| 摘要 |
PURPOSE:To obtain an output optical signal with low distortion by driving a laser diode approximately with a constant voltage AC signal. CONSTITUTION:A resistor 15 having a resistance Rp of the same degree as a dynamic impedance of a laser diode 1 and a constant voltage diode having the nearly equal breakdown voltage as the oscillating threshold voltage of the laser diode are connected in series and they are further connected in parallel with the laser diode 1. While the laser diode 1 is biased with an oscillating threshold current or over, a current flows to the constant voltage diode 16, but its terminal voltage is equal to the breakdown voltage, which is nearly constant, and it is equivalent that the resistor 15 is connected in parallel with the laser diode 1 in terms of AC. Thus, it is regarded as if the laser diode 1 were modulated by an AC signal source having the internal resistance nearly equal to its dynamic impedance or below and driven approximately with the constant voltage AC signal source. Thus, the laser diode is driven approximately by the constant voltage AC signal source to send an output optical signal with low distortion. |
