YAG Laser End and Side Pumped by a Laser Diode

End-pumped 1.5 microm monoblock laser for broad temperature operation

We describe a next-generation monoblock laser capable of a greater than 10 mJ, 1.5 microm output at 10 pulses/s (pps) over broad ambient temperature extremes with no active temperature control. The transmitter design is based on a Nd:YAG laser with a Cr4+ passive Q switch and intracavity potassium titanyl phosphate optical parametric oscillator. To achieve the repetition rate and efficiency goals of this effort, but still have wide temperature capability, the Nd:YAG slab is end pumped with a 12-bar stack of 100 W (each) diode bars. Different techniques for focusing the pump radiation into the 4.25 mmx4.25 mm end of the slab are compared, including a lensed design, a reflective concentrator, and a lens duct. A wide temperature operation (-20 degrees C to 50 degrees C) for each end-pumped configuration is demonstrated.

Efficient operation of a solid-state adaptive laser oscillator

We present the results of a cw diode-pumped Nd:YVO4 laser oscillator based on a self-starting adaptive gain-grating resonator. Adaptive laser operation has been demonstrated with 12-W output for 37 W of diode pumping, producing a TEM00 mode that compensates for thermal aberrations. The issue of the finite aperture of the amplifier is discussed, and a design that incorporates an intracavity lens is used to improve the collection efficiency with severe thermal lensing at high pump powers. The powers of the beams involved in the resonator are compared with theory and are found to be in good agreement. Spectral and temporal behavior of the adaptive laser is investigated, and very interesting behavior is shown, including self-induced temporal modulation dynamics and a switching between a narrowband and a broad bandwidth of operation.