Output Performances Of The Passively Q-switched Ho:YAG Ceramics Laser

Compared to the other gain mediums,Ho:YAG transparent ceramic have different spectral characteristics and inherent advantages,such as higher absorption and emission cross sections,so Ho:YAG transparent ceramic has become a kind of important material for the generation of 2?m laser.Because 2?m laser lies in eye-safe range and atmospheric transmission window,2?m solid-state lasers are in great demand for a number of applications,such as remote atmospheric sensing,homeland security,free space optical communications,biomedical field,laser ranging and Coherent Dopper radar and so on.Furthermore,2?m laser can be used as the pump source of mid-infrared optical parametric oscillator at 3¹2?m.In the thesis,the Cr:ZnS crystal is employed as the Q-switched saturable absorber in the2?m passively Q-switched laser.The operating performances of the passively Q-switch laser based on Ho³⁺-doped laser crystal are investigated theoretically.the rate equations of the Cr:ZnS passive Q-switched Ho³⁺-doped laser is established.the rate equations are solved analytically.The analytical formulas of the pulse energy,the peak power and the pulse width are obtained,which clearly show the dependence of the pulse operating performance on the system parameters.Using a Tm:YLF laser as the pump source,the Ho:YAG ceramic as the gain medium,the Cr:ZnS crystal as the saturable absorber?SA?,a compact diode-pumped continuous wave?CW?and passively Q-switched?PQS?Ho:YAG ceramic laser emitting at2?m is demonstrated.Experimentally,the CW operation of Ho:YAG ceramic laser is investigated at the optical cavity length of 100 mm.The dependence of the output power on pumping under different wavelength,different pump power,and different output couplers of2%,5%and 10%is discussed.The output performance of the PQS Ho:YAG ceramic laser is also investigated by inserting a Cr:ZnS SAs into the cavity.The variation of output power with the pump power is obtained for the different pump wavelength and three output couplers.The dependence of the output wavelength on three coupling transmittances is also investigated.