Investigation Of Passively Q-switched Solid-state Lasers Based On Gold Nano-materials

With the situation of manufacturing transformation,short pulse lasers are playing a more and more important role.Lasers with different wavelengths have different applications.For example,1.06 m lasers are commonly used in cosmetic surgery and material processing.1.1 m laser can be used in the 555 nm generation by frequency doubling.1.3 m lasers have important applications in optical fiber communication for its low loss and low dispersion in fiber.The development of laser technology has caused extensive research in gain medium and saturable absorber.Gold nano-material is a new saturable absorber which attracted attention recently.The optical properties are related to its structure and size.Especially,the gold nanorod surface plasmon resonance absorption can be changed from visible to near infrared by adjusting the aspect ratio,so gold nano-materials can be applied in lasers with different wavelengths.The emphasis of this thesis is the characteristics of passively Q-switched laser with gold nano-materials saturable absorber.The laser crystal we used is Nd:YAG and Nd:GYSGG,respectively.With the pump of semiconductor laser,we obtained Nd:YAG lasers operating at 1.06?m,1.1pm and 1.3?m.The condition of dual-wavelength operation was also studied.We use Nd:GYSGG crystal produced dual-wavelength laser near 1.06 ?m.Then gold nano-materials saturable absorbers are used for passively Q-switch the above lasers.The average power,pulse width and repetition frequency are studied.The main work includes the following:1.We study the recent development status of short pulse lasers,and discuss about the merits of gold nano-materials.Several common saturable absorber(e.g.Cr:YAG,SESAM)and new saturated absorber(e.g.graphene,carbon nanotubes)are introduced.Then we present the applications and research progress of gold nano-materials.2.We use gold nanorods as saturable absorber in diode-pumped passively Q-switched Nd:YAG 1064 nm laser.The maximum output power is 101.3 mW with the shortest pulse width of 223ns.The 223 ns pulse width is the shortest width in passively Q-switched laser with gold-nanorod as saturable absorber.We first use gold nanorods saturable absorber to Q-switch dual-wavelength Nd:GYSGG 1059/1062 nm laser.The average power we obtained was 49.5 mW.The shortest pulse width was 516 ns with pulse repetition frequency of 110 kHz.3.Through the design of output mirror,1112 nm Nd:YAG laser was achieved.We studied the laser characterizes with different output couplers.Then Q-switched operation was realized by gold nanorods,504 ns,120 kHz,1.5?J and 619 ns,200 kHz,1.18 ?J pulses were generated.4.The gold nanorods with absorption peak at 1280 nm were used for Q-switching dua-wavelength 1319/1338nm laser for the first time.The condition of dual-wavelength operation was studied.The shortest pulse width of 404 ns with pulse repetition rates of 150 kHz was obtained.The maximum average power was 147 mW.5.We first reported and demonstrated gold nano-triangles(GNTs)can be used as saturable absorber.The absorption peak of GNTs was at 1.1 ?m.We employ GNTs in the 1064 nm Nd:YAG laser and 1059/1062 nm Nd:GYSGG laser,and 275 ns,220 kHz,171 mW and 374 ns,250 kHz,75 mW pulses were generated,respectively.