Fujitsu Corporation

Kyoto University

Shunsuke Ono

Shigeki Watanabe

Fumio Futami

Ryou Okabe

Masato Nishihara

Etsuko Hayashi

Shinichirou Muro

Setsuhisa Tanabe

A method is for calculating an optical noise index of a signal light extraction apparatus that extracts signal light in a polarization plane by inputting signal light and a sampling pulse, different from the signal light in polarization plane by a given angle, to a nonlinear optical medium, and by passing light output from the nonlinear optical medium through an orthogonal polarizer having a polarization plane orthogonal to that of the signal light. The method includes calculating an output optical noise of the signal light extraction apparatus using a parametric gain of the nonlinear optical medium, a power of a quantum noise of the light having passed through the orthogonal polarizer, and a ratio of a power of the signal light and a power of the signal light sampled by the sampling pulse; and calculating an optical noise index using the output optical noise.

Optical noise index calculation method, optical noise index calculation apparatus, and optical sampling oscilloscope

In an optical amplification characteristics simulation apparatus according to the present invention, using spectrums of a signal light input to an optical amplifier and a characteristic parameter for amplification medium, gain wavelength characteristics of the amplification medium are calculated. A calculating formula for the above has a parameter corresponding to a gain fluctuation portion due to a gain spectral hole burning (GSHB) phenomenon, and this parameter is defined by a function obtained by modeling a physical phenomenon in which a population inversion rate is reduced due to the GSHB, based on that electron occupation numbers in each Stark level on the end level side are increased. Then, based on the calculated gain wavelength characteristics, the output power of the signal light is obtained, to thereby perform the optical amplification characteristics simulation on the optical amplifier. As a result, it is possible to construct a high versatile calculation model based on the physical phenomenon for the gain fluctuation due to the GSHB, to thereby simulate with high precision the optical amplification characteristics of the optical amplifier under arbitrary conditions.

Optical amplification characteristics simulation apparatus and optical amplification characteristics simulation method

A first polarization controller controls a polarization state of measured light. A second polarization controller controls a polarization state of an optical sampling pulse. The measured light and the optical sampling pulse having the polarization states controlled are input to an optical fiber. An optical signal output from the optical fiber is transmitted to a polarizer. A first control unit adjusts the first polarization controller based on the measured light output from the optical fiber and the measured light output from the polarizer. A second control unit adjusts the second polarization controller based on an optical sampling pulse output from the optical fiber. Waveform measurement is performed by using the output of the polarizer.

Optical waveform measurement apparatus and optical waveform measurement method

Reflection means such as a mirror are provided on the output end of an optical fiber, and the input signal light and control light are returned to the optical fiber. Although the zero-dispersion wavelength of the optical fiber fluctuates in the longitudinal direction, if the length is relatively short, it is possible to manufacture a high yield of optical fibers, which monotonically changes the zero-dispersion wavelength. Therefore, a relatively short optical fiber with a monotonic zero-dispersion change can be used. Since the zero-dispersion change is monotonic and the optical fiber is short, the amount of change in the zero-dispersion wavelength is small and the bandwidth becomes broader when the control light is set at the position of the average zero-dispersion wavelength. Additionally, although the length of the optical fiber is short, the operating length is twice as long and thus the generation efficiency does not degrade.

Optical switch

An optical parametric amplifier of the invention comprises a nonlinear amplification section to which a signal light and a pump light are injected via a coupler. The nonlinear amplification section is constructed by connecting in multiple stages a plurality of polarization retaining highly nonlinear optical fibers (HNLFs) having mutually different zero-dispersion wavelengths and dispersion slopes. The zero-dispersion wavelengths of the HNLFs are on the short wavelength side of a pump light wavelength, and are shorter towards the output side HNLF. Furthermore, the arrangement is set such that the dispersion slopes of the HNLFs become steeper towards the output side HNLF. As a result, it is possible to realize an optical parametric amplifier that is high gain and broadband.

Growing community of inventors

Kawasaki, Japan

Shunsuke Ono