| 摘要 |
PURPOSE:To make a bias current and a signal light constant in output power by a method wherein a signal light is received and ramified, whose output corresponding to a direct current component is delayed for a prescribed period and then applied to an end of an LD, and a signal difference between an electric signal which is electrically converted from a monitor light and a signal of an inverted electric signal is obtained and a current corresponding to its output is made to flow through a drive circuit. CONSTITUTION:A monitor light of one output of a laser diode(LD) 100 is converted into an electric signal through a first optoelectronic conversion means 200 and applied to an inversion non-inversion difference output means 700, where difference value between an inputted electric signal and a signal of an inverted inputted electric signal is outputted. The difference output is applied to a level conversion means 800 and converted into a specified value, which output is applied to a second transistor(Tr) 900, and a current corresponding to the output is made to flow through the Tr 900 and a Tr 400 and the LD which are connected with the Tr 900. On the other hand, a signal light from the LD 100 is ramified at a prescribed ratio through an optical directivity coupling means 600 so as to be converted into an electric signal, and an output corresponding to the direct current component contained in the electrical signal is made to delay for a specified period and then applied to one end of the LD 100. |
