| 摘要 |
PURPOSE:To control stably an optical output to a prescribed output value by amplifying a current difference between a reference current having the specific temperature coefficient and optovoltaic current of a photodiode inversely and feeding back the result to the forward current circuit of a laser diode. CONSTITUTION:A reference current source 1 whose temperature coefficient of a set reference current Iref is inverse to the optical output temperature coefficient of a laser diode LD in coding and having a coefficient corresponding optical output temperature coefficient is connected to the output circuit of a photodiode PD monitoring the optical output Po of the laser diode LD. The current difference between the optovoltaic current Is of the photodiode PD and the reference current Iref set to the reference current source 1 is amplified inversely by an inverse amplifier means 2, the result is fed back to the forward current circuit 3 of the laser diode LD and the optical output Po is controlled to an output level corresponding to the reference current Iref. Thus, the optical output is controlled stably to a prescribed value against the temperature change. |
