Abstract

A Stark anomalous dispersion optical filter (SADOF) is an ultra-narrow bandwidth optical filter for applications in laser remote sensing and satellite laser communications. A SADOF consists of an atomic vapor cell between crossed polarizers subjected to an electrical field transverse to the optical path and oriented 45° relative to the crossed polarizers. When linearly polarized light travels through a dispersive atomic vapor cell, a polarization rotation occurs (Stark induced birefringence), Large rotation angles may be obtained when the input light frequency is near the resonant frequencies of the atomic vapor. The transmission peaks of the SADOF correspond to frequencies that have rotation angles of odd integer multiples of π/2 and low absorption in the vapor cell. The transmission curve depends on the electric field and atomic density, the optimum conditions for a SADOF are found through theoretical calculations that include both Stark spectral and polarization rotation. We will present theoretical SADOF transmission curves for some green alkali transition frequencies matched to the doubled Nd lasers. The results show that within the practical electrical field strength, the SADOF can provide about 90% transmission, 1 GHz transmission bandwidth, 5 GHz noise equivalent bandwidth, good operating stability, wide tuning range, and wide field-of- view. The model also predicts that the required optical pump power for the atomic cell is on the order of few mW/cm². The details of the model and calculated results will he presented.

© 1993 Optical Society of America