Investigation On All-solid State Single-frequency Tunable Ti:sapphire Laser Around461nm

All-solid-state continuous-wave blue lasers have a wide field of applications in high-density optical data storage, biomedicine, high-resolution spectroscopy, laser cooling etc. It is known that atomic clock operating at optical rather than microwave frequencies has higher accuracy and stability. The research of the optical clock based on the laser cooling femotosecond optical comb technic has attracted great interest owing to it's potential optical advantages. It will be the new time and frequency standards. Because of the narrow transition width of the strontium atoms, the accuracy of the time can be highly enhanced, they have been widely used in the optical clock system. For laser cooling and trapping, the dipole transition between 'So and1P1states of the strontium atoms at461nm is usually adapted. So a single frequency and tunable high power light at461nm is desired in a strontium optical clock. During the period of my Ph. D study, we have realized a blue light source at461nm by intracavity frequency doubling of a Ti:sapphire laser. The accomplished main works are as following:1. We have analyzed the level structure, absorption and emission spectra, physical and chemical properties of the Ti:Sapphire crystal. Based on those theories, an astigmatically compensated double-folded resonator is designed to give two tight-focus regions, where the Ti:sapphire and BIBO crystals are located. And we have resonablely choiced the parameters of the cavity to satisfy with the optimum mode matching. High efficient output at922nm has been realized.2. By analyzing the features of the birefringence phase matching and quasi-phase matching, we get the merits of quasi-phase matching such as free of walk-off, high effective nonlinear coefficient, wide wavelength range of SHG, tuning convenience etc.3. The tuning properties of the Ti:sapphire laser are analyzed. The laser can be coarsely tuned by BRFS inserted in the laser cavity. And the tuning range of the BRFS is decided by the thinnest plate. The tuning precision is decided by the thickest one. And to improve the tuning precision, an angle-tuned thin etalon is inserted for fine tuning. To control the temperature of the etalon, the frequency of the cavity is continuously tuned.4. We demonstrate a tunable continuous-wave single frequency intracavity frequency doubling Ti:sapphire laser, which uses a homemade single frequency green laser as the pump source. The highest output power of280mW at461,62nm is obtained by employing a type I phase-matched BIBO crystal, and the power fluctuation is less than±1%within3hours. A three-plate birefringent filter allows for the tunable range from457nm to467nm, which covers the absorption line of the strontium atoms(460.86nm). The frequency stability is better than±2.22MHz over lOmin when the laser is locked to a confocal Fabre Perot cavity.5. To improve the quality of the spatial mode, we use PPKTP as a laser frequency doubling crystal to generate461nm blue radiation. Output power of330mW at460.86nm has been achieved at the incident pump power of9.2Watts at532nm. The blue laser can be tuned from460.8263nm460.8795nm by changing the temperature of the etalon. The frequency stability is better than±3.47MHz over15min when the laser is locked to a confocal Fabre Perot cavity.6. A maximal output power of12.9W at532nm wavelength is obtained under a pump power of30W. Analyzing the thermal effect of the laser crystal, a CW laser consisting of a low-doped Nd:YVO4/YVO4composite crystal with a three-mirror V-fold thermal unsensibility resonator has been designed and constructed. Using a Ⅰ-type phase-matching LBO as the frequency doubler, a maximal output power of12.9W at532nm wavelength is achieved.The creative works are as following:A. An astigmatically compensated double-folded resonator with six mirrors is employed to give two tight-focus regions, where the Ti:sapphire and doubling crystals are located. The central wavelength of the laser is922nm.B. Using the BIBO crystal as the intracavity frequency doubler, a tunable single-frequency Ti:sapphire laser has been achieved. It's central wavelength is461.62nm.C. To improve the beam quality, a tunable single-frequency Ti:sapphire laser has been achieved using the PPKTP crystal as the intracavity frequency doubler. It's central wavelength is460.86nm. The blue laser can be tuned from460.8263nm-460.8795nm by changing the temperature of the etalon.