WAVELENGTH DISPERSION MEASURING INSTRUMENT FOR OPTICAL FIBER

摘要

PURPOSE:To remarkably stabilize a measurement system by arranging an optical fiber whose wavelength dispersion characteristic is already known on one optical path of a Mach-Zehnder interferometer and an optical fiber whose wavelength dispersion characteristic is not known on the other optical path. CONSTITUTION:Monochromatic light from a spectroscope 13 is converged by a condenser lens 14 and then inputted to one port of the input terminal of the 1st optical fiber type coupler 15. One piece of luminous flux which is branched by this coupler 15 is sent from one port of the output terminal of the coupler 15 to the optical fiber (reference fiber) 16 whose wavelength dispersion is already known. Further, light from the other port of the output terminal of the coupler 15 is passed through a condenser lens 17 and sent to the optical fiber 18 to be measured whose wavelength dispersion is unknown. The measurement light from the fiber 18 is sent to an optical path length fine adjusting device 12. Then, the light from the optical fiber 16 and the light from the fiber 18 are inputted to two ports of the input terminal of the 2nd fiber type coupler 19. One port of the output terminal of this coupler 19 is dipped in matching oil 20 and the other port is connected to the photodetection surface of a photodetector 8.