Total reflection resonator with hole coupling.

Total internal reflecting surfaces have been proposed as regenerative structures for solid-state lasers; the laser energy is extracted from the resonator through frustrated total re­ flection by a coupling prism. Instead of using frustrated total reflection to extract the energy, we found the energy can be extracted through a hole on the tip of the total reflecting surface. In this experiment, we polished the two ends of a Nd:Yag laser rod into 90° cones with one cone tip polished into a small flat surface (1 mm in diam, with no intention of optimizing the output coupling) as shown in Fig. 1. The 90° cones from the total internal reflecting surfaces and the small flat surface are used as an energy output port. Intuitively, this structure is more or less similar to the hole coupling used in CO2 lasers. This Nd:Yag laser rod, 69 mm in length and 5 mm in diam, with 1.2% Nd + 3 concentration, is then put into a gold-coated circular cavity and pumped by a pulsed xenon flashlamp. The typical discharge condition was a capacity of 50 μF and 600 V. The output energy detected by a P-I-N photodiode