EXPERIMENTAL DEMONSTRATION OF AN EXCITED-STATE FARADAY FILTER OPERATING AT 532 NM

We outline what is to our knowledge the first experimental demonstrati on of an excited-state Faraday filter. The filter consists of potassiu m vapor between crossed polarizers in a dc magnetic field and operates on the 4P1/2 --> 8S1/2 transition in potassium. The 4P1/2 state is po pulated by a linearly polarized, 10-ns light pulse from a dye laser op erating at 769.9 nm. Another linearly polarized, 10-nsec pulse at 532. 33 nm traverses the pumped volume of the K cell and is absorbed from t he 4P1/2 state to the 8S1/2 state. The transmission of the filter is a pproximately 3.5% at 532.33 nm with a bandwidth of less than 10 GHz.