| 摘要 |
PURPOSE:To minimize the minimum reception sensitivity deterioration in a high speed and long distance transmission system using an LED by attaching and detaching a wavelength selective filter and installing an optimum photodetector for the system at the reception end. CONSTITUTION:A wavelength selection filter 3 is added to a connector part 1, condenser lens sphere 2, photodetector 4 and an air-tight package 5. The lighting center of the LED is matched to a wavelength where the material scattering of fiber is zeroed and the light of wavelength deviated from the center is subject to the scattering of material and a cause to the band deterioration. The band deterioration is prevented by using the filter 3 to eliminate the light at surrounding. The effect of band deterioration depends on the LED, fiber in use and the transmission speed and distance. Thus, the band deterioration at the reception end is measured by this invention and the reception sensitivity deterioration is minimized by inserting a filter optimum to each system. After the adjustment, the filter 3 is fixed to the package 5 by a adhesives. |
