Study Of Laser Diode-Pumped Yb Ion-Doped All-Solid-State Lasers

Recently, the rapid developments of laser diodes (LDs) technology make LDs be becoming the main pump sources of solid-state lasers instead of flashlamps and ion lasers due to the high efficiency, miniaturization and integration for all-solid-state lasers. Among of the solid-state gain media, such as Nd³⁺, Er³⁺ and Yb³⁺ doped crystals, Yb³⁺ doped laser materials are more suitable to be pumped by laser diodes because of its unique absorption bands which are well matched with the wavelengths of the commercial laser diodes. Additionally, the Yb-doped crystals have many interesting properties, such as high quantum efficiency, broadband fluorescence and long radioactive lifetime, which are all in favor of tunable, ultrafast and Q-swithed laser operations.This thesis presents our the experimental results on CW, tunable, Q switched and/or mode-locked lasers based on two novel Yb-doped crystals (Yb:LYSO and Yb:GSO). The main conclusions can be outlined as follows.1. In chapter 1, a brief review is given on the history and progress of laser diode-pumped solid-state lasers (LDPSSL), the advantages of LDPSSL by comparing with traditional flashlamp-pumped lasers, as well as the advantages of Yb³⁺ materials and the development of LDPSSL based on Yb ion-doped crystals.2. Chapter 2 introduces firstly the principle of laser tunablity, including some comparisions among the tunings by use of prism, grating and birefringent filters. Then some introductions are also presented on Q swithed and mode locking laser operations. Our emphasis is on the passively mode-locking by semiconductor saturable absorber mirror (SESAM).3. The broadly tunable laser operation is achieved experimently based on a 5at.% Yb:LYSO crystal with a V-shape cavity and a dispersive prism as tuning element. The span of the tenability reachs up to 98 nm, from 1001.9 to 1100 nm. And in the Z-shape cavity Q-switched mode-locked (QML) laser pulses has also output by use of a SESAM as a Q switcher. The laser threshold is 9 W. The maximum output power of 820 mW is achieved when the pump power reaches up to 14.4W, thus the corresponding slope efficiency is 15.4%.4. Chapter 4 reports the laser performance of the tunable Yb.GSO lasers pumped directly by fiber coupled LDs. The laser operation ranges from 1009 to 1112 nm, which is slightly wider than that based on Yb:LYSO crystal. Another interesting result is that as short as 343 fs mode locking pulses around 1033 nm are achieved by use of a Z-shape cavity with five mirrors and a SESAM as passively mode-locked starter.5. Finally, some conclusions are summarized based on the descriptions in former chapters, including the following aims of our research work.