NASA requires compact, rugged optical sources which have a stable reproducible center frequency and a long coherence length (narrow linewidth) for laser metrology applications. This project will use a Doppler-free, two-photon absorption (DF2PA) transition in an alkali vapor as an absolute frequency reference that in turn is used with negative electrical feedback to stabilize a diode laser and narrow its linewidth. This approach offers a wider choice of wavelengths (including visible) than an approach using a saturated resonance line. The objectives in Phase I are to demonstrate stabilization and line narrowing using DF2PA, to identify and minimize the factors which affect the absolute stability of the laser, and to build a compact prototype packaged laser using this approach. The Phase I effort includes modeling specific 2PA transitions, constructing and evaluating various reference cells, and constructing a prototype packaged laser. The result of Phase I will be operational prototype laser hardware and an understanding of how to design flight-qualified hardware to NASA specifications. The availability of a space-qualified stabilized diode laser will be useful to NASA for laser metrology, especially absolute distance measurements in space to assist in assembly of structures. Other applications include improved optical sensors, remote sensing, and communication.
Potential Commercial Applications:Potential commercial applications for stabilized lasers are precision metrology (such as distance measurement), fiber optic sensors (such as laser gyroscopes), and wideband optical communications systems.
