Adela Marian

Demonstration of a HeNe/CH4-based optical molecular clock

We implement a simple optical clock based on the F2(2) [P(7), v3] optical transition in methane. A single femtosecond lasers frequency comb undergoes difference frequency generation to provide an IR comb at 3.39 microm with a null carrier-envelope offset. This IR comb provides a phase-coherent link between the 88-THz optical reference and the rf repetition rate. Comparison of the repetition rate signal with a second femtosecond comb stabilized to molecular iodine shows an instability of 1.2 x 10(-13) at 1 s, limited by microwave detection of the repetition rates. The single-sideband phase noise of the microwave signal, normalized to a carrier frequency of 1 GHz, is below -93 dBc/Hz at 1-Hz offset.

Detailed studies and control of intensity-related dynamics of femtosecond frequency combs from mode-locked Ti:sapphire lasers

The authors have conducted detailed experimental investigations of the intensity-related dynamics of the pulse repetition and carrier-envelope offset frequencies of passively mode-locked Ti:sapphire lasers. Two different laser systems utilizing different intracavity dispersion compensation schemes are used in this study. Theoretical interpretations agree well with experimental data, indicating that intensity-related spectral shifts, coupled with the cavity group-delay dispersion, are important in understanding the dynamics of the frequency comb. Minimization of spectral shifts or the magnitude of group-delay dispersion leads to minimization of the intensity dependence of the femtosecond comb.

High Resolution Atomic Coherent Control via Spectral Phase Manipulation of an Optical Frequency Comb

We demonstrate high resolution coherent control of cold atomic rubidium utilizing spectral phase manipulation of a femtosecond optical frequency comb. Transient coherent accumulation is directly manifested by the enhancement of signal amplitude and spectral resolution via the pulse number. The combination of frequency comb technology and spectral phase manipulation enables coherent control techniques to enter a new regime with natural linewidth resolution.

Phase coherent manipulation of light: from precision spectroscopy to extreme nonlinear optics

Phase control of wide-bandwidth optical frequency combs enables amazing capabilities in optical frequency measurement and synthesis, optical atomic clocks, united time-frequency spectroscopy, coherent pulse synthesis and manipulation, and deterministic studies in sub-cycle physics.

PRECISION MEASUREMENT MEETS ULTRAFAST CONTROL

Optical spectroscopy and frequency metrology at the highest level of precision and resolution are being greatly facilitated by the use of ultracold atoms and phase stabilized light in the form of both cw and ultrashort pulses. It is now possible to pursue simultaneously coherent control of quantum dynamics in the time domain and high precision measurements of global atomic structure in the frequency domain. These coherent light-based precision measurement capabilities may be extended to the XUV spectral region, where new possibilities and challenges lie for precise tests of fundamental physical principles.

Ti:Sapphire Lasers for Frequency Metrology Spanning the Visible and Infrared Spectrum without Nonlinear Fiber

Two different schemes using femtosecond lasers for optical frequency metrology without the use of nonlinear fiber are experimentally demonstrated, allowing phase coherence between the microwave, visible, and infrared portions of the electromagnetic spectrum.

Using the phase coherence of carrier-envelope phase-stabilized fs lasers

The carrier-envelope-phase-stabilization of femtosecond lasers has enabled new applications of ultrafast lasers. We will discuss our work on one such application: coherent locking of 1550-nm mode-locked sources to optical atomic clocks.

Control of coherent light and its broad applications

A remarkable synergy has been formed between precision optical frequency metrology and ultrafast laser science. This has resulted in control of the frequency spectrum produced by mode-locked lasers, which consists of a regular “comb” of sharp lines. Such a controlled mode-locked laser is a “femtosecond optical frequency comb generator.” For a sufficiently broad comb, it is straightforward to determine the absolute frequencies of all of the comb lines. This ability has revolutionized optical frequency metrology and synthesis, and it has also led to recent demonstrations of atomic clocks based on optical frequency transitions. In addition, the comb technology is having a strong impact on time-domain applications, including control of the carrier-envelope phase, precision timing synchronization, and synthesis of a single pulse from independent lasers.

FROM STABLE LASERS TO OPTICAL-FREQUENCY CLOCKS: Merging the UltraFast and the UltraStable, for a New Epoch of Optical Frequency Measurements, Standards, & Applications

This is a report on behalf of the World Team of Stable Laser and Optical Frequency Measurement Enthusiasts, even if most detailed illustrations draw mainly from our work at JILA. Specifically we trace some of the key ideas that have led from the first stabilized lasers, to frequency measurement up to 88 THz using frequency chains, revision of the Definition of the Metre, extension of coherent frequency chain technology into the visible, development of a vast array of stabilized lasers, and finally the recent explosive growth of direct frequency measurement capability in the visible using fs comb techniques. We present our recent work showing a Molecular Iodine-based Optical Clock which delivers, over a range of time scales, rf output at a stability level basically equivalent to the RF stability prototype, the Hydrogen Maser. We note the bifurcation between single-ion-based clocks − likely to be the stability/reproducibility ultimate winners in the next generation − and simpler systems based on gas cells, which can have impressive stabilities but may suffer from a variety of reproducibility-limiting processes. Active Phase-Lock synchronization of independent fs lasers allows sub-fs timing control. Copies of related works in our labs may be found/obtained at our website http://jilawww.colorado.edu/yehalllabs

High-resolution Rb two-photon spectroscopy with ultrafast lasers

A two-photon transition in cold Rb atoms will be probed with a phase-coherent wide-bandwidth femtosecond laser comb. Frequency domain analysis yields a high resolution picture where phase coherence among various transition pathways through different intermediate states produces interference effects on the resonantly-enhanced transition probability. This result is supported by the time domain Ramsey interference effect. The two-photon transition spectrum is analyzed in terms of the pulse repetition rate and carrier frequency offset, leading to a cold-atom-based frequency stabilization scheme for both degrees of freedom of the femtosecond laser.