[show abstract][hide abstract] ABSTRACT: We report the generation of high power extreme ultraviolet frequency combs at 154 MHz repetition rate. The XUV combs are characterized by conducting high resolu-tion spectroscopy and observing the heterodyne beats between two independent systems.
The European Physical Journal Conferences 01/2013; 41(11006).
[show abstract][hide abstract] ABSTRACT: We report on a mid-IR frequency comb source of unprecedented tunability covering the entire 3-10 μm molecular fingerprint region. The system is based on difference frequency generation in a GaSe crystal pumped by a 151 MHz Yb:fiber frequency comb. The process was seeded with Raman-shifted solitons generated in a highly nonlinear suspended-core fiber with the same source. Average powers up to 1.5 mW were achieved at the 4.7 μm wavelength.
[show abstract][hide abstract] ABSTRACT: We present full phase stabilization of an amplified Yb:fiber femtosecond frequency comb using an intracavity electro-optic modulator and an acousto-optic modulator. These transducers provide high servo bandwidths of 580 kHz and 250 kHz for f(rep) and f(ceo), producing a robust and low phase noise fiber frequency comb. The comb was self-referenced with an f-2f interferometer and phase locked to an ultrastable optical reference used for the JILA Sr optical clock at 698 nm, exhibiting 0.21 rad and 0.47 rad of integrated phase errors (over 1 mHz-1 MHz), respectively. Alternatively, the comb was locked to two optical references at 698 nm and 1064 nm, obtaining 0.43 rad and 0.14 rad of integrated phase errors, respectively.
[show abstract][hide abstract] ABSTRACT: We demonstrate a mid-infrared frequency comb of unprecedented tunability covering the entire 3-10 μm fingerprint region. The comb is based on a Raman shifted Yb:fiber laser and difference frequency generation.
[show abstract][hide abstract] ABSTRACT: The development of the optical frequency comb (a spectrum consisting of a series of evenly spaced lines) has revolutionized metrology and precision spectroscopy owing to its ability to provide a precise and direct link between microwave and optical frequencies. A further advance in frequency comb technology is the generation of frequency combs in the extreme-ultraviolet spectral range by means of high-harmonic generation in a femtosecond enhancement cavity. Until now, combs produced by this method have lacked sufficient power for applications, a drawback that has also hampered efforts to observe phase coherence of the high-repetition-rate pulse train produced by high-harmonic generation, which is an extremely nonlinear process. Here we report the generation of extreme-ultraviolet frequency combs, reaching wavelengths of 40 nanometres, by coupling a high-power near-infrared frequency comb to a robust femtosecond enhancement cavity. These combs are powerful enough for us to observe single-photon spectroscopy signals for both an argon transition at 82 nanometres and a neon transition at 63 nanometres, thus confirming the combs' coherence in the extreme ultraviolet. The absolute frequency of the argon transition has been determined by direct frequency comb spectroscopy. The resolved ten-megahertz linewidth of the transition, which is limited by the temperature of the argon atoms, is unprecedented in this spectral region and places a stringent upper limit on the linewidth of individual comb teeth. Owing to the lack of continuous-wave lasers, extreme-ultraviolet frequency combs are at present the only promising route to extending ultrahigh-precision spectroscopy to the spectral region below 100 nanometres. At such wavelengths there is a wide range of applications, including the spectroscopy of electronic transitions in molecules, experimental tests of bound-state and many-body quantum electrodynamics in singly ionized helium and neutral helium, the development of next-generation 'nuclear' clocks and searches for variation of fundamental constants using the enhanced sensitivity of highly charged ions.
[show abstract][hide abstract] ABSTRACT: We address technical impediments to the generation of high-photon flux XUV frequency combs through cavity-enhanced high harmonic generation. These difficulties arise from mirror damage, cavity nonlinearity, the intracavity plasma generated during the HHG process, and imperfect phase-matching. By eliminating or minimizing each of these effects we have developed a system capable of generating > 200 μW and delivering ~20 μW of average power for each spectrally separated harmonic (wavelengths ranging from 50 nm - 120 nm), to actual comb-based spectroscopy experiments.
[show abstract][hide abstract] ABSTRACT: We generate high order harmonics of a femtosecond frequency comb at the
focus of a high finesse optical cavity with 150 MHz repetition rate. The
resulting table top high average brightness extreme ultraviolet (XUV)
light source has promising applications in XUV frequency metrology,
strong field and molecular physics studies, and more traditional XUV
applications currently served by synchrotron light sources. We will
discuss our recent technical achievements and detailed understandings of
the intracavity extreme nonlinear processes that have led to XUV output
power beyond the10 μW per harmonic level and reduced high frequency
optical phase noise. We will also present the latest measurement on the
coherence properties of VUV/XUV frequency combs.
[show abstract][hide abstract] ABSTRACT: We report on the coherent transfer of optical phase from 698nm to 1542nm below the level of 1.5Hz linewidth. Detailed numerical simulations of the supercontinuum generation process support the observed preservation of phase coherence.
[show abstract][hide abstract] ABSTRACT: We demonstrate wavelength tunable coherent Raman soliton generation in a Tm fiber amplifier seeded with a passively mode locked Tm fiber oscillator and subsequent octave spanning continuum generation in highly-nonlinear fibers
[show abstract][hide abstract] ABSTRACT: We present a highly coherent Yb-fiber laser based frequency comb spanning nearly 1.5 spectral octaves. The coherence properties are investigated by optical beat experiments and numerical simulations.
[show abstract][hide abstract] ABSTRACT: We report a simple technique to suppress high-frequency phase noise of a Yb-based fiber optical frequency comb using an active intensity noise servo. Out-of-loop measurements of the phase noise using an optical heterodyne beat with a cw laser show suppression of phase noise by ≥7 dB out to Fourier frequencies of 100 kHz with a unity-gain crossing of ∼700 kHz. These results are enabled by the strong correlation between the intensity and phase noise of the laser. Detailed measurements of intensity and phase noise spectra, as well as transfer functions, reveal that the dominant phase and intensity noise contribution above ∼100 kHz is due to amplified spontaneous emission or other quantum noise sources.
[show abstract][hide abstract] ABSTRACT: We present a Fourier transform spectrometer based on a single repetition rate modulated mode locked Yb-fiber laser configured as a coherent scanning delay line using an imbalanced Mach-Zehnder interferometer. Effective mirror scan rate is 7.5 m/s.
[show abstract][hide abstract] ABSTRACT: We demonstrate a mode-locked Yb fiber soliton oscillator for the generation of
pulse pairs with rapidly scanning pulse separations at interferometric precision.
[show abstract][hide abstract] ABSTRACT: We demonstrate a Fourier transform spectrometer based on a single repetition rate modulated mode-locked Yb-fiber laser configured as a coherent scanning delay line using an imbalanced Mach-Zehnder interferometer. The effective mirror scan rate is 3.75m/s.
[show abstract][hide abstract] ABSTRACT: We report on a high-power fiber frequency comb exhibiting linear chirped-pulse amplification up to 80 W and generating 120 fs pulses. By proper matching of the group delay between the fiber stretcher and compressor, a compression ratio of 3100 could be achieved. Carrier envelope offset self-referencing and long-term phase locking to an rf reference is demonstrated, exemplifying the suitability of this system for generating vacuum and extreme-UV frequency combs via enhancement in passive cavities and high harmonic generation.
[show abstract][hide abstract] ABSTRACT: We report on cavity-enhanced HHG with a frequency comb delivering 120-fs pulses and 80-W average power at 154-MHz repetition rates. With 5-kW average intracavity powers, average HHG powers beyond the microwatt level have been achieved.
[show abstract][hide abstract] ABSTRACT: By coupling a train of low-phase-noise, ultrashort pulses to a
femtosecond enhancement cavity, it is possible to obtain a large
enhancement of the pulse energy and subsequently drive the high harmonic
generation process at ≥100 MHz repetition rates. At these repetition
frequencies, the generated VUV-XUV frequency combs could potentially be
used for a multitude of experiments requiring short wavelength radiation
with exceptional temporal coherence and/or high average photon flux. We
will present recent progress, including power scaling of the driving
field with a corresponding factor of 10 improvement in harmonic power
over previous results, as well as initial coherence tests of the
generated VUV frequency comb.