| 摘要 |
PURPOSE:To freely vary the depth of modulation in high frequency modulation while applying automatic power control to a laser diode. CONSTITUTION:Threshold value current Ith where the laser diode 10 is started to emitting light and read emitting current Ir obtaining specified read power after emitting light are detected, and the differential current (x) of both currents is found, and high frequency modulation current Ihfm is added to the current subtracting the current (nx) multiplying the difference current (x) by (n) to be a coefficient (n) deciding the depth of the modulation from the read emitting current Ir and simultaneously the increase of the current is stopped to be fixed at the point of time when the mean value of light emitting power arrives at read power Pr. After the process flowing the current subtracting the current (nx) multiplying the difference current (x) by (n) from the read emitting current Ir to the laser diode 10 is stopped, the automatic power control making the read power Pr a setting target value is performed. |
