Optical network analyzer for measuring the amplitude characteristics and

Abstract

An optical network analyzer measures the amplitude characteristics and group delay time dispersion characteristics of an optical circuit device. In the optical network analyzer, the intensity of the light generated by a first light source is modulated by use of a modulation signal having a constant frequency and a constant amplitude. Part of the intensity-modulated light is used as a reference optical signal, and the remaining part is made to pass through the optical circuit device, thus obtaining an optical signal to be measured. The reference optical signal and the optical signal to be measured are photoelectrically converted into electric signals, and the modulated signal components of the electric signals are compared with each other, thus obtaining an amplitude ratio and a phase difference. The optical frequency of the first light source is swept in a constant cycle, and the amplitude ratio and phase difference are displayed on a display device in synchronism with the frequency sweeping. To implement an optical frequency marker, light having an arbitrarily-designated optical frequency is generated by a second light source. The light generated by the second light source is made to join part of the light generated by the first light source, so as to produce a peak at the designated optical frequency. The peak is electrically extracted and superimposed on the amplitude ratio and phase difference displayed on the display device.