Abstract: Optical fiber characteristic measuring device comprising a coherent light supply device, a light pulse generating device, a wave mixing device, a opto-electrical converting device, and a processing device, is provided such that parts have the frequency characteristic for corresponding to low frequency component for an opto-electrical converting device and a processing section so as to reduce the cost of the circuits.

Abstract: In a light wavelength dispersion measuring apparatus 1, three band-pass filters BPa1 to BPa3 are connected in parallel, three band-pass filters BPb1 to BPb3 are connected in parallel, and three phase comparators PCa to PCc are connected in parallel for making it possible to conduct phase difference measurement of the nth-order harmonics (n=1, 4, 8) at the same time, so that a wavelength dispersion calculator 10 can calculate the wavelength dispersion values of the nth-order harmonics (n=1, 4, 8) at the same time. As a result, measurement time of measuring the wavelength dispersion characteristic in the light wavelength dispersion measuring apparatus 1 can be shortened.

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: optical fiber characteristic measuring device comprising a coherent light supply device, a light pulse generating device, a wave mixing device, a opto-electrical converting device, and a processing device, is provided such that parts have the frequency characteristic for corresponding to low frequency component for an opto-electrical converting device and a processing section so as to reduce the cost of the circuits.

Abstract: The output light from a light source 10 is incident upon an optical fiber to be measured via an optical directional coupler 11, an optical switch 12, an optical amplifier 13, and an optical directional coupler 14. Light from the optical directional coupler 11 is incident upon a polarization controller 16. The output light from the polarization controller 16 and light returned from the optical fiber 15 are incident into an optical balance circuit 17, and these light are interfered. A fixed frequency, or alternatively a frequency which is varied stepwise, is output from a voltage control oscillator 18, according to a control signal from a DC voltage generation circuit 19 or from a saw tooth wave generation circuit 20. The output of the optical balance circuit 17 and the output of the voltage control oscillator 18 are mixed together by a mixer 26.

Abstract: An optical fiber characteristics measuring device comprises a pulse driving circuit for supplying a pulse driving current to a laser diode; a first optical directional coupler for branching the light output from the laser diode into a signal light and a reference light; a second optical directional coupler for sending the signal light to an optical fiber and for branching a returned light from the optical fiber into a backward scattered light and the signal light; a third optical directional coupler for incorporating the reference light and the backward scattered light and for coupling the backward scattered light onto the reference light; a photoelectric transducer for converting an optical signal output from the third optical directional coupler into an electric signal; and a bias circuit for supplying a continuous driving current to the laser diode at all times.

Abstract: A switch controlling device supplies, to an E/O switch 2 incorporating LiNbO3, an applied voltage having a prescribed voltage value, a light transmission/interruption control signal 32 of controlling the transmission/interruption of an optical input 2a in the E/O switch 2 and a charging/discharging control signal 33 of controlling exchange between the charging operation and discharging operation for the LiNbO3 crystal in the E/O switch 2. The charging/discharging control signal 33 has a signal having a period of 1 to 20 (inclusive) sec. While the optical output 2a is controlled to be transmitted by the light transmission/interruption control signal 32, the charging/discharging control signal 33 does not instruct exchange between the charging operation and the discharging operation.