David Aveline

Stabilizing an optoelectronic microwave oscillator with photonic filters

This paper compares methods of active stabilization of an optoelectronic microwave oscillator (OEO) based on insertion of a source of optical group delay into an OEO loop. The performance of an OEO stabilized with either a high-Q optical cavity or an atomic cell is analyzed. We show that the elements play a role of narrow-band microwave filters improving an OEO stability. An atomic cell also allows for locking the oscillation frequency to particular atomic clock transitions. This reports a proof-of-principle experiment on an OEO stabilization using the effect of electromagnetically induced transparency in a hot rubidium atomic vapor cell.

High power single frequency 780nm laser source generated from frequency doubling of a seeded fiber amplifier in a cascade of PPLN crystals

We report on the generation of over 900 mW of tunable cw light at 780 nm by single pass frequency doubling of a high power fiber amplifier in a cascade of two periodically poled Lithium Niobate (PPLN) crystals. Over 500 mW is generated in the first crystal. In the limit of low pump power, we observe an efficiency of 4.6 mW/W2-cm for a single crystal, and 5.6 mW/W2-cm for a combination of two crystals, with an enhancement of the doubling efficiency observed with two crystals due to the presence of second harmonic light from the first crystal acting as a seed for the second. We have frequency locked this laser source relative to a rubidium D2 hyperfine line and demonstrated its utility in a sophisticated laser cooling apparatus.

Whispering gallery mode resonators augmented with engraved diffraction gratings.

We report the demonstration of whispering gallery mode (WGM) resonators augmented with diffraction gratings. We apply focused ion beam (FIB) methods to precisely engrave a surface grating directly into the perimeter of a crystalline disc. The grating provides a simple and highly directional free-space coupling mechanism with superior stability to evanescent coupling techniques. These integrated gratings can also provide control of the resonance spectrum, significantly reducing the mode density. Our FIB fabrication process does not introduce significant loss; Q≃3×10(7) has been demonstrated. The wavelength dependence of the diffraction angle was found to be in excellent agreement with grating theory. The versatility of spectral control and far-field grating coupling will have significant impact in WGM resonator applications in lasers, sensors, and optoelectronics.

Focused Ion Beam Engineered Whispering Gallery Mode Resonators with Open Cavity Structure

We report the realization of an open cavity whispering gallery mode optical resonator, in which the circulating light traverses a free space gap. We utilize focused ion beam microfabrication to precisely cut a 10 μm wide notch into the perimeter of a crystalline disc. We have shown that this modified resonator structure supports high quality modes, and demonstrated qualify factor, Q ~/= 10(6), limited by the notch surface roughness due to the ion milling process. Furthermore, we investigated the spatial profile of the modes inside the open cavity with a microfabricated probe mechanism. This new type of resonator structure facilitates interaction of the cavitys optical field with mechanical resonators as well as individual atoms or molecules.

Supercritical CO 2 Cleaning for planetary protection and contamination control

We have designed and built a new Supercritical CO2 Cleaning (SCC) system1,2 to conduct cleaning efficiency studies using Supercritical CO2 and liquid CO2 to remove trace amounts of microbial and organic contaminants from spacecraft material surfaces. The objective of this task is to develop an effective CO2 cleaning method and to demonstrate and validate its ability to achieve ultra-clean surfaces of sample handling devices, sample storage units, and science instruments. This new capability will meet planetary protection and contamination control requirements for future Astrobiology science missions. The initial cleaning test results using this new cleaning device showed that both supercritical CO2 and liquid CO2 could achieve cleanliness levels of 0.01 µg/cm2 or less for hydrophobic contaminants. Experiments under supercritical condition using compressed Martian air mix, which consists of 95% CO2, produced similar cleaning effectiveness on the hydrophobic compounds. This opens up the possibility of further development potential for in situ CO2 cleaning and sterilization using Martian air for future Mars missions. We plan to further investigate the cleaning condition for hydrophilic compounds and bacterial spores, as well as introducing polar co-solvent to the cleaning apparatus.

Sample tube seal testing for Mars Sample Return

Four sealing methods for encapsulating samples in 1 cm diameter thin-walled sample tubes were designed, along with a set of tests for characterization and evaluation of sample preservation capability for the proposed Mars Sample Return (MSR) campaign. The sealing methods include a finned shape memory alloy (SMA) plug, expanding torque plug, contracting SMA ring cap, and expanding SMA ring plug. Mechanical strength and hermeticity of the seal were measured. Robustness of the seal to Mars simulant dust, surface abrasion, and pressure differentials were tested. Survivability tests were run to simulate thermal cycles on Mars, vibration from a Mars Ascent Vehicle (MAV), and shock from Earth Entry Vehicle (EEV) landing. Material compatibility with potential sample minerals and organic molecules were studied to select proper tube and seal materials that would not lead to adverse reactions nor contaminate the sample. Cleaning and sterilization techniques were executed on coupons made from the seal materials to assess compliance with planetary protection and contamination control. Finally, a method to cut a sealed tube for sample removal was designed and tested.

Micro-slotted whispering gallery mode resonators for optomechanical applications

We present a study of augmented whispering gallery mode optical resonators that contain one or more narrow slots, through which the optical field exits the resonators dielectric material and propagates in free space. We developed a theoretical model describing the micro-slotted resonator mode spectrum, and we find the theoretical results of the single-slot case are in close agreement with experimental observations. Furthermore, we examine a double-slot configuration that forms a cantilever-like partition within the circulating high-Q optical modes. The system exhibits high displacement sensitivity that could lead to optomechanical sensing applications.

Two-species cold atomic beam

We generate a bright atomic beam containing laser-cooled rubidium and cesium, and we use this beam to load a mixed-species ultrahigh-vacuum (UHV) magneto-optical trap. We have characterized our two-species atomic beam over a range of operating conditions, and we obtain similar atom fluxes for each species. Within the UHV trap, interspecies inelastic collisions are observed in the form of enhanced decay rates of a given species in the presence of a second trapped species. We analyze the trap decays to obtain a loss rate due to heteronuclear cold collisions, and we compare our result to similar measurements in vapor-cell traps Phys. Rev. A 63 , 033406 (2001).

NASA’s Cold Atom Lab (CAL): system development and ground test status

We report the status of the Cold Atom Lab (CAL) instrument to be operated aboard the International Space Station (ISS). Utilizing a compact atom chip-based system to create ultracold mixtures and degenerate samples of 87Rb, 39K, and 41K, CAL is a multi-user facility developed by NASA’s Jet Propulsion Laboratory to provide the first persistent quantum gas platform in the microgravity conditions of space. Within this unique environment, atom traps can be decompressed to arbitrarily weak confining potentials, producing a new regime of picokelvin temperatures and ultra-low densities. Further, the complete removal of these confining potential allows the free fall evolution of ultracold clouds to be observed on unprecedented timescales compared to earthbound instruments. This unique facility will enable novel ultracold atom research to be remotely performed by an international group of principle investigators with broad applications in fundamental physics and inertial sensing. Here, we describe the development and validation of critical CAL technologies, including demonstration of the first on-chip Bose–Einstein condensation (BEC) of 87Rb with microwave-based evaporation and the generation of ultracold dual-species quantum gas mixtures of 39K/87Rb and 41K/87Rb in an atom chip trap via sympathetic cooling.Ultracold atomic physics: space station boundUS scientists are developing and testing an instrument for trapping and cooling ultracold atoms in preparation for the launch of the device to the International Space Station (ISS). Quantum mechanical effects are enhanced at temperatures near absolute zero, and the microgravity conditions of the ISS will allow atom traps to decompress to a new regime of picokelvin temperatures and ultra-low densities. David Aveline and colleagues from the Jet Propulsion Laboratory at the California Institute of Technology present a status of the Cold Atom Lab (CAL) instrument’s ground development and test progress. The team demonstrates the system capabilities by creating Bose-Einstein condensates of rubidium atoms with microwave-based evaporative cooling and quantum gas mixtures of rubidium and potassium in a magnetic trap formed by current carrying wires on a compact chip.

Cold atom laboratory mission system design

Cold Atom Laboratory (CAL) is a multi-user facility that will provide the ability to study ultra-cold quantum gases in a microgravity environment. The laboratory is an internal payload that will operate on the International Space Station (ISS) in 2016. Principal Investigators from various universities will trade off in designing experiment sequences that vary different parameters, such as magnetic field strength or timing. The primary science data consists of two images of the cold atoms captured successively at the end of each experiment.