| 摘要 |
PURPOSE:To obtain an optical communication system for preventing malfunction due to noise charge caused by alpha ray by transmitting optical signals such that the conditions can be satisfied by energy of the optical signals at the light-receiving section of a semiconductor light-receiving device. CONSTITUTION:The incident condition of alpha ray where the largest quantity of noise electric charge is generated is that when alpha rays pass through along a diagonal line 7 of a light-absorbing layer 2 of a light-receiving device, generated noise electric charge Qn is expressed by Formula II: when silicon is used as a material, the produced number of electron-hole pairs is about 50000 pairs/mum; when l=20mum, the is Qn=160fC, and the signal electric charge quantity Qs is expressed by Formula III. Conventionally, when noise electric charge due to alpha ray is not taken into account, Es is approximately 3fJ at transmitting rate 1Gb/s. For example, when u=0.8, Es=3fJ, nu=380THz (lambda=0.8mum), the signal electric charge quantity is Qs=1.5fC. In other works, when alpha rays strike the light receiving device, conventional Es causes a wrong operation. However, a wrong operation caused by noise electric charge can be prevented by setting optical signal energy Es of Formula I so that Qs is larger than Qn by taking into account the noise electric charge. |
