Investigation On Self-injection Locked CW Single-frequency Tunable Ti:sapphire Laser

Compared to lasers with constant output wavelength,the tunable laser can realize different wavelength output in an identical laser system,which not only increases the practicability of the laser source,but also satisfy the specificrequirementsoflotsofresearches.Amongthem,the continuous-wave（CW）single-frequency tunable Ti:Sapphire laser is one of the most important laser sources,and have been widely applied in quantum optics,atomic physics,spectroscopy,biological medicine,communications,gravitational wave detection,laser radar and so on because of theirs intrinsic advantages including good beam quality,wide output spectrum,continuous frequency-tuning,high output power,and so on.Therefore,developing the Ti:sapphire lasers and improving their performance become particularly important.For this purpose,the compact self-injection locked CW single-frequency tunable Ti:Sapphire laser is investigated and designed.The main content is as follows:1.The compact astigmatism-compensated ring cavity composed of four mirrors is designed,where the stability zone of the resonator and the waist spot characteristics are concerned with resonant cavity length parameters,and the waist spot characteristics are relate to the injected pump power are successively calculated and analyzed.In order to compensate the pump astigmatism caused by the Brewster-angle-cut Ti:sapphire,a plane-concave mirror is used to replace the original convex lens to achieve the efficiently coupling between the pump and oscillation laser.A birefringent filter（BRF）with a thickness ratio of 0.5:2:8 mm and a electro-optic etalon with the thickness of 1mm are used as roughly and fine frequency selective elements in the intra-cavity of Ti:sapphire laser,respectively.2.A CW single-frequency tunable Ti:sapphire laser with stable unidirectional operation is achieved by using a retro-reflecting device with alterable reflection,which can retro-reflect a arm beam from one direction back to the counter-propagating filed.On the basis,the influence of transmission of output mirror on the unidirectional operation and the essential condition of the stable unidirectional operation of self-injection locked Ti:sapphire are investigated.When the optimal output mirror with transmission of 6.5%is used and the laser works at the wavelength of 795nm corresponding to D₁ transitions of ⁸⁷Rb atoms,the maximal output power of5W with stable unidirectional operation CW single-frequency Ti:sapphire laser under the pump power of 18W is achieved,the slope efficiency can reach 34.8%.The power stability and M² are as better as±0.9%and 1.1,respectively.The maximal tuning range and continuous frequency-tuning are as wide as 120nm and 40.75GHz,respectively.The compact self-injection locked Ti:sapphire have been made.