Article
Adaptive beam combining and interferometry with photorefractive quantum wells
J. Opt. Soc. Am. B
(2001)
Abstract
We present a comprehensive study of excitonic electroabsorption and two-wave mixing in photorefractive
quantum wells. By combining these two measurements, we are able to determine the internal grating writing
efficiency for converting an external spatial light modulation into an internal space-charge field. The internal
writing efficiency at a fringe spacing L 5 40mm is found to be a decreasing function of applied field, varying
from j 5 0.4 at low fields to 0.2 at 12 kV/cm. The two-wave mixing efficiency in the quantum wells exceeds
40% and is used for adaptive beam combining and laser-based ultrasound detection. The quantum wells balance
the hot-electron-induced photorefractive phase shift with excitonic spectral phase to guarantee quadrature
in homodyne detection of ultrasound-induced surface displacements. The ability to tune through multiple
quadratures is demonstrated here for the first time to our knowledge. We derive a noise-equivalent
surface displacement of 1.7 3 1026 Å (W/Hz)1/2 at a field of 12 kV/cm and a fringe spacing of L 5 40mm. This
value is within a factor of 7 of the shot-noise limit of an ideal interferometer.
Keywords
- Photorefractive Effect
Disciplines
Publication Date
2001
Citation Information
David D Nolte. "Adaptive beam combining and interferometry with photorefractive quantum wells" J. Opt. Soc. Am. B Vol. 18 (2001) p. 195 Available at: http://works.bepress.com/ddnolte/44/