Experiments on Single-Pass and Double-Pass Birefringent Networks*†

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Abstract
Procedures have recently been given by Harris et al. and by Ammann for synthesizing single-pass and double-pass birefringent networks having arbitrary transmittance-vs-frequency characteristics. This paper describes the results of experiments which were performed on these two types of optical networks. A three-stage network was tested in the single-pass experiments, while three-, five-, and seven-stage networks were used in the double-pass experiments. Each stage of these networks consisted of a calcite crystal 2 cm in length followed by a quartz compensator. The transmittance characteristics of the networks were obtained by measuring network transmittance (at a fixed optical frequency) as a function of network temperature. Since the phase difference between fast- and slow-axis light components passing through a calcite crystal has the same functional dependence upon temperature as upon optical frequency, the transmittance-vs-temperature characteristic of a birefringent network will be the same as the transmittance-vs-frequency characteristic. This gives a very convenient, high-resolution method of measuring the transmittance of birefringent networks. The measured transmittances are shown together with values predicted by theory. The excellent agreement obtained serves both as a verification of the synthesis procedures and as a demonstration of the utility of the measurement technique.