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R. Paschotta

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Dr. Rüdiger Paschotta has an international reputation as a distinguished expert in technical areas such as lasers and amplifiers, nonlinear optics, fiber technology, ultrashort pulses, and noise in optics. He is author or coauthor of many publications, in particular of over 100 articles in scientific journals, over 120 presentations at international conferences, and of several books and book chapters. Also, he is the author of the well-known online Encyclopedia of Laser Physics and Technology. He is founder and managing director of RP Photonics Consulting GmbH, which offers technical consultancy as well as advanced simulation and design software, e.g. for fiber lasers and amplifiers, fiber optics, laser resonator design, pulse propagation and thin-film coating design.

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Macquarie University

Nikolay Kuleshov

Patrick Georges

Klaus Petermann

Universität Stuttgart

University of Michigan

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Papers by R. Paschotta

240-fs pulses with 22-W average power from a mode-locked thin-disk Yb:KY(WO_4)_2 laser

Optics Letters, 2002

We demonstrate what is to our knowledge the first passively mode-locked thin-disk Yb:KY͑WO 4 ͒ 2 ... more We demonstrate what is to our knowledge the first passively mode-locked thin-disk Yb:KY͑WO 4 ͒ 2 laser. The laser produces pulses of 240-fs duration with an average power of 22 W at a center wavelength of 1028 nm. At a pulse repetition rate of 25 MHz, the pulse energy is 0.9 mJ, and the peak power is as high as 3.3 MW. The beam quality is very close to the diffraction limit, with M 2 1.1.

Lifetime quenching in Yb-doped fibres

Optics Communications, 1997

Noise of mode-locked lasers (Part II): timing jitter and other fluctuations

Applied Physics B, 2004

This work present a comprehensive discussion of the noise properties of mode-locked lasers, with ... more This work present a comprehensive discussion of the noise properties of mode-locked lasers, with an emphasis on the effect of quantum noise in passively mode-locked solid-state lasers. Of special interest is the timing jitter, which is coupled to noise in various other pulse parameters. The study is based on analytical results and on numerical tools as described in part one of this study. It results in useful guidelines for the comparison and optimization of different kinds of lasers concerning timing jitter.

Diode-pumped 40GHz passively mode-locked Nd: YVO/sub 4/ laser with 288mW average output power

Annals of Physical and Rehabilitation Medicine, 2004

We present a diode-pumped passively mode-locked Nd:YVO/sub 4/ laser with a repetition rate as hig... more

Design guidelines for passively Q-switched microchip lasers using semiconductor saturable absorber mirrors

Advanced Solid State Lasers, 2001

ABSTRACT We present a model for passively Q-switched microchip lasers and derive simple equations... more ABSTRACT We present a model for passively Q-switched microchip lasers and derive simple equations for the pulse width, repetition rate, and pulse energy. We experimentally verified the validity of the model by systematically varying the relevant device parameters. We used the model to derive practical design guidelines for realizing operation parameters that can be varied in large ranges by adoption of the parameters of the semiconductor saturable-absorber mirror and choice of the appropriate gain medium. Applying these design guidelines, we obtained 37-ps pulses, which to our knowledge are the shortest pulses ever generated in a passively Q-switched solid-state laser.

Power scalability as a precise concept for the evaluation of laser architectures

2007 European Conference on Lasers and Electro-Optics and the International Quantum Electronics Conference, 2007

This paper establishes power scaling of lasers as a clearly defined concept, based on a power sca... more This paper establishes power scaling of lasers as a clearly defined concept, based on a power scaling procedure which must satisfy various criteria. It is demonstrated that this concept creates useful insight particularly for the evaluation of the future performance potential of different laser architectures, and for identifying technological aspects which will need to be modified for generating higher powers. It turns out that some aspects (such as e.g. thermal lensing in thin disk lasers) can have rather benign scaling properties, not causing problems even at very high power levels, while other aspects can become essential even if they initially may have appeared to be insignificant.

Mode-locked Nd:YVO/sub 4/ laser with 157 GHz repetition rate

Summaries of Papers Presented at the Lasers and Electro-Optics. CLEO '02. Technical Diges, 2002

ABSTRACT

High power Yb:KGW and Yb:KYW thin disk laser operation

Technical Digest. Summaries of papers presented at the Conference on Lasers and Electro-Optics. Postconference Technical Digest (IEEE Cat. No.01CH37170), 2001

Summary form only given. The Yb3+-doped potassium tungstates KY(WO4)2 (KYW) and KGd(WO4) 2 (KGW) ... more Summary form only given. The Yb3+-doped potassium tungstates KY(WO4)2 (KYW) and KGd(WO4) 2 (KGW) are for several reasons of great interest for diode-pumped solid state lasers. Compared with Yb:YAG, they have a smaller quantum defect of only ~4% and higher absorption and emission cross sections. Furthermore Yb:KGW and Yb:KYW have a broad emission bandwidth, comparable to that of Yb:glass, which

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

New Journal of Physics, 2004

We review and compare several recently introduced approaches for the generation of picosecond pul... more We review and compare several recently introduced approaches for the generation of picosecond pulse trains with multi-GHz repetition rates and relatively high average output power (up to several watts). Specifically, we consider passively mode-locked lasers with different gain media (Nd:YVO 4 , Er:Yb:glass, and surface-emitting semiconductor structures) as well as optical parametric oscillators.

Noise as a resolution limiting factor in group delay dispersion measurements with spectrally integrated white light interferometers

CLEO/Europe. 2005 Conference on Lasers and Electro-Optics Europe, 2005., 2005

ABSTRACT A detailed theoretical and experimental analysis of the relationship between spectral re... more

Passively mode-locked Nd: YV0 4 laser with up to 13 GHz repetition rate

Femtosecond fiber-feedback OPO

ABSTRACT We demonstrate the first synchronously pumped high-gain optical parametric oscillator wi... more

Passively mode-locked 25-GHz and 40-GHz Er: Yb: glass lasers

ABSTRACT We demonstrate compact, passively fundamental-mode-locked Er:Yb:glass lasers with 25 GHz... more

Pulse-generating laser

Passively modelocked surface-emitting semiconductor lasers

Physics Reports, 2006

This paper will review and discuss pico-and femtosecond pulse generation from passively modelocke... more This paper will review and discuss pico-and femtosecond pulse generation from passively modelocked vertical-external-cavity surface-emitting semiconductor lasers (VECSELs). We shall discuss the physical principles of ultrashort pulse generation in these lasers, considering in turn the role played by the semiconductor quantum well gain structure, and the saturable absorber. The paper will analyze the fundamental performance limits of these devices, and review the results that have been demonstrated to date. Different types of semiconductor saturable absorber mirror (SESAM) design, and their characteristic dynamics, are described in detail; exploring the ultimate goal of moving to a wafer integration approach, in which the SESAM is integrated into the VECSEL structure with tremendous gain in capability. In particular, the contrast between VECSELs and diode-pumped solid-state lasers and edge-emitting diode lasers will be discussed. Optically pumped VECSELs have led to an improvement by more than two orders of magnitude to date in the average output power achievable from a passively modelocked ultrafast semiconductor laser.

Optical parametric oscillator with a 10-GHz repetition rate and 100-mW average output power in the spectral region near 1.5 μm

Optics Letters, 2002

We demonstrate a synchronously pumped optical parametric oscillator that emits picosecond pulses ... more We demonstrate a synchronously pumped optical parametric oscillator that emits picosecond pulses at an ϳ1.55-mm wavelength with a repetition rate as a high as 10 GHz and as much as 100 mW of average power. It is pumped with a diode-pumped passively mode-locked 10-GHz Nd:YVO 4 laser. Because of its high repetition rate and its potential for ultrabroad tunability, this kind of system is useful for telecom applications. It should be scalable to 40 GHz and higher as required for future telecom networks.

Single-frequency ytterbium-doped fiber laser stabilized by spatial hole burning

Optics Letters, 1997

Soliton mode-locked Er:Yb:glass laser

Optics Letters, 2005

We report on a simple diode-pumped passively mode-locked Er:Yb:glass laser generating transform-l... more We report on a simple diode-pumped passively mode-locked Er:Yb:glass laser generating transform-limited 1536-nm solitons of 255-fs duration with a repetition rate of 50 MHz and average power of 58 mW. We also discuss timing jitter and the trade-off between short pulses and high output power in these lasers.

60-W average power in 810-fs pulses from a thin-disk Yb:YAG laser

Optics Letters, 2003

We demonstrate a passively mode-locked diode-pumped thin-disk Yb:YAG laser generating 810-fs puls... more We demonstrate a passively mode-locked diode-pumped thin-disk Yb:YAG laser generating 810-fs pulses at 1030 nm with as much as 60 W of average output power (without using an amplifier). At a pulse repetition rate of 34.3 MHz, the pulse energy is 1.75 mJ and the peak power is as high as 1.9 MW. The beam quality is close to the diffraction limit, with M 2 , 1.1.

Characterization and modeling of thulium:ZBLAN blue upconversion fiber lasers

Journal of the Optical Society of America B, 1997

We have investigated the performance of blue upconversion fiber lasers based on thulium-doped ZBL... more We have investigated the performance of blue upconversion fiber lasers based on thulium-doped ZBLAN fiber, operating at 480 nm with a 1140-nm pump. Extensive fluorescence measurements have provided the necessary spectroscopic data to present a computer model that describes the performance of such lasers with good accuracy despite the complicated three-step upconversion mechanism and the influence of ion-ion energy transfer processes. We have identified the mechanisms that populate the levels above the 1 G 4 level and are able to specify the corresponding spectroscopic parameters. We discuss the relevance of these processes to the 480-nm laser performance. Furthermore, we have calculated optimized parameters for such lasers.

240-fs pulses with 22-W average power from a mode-locked thin-disk Yb:KY(WO_4)_2 laser

Optics Letters, 2002

We demonstrate what is to our knowledge the first passively mode-locked thin-disk Yb:KY͑WO 4 ͒ 2 ... more We demonstrate what is to our knowledge the first passively mode-locked thin-disk Yb:KY͑WO 4 ͒ 2 laser. The laser produces pulses of 240-fs duration with an average power of 22 W at a center wavelength of 1028 nm. At a pulse repetition rate of 25 MHz, the pulse energy is 0.9 mJ, and the peak power is as high as 3.3 MW. The beam quality is very close to the diffraction limit, with M 2 1.1.

Lifetime quenching in Yb-doped fibres

Optics Communications, 1997

Noise of mode-locked lasers (Part II): timing jitter and other fluctuations

Applied Physics B, 2004

This work present a comprehensive discussion of the noise properties of mode-locked lasers, with ... more This work present a comprehensive discussion of the noise properties of mode-locked lasers, with an emphasis on the effect of quantum noise in passively mode-locked solid-state lasers. Of special interest is the timing jitter, which is coupled to noise in various other pulse parameters. The study is based on analytical results and on numerical tools as described in part one of this study. It results in useful guidelines for the comparison and optimization of different kinds of lasers concerning timing jitter.

Diode-pumped 40GHz passively mode-locked Nd: YVO/sub 4/ laser with 288mW average output power

Annals of Physical and Rehabilitation Medicine, 2004

We present a diode-pumped passively mode-locked Nd:YVO/sub 4/ laser with a repetition rate as hig... more

Design guidelines for passively Q-switched microchip lasers using semiconductor saturable absorber mirrors

Advanced Solid State Lasers, 2001

ABSTRACT We present a model for passively Q-switched microchip lasers and derive simple equations... more ABSTRACT We present a model for passively Q-switched microchip lasers and derive simple equations for the pulse width, repetition rate, and pulse energy. We experimentally verified the validity of the model by systematically varying the relevant device parameters. We used the model to derive practical design guidelines for realizing operation parameters that can be varied in large ranges by adoption of the parameters of the semiconductor saturable-absorber mirror and choice of the appropriate gain medium. Applying these design guidelines, we obtained 37-ps pulses, which to our knowledge are the shortest pulses ever generated in a passively Q-switched solid-state laser.

Power scalability as a precise concept for the evaluation of laser architectures

2007 European Conference on Lasers and Electro-Optics and the International Quantum Electronics Conference, 2007

This paper establishes power scaling of lasers as a clearly defined concept, based on a power sca... more This paper establishes power scaling of lasers as a clearly defined concept, based on a power scaling procedure which must satisfy various criteria. It is demonstrated that this concept creates useful insight particularly for the evaluation of the future performance potential of different laser architectures, and for identifying technological aspects which will need to be modified for generating higher powers. It turns out that some aspects (such as e.g. thermal lensing in thin disk lasers) can have rather benign scaling properties, not causing problems even at very high power levels, while other aspects can become essential even if they initially may have appeared to be insignificant.

Mode-locked Nd:YVO/sub 4/ laser with 157 GHz repetition rate

Summaries of Papers Presented at the Lasers and Electro-Optics. CLEO '02. Technical Diges, 2002

ABSTRACT

High power Yb:KGW and Yb:KYW thin disk laser operation

Technical Digest. Summaries of papers presented at the Conference on Lasers and Electro-Optics. Postconference Technical Digest (IEEE Cat. No.01CH37170), 2001

Summary form only given. The Yb3+-doped potassium tungstates KY(WO4)2 (KYW) and KGd(WO4) 2 (KGW) ... more Summary form only given. The Yb3+-doped potassium tungstates KY(WO4)2 (KYW) and KGd(WO4) 2 (KGW) are for several reasons of great interest for diode-pumped solid state lasers. Compared with Yb:YAG, they have a smaller quantum defect of only ~4% and higher absorption and emission cross sections. Furthermore Yb:KGW and Yb:KYW have a broad emission bandwidth, comparable to that of Yb:glass, which

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

New Journal of Physics, 2004

We review and compare several recently introduced approaches for the generation of picosecond pul... more We review and compare several recently introduced approaches for the generation of picosecond pulse trains with multi-GHz repetition rates and relatively high average output power (up to several watts). Specifically, we consider passively mode-locked lasers with different gain media (Nd:YVO 4 , Er:Yb:glass, and surface-emitting semiconductor structures) as well as optical parametric oscillators.

Noise as a resolution limiting factor in group delay dispersion measurements with spectrally integrated white light interferometers

CLEO/Europe. 2005 Conference on Lasers and Electro-Optics Europe, 2005., 2005

ABSTRACT A detailed theoretical and experimental analysis of the relationship between spectral re... more

Passively mode-locked Nd: YV0 4 laser with up to 13 GHz repetition rate

Femtosecond fiber-feedback OPO

ABSTRACT We demonstrate the first synchronously pumped high-gain optical parametric oscillator wi... more

Passively mode-locked 25-GHz and 40-GHz Er: Yb: glass lasers

ABSTRACT We demonstrate compact, passively fundamental-mode-locked Er:Yb:glass lasers with 25 GHz... more

Pulse-generating laser

Passively modelocked surface-emitting semiconductor lasers

Physics Reports, 2006

This paper will review and discuss pico-and femtosecond pulse generation from passively modelocke... more This paper will review and discuss pico-and femtosecond pulse generation from passively modelocked vertical-external-cavity surface-emitting semiconductor lasers (VECSELs). We shall discuss the physical principles of ultrashort pulse generation in these lasers, considering in turn the role played by the semiconductor quantum well gain structure, and the saturable absorber. The paper will analyze the fundamental performance limits of these devices, and review the results that have been demonstrated to date. Different types of semiconductor saturable absorber mirror (SESAM) design, and their characteristic dynamics, are described in detail; exploring the ultimate goal of moving to a wafer integration approach, in which the SESAM is integrated into the VECSEL structure with tremendous gain in capability. In particular, the contrast between VECSELs and diode-pumped solid-state lasers and edge-emitting diode lasers will be discussed. Optically pumped VECSELs have led to an improvement by more than two orders of magnitude to date in the average output power achievable from a passively modelocked ultrafast semiconductor laser.

Optical parametric oscillator with a 10-GHz repetition rate and 100-mW average output power in the spectral region near 1.5 μm

Optics Letters, 2002

We demonstrate a synchronously pumped optical parametric oscillator that emits picosecond pulses ... more We demonstrate a synchronously pumped optical parametric oscillator that emits picosecond pulses at an ϳ1.55-mm wavelength with a repetition rate as a high as 10 GHz and as much as 100 mW of average power. It is pumped with a diode-pumped passively mode-locked 10-GHz Nd:YVO 4 laser. Because of its high repetition rate and its potential for ultrabroad tunability, this kind of system is useful for telecom applications. It should be scalable to 40 GHz and higher as required for future telecom networks.

Single-frequency ytterbium-doped fiber laser stabilized by spatial hole burning

Optics Letters, 1997

Soliton mode-locked Er:Yb:glass laser

Optics Letters, 2005

We report on a simple diode-pumped passively mode-locked Er:Yb:glass laser generating transform-l... more We report on a simple diode-pumped passively mode-locked Er:Yb:glass laser generating transform-limited 1536-nm solitons of 255-fs duration with a repetition rate of 50 MHz and average power of 58 mW. We also discuss timing jitter and the trade-off between short pulses and high output power in these lasers.

60-W average power in 810-fs pulses from a thin-disk Yb:YAG laser

Optics Letters, 2003

We demonstrate a passively mode-locked diode-pumped thin-disk Yb:YAG laser generating 810-fs puls... more We demonstrate a passively mode-locked diode-pumped thin-disk Yb:YAG laser generating 810-fs pulses at 1030 nm with as much as 60 W of average output power (without using an amplifier). At a pulse repetition rate of 34.3 MHz, the pulse energy is 1.75 mJ and the peak power is as high as 1.9 MW. The beam quality is close to the diffraction limit, with M 2 , 1.1.

Characterization and modeling of thulium:ZBLAN blue upconversion fiber lasers

Journal of the Optical Society of America B, 1997

We have investigated the performance of blue upconversion fiber lasers based on thulium-doped ZBL... more We have investigated the performance of blue upconversion fiber lasers based on thulium-doped ZBLAN fiber, operating at 480 nm with a 1140-nm pump. Extensive fluorescence measurements have provided the necessary spectroscopic data to present a computer model that describes the performance of such lasers with good accuracy despite the complicated three-step upconversion mechanism and the influence of ion-ion energy transfer processes. We have identified the mechanisms that populate the levels above the 1 G 4 level and are able to specify the corresponding spectroscopic parameters. We discuss the relevance of these processes to the 480-nm laser performance. Furthermore, we have calculated optimized parameters for such lasers.