Kerr-lens Mode-locked, Synchronously Pumped, Ultra-broadband Breathing Pulse Optical Parametric Oscillator
09 May 2021-
Abstract: Profiting from a breathing pulse design, we demonstrate a Kerr-lens mode locked non-collinear optical parametric oscillator, which is capable of delivering stable ultrabroadband signal spanning from 628 nm to 890 nm at -10 dB level.
Kerr-lens mode locked, synchronously pumped, ultra-broadband breathing
pulse optical parametric oscillator
, David Zuber
, Robin Mevert
, Tino Lang
, Thomas Binhammer
, Uwe Morgner
1. Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover, Germany
2. Cluster of Excellence PhoenixD (Photonics, Optics, and Engineering-Innovation Across Disciplines), 30167, Hannover, Germany
3. Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
4. neoLASE GmbH, Hollerithallee 17, 30419 Hannover, Germany
5. Laser Zentrum Hannover e.V., Hollerithallee 8, 30419 Hannover, Germany
High repetition rate, ultrabroadband light sources in the near infrared spectral region have gained
considerable research interest and emerged as a powerful basis for various applications, such as time-resolved
spectroscopy, attoscience, and frequency comb generation . Kerr-lens mode locked (KLM) Ti:sapphire lasers
oscillators remain the major workhorse of the research field due to the remarkable spectral bandwidth of this
gain material. However, these systems suffer limitation in terms of power scaling mainly owing to unavoidable
heat load in the laser crystal. Alternatively, optical parametric oscillators (OPOs) have rapidly developed over
the last decade and are a promising candidate to generate high power broadband tunable radiations. However, the
pulse forming dynamics in OPOs is more complicated and so far limited the achievable pulse duration to 13 fs
. In this work, by introducing a breathing pulse dispersion management scheme, we report the first
experimental demonstration of a KLM non-collinear OPO (KLM-NOPO) that emits an ultrabroadband signal
spanning from 700 nm to 900 nm at the -10 dB level which would support sub-10 fs pulse durations.
The schematic of the proposed KLM-NOPO is presented in Fig. 1(a). The OPO is pumped by a frequency-
doubled home-built Yb-fiber laser. The pump laser has an average power of 7 W at a repetition rate of 50.2 MHz
with a FWHM pulse duration 270 fs and a central wavelength 520 nm. The KLM-NOPO is configured as a
double foci ring cavity. The 2 mm BBO crystal in one focus serves as the parametric gain medium, while a
1.7 mm Ti:sapphire crystal used as Kerr-medium is placed in another focus. The whole cavity is equipped with
double-chirped mirrors (DCMs) that support a flat spectral phase over 600~1200 nm . A pair of BaF
is employed to fine adjust the cavity dispersion, and accordingly the overall dispersion of the cavity is close to
zero. Note that a strong unbalanced dispersion between two foci is realized in our setup, leading to pulse
breathing in one round trip. To this end, a long positive dispersed signal pulse as expected for a good temporal
overlap in the BBO together with a short transform limited pulse in the Ti:sapphire is realized. For synchronous
pumping, the cavity length is set to match twice the pump lasers repetition rate.
The “magic angle” of 2.5° between the pump beam and the signal beam in non-collinear pointing vector
walk-off compensation geometry is selected where ultra-broadband phase matching from 650 to 1200 nm
enables broadband operation. By optimizing the position of the Kerr medium, the KLM NOPO can be triggered.
As can be seen in Fig. 1(b), this broadband output spectrum covering 670~920 nm provides strong evidence for
mode-locked NOPO. This bandwidth results in a transform limited pulse duration of 8.5 fs. Up to 420 mW of
output power is measured with the maximum pump power of 7 W. A stable mode-locking performance of our
KLM NOPO is indicated by the clean radio-frequency spectrum of the signal (see Fig. 1(c)). In conclusion, the
proposed dispersion managed KLM NOPO can generate a stable pulse with an ultra-broadband spectrum capable
of handling sub-10 fs pulses. The great potential for power scaling and the flexibility in wavelength of this novel
KLM NOPO open the door for the next generation of few-cycle high power laser oscillators.
Fig. 1 (a) Schematics illustration of the experimental set-up. L1 and L2: lens; DM: dichroic mirror; DCMs: double-
chirped mirror pairs; OC: output coupler. (b) Measured output spectrum (c) Radio-frequency spectrum over a 100
kHz span with 100 Hz resolution.
1 S. A. Diddams, L. Hollberg, and V. Mbele, “Molecular fingerprinting with the resolved modes of a femtosecond laser frequency comb,”
Nature 445, 627–630 (2007).
 G. M. Gale, M. Cavallari, T. J. Driscoll, and F. Hache, “Sub-20-fs tunable pulses in the visible from an 82-MHz optical parametric
oscillator,” Opt. Lett. 20, 1562 (1995).
 S. Rausch, T. Binhammer, A. Harth, J. Kim, R. Ell, F. X. Kärtner, and U. Morgner, "Controlled waveforms on the single-cycle scale from
a femtosecond oscillator," Opt. Express 16, 9739-9745 (2008)
© The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0
EPJ Web of Conferences 243, 18002 (2020) https://doi.org/10.1051/epjconf/202024318002
TL;DR: The technique for direct and parallel accessing of stabilized frequency comb modes could find application in high-bandwidth spread-spectrum communications with increased security, high-resolution coherent quantum control, and arbitrary optical waveform synthesis with control at the optical radian level.
Abstract: The control of the broadband frequency comb emitted from a mode-locked femtosecond laser has permitted a wide range of scientific and technological advances--ranging from the counting of optical cycles for next-generation atomic clocks to measurements of phase-sensitive high-field processes. A unique advantage of the stabilized frequency comb is that it provides, in a single laser beam, about a million optical modes with very narrow linewidths and absolute frequency positions known to better than one part in 10(15) (ref. 5). One important application of this vast array of highly coherent optical fields is precision spectroscopy, in which a large number of modes can be used to map internal atomic energy structure and dynamics. However, an efficient means of simultaneously identifying, addressing and measuring the amplitude or relative phase of individual modes has not existed. Here we use a high-resolution disperser to separate the individual modes of a stabilized frequency comb into a two-dimensional array in the image plane of the spectrometer. We illustrate the power of this technique for high-resolution spectral fingerprinting of molecular iodine vapour, acquiring in a few milliseconds absorption images covering over 6 THz of bandwidth with high frequency resolution. Our technique for direct and parallel accessing of stabilized frequency comb modes could find application in high-bandwidth spread-spectrum communications with increased security, high-resolution coherent quantum control, and arbitrary optical waveform synthesis with control at the optical radian level.
TL;DR: Spectra extending from 600 to 1200 nm have been generated from a Kerr-lens mode-locked Ti:sapphire laser producing 5-fs pulses, to the authors' knowledge the broadest ever generated directly from a laser oscillator.
Abstract: Spectra extending from 600 to 1200 nm have been generated from a Kerr-lens mode-locked Ti:sapphire laser producing 5-fs pulses. Specially designed double-chirped mirror pairs provide broadband controlled dispersion, and a second intracavity focus in a glass plate provides additional spectral broadening. These spectra are to our knowledge the broadest ever generated directly from a laser oscillator.
TL;DR: P pulses tunable in the 590-666-nm range are produced, with durations down to 13 fs, using an 82-MHz Ti:sapphire second-harmonic-pumped, high-bandwidth, beta-barium borate optical parametric oscillator in a fused-silica prism group-delay-dispersion-compensated, six-mirror folded ring cavity.
Abstract: We have produced pulses tunable in the 590-666-nm range, with durations down to 13 fs, using an 82-MHz Ti:sapphire second-harmonic-pumped, high-bandwidth, beta-barium borate optical parametric oscillator in a fused-silica prism group-delay-dispersion-compensated, six-mirror folded ring cavity.
TL;DR: An octave-spanning Ti:sapphire oscillator supporting Fourier-limited pulses as short as 3.7 fs is presented, allowing for full control of the electric pulse field on a sub-femtosecond time-scale.
Abstract: We present an octave-spanning Ti:sapphire oscillator supporting Fourier-limited pulses as short as 3.7 fs. This laser system can be directly CEO-phase stabilized delivering an average output power of about 90 mW with a pulse duration of 4.4 fs. The phase-stabilization is realized without additional spectral broadening using an f-2f interferometer approach allowing for full control of the electric pulse field on a sub-femtosecond time-scale.
TL;DR: An ultra-widely tunable non-collinear optical parametric oscillator with an average output power of more than 3 W and a repetition frequency of 34 MHz that can be rapidly tuned over a wide range from the visible to the NIR.
Abstract: We present an ultra-widely tunable non-collinear optical parametric oscillator with an average output power of more than 3 W and a repetition frequency of 34 MHz. The system is pumped by the second harmonic of a femtosecond Yb:KLu(WO4)2 thin-disk laser oscillator. The wavelength of the signal pulse can be rapidly tuned over a wide range from the visible to the NIR just by scanning the resonator length.
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