Kyle W. Martin

The optical rubidium atomic frequency standard at AFRL

We present a compact optical frequency standard based on two-photon spectroscopy at 778 nm in a rubidium vapor cell. We demonstrate fractional instability of 3e-13/, √τ/s for timescales up to 10,000 s. Additionally, we describe a secondary system operation in which the short-term stability is improved (though at the expense of the long-term stability) using increased laser power, resulting in 1 s instability < 1e-13. The system has been designed as an advanced atomic frequency standard for GNSS applications, and is currently being investigated for demonstration on AFRLs Navigation Technology Satellite 3 (NTS-3), an upcoming space flight experiment to middle earth orbit scheduled for launch in 2022.

High-temperature calcium vapor cell construction and spectroscopy

We describe the construction, operation, and resulting spectroscopy of a high-temperature calcium vapor cell using the 657 nm intercombination transition in neutral calcium. Alkali contaminants inside the cell resulted in the emission of off-resonant fluorescence. The resulting lifetime of the 3P1 state in calcium atoms subjected to collisions with the contaminant vapor is quantified.

A compact, high-performance all optical atomic clock based on telecom lasers

We discuss an optical atomic clock based on a two-photon transition at 778 nm in rubidium. In particular, we discuss the fundamental limitations to the short-term stability of a system based on a commercial C-band telecom laser as opposed to a near infrared laser. We show that this system is fundamentally capable of besting a hydrogen MASER in frequency stability and size.

Thermal design of high temperature alkaline-earth vapor cells

Europium doped calcium fluoride is a machinable and alkaline-earth resistant crystal that is suitable for constructing a calcium or strontium vapor cell. However, its heat capacity, emissivity, and high coefficient of thermal expansion make it challenging to achieve optically dense calcium vapors for laser spectroscopy on narrow linewidth transitions. We discuss a low size, weight and power heating package that is under development at the Air Force Research Laboratory.