Esa Saarinen - Academia.edu (original) (raw)

Papers by Esa Saarinen

Physical Review E Statistical Nonlinear and Soft Matter Physics, 2008

We report on bistable mode-locking in a semiconductor disk laser. The disk laser mode-locked with... more We report on bistable mode-locking in a semiconductor disk laser. The disk laser mode-locked with a semiconductor saturable absorber is investigated for different designs of the gain medium that allow the hysteresis loop to be controlled. Hysteresis formation in the pulsed regime of a semiconductor oscillator with saturable absorption and unsaturated gain is discussed qualitatively. The laser represents an attractive setup for generation and manipulation of dissipative solitons and observation of their interaction.

Optics Express, Oct 7, 2013

ABSTRACT A proof-of-principle study of a 1.97-µm Tm:Lu2O3 ceramic disk laser, intracavity pumped ... more ABSTRACT A proof-of-principle study of a 1.97-µm Tm:Lu2O3 ceramic disk laser, intracavity pumped by a 1.2-µm semiconductor disk laser, is presented. The demonstrated concept allows for improved pump absorption and takes advantage of the broad wavelength coverage provided by semiconductor disk laser technology. For thin disk lasers the small thickness of the gain element typically leads to inefficient pump light absorption. This problem is usually solved by using a complex multi-pass pump arrangement. In this study we address this challenge with a new laser concept of an intracavity pumped ceramic thin disk laser. The output power at 1.97 µm was limited to 250 mW due to heat spreader-less mounting scheme of the ceramic gain disk.

That success story of instrumental reason, scientific method and of rationalism is however jeopar... more That success story of instrumental reason, scientific method and of rationalism is however jeopardized by the cumulative effects they are creating for the world as a living organism. Instrumental reason has created techniques and technologies that are superbly efficient in ...

Extended Abstract Multicriteria decision and negotiation support are not only about mathematical ... more Extended Abstract Multicriteria decision and negotiation support are not only about mathematical models for eliciting preferences and reaching efficient solutions. By today we have already understood the importance of the decision support process itself and that it must be interactive. Thus also the way the participation is arranged matters. Participation engages the analyst or facilitator into the process with all the complexities related to human interaction. People react to the environment and to the way the issues are presented and framed. Problem structuring and framing is unavoidably systemic in the attempt to include all the impacts found important by the different stakeholders. People's beliefs and beliefs about the beliefs of others can have an impact, too. Recent research emphasizes how values are not constant but constructed in the situation by learning and experiencing (Lichtenstein and Slovic 2006). We are dealing with a phenomenon in which the agents as well as the...

This paper outlines the basic features of Systems Intelligence and discusses some of its fundamen... more This paper outlines the basic features of Systems Intelligence and discusses some of its fundamentals. Systems Intelligence combines insights of Systems Thinking with a pragmatic orientation and philosophy of life. We argue that Systems Intelligence is a new concept that is highly useful for understanding human behaviour in complex interactive settings, and in concrete efforts to generate change. We suggest that Systems Intelligence is something we apply as humans instinctively. Systems Intelligence combines engineering thinking with human sensitivity and thus serves as a foundation for a down-to-earth pragmatic philosophy of life of optimism and change.

This article studies leadership from a systems intelligence perspective. Referring to Lincoln, Ma... more This article studies leadership from a systems intelligence perspective. Referring to Lincoln, Martin Luther King and a number of other exemplary leadership cases, we argue that the holistic, contextual and choice-intensive features of systems intelligence make it an illuminating frame of reference for understanding the actual practice of leaders. The key words in the article include "the need to act", "the living presence", "the in-between", "systems intelligent interventions", "flourishment", "choice", "connectivity", "sharing", "change", "microbehaviours", "sensibilities", "super- productivity", "thinking on the fly", "emergence", "systems of holding back", "positivity", "hope", "human potential", and "the symbolic order". We indicate three critical systems intelligent leadership questions, an...

Proceedings of SPIE - The International Society for Optical Engineering

We present new approaches for power scaling and tunability in semiconductor disk lasers. The nove... more We present new approaches for power scaling and tunability in semiconductor disk lasers. The novel concepts allow for reduced thermal load of the gain material, increasing the threshold of rollover and extending the capability for boosting the output power without significant degradation in the beam quality. The proposed technique for power scaling of optically-pumped semiconductor disk lasers is based on the multiple gain scheme. The method allows for significant power improvement while preserving good beam quality. Total power of over 8 W was achieved in dual-gain configuration, while one-gain lasers could produce separately about 4 W, limited by the thermal rollover of the output characteristics. The results show that reduced thermal load to a gain element in a dual-gain cavity allows extending the range of usable pump powers boosting the laser output. Tunable Sb-based semiconductor disk laser operating at 2-mum is demonstrated with nearly 100 nm operation range. The maximum outp...

IEEE Photonics Technology Letters, 2015

ABSTRACT We present a light source that can generate a pulse train with an extremely high repetit... more ABSTRACT We present a light source that can generate a pulse train with an extremely high repetition rate, tens of watts of average output power, and a low-divergence output beam. This unique combination of system characteristics is achieved with single-stage amplification of a passively harmonically mode-locked semiconductor disk laser in a tapered Yb-doped double-clad fiber. With the short-length tapered fiber amplifier an amplification factor >17 dB is reached, while preserving the 930-fs pulse duration of the semiconductor disk laser. The demonstrated pulse source with a beam quality factor <2 enables efficient coupling into single-mode fibers for nonlinear optical experiments and ultracoarse frequency comb generation.

Laser Optics 2010, 2010

ABSTRACT The concept of multiple gain element cavity was applied for power scaling a passively mo... more ABSTRACT The concept of multiple gain element cavity was applied for power scaling a passively mode-locked semiconductor disk laser. 400 mW of average output power for the laser with a single gain element was boosted to 900 mW for the laser with the dual gain cavity. The increase in output power was accompanied by an increase in the order of mode-locking harmonic.

This paper discusses the key aspects of Good Economy as presented by Edmund Phelps.

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

Optics InfoBase is the Optical Society's online library for flagship journals, partnered and... more Optics InfoBase is the Optical Society's online library for flagship journals, partnered and copublished journals, and recent proceedings from OSA conferences.

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

Abstract We demonstrate a semiconductor disk laser with frequency shifted feedback producing puls... more Abstract We demonstrate a semiconductor disk laser with frequency shifted feedback producing pulses of 29 ps duration at the repetition rate of 300 MHz. The method provides a robust starting mechanism for stable pulsed operation.

American Psychologist, 2014

Physical Review E Statistical Nonlinear and Soft Matter Physics, 2008

We report on bistable mode-locking in a semiconductor disk laser. The disk laser mode-locked with... more We report on bistable mode-locking in a semiconductor disk laser. The disk laser mode-locked with a semiconductor saturable absorber is investigated for different designs of the gain medium that allow the hysteresis loop to be controlled. Hysteresis formation in the pulsed regime of a semiconductor oscillator with saturable absorption and unsaturated gain is discussed qualitatively. The laser represents an attractive setup for generation and manipulation of dissipative solitons and observation of their interaction.

Optics Express, Oct 7, 2013

ABSTRACT A proof-of-principle study of a 1.97-µm Tm:Lu2O3 ceramic disk laser, intracavity pumped ... more ABSTRACT A proof-of-principle study of a 1.97-µm Tm:Lu2O3 ceramic disk laser, intracavity pumped by a 1.2-µm semiconductor disk laser, is presented. The demonstrated concept allows for improved pump absorption and takes advantage of the broad wavelength coverage provided by semiconductor disk laser technology. For thin disk lasers the small thickness of the gain element typically leads to inefficient pump light absorption. This problem is usually solved by using a complex multi-pass pump arrangement. In this study we address this challenge with a new laser concept of an intracavity pumped ceramic thin disk laser. The output power at 1.97 µm was limited to 250 mW due to heat spreader-less mounting scheme of the ceramic gain disk.

That success story of instrumental reason, scientific method and of rationalism is however jeopar... more That success story of instrumental reason, scientific method and of rationalism is however jeopardized by the cumulative effects they are creating for the world as a living organism. Instrumental reason has created techniques and technologies that are superbly efficient in ...

Extended Abstract Multicriteria decision and negotiation support are not only about mathematical ... more Extended Abstract Multicriteria decision and negotiation support are not only about mathematical models for eliciting preferences and reaching efficient solutions. By today we have already understood the importance of the decision support process itself and that it must be interactive. Thus also the way the participation is arranged matters. Participation engages the analyst or facilitator into the process with all the complexities related to human interaction. People react to the environment and to the way the issues are presented and framed. Problem structuring and framing is unavoidably systemic in the attempt to include all the impacts found important by the different stakeholders. People's beliefs and beliefs about the beliefs of others can have an impact, too. Recent research emphasizes how values are not constant but constructed in the situation by learning and experiencing (Lichtenstein and Slovic 2006). We are dealing with a phenomenon in which the agents as well as the...

This paper outlines the basic features of Systems Intelligence and discusses some of its fundamen... more This paper outlines the basic features of Systems Intelligence and discusses some of its fundamentals. Systems Intelligence combines insights of Systems Thinking with a pragmatic orientation and philosophy of life. We argue that Systems Intelligence is a new concept that is highly useful for understanding human behaviour in complex interactive settings, and in concrete efforts to generate change. We suggest that Systems Intelligence is something we apply as humans instinctively. Systems Intelligence combines engineering thinking with human sensitivity and thus serves as a foundation for a down-to-earth pragmatic philosophy of life of optimism and change.

This article studies leadership from a systems intelligence perspective. Referring to Lincoln, Ma... more This article studies leadership from a systems intelligence perspective. Referring to Lincoln, Martin Luther King and a number of other exemplary leadership cases, we argue that the holistic, contextual and choice-intensive features of systems intelligence make it an illuminating frame of reference for understanding the actual practice of leaders. The key words in the article include "the need to act", "the living presence", "the in-between", "systems intelligent interventions", "flourishment", "choice", "connectivity", "sharing", "change", "microbehaviours", "sensibilities", "super- productivity", "thinking on the fly", "emergence", "systems of holding back", "positivity", "hope", "human potential", and "the symbolic order". We indicate three critical systems intelligent leadership questions, an...

Proceedings of SPIE - The International Society for Optical Engineering

We present new approaches for power scaling and tunability in semiconductor disk lasers. The nove... more We present new approaches for power scaling and tunability in semiconductor disk lasers. The novel concepts allow for reduced thermal load of the gain material, increasing the threshold of rollover and extending the capability for boosting the output power without significant degradation in the beam quality. The proposed technique for power scaling of optically-pumped semiconductor disk lasers is based on the multiple gain scheme. The method allows for significant power improvement while preserving good beam quality. Total power of over 8 W was achieved in dual-gain configuration, while one-gain lasers could produce separately about 4 W, limited by the thermal rollover of the output characteristics. The results show that reduced thermal load to a gain element in a dual-gain cavity allows extending the range of usable pump powers boosting the laser output. Tunable Sb-based semiconductor disk laser operating at 2-mum is demonstrated with nearly 100 nm operation range. The maximum outp...

IEEE Photonics Technology Letters, 2015

ABSTRACT We present a light source that can generate a pulse train with an extremely high repetit... more ABSTRACT We present a light source that can generate a pulse train with an extremely high repetition rate, tens of watts of average output power, and a low-divergence output beam. This unique combination of system characteristics is achieved with single-stage amplification of a passively harmonically mode-locked semiconductor disk laser in a tapered Yb-doped double-clad fiber. With the short-length tapered fiber amplifier an amplification factor >17 dB is reached, while preserving the 930-fs pulse duration of the semiconductor disk laser. The demonstrated pulse source with a beam quality factor <2 enables efficient coupling into single-mode fibers for nonlinear optical experiments and ultracoarse frequency comb generation.

Laser Optics 2010, 2010

ABSTRACT The concept of multiple gain element cavity was applied for power scaling a passively mo... more ABSTRACT The concept of multiple gain element cavity was applied for power scaling a passively mode-locked semiconductor disk laser. 400 mW of average output power for the laser with a single gain element was boosted to 900 mW for the laser with the dual gain cavity. The increase in output power was accompanied by an increase in the order of mode-locking harmonic.

This paper discusses the key aspects of Good Economy as presented by Edmund Phelps.

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

Optics InfoBase is the Optical Society's online library for flagship journals, partnered and... more Optics InfoBase is the Optical Society's online library for flagship journals, partnered and copublished journals, and recent proceedings from OSA conferences.

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

Abstract We demonstrate a semiconductor disk laser with frequency shifted feedback producing puls... more Abstract We demonstrate a semiconductor disk laser with frequency shifted feedback producing pulses of 29 ps duration at the repetition rate of 300 MHz. The method provides a robust starting mechanism for stable pulsed operation.

American Psychologist, 2014