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Ultrafast Laser Physics and Precision Metrology Group

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Frequency combs and Ramsey-combs from IR to XUV


Frequency combs
Frequency combs and Ramsey-Comb spectroscopy

We have developed a new laser system, which amplifies 2 frequency comb pulses with a variable delay under computer control to the mJ level. At this power level the central wavelength of the pulses can be converted easily by nonlinear conversion, to produce a variety of wavelengths other than the 800 nm we start with through nonlinear conversion. The phase shift between the amplified comb pulses remains stable within a few mrad over more than 600 ns (and more!). With this system we now have developed a new combination of Ramsey Spectroscopy and Frequency Combs, which we call "Ramsey Comb Spectroscopy". The method combines the accuracy of frequency combs with the convenience and power of Ramsey spectroscopy. This combination has special properties, and very good prospects to enable direct frequency comb spectroscopy with kHz accuracy from IR to XUV wavelengths. Our first paper about it with a demonstration at NIR wavelengths was published in Nature Physics in 2014. We now extended the range to the Deep-Ultraviolet (at 212 nm), which was recently published in Phys. Rev. Lett. (see below).

R.K. Altmann, S. Galtier, L.S. Dreissen, and K.S.E. Eikema,
High-Precision Ramsey-Comb spectroscopy at Deep-Ultraviolet Wavelengths
Phys. Rev. Lett. 117, 173201 (2016)
http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.117.173201

J. Morgenweg, I. Barmes and K.S.E. Eikema,
Ramsey-comb spectroscopy with intense ultrashort laser pulses
Nature Physics 10, 30-33 (2014)
http://www.nature.com/nphys/journal/v10/n1/full/nphys2807.html

Also see the News and Views by Scott A. Diddams on page 8-9 of the same issue:
http://www.nature.com/nphys/journal/v10/n1/full/nphys2852.html

Other papers:

J. Morgenweg, K.S.E. Eikema
Multi-delay, phase coherent pulse pair generation for precision Ramsey-frequency comb spectroscopy
Optics Express 21, 5275-5286 (2013)


J. Morgenweg, K.S.E. Eikema,
A 1.8 mJ, picosecond Nd:YVO4 bounce amplifier pump front-end for high-accuracy XUV-frequency comb spectroscopy
Laser Physics Letters 9, 781-785 (2012)

J. Morgenweg, K.S.E. Eikema,
Tailored pulse sequences from an 880 nm pumped Nd:YVO4 bounce amplifier
Opt. Lett. 37, 208-210 (2012)





XUV Ramsey-frequency combs

We have demonstrated an easily tunable Ramsey-XUV frequency comb based on harmonic upconversion of two amplified frequency comb pulses. With a combination of different harmonics and different central wavelengths, we have demonstrated precision spectroscopy down to 51 nm at a few-MHz level (see also the Precision Spectroscopy section). Currently we are constructing a new system that should reach kHz-level accuracy, at wavelengths as short as 30 nm. A new table was installed recently to built a separate XUV Ramsey-comb laser including high-harmonic generation. The new vacuum setup for it is almost completed with refocusing optics for the 1S-2S He+ spectroscopy project.

Papers:

D.Z. Kandula, C. Gohle, T.J. Pinkert, W. Ubachs, K.S.E. Eikema, "XUV frequency-comb metrology on the He ground state of helium",
Phys. Rev. A 84, 062512 (2011)

T.J. Pinkert, D.Z. Kandula, C. Gohle, I. Barmes, J. Morgenweg, K.S.E. Eikema, "Widely tunable XUV frequency comb generation",
Opt. Lett. 36, 2026-2028 (2011)

D.Z. Kandula, C. Gohle, T.J. Pinkert, W. Ubachs, K.S.E. Eikema,
"Extreme Ultraviolet Frequency Comb Metrology",
Phys. Rev. Lett. 105, 063001 (2010)

and also see Physics Synopsys, and the Research Highlight in Nature
XUV comb principle


coh control
NIR and IR Frequency comb

We had a dual Yb-fiber comb available for heterodyning frequency comb spectroscopy. In collaboration with the group of prof. Marco Marangoni from the Politecnico di Milano, we produced IR combs from 10 micron - 3 micron wavelengths (see paper) by difference frequency mixing.

We now bought a new ultra-low noise (ULN) Erbium-fiber based frequency comb from Menlo Systems GmbH for the new He+ ion 1S-2S experiments.

Papers:

A. Ruehl, A. Gambetta, H. Ingmar, M.E. Fermann, K.S.E. Eikema, M. Marangoni, "Widely-tunable mid-infrared frequency comb source based on difference frequency generation"
Opt. Lett. 37, 2232-2234 (2012)



Miniature frequency  combs based on quantum dots

In a collaboration with the Technical University Eindhoven, we have investigated the possibilities of making miniature frequency combs based on semiconductor lasers at 1.5 micrometer wavelength using quantum-dot material.

Papers:

T.J. Pinkert, E.J. Salumbides, M.S. Tahvilli, W. Ubachs, E.A.J.M. Bente, K.S.E. Eikema,  "Frequency comb generation by CW laser injection into a quantum-dot mode-locked laser"
Opt. Expr. 20, 21357-21371 (2012)

M.J.R. Heck et al., "Analysis of hybrid mode-locking of two-section quantum dot lasers operating at 1.5 micrometer",
Opt. Expr. 17, 18063 (2009)

M.J.R. Heck, et al., "Passively Mode-Locked 4.6 and 10.5 GHz Quantum Dot Laser Diodes Around 1.55 micrometer With Large Operating Regime"
IEEE. J. Sel. Top. Quant. El. 15, 634 (2009)
X-ray imaging




We gratefully acknowledge financial support from (including the Memphis Project):
NWO FOM Laser Europe STW VU erc

Questions? Contact: k.s.e.eikema@vu.nl