| 摘要 |
PURPOSE:To improve the distortion property without marring the sensitivity by fixing the end of a fiber to the point where the secondary distortion of PD reaches a specified value or under, besides being on the side of a lens more than the point where the sensitivity is maximum. CONSTITUTION:It is in the region of a length of about 0.5mm of Z (distance between a lens and the end of a fiber)=0.8-1.3mm that the sensitivity of AC becomes maximum. Secondary distortion (1MD2) takes its maximum value at Z=1.4mm. The maximum point Zm of the secondary distortion does not exist in the maximum region of the AC sensitivity It is biased to the side where Z is larger in the maximum region of AC sensitivity. There is a place where the secondary distortion becomes smaller than -75dBc in the region (Z<Z0) where Z is smaller than Z0. It is at both points Z2 and Z3 that the secondary distortion gives -75dBc, and it is at Z2=0.92mm that the secondary distortion becomes -75dBc on the right, and the sensitivity is 0.96A/W. The distortion property can be improved without lowering the sensitivity in light reception by fixing the fiber end to the point of Z1=0.80mm, leaving a margin in this secondary distortion Z2. |
