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(a) Experimental setup. OC: output coupler, HD: high-dispersion mirrors, HR: high-reflection end mirror, KM: Kerr medium, R1 and R2: concave mirrors with radii of curvature of 150 mm and 50 mm. (b) Beam profile at the output.
Source publication
The concept of distributed Kerr-lens mode-locking and a thin-disk Yb:YAG oscillator based on this concept are presented. The described oscillator directly generates pulses with a duration of 49 fs and spectral width of 33 nm
Contexts in source publication
Context 1
... experimental setup is shown in Fig. 1(a). We use an Yb:YAG thin-disk as a folding mirror and a fused silica plate as the Kerr medium. A strongly asymmetric cavity is realized by using two concave mirrors with different radii of curvature (ROC), resulting in a large beam diameter in one of the cavity arms. The thin-disk is placed in this arm to enable a beam size well matched ...
Context 2
... an output coupler of 3%, the oscillator delivers 3.5 W pulses with a beam quality of M 2 ≈1.1 ( Fig. 1(b)). The measured spectrum shown in Fig. 2(a) exhibits an asymmetric shape, covering the wavelength from 990 nm to 1080 nm with the full width at half intensity maximum (FWHM) of 33 nm. A retrieved FWHM pulse duration of 49 fs could be obtained by second-harmonic generation frequency-resolved optical gating (SHG-FROG) measurement (see ...
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Citations
... Such a change of approach (see [43]) was implemented by means of the so-called distributed Kerrlens mode-locking (DKLM) technique. DKLM allows for the effective energy harvesting of femtosecond pulses in thin-disk solid-state oscillators, operating in both normal or anomalous chromatic dispersion regimes [44]. The obvious resource for energy harvesting is the up-scaling of the laser mode size, which is prone to introduce multimode instabilities. ...
In this work, we introduce a method for the stabilization of spatiotemporal solitons. These solitons correspond to light bullets in multimode optical fiber lasers, or localized coherent patterns in Bose-Einstein condensates. We show that a three-dimensional confinement potential, formed by a two-dimensional graded refractive index including radially-graded dissipation, in combination with external temporal phase modulation, may permit the generation of stable spatiotemporal dissipative solitons. This corresponds to combining harmonic mode-locking with the distributed Kerr-lens mode locking mechanism. Our study of the soliton characteristics and stability is based on analytical and numerical solutions of the generalized dissipative Gross-Pitaevskii equation. This approach could lead to higher energy (or condensate mass) harvesting in coherent spatio-temporal beam structures formed in multimode fiber lasers (or weakly-dissipative Bose-Einstein condensates
... Recently, with an improved design, 17-fs de-chirped pulses with ∼400 nm bandwidth were generated from an Yb: fiber mode-locked laser [9]. SPM-induced spectral broadening was also introduced in Kerr-lens mode-locked bulk oscillators by inserting additional Kerr media into the laser cavity, and generation of spectrum exceeding the emission bandwidth of the laser gain medium was demonstrated [10]. ...
We report a chirped-pulse optical parametric oscillator (OPO) generating light pulses with an instantaneous-bandwidth much wider than the parametric gain-bandwidth of nonlinear crystals. Our numerical simulations show that a relatively high residual second-order-dispersion within the OPO cavity is required in order to achieve the maximum signal-bandwidth from an OPO system. Based on this principle, we constructed an OPO using a 3-mm-long PPLN crystal, which produced a signal wave with an instantaneous-bandwidth of 20 THz (at −20 dB) covering 1447-1600 nm, roughly twice as much as the phase-matching bandwidth of the nonlinear crystal. This scheme represents a promising technical route for generating high-repetition-rate, ultrashort optical pulses with a wide bandwidth at various wavelengths, which may benefit many applications, including optical coherence tomography, pulse synthesis and spectroscopy.
... Due to the rapid progress in the technology of InGaAs laser diodes (LDs) emitting in the range of 0.9 µm to1.1 µm, the Yb 3+ doped YAG laser materials are very promising ultra-fast laser media [18][19][20][21][22]. There are some advantages for the Yb 3+ doped YAG: simple energy level scheme, low quantum defect, long upper-state lifetime, broad absorption bands that can be easily pumped by the high-power LDs, and broad emission bands that can be used in tunable emission and ultra-fast pulses generation [23][24][25][26]. ...
10 at.% Yb:Y3ScxAl5-xO12 (x = 0.25, 0.5, 1.0 and 1.5) transparent ceramics have been successfully fabricated by the solid state reaction method combined with vacuum sintering, whose transmittances reach 80% at 1100 nm with thickness of 3.0 mm. The full width at half maximum (FWHM) of the emission peaks located at about 1030 nm increases for increasing the Sc3+ content, and a maximum FWHM of 14.53 nm is obtained for 10 at.%Yb:Y3Sc1.5Al3.5O12 ceramics, which is 1.4 times larger than that of the 10 at.% Yb:Y3Al5O12 (Yb:YAG) ceramics. Finally, the laser performance of the 10 at.% Yb:Y3Sc1.5Al3.5O12 ceramics was tested and compared with that of a standard 10 at.% Yb:YAG sample. In quasi continuous wave (QCW) regime, a maximum laser output power of 10.8 W was obtained with the slope efficiency of 66.4%. The tuning range significantly broadens in the case of the Yb:YSAG sample, reaching a width of 86.2 nm.
... Recently, high power KLM lasers with MM LD pumping and an enhanced Kerr effect have been reported for Yb:Lu 2 O 3 ceramic (135 fs, 1.83 W) [21] and Yb:CALYO lasers (68 fs, 1.5 W) [19]. For KLM thin-disk lasers, additional Kerr medium is a necessary part of the laser system owing to the small amount of the Kerr effect which can be induced by the thin laser medium [32][33][34]. ...
Kerr-lens mode-locked operation of a Yb:KGW laser pumped by a multimode laser diode with the help of an additional Kerr medium is reported. With an enhanced Kerr lensing effect in the laser cavity operating far from the stability edge limit, the laser delivered 74 fs pulses with an average output power of 500 mW. In the high power regime of operation (>500 mW), the mode-locked laser output was accompanied by a continuous wave background radiation. Owing to the self-phase modulation effect, the laser demonstrated the generation of shorter pulses as compared to the case without an additional Kerr medium.
... For some time it has been a common understanding that lasers providing shorter pulse durations generally tend to deliver less output power. However , KLM Yb:YAG oscillators have also been demonstrated with extremely short pulses at very high average powers [60, 61, 14], even going down to sub-50 fs, corresponding to a spectral width exceeding the fluorescence bandwidth of the gain material [62] . An overview of achieved pulse durations and average output powers in mode-locked thin-disk lasers based on different disk materials is shown on the left side ofFig. ...
... These lasers might also be based on broadband materials other than Yb:YAG. But even with Yb:YAG, sub-50 fs pulse durations, well below the fluorescence-bandwidth-limit of the gain medium, have been obtained in 2015, using distributed Kerr-lens mode-locking, representing the shortest pulse duration achieved from any thin-disk oscillator and any Yb:YAG oscillator (at 1030 nm central wavelength) [62]. Alternatively, well established pulse shortening schemes based on nonlinear spectral broadening of Yb:YAG-based oscillators and subsequent pulse compression have already demonstrated durations below 10 fs [26], in this case using a hollow-core Kagomé type gas filled optical fiber. ...
... For some time it has been a common understanding that lasers providing shorter pulse durations generally tend to deliver less output power. However, KLM Yb:YAG oscillators have also been demonstrated with extremely short pulses at very high average powers[60,61,14], even going down to sub-50 fs, corresponding to a spectral width exceeding the fluorescence bandwidth of the gain material[62]. An overview of achieved pulse durations and average output powers in mode-locked thin-disk lasers based on different disk materials is shown on the left side ofFig. ...
Thin-disk laser technology combines the inherent advantages of allowing extremely high average power, excellent beam quality, and high peak power levels. In this chapter the benefits and limitations of the thin-disk concept with respect to ultrafast operation will be discussed. Different aspects of pulse duration, energy, peak- and average-power will be presented, reflecting the state of the art, with latest updates as of 2015.
... There are only a few works that attained high peak power (>100 kW) operation in sub-100-fs regime. One way to produce such pulses is to use a thin disk geometry [1,2]. In the case of bulk crystals, H. Zhao et al. [3] and A. Greborio et al. [4] managed to generate 85 fs and 94 fs pulses with MW peak power using Yb:KGW and Yb:CALGO crystals, respectively. ...
A sub-50-fs diode-pumped Yb:CALGO laser oscillator was demonstrated. The highest peak power achieved for 48-fs pulses directly from the oscillator was 1.6 MW. The shortest generated pulses were 40-fs with 177 kW of peak power.
We report a chirped-pulse optical parametric oscillator (CPOPO) based on a ${\rm KTiOAsO}_4$ K T i O A s O 4 (KTA) crystal. Due to the relatively low ratio between its second-order and third-order nonlinear susceptibility, a single KTA crystal could provide parametric gain and intra-cavity spectral broadening simultaneously in a CPOPO. Numerical simulations show that a signal-bandwidth of 390 nm can be obtained from a KTA-based CPOPO, and the pulses can be de-chirped with a width of ${\sim}{20}\;{\rm fs}$ ∼ 20 f s outside the OPO cavity. Experimentally, from a fiber-laser-pumped OPO with a 3-mm-long KTA crystal, we obtained a signal wave covering 1332–1667 nm, with a ${-}{20}\;{\rm dB}$ − 20 d B bandwidth of 45.3 THz, around 12 times as much as the gain-bandwidth of the KTA crystal.
A high-power sub-50 fs diode-pumped Yb:CALGO laser oscillator is demonstrated. The peak power achieved for 45 fs pulses directly from the oscillator was 1.7 MW. To the best of our knowledge, this is the highest peak power in the sub-50 fs pulse regime that has ever been produced directly from any diode-pumped Yb-ion-doped laser oscillator to date. The shortest generated pulses were 38 fs long with 187 kW of peak power.
We demonstrated a robust power-scalable Kerr-lens mode-locked (KLM) operation based on a Yb:YAG thin-disk oscillator. 15-W, 272-fs pulses were realized at a repetition rate of 86.7 MHz with an additional Kerr medium and a 2.5 mm hard aperture in the cavity. 247-fs pulses with an average power of 11 W could also be obtained by using a 2.4 mm hard aperture. Based on this shorter pulse, high efficient second-harmonic generation (SHG) was performed with a 1.7-mm-long LiB3O5 (LBO) crystal. The SHG laser power was up to 5 W with the power fluctuation RMS of 1% measured over one hour.
