Browsing by Subject "Pulse energies"

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    33-fs Yb-fiber laser comb locked to Cs-atomic clock
    (IEEE, 2013) Şenel, Çağrı; Hamid, R.; Erdoğan, C.; Çelik, M.; Kara, O.; İlday, Fatih Ömer
    Despite the prevalence of fiber frequency combs around 1.5 μm, few fully stabilized frequency combs have been demonstrated around 1.0 μm, despite the generally superior performance of Yb-fiber lasers compared to Er-fiber lasers. Short pulses are to generate coherent supercontinuum using anomalous dispersion regime of microstructured fibers. Near-zero cavity dispersion is highly desirable for low-noise frequency comb performance. Here, we report a Yb-doped fiber laser that operates at net-zero group-velocity dispersion and produces pulses that can be compressed externally to 33-fs. The frequency comb generated by this system is repetition-and carrier-envelope-phase-locked to Cs atomic clocks. The laser oscillator design is based on a novel algorithmic methodology, which allows us to design cavities to meet specific requirements; in this case, there was the need to generate as short pulses as possible, while having several nJ of pulse energy and the cavity at strictly zero total dispersion.
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    50-W, 1.6-GHz pulse repetition rate from a burst-mode Yb-doped fiber laser
    (IEEE, 2017) Elahi, Parviz; Ertek, A. C.; Eken, K.; İlday, Fatih Ömer
    We report a 50-W average power Yb-doped fiber laser amplifier system. The laser system produces bursts at a minimum rate of 200 kHz, with 1.6 GHz intraburst repetition rate. The total energy delivers in a burst is 250 μJ and the individual pulse energy is about 0.4 μJ. The output pulses are compressed to 270 fs by using two compressor gratings.
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    Burst-mode Yb fiber amplifier producing 30 μJ individual pulse energy
    (Optical Society of America, 2012) Kalaycıoğlu, Hamit; Burak Eldeniz, Y.; İlday, F. Ömer; Eken, K.
    We report 30-μJ individual pulse energy for 150-ns long amplified bursts of 0.4 mJ total energy from a 1-kHz Yb-fiber amplifier. Non-uniformity of pulse energy distribution inside amplified bursts is significantly reduced. ©2012 Optical Society of America.
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    Doping management for high-power fiber lasers: 100 W, few-picosecond pulse generation from an all-fiber-integrated amplifier
    (Optical Society of America, 2012-07-16) Elahi, P.; Yilmaz, S.; Akçaalan, Ö.; Kalaycioğlu, H.; Öktem, B.; Şenel, Ç.; Ilday, F. Ö.; Eken, K.
    Thermal effects, which limit the average power, can be minimized by using low-doped, longer gain fibers, whereas the presence of nonlinear effects requires use of high-doped, shorter fibers to maximize the peak power. We propose the use of varying doping levels along the gain fiber to circumvent these opposing requirements. By analogy to dispersion management and nonlinearity management, we refer to this scheme as doping management. As a practical first implementation, we report on the development of a fiber laser-amplifier system, the last stage of which has a hybrid gain fiber composed of high-doped and low-doped Yb fibers. The amplifier generates 100 W at 100 MHz with pulse energy of 1 μJ. The seed source is a passively mode-locked fiber oscillator operating in the all-normaldispersion regime. The amplifier comprises three stages, which are all-fiber-integrated, delivering 13 ps pulses at full power. By optionally placing a grating compressor after the first stage amplifier, chirp of the seed pulses can be controlled, which allows an extra degree of freedom in the interplay between dispersion and self-phase modulation. This way, the laser delivers 4.5 ps pulses with ∼200 kW peak power directly from fiber, without using external pulse compression.
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    Fiber amplification of pulse bursts up to 20 μj pulse energy at 1 kHz repetition rate
    (Optical of Society of America, 2011-08-23) Kalaycıoğlu, Hamit; Eken, K.; İlday, F. Ömer
    We demonstrate burst-mode operation of a polarization-maintaining Yb-doped fiber amplifier. Groups of pulses with a temporal spacing of 10 ns and 1 kHz overall repetition rate are amplified to an average pulse energy of ∼20 μJ and total burst energy of 0:25 mJ. The pulses are externally compressed to ∼400 fs. The amplifier is synchronously pulsed-pumped to minimize amplified spontaneous emission between the bursts. We characterize the influence of pump pulse duration, pump-to-signal delay, and signal burst length.
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    Generation of InN nanocrystals in organic solution through laser ablation of high pressure chemical vapor deposition-grown InN thin film
    (Springer, 2012-07-27) Alkis, S.; Alevli, M.; Burzhuev, S.; Vural, H. A.; Okyay, Ali Kemal; Ortaç, B.
    We report the synthesis of colloidal InN nanocrystals (InN-NCs) in organic solution through nanosecond pulsed laser ablation of high pressure chemical vapor deposition-grown InN thin film on GaN/sapphire template substrate. The size, the structural, the optical, and the chemical characteristics of InN-NCs demonstrate that the colloidal InN crystalline nanostructures in ethanol are synthesized with spherical shape within 5.9-25.3, 5.45-34.8, 3.24-36 nm particle-size distributions, increasing the pulse energy value. The colloidal InN-NCs solutions present strong absorption edge tailoring from NIR region to UV region.
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    High average and peak power femtosecond large-pitch photonic-crystal-fiber laser
    (2011) Baumgartl, M.; Jansen F.; Stutzki F.; Jauregui, C.; Ortaç, B.; Limpert J.; Tünnermann, A.
    We report on the generation of high-average-power and high-peak-power ultrashort pulses from a mode-locked fiber laser operating in the all-normal-dispersion regime. As gain medium, a large-mode-area ytterbium-doped large-pitch photonic-crystal fiber is used. The self-starting fiber laser delivers 27 W of average power at 50:57 MHz repetition rate, resulting in 534 nJ of pulse energy. The laser produces positively chirped 2 ps output pulses, which are compressed down to sub-100 fs, leading to pulse peak powers as high as 3:2 MW. © 2011 Optical Society of America.
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    High-energy femtosecond photonic crystal fiber laser
    (2010) Lecaplain, C.; Ortaç, B.; MacHinet G.; Boullet J.; Baumgart, M.; Schreiber, T.; Cormier, E.; Hideur, A.
    We report the generation of high-energy high-peak power pulses in an all-normal dispersion fiber laser featuring large-mode-area photonic crystal fibers. The self-starting chirped-pulse fiber oscillator delivers 11 W of average power at 15:5 MHz repetition rate, resulting in 710 nJ of pulse energy. The output pulses are dechirped outside the cavity from 7 ps to nearly transform-limited duration of 300 fs, leading to pulse peak powers as high as 1:9 MW. Numerical simulations reveal that pulse shaping is dominated by the amplitude modulation and spectral filtering provided by a resonant semiconductor saturable absorber. © 2010 Optical Society of America.
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    Microjoule pulse energies at 1 MHz repetition rate from an all-fiber nonlinear chirped-pulse amplifier
    (Optical Society of America, 2010) Kalaycioǧlu H.; Oktem, B.; Ömer Ilday F.
    We report a 1-MHz robust, all-fiber amplifier-oscillator system. Amplified pulses of 3 μJ are externally compressed to 140 fs. The highest peak power from an integrated fiber source, up to 50 kW, is obtained. © 2010 Optical Society of America.
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    Properties of a microjoule-class fiber oscillator mode-locked with a SESAM
    (IEEE, 2011) Lecaplain, C.; Ortac, Bülend; MacHinet G.; Boullet J.; Baumgartl, M.; Schreiber, T.; Cormier, E.; Hideur, A.
    Energy scaling of ultrafast Yb-doped fiber oscillators has experienced rapid progress largely driven by many applications that require high average power femtosecond pulses. The fundamental challenge for ultrafast fiber lasers relies on the control of excessive nonlinearity, which limits pulse energy. The development of all-normal dispersion laser cavities based on large-mode-area photonic crystal fibers (PCFs) has enabled significant energy scaling [1-3]. In particular, up to microjoule energy levels have been achieved from rod-type fiber-based oscillators [2-3]. In such lasers, pulse shaping is dominated by the strength of the mode-locking mechanism which determines the pulse properties. In this contribution, we report the generation of high-energy sub-picosecond pulses from a highly normal dispersion fiber laser featuring an Yb-doped rod-type PCF and a large-mode-area PCF [Fig.1(a)]. Passive mode-locking is achieved using saturable absorber mirrors (SAMs). We study the influence of the SAM parameters on performances obtained in this new class of fiber oscillators. The structures exhibit 20 % modulation depths and 500 fs relaxation time with resonant and antiresonant designs. The antiresonant SAM structures ensure absorption bandwidths 45 nm while the resonant structures exhibit 20 nm bandwidths. Stable mode locking with average powers as high as 15 μW at 15 MHz repetition rate, corresponding to microjoule energy level are obtained with all the structures. However, pulse properties and pulse shaping mechanism distinguish between resonant and antiresonant designs. Using a broadband antiresonant SAM leads to generation of highly-chirped pulses with 30 ps duration and 10 nm spectral width [Fig.1(b)]. The output pulses are extra-cavity dechirped down to 550 fs duration. By increasing the strength of the mode-locking mechanism through the combination of the SAM with the NPE process, we obtain shorter pulses with slightly boarder spectra. Indeed, the output pulse duration is decreased from 30 ps to 13 ps by adjusting the wave-plates settings. The dechirped pulse duration is then shortened to 450 fs. We note that the current laser performances are limited to 1 J by the available pump power. Using a resonant SAM structure, the output pulse duration is decreased to 7 ps [Fig.1(b)]. This pulse shortening results from the spectral filtering induced by the limited SAM bandwidth. All these results are in good agreement with numerical simulations which will be discussed in this communication. © 2011 IEEE.
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    Spectrally breathing femtosecond pulses from an Er-doped fiber laser
    (IEEE, 2008) Öktem, Bülent; Ülgüdür, Coşkun; İlday, Fatih Ömer
    We report order-of-magnitude spectral breathing in a dispersion-managed Er-fiber laser with an intracavity bandpass filter. This is to our knowledge the highest of any laser reported. Pulse energy is 1.7 nJ, width is 110 fs.
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    Sub-80 fe dissipative soliton large-mode-area fiber laser
    (2010) Baumgartl, M.; Ortaç, B.; Lecaplain, C.; Hideur, A.; Limpert J.; Tünnermann, A.
    We report on high-energy ultrashort pulse generation from an all-normal-dispersion large-mode-area fiber laser by exploiting an efficient combination of nonlinear polarization evolution (NPE) and a semiconductor-based saturable absorber mode-locking mechanism. The watt-level laser directly emits chirped pulses with a duration of 1 ps and 163 nJ of pulse energy. These can be compressed to 77 fs, generating megawatt-level peak power. Intracavity dynamics are discussed by numerical simulation, and the intracavity pulse evolution reveals that NPE plays a key role in pulse shaping. © 2010 Optical Society of America.