| 摘要 |
PURPOSE:To emit ultrashort pulsed light by a method wherein one mode other than the main oscillation mode raised by pulse driving is made selectively to pass through a filter specifically provided. CONSTITUTION:A system comprising a distribution feedback type laser 11, a grating 5 as a filter and a slit 6 is used as a semiconductor laser. In order to facilitate the oscillation in Fabry-Perot mode in addition to the main oscillation mode, a coated film 29 in low reflecting power of 5-15% is formed on the end of the laser 11. When the laser 11 is pulse-driven, multiple modes including the second mode of the wavelength lambda2 on the short wavelength side in addition to the main oscillation mode of the wavelength lambda1 are raised. Finally, the laser beams emitted through the film 29 are focussed on the grating 5 by lens 7 and then the diffracted laser beams are scattered to pick up the laser beams of wavelength lambda2 from the slit 6. |
