Tunable Finesse and Beam Transformations with Coupled Cavities

I will describe several related tools for use in atomic physics experiments and general laser manipulation, which rely on techniques using coupled optical cavities. The first is a tunable finesse cavity whose coupling to free space can be changed by orders of magnitude, amounting to a variable photon lifetime. Then I will demonstrate that, with the correct configuration of coupled resonators, an input Hermite-Gaussian beam can have its spatial and frequency properties drastically altered with little loss of power. These tools are easily constructed and robust to high laser powers.