Picosecond pulse sources with multi-GHz repetition rates and high output power

Paschotta, Rüdiger; Krainer, L.; Lecomte, Steve; Spühler, G.J.; Zeller, S. C.; Aschwanden, A.; Lorenser, Dirk; Unold, H.J.; Weingarten, K. J.; Keller, U.

doi:10.1088/1367-2630/6/1/174

Cited by 42 publications

(23 citation statements)

References 36 publications

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“…Furthermore, the much larger gain crosssection of the semiconductor material (in the order of 10 À14 cm 2 ) compared to diode-pumped solidstate lasers (typically in the order of G 10 À19 cm 2 ) enables stable mode-locking at high repetition rates without unwanted Q-switching instabilities [23]. These Q-switching instabilities become even worse for the small intracavity pulse energies in the gigahertz repetition rate regime [24]. Nevertheless, for a 10-GHz SESAM mode-locked diode-pumped solid-state laser a nearly quantumnoise limited timing jitter was achieved by a stable mechanical setup and moderate intracavity nonlinearities [6].…”

Section: Introductionmentioning

confidence: 99%

Amplitude Noise and Timing Jitter Characterization of a High-Power Mode-Locked Integrated External-Cavity Surface Emitting Laser

Mangold¹,

Link²,

Klenner³

et al. 2014

IEEE Photonics J.

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We present a timing jitter and amplitude noise characterization of a high-power mode-locked integrated external-cavity surface emitting laser (MIXSEL). In the MIXSEL, the semiconductor saturable absorber of a SESAM is integrated into the structure of a VECSEL to start and stabilize passive mode-locking. In comparison to previous noise characterization of SESAM-mode-locked VECSELs, this first noise characterization of a MIXSEL is performed at a much higher average output power. In a free-running operation, the laser generates 14.3-ps pulses at an average output power of 645 mW at a 2-GHz pulse repetition rate and an RMS amplitude noise of G 0.15% [1 Hz, 10 MHz]. We measured an RMS timing jitter of 129 fs [100 Hz, 10 MHz], which represents the lowest value for a free-running passively mode-locked semiconductor disk laser to date. Additionally, we stabilized the pulse repetition rate with a piezo actuator to control the cavity length. With the laser generating 16.7-ps pulses at an average output power of 701 mW, the repetition frequency was phase-locked to a low-noise electronic reference using a feedback loop. In actively stabilized operation, the RMS timing jitter was reduced to less than 70 fs [1 Hz, 100 MHz]. In the 100-Hz to 10-MHz bandwidth, we report the lowest timing jitter measured from a passively mode-locked semiconductor disk laser to date with a value of 31 fs. These results show that the MIXSEL technology provides compact ultrafast laser sources combining highpower and low-noise performance similar to diode-pumped solid-state lasers, which enable world-record optical communication rates and low-noise frequency combs.

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Section: Introductionmentioning

confidence: 99%

Amplitude Noise and Timing Jitter Characterization of a High-Power Mode-Locked Integrated External-Cavity Surface Emitting Laser

Mangold¹,

Link²,

Klenner³

et al. 2014

IEEE Photonics J.

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“…A technological key point is to avoid Q-switching instabilities [5], which can be provoked as an unwanted side effect of using a saturable absorber in a laser cavity. Especially for lasers with high pulse repetition rates [6,7] or high average output powers [8], the tendency for Q-switched mode locking (QML), which is typically observed below a certain threshold for the intracavity power, is a crucial limiting factor. Often it is difficult to achieve a low enough QML threshold.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, it was surprising that a significant roll-over was observed even in this regime [9], while many earlier experiments on other SESAMmode-locked lasers did not provide evidence for this effect. Note that the need to suppress Q-switching instabilities has enforced the use of SESAMs with reduced modulation depth (maximum nonlinear reflectivity change) of below 1%, particularly in the context of lasers with multi-GHz repetition rates [7]. For such low modulation depths, small induced nonlinear absorption effects acquire importance that always had been covered by the stronger saturable absorption in earlier SESAMs with modulation depth well above 1%.…”

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confidence: 99%

New regime of inverse saturable absorption for self-stabilizing passively mode-locked lasers

et al. 2005

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Appl. Phys. B 80, 151-158 (2005) Lasers and Optics Applied Physics B ABSTRACT The reflectivity of a semiconductor saturable absorber mirror (SESAM) is generally expected to increase with increasing pulse energy. However, for higher pulse energies the reflectivity can decrease again; we call this a 'roll-over' of the nonlinear reflectivity curve caused by inverse saturable absorption. We show for several SESAMs that the measured roll-over is consistent with two-photon absorption only for short (femtosecond) pulses, while a stronger (yet unidentified) kind of nonlinear absorption is dominant for longer (picosecond) pulses. These inverse saturable absorption effects have important technological consequences, e.g. for the Q-switching dynamics of passively mode-locked lasers. A simple equation using only measurable SESAM parameters and including inverse saturable absorption is derived for the Q-switched modelocking threshold. We present various data and discuss the sometimes detrimental effects of this roll-over for femtosecond high repetition rate lasers, as well as the potentially very useful consequences for passively mode-locked multi-GHz lasers. We also discuss strategies to enhance or reduce this induced absorption by using different SESAM designs or semiconductor materials.PACS 42.60.Fc; 42.70.Nq; 78.20.Ci IntroductionSince 1992, semiconductor saturable absorber mirrors (SESAMs) have been used with great success for selfstarting passive continuous-wave mode locking of various types of solid-state lasers [1][2][3][4]. A technological key point is to avoid Q-switching instabilities [5], which can be provoked as an unwanted side effect of using a saturable absorber in a laser cavity. Especially for lasers with high pulse repetition rates [6,7] or high average output powers [8], the tendency for Q-switched mode locking (QML), which is typically observed below a certain threshold for the intracavity power, is a crucial limiting factor. Often it is difficult to achieve a low enough QML threshold.Theoretical results for the QML threshold [5] have generally been found to be in good agreement with experimental u Fax: +41-1-633-1059, E-mail: grange@phys.ethz.ch values. However, particularly for some recent high repetition rate lasers, the QML threshold was found to be significantly lower than expected. Recently, it was shown that for some Er:Yb:glass lasers this could be explained with modified saturation characteristics of the SESAMs used, namely with a rollover of the nonlinear reflectivity for higher pulse fluences [9]. Two-photon absorption (TPA) has been widely used for optical power limiter [10]. And it has long been known that TPA causes a roll-over in the nonlinear reflectivity which lowers the Q-switching threshold [11,12]. However, for picosecond pulse durations as in the mentioned Er:Yb:glass lasers this effect would be too weak to be significant for practical values of the pulse fluence. Therefore, it was surprising that a significant roll-over was observed even in this regime [9], while many earlier exp...

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“…Thus, increasing repetition rate requires decreasing modulation depth and saturation fluence of the absorber. Multi-gigahertz repetition rates have been demonstrated using QW-SAMs [131][132][133][134][135][136] but that is not an easy task. The fact is that in QW-SAMs the saturation fluence can be lowered only by increasing the optical electric field amplitude at the position of QW.…”

Section: Quantum-dot Saturable Absorbers: Basic Principles and Fabricmentioning

confidence: 99%

Semiconductor Quantum‐Dot Saturable Absorber Mirrors for Mode‐Locking Solid‐State Lasers

Pasiskevicius

Meiser

Butkus

et al. 2014

The Physics and Engineering of Compact Quantum Dot‐based Lasers for Biophotonics

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Scope of the ChapterThe main aim of this chapter is to give an account of the recent achievements in the development of semiconductor quantum dot saturable absorber mirrors (QD-SAMs) for picosecond and subpicosecond pulse generation in bulk solid-state lasers. This work benefited immensely from previous development of methods for self-assembled growth of uniform, controlled-size, and high-density InAs QD layers on GaAs substrates and the technologies, primarily destined for diode lasers [1].This work also leans heavily on the knowledge developed in the area of passively mode-locked solid-state lasers employing quantum-well saturable absorbers (QWSAMs). Indeed, the dynamics in a mode-locked bulk solid-state laser is similar for quantum well (QW) and QD-SAMs and therefore most of the design guidelines devised for QW structures apply for QD-SAMs as well. Nevertheless, QD-SAMs offer certain unique physical properties such as low saturation fluence, temperature stability, relatively large inhomogeneous broadening, and transition energy scaling due to quantum size effect, all of which can be exploited to advantage in mode-locked solid-state lasers.Realizing that we are approaching the 50-year anniversary from the first demonstration of mode-locked laser operation, we felt it appropriate to give a brief overview of the development of passively mode-locked lasers and try to give a brief account of how the semiconductor saturable absorber technology emerged and was developed to become dominant as it is today. Owing to limitations on the length of this text, this overview is necessarily very cursory where we only mark certain milestones of this exciting journey. A large and growing number of review articles have appeared along the way, and the interested reader is well advised to turn to those in order to delve deeper into the different aspects of the subject. Following the brief overview, we focus in more detail on specific requirements and properties of QD-SAMs. After that we give an account of the experimental realization of mode-locked bulk solid-state lasers in different spectral ranges: Yb:KYW operating around 1.04 μm, Cr:forsterite -around 1.26 μm, and Er:Yb:glass laser -around 1.53 μm, all usingThe Physics and Engineering of Compact Quantum Dot-based Lasers for Biophotonics, First Edition. Edited by Edik U. Rafailov.

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Picosecond pulse sources with multi-GHz repetition rates and high output power

Cited by 42 publications

References 36 publications

Amplitude Noise and Timing Jitter Characterization of a High-Power Mode-Locked Integrated External-Cavity Surface Emitting Laser

Amplitude Noise and Timing Jitter Characterization of a High-Power Mode-Locked Integrated External-Cavity Surface Emitting Laser

New regime of inverse saturable absorption for self-stabilizing passively mode-locked lasers

Semiconductor Quantum‐Dot Saturable Absorber Mirrors for Mode‐Locking Solid‐State Lasers

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