Preparation, Characterization And Application Of Transistor-like Saturable Absorbers In Solid-state Lasers

All-solid-state pulsed laser has many advantages,such as high energy,small volume and good beam quality,which has been widely used in laser processing,medical treatment,national defense,military affairs,industrial production and other fields.Among them,the passive Q-switched lasers develop so fast that have made great progress in nonlinear pulse dynamics,near-infrared band solid-state laser.Due to the uncontrollable modulation depth of the traditional saturable absorber,the pulsed laser based on two-dimensional SA is hard to meet the increasing practical demands,and faces the inherent defects of high-power consumption,as well as slow speed and low efficiency.In this paper,a novel integrated graphene-insulator-semiconductor(GIS)transistor saturable absorber has been designed and fabricated.The electro-optical real-time modulation of the output characteristics of pulse laser is realized by using the gate voltage which can controll the nonlinear optical absorption characteristics of garphene.The GIS device provides a new technical scheme for the development of miniaturization,low power consumption and adjustable pulse laser.The specific contents of the study are as follows:(1)The design and fabrication of the graphene transistor device(GIS-SA)are completed.The carrier density distribution in the device is simulated by using the finite element method.The effect of different electrode structures on the carrier concentration is simulated,the structure of interdigital electrode is established.Graphene films are prepared by plasma enhanced chemical vapor deposition,and the active-control graphene transistor saturable absorber is fabricated by inkjet printing,dispensing and drying.(2)The photoelectric performance of the graphene transistor is studied,the capacitance characteristic and current transmission curve of GIS-SA are tested,which shows that the device has good modulation performance.The linear absorption and nonlinear transmission characteristics of the center region of GIS-SA interdigital electrode are studied.The results show that the vertical electric field can enhance and control the optical absorption of graphene devices.The modulation depth of graphene is about 3.9%and the saturation intensity is 8.14MW/cm~2 when the gate voltage is 0 V,and the modulation depth is about 5.5%when the modulation voltage is 60V,the saturation intensity is 10.53 MW/cm~2.(3)The active control nanosecond Q-switched laser output based on GIS-SA is realized by building the 1064 nm all-solid-state pulsed laser system,which can realize pulse width controllable adjustment and peak power increase(60%)at ultra-low electric modulation power(～10 p A current,<0.5 n W Power),as well as wavelength tuning(1062.08-1064.02nm).When the pump power is stable at 1.67 W,the maximum output power is about 530 m W.The pulse width can be regulated stably from 1μs to 360 ns by applying gate voltage,and the corresponding repetition frequency is increased from 160 kHz to 390 kHz.