Preparation And Research Of Planar Waveguides Based On Dy-doped LPS Crystal And YAG Ceramic

In the past few decades,the development of solid-state waveguide lasers has greatly depended on the innovation of the geometry of the gain medium.The waveguide structure prepared by rare earth ion doped optical materials can limit the beam to the micron range and achieve higher density optical storage,which is beneficial to the preparation of micro light source with high gain and low laser pumping threshold power,and has achieved exciting development results in the field of integrated optics.In addition,a high-power semiconductor laser can be used to pump the end face or side of the waveguide structure.Such geometric structure innovation provides a good thermal management for the waveguide laser.The waveguide structure is an important component in waveguide laser.Therefore,the preparation of high-gain,low-loss waveguide structures is the key to further development of waveguide lasers.The rare earth dysprosium ion has a rich energy level structure and is a potential activator.Semiconductor laser can be used to pump dysprosium ion doped laser medium.Using the ⁴F_9/2→⁶H_13/2,⁶H_13/2→⁶H_15/2 and ⁶H_11/2→⁶H_13/2 energy level transitions of dysprosium ions,yellow laser at570～590 nm and mid-infrared laser output at～3μm and～4μm can be obtained respectively.In this paper,dysprosium ion-doped lutetium pyrosilicate crystal and yttrium aluminum garnet ceramic are used as substrate materials,and planar waveguide structures are prepared on their surfaces by ion implantation technology.Different optical coupling techniques are used to explore the optical properties of waveguides,which lays a foundation for the preparation of dysprosium-doped plannar waveguide lasers.The main research contents of this paper include the following aspects:Firstly,the important applications of waveguide lasers in integrated optics are discussed.The waveguide substrate materials based on laser crystals and laser ceramics are briefly introduced.The application and research status of Dy³⁺ions in mid-infrared laser and yellow laser emission are introduced in detail.Finally,the optical properties of two different laser crystals（LPS crystal and YAG ceramic）are briefly introduced.Secondly,the absorption spectra of 5 at.%Dy:LPS crystal was measured by the spectrophotometer of Lambda 950 UV/VIS/NIR Spectrometer,and the spectral properties of the sample was analyzed by J-O theory.Thirdly,the Dy:LPS planar waveguides were prepared by ion implantation technology,and the optical properties of waveguides implanted with He⁺ions and H⁺ions were discussed respectively.The ion implantation process can be simulated by the SRIM 2010 program,which can also calculate the ion range distribution and energy loss distribution.In order to evaluate the quality of the planar optical waveguides prepared by two different light ion implantations,the dark mode characteristic curves of the two waveguides at the wavelength of 632.8 nm were first measured.According to the ion range distribution and the effective refractive index read from the dark mode characteristic curve,the RCM program was used to fit the refractive index distribution of the waveguide structure.The beam emitted by the He-Ne laser is coupled into the waveguide by the end-face coupling technique to observe the near-field intensity distribution of the excited guided mode.It is found that the Dy:LPS planar waveguide structure implanted with H⁺ions has better confinement force on the light in the direction perpendicular to the implanted surface,and its transmission loss is about 2.36 d B/cm.According to the distribution of refractive index fitted by RCM,the number of propagation modes of the waveguide at the wavelength of 632.8 nm is 3.Comparative experiments show that the implantation of both H⁺ions and He⁺ions lead to a decrease in the refractive index of Dy:LPS crystals in the implanted region,and the Dy:LPS planar optical waveguide implanted by H⁺ions has better optical properties.Fourthly,Dy:YAG planar waveguide was prepared by H⁺ion implantation technology,and the waveguide structure was annealed for 1 hour at 260℃and 310℃,respectively.By comparing and analyzing the optical properties of the waveguide,the prepared Dy:YAG planar waveguide has good transmission loss,and the loss value is about 2.07 d B/cm.After annealing treatment,the optical properties of the waveguide was decreased,and the effective refractive index of the waveguide was shifted slightly.The structure of Dy:YAG planar waveguide F-P resonator based on low loss was proposed,which lays a foundation for the design of waveguide laser.