Research For Q-switched Frequency-doubled Green Pulse Laser Based On Graphene Oxide

The energy level structure of traditional saturable absorption materials makes them effective only in a narrow wavelength range.However,graphene oxide(GO)can be used as a wavelength-insensitive SA because of their excellent optical properties,ultra-wide transmittance and high damage thresholds.Graphene oxide is successfully prepared using an improved modified Hummers method.The suspension was dispersed by using an ultrasonic apparatus.Subsequently,a drop of the dispersed suspension was spin coated on a square quartz substrate.A highly efficient 808nm LD pumped 532nm Q-switched green laser hasbeen designed with the GO as the saturable absorber.Further,green pulse laser with high repetition rate and narrow pulse duration is achieved.The contents are concluded as follows:1?the main parameters of the Q-switched laser such as the peak power,the pulse energy and the energy efficiency of a single pulse are obtained by numerical solutions based on the rate equation.We explained the principle of Q-switched technology based on the rate equation.Then the applicable fields,advantages and disadvantages of different kinds of Q-switched devices are introduced in detail.2?The structural characteristics and optical properties of graphene and graphene oxide are highlighted.During the oxidation progress,the lattice and energy band of graphene are not destroyed,so graphene oxide exhibits a similar favorable optical performance as graphene and may be produced using several simple methods.Furthermore,the prepared GO is made to contain a high hydroxyl content,which is beneficial for film formation on the substrate to fabricate the Q-switching element,3?In the experiment,the graphene oxide is successfully prepared using an improved modified Hummers method.The suspension was dispersed by using an ultrasonic apparatus.Subsequently,a drop of the dispersed suspension was spin coated on a square quartz substrate.The Raman shift,X-ray diffraction(XRD),and scanning electron microscope(SEM)measurement techniques are used to characterize the GO.In the experiment,a linear cavity of 808nm LD pumped 532nm pulse laser is designed based on the PPLN crystal and GOsaturable absorber.The experimental results show that,under the absorbed pump power of 5.16W,the output power of 536mW for the 532nm pulse laser is achieved with the repetition rate,the pulse duration,and the optical-optical conversion efficiency of 71.4kHz,98ns,10.3%,respectively.