| 摘要 |
PROBLEM TO BE SOLVED: To suppress the lowering of output in case when a laser diode in vertical single mode is operated in multi mode in a wavelength conversion laser. SOLUTION: A DC driving current Iop (e.g. 300 mA) that is larger than two times of a threshold current Ith (e.g. 70 mA) of an infrared laser diode 1 is applied through an APC circuit 4, and a square wave pulse current I<SB>HF</SB>(e.g. frequency of 3 MHz, current value of 100 mA, duty ratio of 60%) is superimposed in a direction for increasing a current I<SB>LD</SB>applied in the infrared laser diode 1. Thus, the infrared laser diode 1 can be stably operated in multi-mode by comparatively low frequency of a harmonic element in the square wave pulse current I<SB>HF</SB>. In addition, lowered output after conversion can be compensated when the multi mode is used. A square wave pulse generating circuit 5 requires smaller number of parts in comparison with a sine wave generating circuit, resulting in a simplified structure. COPYRIGHT: (C)2006,JPO&NCIPI |
