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Diode-Pumped All-solid-state Single-longitudinal-mode Laser

Posted on:2005-05-15Degree:MasterType:Thesis
Country:ChinaCandidate:E WuFull Text:PDF
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The all-solid-state laser pumped by laser diode instead of flash lamp has attracted focus of interest for its high energy transference, long-lived operation, stable output frequencies, compact structure, and low thermal effects. Especially, the LD pumped single-longitudinal-mode all-solid-state lasers are widely used in coherent range-finding, coherent optical communication, ultra-sensitive laser spectroscopy, nonlinear frequency conversion, quantum optics and so forth.In this dissertation, two kinds of laser diode pumped all-solid-state single-longitudinal-mode lasers are presented. The single-longitudinal-mode outputs of these two lasers are obtained both by means of eliminating the spatial hole-burning in the gain material.One is a ring laser with a twin off-axially cut Nd:YVO4 in a compact linear cavity We analyzed the intracavity polarization of the ring laser by using the Jones matrix, figured out its eigen-states including its eigen-polarizations and ei gen-frequencies, and confirmed theoretically the single longitudinal mode running of this laser. The spectral measurement of the output laser beam was performed with a scanning Fabry-Perot interferometer, which demonstrated single-mode operation of the ring laser as theoretical analyses predicted. The experimental observation of the polarization states of the output laser clearly verified that ring circulation of polarized laser beams took place inside the twin off-axially cut Nd:YVO4 crystals.Another is a twisted-mode cavity laser using a piece of c-cut Nd:GdVO4 crystal as the laser active material. Although Nd:GdVO4 is a positive uniaxial crystal possessing birefringence, we established a single-longitudinal-mode twisted-mode cavity laser by choosing the c-cut crystal as the gain material. Output spectra were scanned by ascanning Fabry-Perot interferometer and the single-longitudinal-mode laser operation was observed in the twisted-mode cavity. A maximum single-longitudinal laser output power of 2.5 W was obtained when the pump power was 19.0 W. The pump slope efficiency was about 17.4%. Passively Q-switched single-longitudinal-mode laser was also achieved by using a piece of Cr4+:YAG as an intracavity saturable absorber.A robust solid-state saturable absorber is also introduced in this dissertation. The cobalt ions doped tellurite glasses has a much broad saturable absorption band in the near infrared region. Nonlinear optical absorption was measured using the z-scan technique. By numerically fitting the z-scan experimental data, the excited-state absorption cross sections at the laser wavelength of 1064 nm was obtained.
Keywords/Search Tags:LD-pumped, all-solid-state, single-longitudinal-mode, spatial hole-burning, Jones matrix, twisted-mode cavity (TMC), Nd:GdVO4, passive Q-switch, saturable absorber
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