| The passively Q-switched laser has been of intense interest because it is generally simple, convenient, and requires a minimum of intracavity elements and no external high voltage or RF drivers.; Z-scan technique was used to obtain more realistic values of the ground and excited state absorption cross sections of Cr:YAG, one of the most important solid state saturable absorbers. Other spectroscopic research revealed that Cr:YAG performs stably over the wide temperature range from –70 to +80°C.; A generalized model of a passively Q-switched laser was developed. It enables performance optimization including general cases in which the saturable absorber exhibits both ground and excited state absorption at the laser wavelength. Based on the theory, we built and tested a Nd:glass laser passively Q-switched by a Cr4+:YAG crystal and found excellent agreement with our model.; The model was then extended to the case where an optical parametric oscillator (OPO) is contained inside the passively Q-switched laser cavity. In such a laser there is no output at the fundamental or pump wavelength. When the OPO signal field begins to build up, it acts as a loss for the pump and cavity dumps the pump resonator. The extended model describes the complicated interactions between the fundamental laser gain medium, saturable absorber, fundamental laser cavity, and OPO cavity. The model developed enables one to select OPO parameters which optimize the system's performance. Application of the model to a very compact, lightweight, eye-safe laser range finder operating at 1.54 μm will also be presented.; Many applications demand lasers to be operated over a wide temperature range (–55—75°C). Efforts were dedicated to obtaining information on the temperature dependence of the emission cross section of Nd,Cr:GSGG and the optical properties of certain laser resonator optics. The data serve as input parameters to the models to design passively Q-switched laser systems with predictable temperature dependence. The performance of this type of laser design has been confirmed by independent experimentation at the Sandia National Laboratory. |
