In order to get stable continuous wave (CW) mode-locked (ML) laser, conventionally, the laser cavity was designed to reach very small mode radius in the laser crystal to make the laser material saturated. While for the laser diode (LD) end pumped Nd:YVO4 without fiber coupling transmission, as long as choosing the appropriate short focus lens and making the focus area in front of the Nd:YVO4 small enough, we found even large cavity mode volume can make the laser material saturated. In addition, relatively large cavity mode volume can make high power output with single mode come true. Ideal beam quality without high order transverse mode oscillating, the CW ML state turned to be very stable. Accordingly, relatively large mode volume in the laser crystal was designed with semiconductor saturated absorber mirror (SESAM), over 1.5-W CW ML output with near diffraction limited was acquired. The optical-to-optical conversion efficiency reached 30%.
© 2007 Chinese Optics LettersPDF Article