Anritsu Corporation

Yukio Tsuda

Hiroshi Goto

Hiroshi Komazawa

Youji Sonobe

Frequencies of plural peak signals which appear in a band &#xbd; of a sampling frequency are detected from a spectrum obtained from a measuring target signal sampled with the sampling frequency in order to detect the repetition frequency of the measuring target signal having plural harmonic components with a similar power. Each of the plural peak signals is successively assumed to be a fundamental wave beat component originating from the fundamental wave of the measuring target signal and theoretical frequencies of harmonic beat components originating from harmonic components of the measuring target signal are successively calculated. The theoretical frequencies are compared with the frequencies of the plural peak signals to determine one of the plural peak signals as a fundamental wave beat component originating from the fundamental wave of the measuring target signal.

Fundamental wave beat component detecting method and measuring target signal sampling apparatus and waveform observation system using the same

In a method of detecting a repetition frequency of a measured signal, in order to detect the waveform repetition frequency of the measured signal with high accuracy even in the presence of a frequency fluctuation in the measured signal, the repetition frequency of the measured signal acquired by the conventional method is used as a provisional repetition frequency, and the frequency change amount of the specified signal obtained in the case where the measured signal is sampled sequentially with a sampling frequency greatly changed from the provisional sampling frequency to generate a frequency fold at the time of sampling is detected. Based on the detected frequency change amount of the specified signal and the change amount of the sample number indicating how many times the frequency fold has occurred in the process, the error contained in the sampling number with a frequency fluctuation contained in the measured signal is calculated. Then, based on the error contained in this sample number, the provisional repetition frequency of the measured signal is corrected, thereby calculating the regular repetition frequency of the measured signal.

Measured-signal repetition frequency detection method, and sampling apparatus and waveform observation system using the method

A two-beam interferometer splits an incident light in two optical paths, combines and outputs split lights together again. The two-beam interferometer generates at least one or more combined light made from two beams each having a polarization different from each other. A polarization state detector detects a variation in the polarization of the combined light generated by the two-beam interferometer. An electric circuit calculates an wavelength of the incident light based on the variation in the polarization detected by the polarization state detector. The two optical paths of the two-beam interferometer has a difference in length between a point of splitting the incident light and a point of combining the split lights, for the detection of polarization variation in the combined light by the polarization state detector. The optical path length difference between the two paths is fixed.

Light wavelength measuring apparatus and method for measuring wavelength of subject light with high speed by using two-beam interferometer

This invention is applied to an optical amplifier evaluation method of modulating by an optical modulator,light output from a light source,into a rectangular optical signal which is enabled/disabled in a predetermined period, then applying the optical signal to an optical fiber amplifier,to be measured, and obtaining the gain and noise figure of the optical fiber amplifier from the light intensities in the ON and OFF periods of an optical signal output from the optical fiber amplifier and the light intensity in the ON period of an optical signal input to the optical fiber amplifier. Output light from the optical fiber amplifier in a no-input state is passed through an optical path extending from the light source to the optical fiber amplifier and an optical path extending from the optical fiber amplifier to a light intensity measurement position, thereby obtaining optical losses on the respective optical paths. By the obtained optical losses, the light intensities are corrected. As a result, the gain G and noise figure NF of the optical fiber amplifier,can be attained with high precision.

Optical amplifier evaluation method and optical amplifier evaluation device

In an optical amplifier evaluating system of this invention, a pulse method using optical modulators and a probe method are combined to obtain a gain G and noise figure NF of an optical fiber amplifier. A first optical modulator turns on and off signal light output from a first light source. An optical multiplexer multiplexes the optical signal turned on and off by the first optical modulator and probe light output from a second light source. This optical signal multiplexed by the optical multiplexer is selectively fed into an optical fiber amplifier. A controller properly switches optical path switches to allow an optical spectrum analyzer to measure (1) the light intensity of an input signal of the probe light to the optical fiber amplifier, (2) the light intensity in a region where signal light extracted from the output signal light from the optical fiber amplifier by a second optical modulator is in an OFF period and the probe light is output, and (3) the light intensity in a region where the signal light extracted by the second optical modulator is in the OFF period and no probe light is output. On the basis of measured light intensities (1), (2), and (3), the controller calculates the gain G and noise figure NF of the optical fiber amplifier. In this manner, the optical amplifier evaluating system of this invention can accurately obtain the gain G and noise figure NF of the optical fiber amplifier.

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Aiko-gun, Japan

Yukio Tsuda