4, and a filter A 6 for generating an I signal for quadrature modulation and a noise source B 3, an amplifier B 5, and a filter B 7 for generating a Q signal for quadrature modulation and performs quadrature modulation for the I and Q signals generated by the circuits by a quadrature modulator 8 in accordance with a local signal supplied from a local signal source 9, then outputs a noise signal.