ACOUSTIC OPTICAL Q-MODULATING METHOD FOR DOUBLE-CLAD FIBER LASER AND APPARATUS

摘要

In the acoustic optical Q-modulating method, quartz optical fiber of double-clad fiber laser is used as acoustic optic medium directly. Stationary field of sound wave or traveling wave field is formed in the medium so as to form phasegrating. Deflection of transmitting direction of oscillated laser occurred caused by diffraction under effect of the phase grating is as a leaking wave. The leaking wave prevents forming oscillated laser. Thus, laser of optical fiber is in state of low Q value. When traveling wave field is disappeared, laser is in state of high Q value. The acoustic optical Q switch includes a radio frequency excited ultrasonic transducer, medium for sound propagation, sound reflection interface or body of sound absorption. The medium for sound propagation is placed between the transducer and the interface or body of sound absorption. The double-clad fiber is in medium for sound propagation. The acoustic opticical Q switch is realized in coated fiber directly so as to lower insertion loss.