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Proceedings Paper

VCSELs for atomic clocks
Author(s): Darwin K. Serkland; Gregory M. Peake; Kent M. Geib; Robert Lutwak; R. Michael Garvey; Mathew Varghese; Mark Mescher
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Paper Abstract

The spectroscopic technique of coherent population trapping (CPT) enables an all-optical interrogation of the groundstate hyperfine splitting of cesium (or rubidium), compared to the optical-microwave double resonance technique conventionally employed in atomic frequency standards. All-optical interrogation enables the reduction of the size and power consumption of an atomic clock by two orders of magnitude, and vertical-cavity surface-emitting lasers (VCSELs) are preferred optical sources due to their low power consumption and circular output beam. Several research teams are currently using VCSELs for DARPA's chip-scale atomic clock (CSAC) program with the goal of producing an atomic clock having a volume < 1 cm^3, a power consumption < 30 mW, and an instability (Allan deviation) < 1x10^-11 during a 1-hour averaging interval. This paper describes the VCSEL requirements for CPT-based atomic clocks, which include single mode operation, single polarization operation, modulation bandwidth > 4 GHz, low power consumption (for the CSAC), narrow linewidth, and low relative intensity noise (RIN). A significant manufacturing challenge is to reproducibly obtain the required wavelength at the specified VCSEL operating temperature and drive current. Data are presented that show the advantage of operating at the D1 (rather than D2) resonance of the alkali atoms. Measurements of VCSEL linewidth will be discussed in particular, since atomic clock performance is especially sensitive to this parameter.

Paper Details

Date Published: 10 February 2006
PDF: 11 pages
Proc. SPIE 6132, Vertical-Cavity Surface-Emitting Lasers X, 613208 (10 February 2006); doi: 10.1117/12.647095
Show Author Affiliations
Darwin K. Serkland, Sandia National Labs. (United States)
Gregory M. Peake, Sandia National Labs. (United States)
Kent M. Geib, Sandia National Labs. (United States)
Robert Lutwak, Symmetricom, Inc. (United States)
R. Michael Garvey, Symmetricom, Inc. (United States)
Mathew Varghese, Charles Stark Draper Lab., Inc. (United States)
Mark Mescher, Charles Stark Draper Lab., Inc. (United States)

Published in SPIE Proceedings Vol. 6132:
Vertical-Cavity Surface-Emitting Lasers X
Chun Lei; Kent D. Choquette, Editor(s)

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