Dr. Manuel Ryser Profile

Dr. Manuel Ryser

at 8Photonics

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Publications (12)

SPIE Journal Paper | 26 February 2022 Open Access

Corneal absorption spectra in the deep UV range

Dominik Inniger, Alessio Poretti, Manuel Ryser, Christoph Meier, Christian Rathjen, Thomas Feurer

JBO, Vol. 27, Issue 02, 025004, (February 2022) https://doi.org/10.1117/12.10.1117/1.JBO.27.2.025004

KEYWORDS: Absorption, Cornea, Refractive index, Water, Prisms, Ultraviolet radiation, Deep ultraviolet, Surgery, In vivo imaging, Laser ablation

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Significance: Refractive surgery in ophthalmology uses pulsed lasers at 193, 210, or 213 nm. The reason is that most molecular constituents of cornea absorb strongly in this wavelength range. Precise refractive surgery via ablation requires an accurate knowledge of the absorption coefficient at the relevant wavelengths. Yet, the absorption coefficients of corneal tissue reported in literature vary by almost an order of magnitude; moreover, they were measured mostly at the wavelengths mentioned earlier. Aim: By measuring the corneal absorption coefficient of intact eyeballs stored at different environmental conditions, prepared by following different procedures, and as a function of postmortem time, we determine the absorption coefficient for the entire wavelength range between 185 and 250 nm for as close as possible to in-vivo conditions. Approach: We use a specially designed UV ellipsometer to measure refractive index and absorption coefficient. Specifically, we investigate the temporal evolution of refractive index and absorption coefficient after enucleation of the eyeballs under different environmental conditions and preparation procedures. Results: Our measurements provide accurate values for refractive index as well as absorption coefficient of cornea in the wavelength range between 185 and 250 nm. We find that the absorption coefficient decreases with time and that neither storage conditions nor preparation procedures but a continuous degeneration of the cornea is responsible for the observed time evolution. We use the measured time evolution to extrapolate refractive index and absorption coefficient to in-vivo conditions. Conclusion: Our measurements of the close to in-vivo absorption coefficient of cornea between 185 and 250 nm allow for a better understanding and modeling of refractive cornea surgery, also at other than the three commonly used wavelengths. In the future, this may be relevant when new pulsed laser sources with other wavelengths become available.

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Proceedings Article | 26 February 2018 Presentation + Paper

Self-injection linear polarization locking of a fiber laser

C. Bacher, A. Heidt, V. Romano, M. Ryser

Proceedings Volume 10512, 105121L (2018) https://doi.org/10.1117/12.2290450

KEYWORDS: Polarization, Fiber Bragg gratings, Fiber lasers, Polarizers, Laser resonators, Reflectivity, Semiconductor lasers, Continuous wave operation, Diodes

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Proceedings Article | 26 February 2018 Presentation + Paper

Self-optimizing additive pulse mode-locked fiber laser: wavelength tuning and selective operation in continuous-wave or mode-locked regime

Manuel Ryser, Christoph Bacher, Christoph Lätt, Alexander Heidt, Philippe Raisin, Thomas Feurer, Valerio Romano

Proceedings Volume 10512, 105121C (2018) https://doi.org/10.1117/12.2290645

KEYWORDS: Mode locking, Fiber lasers, Polarization, Continuous wave operation, Genetic algorithms, Pulsed laser operation

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Proceedings Article | 16 May 2017 Presentation + Paper

Spectroscopy of a heated Yb-doped optical fiber with high aluminum content

C. Bacher, J. Scheuner, S. Pilz, A. El Sayed, M. Ryser, A. Heidt, V. Romano

Proceedings Volume 10232, 102320J (2017) https://doi.org/10.1117/12.2268872

KEYWORDS: Aluminum, Spectroscopy, Optical fibers, Fiber lasers, Silica, Ytterbium, Absorption, Laser systems engineering, Materials processing

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Proceedings Article | 27 April 2016 Paper

Yellow light generation by frequency doubling of a ﬁber oscillator

Christoph Bacher, Ricardo Oliveira, Rogério Nogueira, Valerio Romano, Manuel Ryser

Proceedings Volume 9893, 989303 (2016) https://doi.org/10.1117/12.2230681

KEYWORDS: Fiber amplifiers, Fiber Bragg gratings, Optical amplifiers, Oscillators, Fiber lasers, Absorption, Second-harmonic generation, Lawrencium, Temperature metrology, Laser crystals, Zoom lenses

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Proceedings Article | 27 April 2016 Paper

Two-dimensional refractive index profiling of optical fibers by modified refractive near-field technique

A. El Sayed, Soenke Pilz, Manuel Ryser, Valerio Romano

Proceedings Volume 9886, 98861N (2016) https://doi.org/10.1117/12.2229618

KEYWORDS: Refractive index, Optical fibers, Near field, Calibration, Imaging systems, Objectives, CCD cameras, Spatial resolution, Profiling, Dispersion, Nanolithography, Waveguides, Refraction

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Proceedings Article | 27 April 2016 Paper

Progress in the fabrication of optical fibers by the sol-gel-based granulated silica method

S. Pilz, H. Najafi, A. El Sayed, J. Boas, D. Kummer, J. Scheuner, D. Etissa, M. Ryser, P. Raisin, S. Berger, V. Romano

Proceedings Volume 9886, 988614 (2016) https://doi.org/10.1117/12.2227569

KEYWORDS: Silica, Sol-gels, Refractive index, Active optics, Aluminum, Scanning transmission electron microscopy, Fabrication, Optical fibers, Ytterbium, Glasses, Optical fibers, Ytterbium, Cladding, Chemical elements

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Proceedings Article | 24 February 2016 Paper

Two-dimensional refractive index profiling of optical fibers by modified refractive near-field technique

A. El Sayed, Soenke Pilz, Manuel Ryser, Valerio Romano

Proceedings Volume 9744, 97440N (2016) https://doi.org/10.1117/12.2211002

KEYWORDS: Refractive index, Optical fibers, Near field, Imaging systems, Objectives, CCD cameras, Spatial resolution, Profiling, Dispersion, Waveguides, Calibration, Nanolithography, Refraction

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Proceedings Article | 7 May 2015 Paper

High-precision confocal reflection measurement for two dimensional refractive index mapping of optical fibers

Philippe Raisin, Jonas Scheuner, Valerio Romano, Manuel Ryser

Proceedings Volume 9507, 95070O (2015) https://doi.org/10.1117/12.2180988

KEYWORDS: Refractive index, Confocal microscopy, Calibration, Cladding, Microscopes, Optical fibers, Collimators, Sensors, Light, Reliability

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Proceedings Article | 4 March 2015 Paper

Yellow laser light generation by frequency doubling of the output from a master oscillator fiber power amplifier system

Manuel Ryser, Carlos Marques, Rogério Nogueira, Valerio Romano

Proceedings Volume 9344, 934410 (2015) https://doi.org/10.1117/12.2080203

KEYWORDS: Second-harmonic generation, Optical fibers, Fiber Bragg gratings, Optical amplifiers, Optical filters, Crystals, Electronic filtering, Amplifiers, Fiber lasers, Oscillators

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Proceedings Article | 26 April 2012 Paper

Rare earth doped optical fiber fabrication by standard and sol-gel derived granulated oxides

D. Etissa, M. Neff, S. Pilz, M. Ryser, V. Romano

Proceedings Volume 8426, 84261I (2012) https://doi.org/10.1117/12.922629

KEYWORDS: Sol-gels, Silica, Ytterbium, Optical fibers, Scattering, Oxides, Glasses, Crystals, Refractive index, X-ray diffraction

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Proceedings Article | 16 February 2012 Paper

Gain-switched laser diode seeded Yb-doped fiber amplifier delivering 11-ps pulses at repetition rates up to 40-MHz

Manuel Ryser, Martin Neff, Soenke Pilz, Andreas Burn, Valerio Romano

Proceedings Volume 8237, 82373I (2012) https://doi.org/10.1117/12.908045

KEYWORDS: Semiconductor lasers, Picosecond phenomena, Polarization, Fiber amplifiers, Diodes, Fiber couplers, Cladding, Ytterbium, Polarizers, Wavelength division multiplexing

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Showing 5 of 12 publications

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