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Theoretical And Experimental Studies On2μm All Solid-State Tunable Laser

Posted on:2013-10-07Degree:MasterType:Thesis
Country:ChinaCandidate:M SunFull Text:PDF
GTID:2248330392455018Subject:Optics
Abstract/Summary:PDF Full Text Request
Laser systems that operate in the2-μm region offer exceptional advantages for free space applications compared to conventional systems that operate at shorter wavelengths. This gives them a great market potential for the use in LIDAR and gas sensing systems and for direct optical communication applications. The favourable absorption in water makes such laser also very useful for medical applications. There is a strong absorption peak near2-μm which reduces the penetration depth of this wavelength in tissue to a few hundred μm. The2-μm laser can also be used as the pump source of3-5μm mid-infrared optical parametric oscillators.Using Tm3+-doped laser emission was achieved in many different host crystals and glass fibers. Tm3+ion has a broad fluorescence spectrum. This property is beneficial for tunable laser operation. Recently, mixed laser crystals have attracted many research interests due to their longer fluorescence lifetime and broad emission bandwidth resulting from their disordered natures. This property is also beneficial for tunable laser operation. In this paper, we study the field of CW(continuous wave) and tunable mixed crystal Tm:(LuxY1-x)3A15O12(Tm:LuYAG) laser with a volume Bragg grating(VBG) as a tunable component.Theoretically, we have analyzed the energy processes and rate equations of Tm3+-doped laser. In the Tm3+-doped laser system, the cross relaxation, upconversion possesses, reabsorption and ground-state depletion of the Tm-doped laser crystal are analyzed. Secondly, the coupled wave theory was introduced. We can get the diffraction efficiency of VBG with different gratings parameter, such as thickness of the grating, refractive index modulation and so on. The spectral selectivity was also given. Thirdly, the material properties of VBG are introduced. The photo-thermo-refractive(PTR) glass was introduced and the processes of fabrication were explained.Experimentally, first we achieved the free running continuous wave(CW)2-μm laser output. We used two mirrors cavity, and the max maximum output power is3W, and the maximum slope efficiency is-33%. Secondly, a three-mirrors "V-shaped" folded resonator with the VBG as one of end mirrors was employed, the output laser wavelength is1999.7nm, and the max maximum output power is1.76W. Thirdly, We constructed a four-mirrors "Z-shaped" folded resonator configuration, in which the VBG was introduced as one of the folded mirrors. We get the2-μm tunable laser, the laser wavelength was continuously tunable from1935.3nm to1994.9nm(-60nm). The variation of the power in the tunable range are analysed.
Keywords/Search Tags:2-μm solid-state laser, tunable, volume Bragg grating, mixed laser crystal
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