Microjoule-energy, 1 MHz repetition rate pulses from all-fiber-integrated nonlinear chirped-pulse amplifier

Kalaycıoğlu, Hamit; Öktem, Bülent; Şenel, Çağrı; Paltani, Punya Prasanna; Ilday, F. Ö.

doi:10.1364/ol.35.000959

Cited by 31 publications

(16 citation statements)

References 12 publications

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“…The laser source was a home-built Yb-doped fibre laser, operating at a central wavelength of 1,060 nm and generating pulses with up to 1 mJ energy at 1 MHz, which can be compressed to 100 fs (ref. 20). The powers incident on the samples ranged from 100 mW to 1 W. The pulse-to-pulse power stability was on the order of 0.05% (measured from 3 Hz to 250 kHz).…”

Section: Methodsmentioning

confidence: 99%

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Nonlinear laser lithography for indefinitely large-area nanostructuring with femtosecond pulses

Öktem¹,

Pavlov²,

İlday³

et al. 2013

Nature Photon

314

211

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Dynamical systems based on the interplay of nonlinear feedback mechanisms are ubiquitous in nature [1][2][3][4][5] . Well-understood examples from photonics include mode locking 6 and a broad class of fractal optics 7 , including self-similarity 8 . In addition to the fundamental interest in such systems, fascinating technical functionalities that are difficult or even impossible to achieve with linear systems can emerge naturally from them 7 if the right control tools can be applied. Here, we demonstrate a method that exploits positive nonlocal feedback to initiate, and negative local feedback to regulate, the growth of ultrafast laser-induced metal-oxide nanostructures with unprecedented uniformity, at high speed, low cost and on non-planar or flexible surfaces. The nonlocal nature of the feedback allows us to stitch the nanostructures seamlessly, enabling coverage of indefinitely large areas with subnanometre uniformity in periodicity. We demonstrate our approach through the fabrication of titanium dioxide and tungsten oxide nanostructures, but it can also be extended to a large variety of other materials.The fabrication of nanostructures on surfaces is of paramount importance in nanotechnology and materials science 9 . There are several established techniques, including photolithography, electron-beam lithography, imprint lithography 10 and laser interference lithography 11 , as well as non-conventional approaches such as selfassembly 12 and direct laser writing 13 . These techniques require either high-cost, complex systems or offer limited flexibility. An alternative flexible and potentially very low-cost method is laserinduced periodic surface structuring (LIPSS). The first observation of LIPSS dates back to 1965 14 . However, after almost 50 years and a large body of published work that has demonstrated LIPSS on various metals, semiconductors and glasses [15][16][17][18][19] , the method has not found widespread use due to the stubborn problem of quality control 18,19 .Despite the evident role of self-assembly in the LIPSS process, uniformity and long-range order remain poor, a problem we identified as originating from the fact that the structures are initiated from multiple seed locations concurrently and independently, thereby producing an irregular pattern. Because the process is irreversible, without self-correction, these irregularities become frozen. Our solution to this relies on carefully exploiting feedback mechanisms to tightly regulate the formation of nanostructures induced by ultrashort pulses. This process can be summarized in three steps.(1) The laser beam, with a peak intensity close to the ablation threshold for titanium, is focused on a titanium surface, where it is scattered by existing nanostructures or any surface defects 15 . The interference of the scattered and incident fields leads to intensity variations in the immediate neighbourhood of the scattering point. (2) At points where the threshold intensity for ablation is exceeded, titanium reacts rapidly with O 2 from the air, form...

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Section: Methodsmentioning

confidence: 99%

“…2 and Methods) consists of an ultrafast fibre laser 20 coupled to a microscope system for real-time observation of the nanofabrication process. All experiments were guided by a semi-phenomenological theoretical model developed by us.…”

mentioning

confidence: 99%

Nonlinear laser lithography for indefinitely large-area nanostructuring with femtosecond pulses

Öktem¹,

Pavlov²,

İlday³

et al. 2013

Nature Photon

314

211

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“…The maximum peak power of amplified pulses is 57 kW and the compressed pulse duration is 150-200 fs. A detailed description of the second system is provided in [18]. Both ultrafast systems can be used in picosecond mode by simply bypassing the pulse compressor.…”

Section: Introductionmentioning

confidence: 99%

Texturing of titanium (Ti6Al4V) medical implant surfaces with MHz-repetition-rate femtosecond and picosecond Yb-doped fiber lasers

Erdoğan¹,

Öktem²,

Kalaycıoğlu³

et al. 2011

Opt. Express

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Abstract:We propose and demonstrate the use of short pulsed fiber lasers in surface texturing using MHz-repetition-rate, microjoule-and sub-microjoule-energy pulses. Texturing of titanium-based (Ti6Al4V) dental implant surfaces is achieved using femtosecond, picosecond and (for comparison) nanosecond pulses with the aim of controlling attachment of human cells onto the surface. Femtosecond and picosecond pulses yield similar results in the creation of micron-scale textures with greatly reduced or no thermal heat effects, whereas nanosecond pulses result in strong thermal effects. Various surface textures are created with excellent uniformity and repeatability on a desired portion of the surface. The effects of the surface texturing on the attachment and proliferation of cells are characterized under cell culture conditions. Our data indicate that picosecond-pulsed laser modification can be utilized effectively in low-cost laser surface engineering of medical implants, where different areas on the surface can be made cell-attachment friendly or hostile through the use of different patterns. 192-203 (1997) Lett. 17, 733-737 (2004). 25. S. P. S. Porto, P. A. Fleury, and T. C. Damen, "Raman spectra of TiO2, MgF2, Zn F2, FeF2, and MnF2," Phys. Rev. 154, 522-526 (1967

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“…One relies on nonlinear CPA [2] and uses a standard single mode fiber (SMF) stretcher in combination with a pair of gratings. The main disadvantage of this scheme is that the pulse fidelity is strongly degraded with a considerably portion of the pulse energy in the pulse pedestal [3]. The other approach uses a longer polarization maintaining (PM) SMF stretcher in combination with a grism compressor, while keeping the nonlinearities low throughout the amplifier, allowing for the generation of high-fidelity µJ level pulses [1,4].…”

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confidence: 99%

Ytterbium fiber system using a dispersion compensating fiber stretcher

Verhoef

Fernández

Jespersen

et al. 2011

2011 Conference on Lasers and Electro-Optics Europe and 12th European Quantum Electronics Conference (CLEO EUROPE/EQEC)

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Ytterbium doped fiber amplifiers (YDFA) delivering high-fidelity sub 200-fs pulses are very attractive scalable sources for seeding and pumping of CEP stable DFG OPAs [1]. Replacing the grating stretcher optics by a fiberstretcher in YDFA is of key importance for achieving a robust turn-key alignment-free all-fiber integrated design. A major problem when designing a fiber stretcher is to match the dispersion requirements of the compressor unit in the whole spectral range of the pulses. Two main approaches have been used in all-fiber integrated YDFA. One relies on nonlinear CPA [2] and uses a standard single mode fiber (SMF) stretcher in combination with a pair of gratings. The main disadvantage of this scheme is that the pulse fidelity is strongly degraded with a considerably portion of the pulse energy in the pulse pedestal [3]. The other approach uses a longer polarization maintaining (PM) SMF stretcher in combination with a grism compressor, while keeping the nonlinearities low throughout the amplifier, allowing for the generation of high-fidelity µJ level pulses [1,4]. In this contribution we report on a simplified monolithic YDFA scheme that uses a non-PM dispersion compensating fiber (DCF) stretcher [5] specially designed to match the dispersion of a compressor unit consisting of a pair of 1480 lines/mm gratings. The system delivers high fidelity >5 µJ sub-165 fs pulses. The experimental setup is shown in Fig. 1. It consists of an Yb-fiber oscillator, two PM SMF preamplifiers and a PM large mode area (LMA) fiber amplifier. The seed pulses are stretched in a hybrid fiber-pulse stretcher which consists of ~8 m of PM980 fiber (pre-stretcher) followed by 100m DCF. After the stretcher a polarization controller and inline polarizer are used to ensure linear polarization in the amplifier.The measured GDD at 1043 nm is ~12 ps 2 resulting in a stretched pulse duration of ~350 ps. The compressor was optimized for maximum compressibility by fine tuning the incident angle on the gratings. Fig. 2 shows the retrieved pulse and spectral phase for 10 µJ pulse energy measured behind the free space optical isolator. The deviation from ideal phase can be mainly attributed to a residual uncompensated higher order dispersion contribution that limited pulse compressibility at the spectral wings. Similar results were observed for pulse energies up to 12 µJ. In summary, we developed a highly integrated YDFA that uses a specially designed DCF stretcher unit that closely matches the dispersion requirements of a 1480 lines/mm grating compressor. High fidelity sub-165 fs pulses with more than 5.5 µJ pulse energy after compression were obtained at 1040 nm. Fig. 1: Experimental layout of the monolithic YDFA with a DFC stretcher. On the right the far-field mode profile of the YDFA output is shown.Fig. 2: SHG FROG characterization of the YDFA output: (a) Measured and (b) retrieved SHG FROG traces; (c) retrieved temporal pulse profile and temporal phase; (d) measured and retrieved spectra together with the spectral phase.

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Microjoule-energy, 1 MHz repetition rate pulses from all-fiber-integrated nonlinear chirped-pulse amplifier

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Cited by 31 publications

References 12 publications

Nonlinear laser lithography for indefinitely large-area nanostructuring with femtosecond pulses

Nonlinear laser lithography for indefinitely large-area nanostructuring with femtosecond pulses

Texturing of titanium (Ti6Al4V) medical implant surfaces with MHz-repetition-rate femtosecond and picosecond Yb-doped fiber lasers

Ytterbium fiber system using a dispersion compensating fiber stretcher

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