Research On Photonic Crystal Fiber Supercontinuum & Laser And Nd:Gdvo₄ Laser

Photonic crystal fibers (PCFs), a novel class of fibers in which a solid cladding, typical of standard optical fibers, is replaced by a silica–air or glass–air microstructure cladding, offer new and exciting possibilities in many application fields. PCFs are attracting considerable interest as transmission media and optical functional devices. It is of paramount importance in applications to research the supercontinuum generation in PCF and the PCF laser. As a relatively new laser material, Neodymium-doped gadolinium vanadate (Nd:GdVO4) was firstly developed by Zagumennyi et al. in 1992. Besides the advantages that Nd:YVO4 crystals possess, Nd:GdVO4 crystals have a large thermal conductivity, even higher than that of Nd:YAG crystals. So Nd:GdVO4 crystal is recognized as a promising substitute for Nd:YAG and Nd:YVO4 in diode-pumped solid-state lasers. The main contents in the dissertation are summarized as follows:The conceptions, principle, characteristics, classes, preparation, calculation methods, applications and foreground of photonic crystals were summarized systematically. The characteristics, classes, preparation methods, development and potential application were also introduced briefly.Supercontinuum was generated with a bandwidth of 300 nm to 1350 nm, which is over two octaves, in a 2.5 m-long PM-PCF pumped by Optical Parameter Amplifier (OPA). The spectral components were also observed in the region of 1.5 (m to 1.8 (m.Nearly 1000 nm broad continuum from 390 nm to 1370 nm is generated in a 2-m long NL-PCF. The maximum total power of supercontinuum is measured to be 60 mW with the pumping power of 800 mW output from a 200 fs Ti-Sapphire laser.Supercontinuum with an ultra-broad bandwidth of 380 nm to 1750 nm was generated by injecting 250 kHz, 200 fs optical pulses produced from a regeneratively amplified Ti:sapphire laser into a 2.5 m-long polarization-maintaining photonic crystal fiber.A 30-m ytterbium-doped double-clad and D type fiber laser with output power of 8.6 W and the wavelngth of 1.09 (m was obtained, which was pumped by high power LD arrays. The laser with output power of 7.2 W and the wavelength of 1.07 (m was generated from a 5-m ytterbium-doped double-clad fiber with D type and multiple modes pumped by high power and multi-mode LD. 65 mW and 1.03 (m ytterbium-doped double-clad and large mode area PCF laser was successfully obtained; The laser with output power of 15 W and the wavelength of 1.09 (m was obtained from a 20-m ytterbium-doped double-clad PCF pumped by high power and multi-mode 980 nm LD.The main characteristics and pumping-geometries were introduced, respectively. Based on the differential equation of saturated intensity in gain media, the analytical expressions of the output power, threshold pump power and slope efficiency were derived respectively. The optimum laser crystal length and output coupler were also analyzed based on the expressions. The thermal effects of laser crystals in DPSSL were introduced briefly. The main characteristics of several typical solid-state laser materials for DPSSL were summarized.The fluorescence and polarized absorption spectra of Nd:YVO4 and Nd:GdVO4 crystals at room temperature were measured respectively. For the first time to our knowledge, the laser performance of Nd:GdVO4 crystal at 1.34(m under 70-W single-end pump power was investigated. The highest CW output power of 8.23 W was achieved, which is the highest CW 1.34 (m output power obtained with a Nd:GdVO4 crystal utilized in an end-pumped laser to date. It indicated the good thermal property and laser performance of Nd:GdVO4 crystal at high end-pump power.