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Narrow linewidth visible light lasers are critical for atomic, molecular and optical (AMO) applications including atomic clocks, quantum computing, atomic and molecular spectroscopy, and sensing. Historically, such lasers are implemented at the tabletop scale, using semiconductor lasers stabilized to large optical reference cavities. Photonic integration of high spectral-purity visible light sources will enable experiments to increase in complexity and scale. Stimulated Brillouin scattering (SBS) is a promising approach to realize highly coherent on-chip visible light laser emission. While progress has been made on integrated SBS lasers at telecommunications wavelengths, barriers have existed to translate this performance to the visible, namely the realization of Brillouin-active waveguides in ultra-low optical loss photonics. We have overcome this barrier, demonstrating the first visible light photonic integrated SBS laser, which operates at 674 nm to address the 88Sr+ optical clock transition. To guide the laser design, we use a combination of multi-physics simulation and Brillouin spectroscopy in a 2 meter spiral waveguide to identify the 25.110 GHz first order Stokes frequency shift and 290 MHz gain bandwidth. The laser is implemented in an 8.9 mm radius silicon nitride all-waveguide resonator with 1.09 dB per meter loss and Q of 55.4 Million. Lasing is demonstrated, with an on-chip 14.7 mW threshold, a 45% slope efficiency, and linewidth narrowing as the pump is increased from below threshold to 269 Hz. To illustrate the wavelength flexibility of this design, we also demonstrate lasing at 698 nm, the wavelength for the optical clock transition in neutral strontium. This demonstration of a waveguide-based, photonic integrated SBS laser that operates in the visible, and the reduced size and sensitivity to environmental disturbances, shows promise for diverse AMO applications., 23 pages, 10 figures

For more than 100 years, optical atomic/molecular frequency references have played important roles in science and technology, and provide standards enabling precision measurements. Frequency-stable optical sources have been central to experimental tests of Einstein's relativity, and also serve to realize our base unit of length. The technology has evolved from atomic discharge lamps and interferometry, to narrow atomic resonances in laser-cooled atoms that are probed by frequency-stabilized cw lasers that in turn control optical frequency synthesizers (combs) based on ultra-fast mode-locked lasers. Recent technological advances have improved the performance of optical frequency references by almost four orders of magnitude in the last eight years. This has stimulated new enthusiasm for the development of optical atomic clocks, and allows new probes into nature, such as searches for time variation of fundamental constants and precision spectroscopy.

A high-power picosecond optical parametric oscillator (OPO) based on a 47-mm periodically poled lithium niobate crystal is described. More than 12 W of total average power-almost 8 W of signal power at 1.85 microm and more than 4 W of idler radiation at 2.5 microm -is simultaneously extracted from less than 18 W of average pump power. The OPO is synchronously pumped by 80-ps (FWHM) cw mode-locked pulses at 1.064 microm , and its output is tunable from 1.7 to 2.84microm . Nearly transform-limited signal pulses are obtained following the introduction of two intracavity etalons.

We describe a new laser system we have developed to probe the ultra-narrow 1S0 harr 3P0 clock transition at 578 nm in neutral ytterbium. The yellow light is produced by sum frequency generation in a periodically poled waveguide. With approximately 100 mW each from a fiber laser and Nd:YAG laser, we produce 10 mW of visible light. Stabilization of the laser to a resonance of a high finesse, environmentally isolated cavity has enabled resolution of spectroscopic features as narrow as 5 Hz.

We report high resolution spectroscopy of optical lattice-confined 174Yb atoms. We demonstrate spectroscopic linewidths as narrow as 4 Hz (full-width at half-maximum) using the highly forbidden clock transition (1S0-3P0) in a one-dimensional optical lattice.

This paper discusses an optical atomic clock that uses a narrow atomic resonance to control the frequency of a spectrally narrow laser source. The atomically controlled frequency of the laser gives the clock oscillation frequency as an optical output and provides the stable reference for frequency and timing.

In the past four years have shown a dramatic improvement in the performance of optical frequency references and in the methods by which they are calibrated and utilized. These revolutionary changes result from better stabilized lasers that probe narrow-linewidth transitions in laser-cooled atoms and ions, and from the development of a convenient method for synthesizing, measuring and distributing optical frequencies based on mode-locked lasers.

Optical cooling of solids was first demonstrated in 1995. Since that time our efforts have concentrated on using this phenomenon to produce a viable optical cryocooler. A bench-top, solid-state optical cooler was demonstrated recently with 54 °C of cooling from room temperature and a heat lift of 25 mW when it was pumped with 1.6 watts of laser light. Based on the bench-top cooler results a compact, rugged, self-contained system with laser-diode pumping is being constructed as a prototype for research and commercial applications. Recent results, designs and plans for future work are discussed. In addition to prototype work, our efforts have continued on producing additional optical materials which demonstrate optical cooling and will improve the efficiency and useful temperature range of optical coolers. New materials with promising results are discussed.

Recent developments in cooling thulium-doped heavy-metal fluoride glass are presented. Thulium-doped fluorozirconate (ZBLANP) is cooled to 19 K below ambient with a multiple-pass pump scheme. This represents over an order of magnitude increase from the previously reported single-pass geometry. The results agree with a simple model for anti-Stokes fluorescence cooling that includes considerations of quantum efficiency and parasitic heating mechanisms. Issues relating to a practical optical refrigerator are examined, including a general model for the effects of multiple pump passes.