Tunable optical delay in Doppler-broadened cesium vapor.

摘要

Variable-delay tunable optical delay line or optical buffers are critical for the development of all-optical networks components as well as interferometry and analytic instruments. Recent research on slow light may hold the key for the development of the first practical tunable optical delay device. In this research an atomic vapor pulse delay model is developed including hyperfine structure and Voigt lineshape. Frequency tunable pulse delays of 0-37 ns are achieved in Cs D2 at various vapor pressures of 0.15-5.28 mTorr between 78.9°C and 137.2°C in agreement with model prediction. Furthermore full-frequency Cs D1 line hyperfine optical delay model is validated with the observation of delays of 1.6 ns to 24.1 ns. Additional optical control of delays were demonstrated by pumping the Cs D2 transition and observing resulting effects in the D1 delay spectrum. For a pump at four times the saturation intensity, delays are reduced by a maximum of 78% in a narrow region of 110 MHz in agreement with a Kramers-Kronig model prediction. Diode-pumped alkali laser (DPAL) systems depend on accurate models to scale to high power and optimize performance. There is currently no validated bleach wave model of an operating DPAL system. This work partially examines the bleached wave temporal dynamics during a 10 ns high-power D2 pulse event with 0-400 Torr helium buffer gas. The linear dispersion delay model is a valuable improvement over currently used Lorentzian approximations and provides a significant addition to the field tunable slow light delays. This work presents the first reported spectral hole-burnt linear dispersion delay effects in an alkali vapor. The hyperfine relaxation observations present insight into the complex bleach wave dynamics during a high-intensity pulsed pump in DPAL systems.