Japan Science and Technology Agency

Koichiro Nakamura

Hiromasa Ito

Masato Yoshida

Toshiyuki Miyamoto

A group velocity dispersion measuring device capable of measuring group velocity dispersion (GVD) with a simple configuration and in a short time, comprising an FSF laser (FSFL) () for generating frequency chirp light, an optical amplifier (AMP) () for amplifying the frequency chirp light, an optical coupler (), a circulator () for branch-controlling optical signals, a photodetector () for receiving a ray of light before and after its propagation through an optical fiber () to be measured, and an RF spectrum analyzer (RFSA) () for observing an optical spectrum waveform. Beat signals generated between chirp lights before and after the propagation, through the optical fiber () to be measured, of frequency chirp light emitted from the FSF laser () are alternately observed to calculate a GVD value from frequency differences between these beat signals.

Group velocity dispersion measuring device and group velocity dispersion measuring method

An apparatus and method for measuring polarization mode dispersion (PMD) using a polarization mode dispersion measuring device, comprising an FSF laser generating frequency chirped light, an optical amplifier amplifying the frequency chirped light, an offset circuit, a &#x3bb;/2 plate, a beam splitter, an analyzer retrieving polarization components measured from each light wave after propagating through the fast axis and the delay axis of the optical fiber under test, a lens, a photodetector detecting a light wave passed through the lens, and an RF spectrum analyzer observing a spectrum waveform of the light wave. The frequency chirped light, after propagating through the optical fiber under test and passing through the analyzer, is detected and the variation in beat frequency is measured to determine a PMD value.

Growing community of inventors

Sendai, Japan

Koichiro Nakamura