Henry Kapteyn - Academia.edu (original) (raw)
Papers by Henry Kapteyn
Optics and Photonics News, 2006
Optics express, Jan 13, 2012
We extend coherent diffraction imaging (CDI) to a high numerical aperture reflection mode geometr... more We extend coherent diffraction imaging (CDI) to a high numerical aperture reflection mode geometry for the first time. We derive a coordinate transform that allows us to rewrite the recorded far-field scatter pattern from a tilted object as a uniformly spaced Fourier transform. Using this approach, FFTs in standard iterative phase retrieval algorithms can be used to significantly speed up the image reconstruction times. Moreover, we avoid the isolated sample requirement by imaging a pinhole onto the specimen, in a technique termed apertured illumination CDI. By combining the new coordinate transformation with apertured illumination CDI, we demonstrate rapid high numerical aperture imaging of samples illuminated by visible laser light. Finally, we demonstrate future promise for this technique by using high harmonic beams for high numerical aperture reflection mode imaging.
Proceedings of LEOS '93
In conclusion, we have demonstrated a simple and reliable Ti:sapphire laser amplifier capable of ... more In conclusion, we have demonstrated a simple and reliable Ti:sapphire laser amplifier capable of generating pulses of unprecedented short duration. Our results confirm the fact that third-order dispersion is the primary factor limiting pulse duration in these lasers. Also, chirped-pulse amplification designs capable of propagating sub-2O fs pulses have been tested
Optics Express, 2012
We demonstrate a cryogenically cooled Ti:sapphire ultrafast regenerative amplifier laser system p... more We demonstrate a cryogenically cooled Ti:sapphire ultrafast regenerative amplifier laser system producing >20 µJ energies at 50 kHz, >12 µJ at 200 kHz and >3.5 µJ at 1MHz with repetition rates continuously tunable from 50 kHz up to 1.7 MHz in a footprint of only 60x180 cm 2. This laser uses down-chirped pulse amplification employing a grism stretcher and a glass-block compressor, achieving sub-60-fs pulse duration. This laser represents a several-times improvement in repetition-rate and average power over past Ti:sapphire-based ultrafast lasers in this class. We discuss the unique challenges and solutions for this laser system. This laser system has wide applications especially in ultrafast photoemission, nonlinear imaging and spectroscopy, as well as for micro/nano-machining and ultrafast laser therapy and surgery.
2013 Conference on Lasers & Electro-Optics Europe & International Quantum Electronics Conference CLEO EUROPE/IQEC, 2013
ABSTRACT form only given. The past three years in a row marked the 50th anniversaries of three si... more ABSTRACT form only given. The past three years in a row marked the 50th anniversaries of three significant innovations in optics: the invention of the laser; the discovery of the nonlinear upconversion of laser light in a spectral region where laser light has not been available; and the outlining of phase matching of this upconversion process - a recipe that makes the newly generated laser-like light bright and usable for applications. The same revolution that made it possible to create well directed beams in the visible region of the spectrum is only now happening for X-rays. Large-scale X-ray free electron lasers are promising to capture images of ultrafast dynamics in a single shot. An extreme version of nonlinear optics - high harmonic generation (HHG) - can also generate bright, coherent, beams of X-rays, with very short wavelengths <;7.7 angstroms, in a tabletop-scale setup for the first time [1]. This practically realizes a coherent version of the Roentgen X-ray tube in the soft X-ray region. Improved understanding of the microscopic quantum physics and macroscopic nonlinear optics of high harmonic generation [2-5], as well as the development of novel ultrafast mid-IR lasers [6] have lead to this rapid progress in the past few years, essentially solving the phase matching problem of HHG in the X-ray region. In addition, these kiloelectronvolt HHG X-rays have a supercontinuum structure with the broadest coherent bandwidth (>1.3 keV) that any light source, large or small scale, can generate to date. Such an ultrabroad spectral bandwidth can support X-ray pulses as short as 2.5 attoseconds and is scalable towards zeptosecond pulse durations. These unique, ultrafast, laser-like X-ray beams promise revolutionary new capabilities for understanding and controlling how the nanoworld works on its fundamental time and length scales. This understanding is relevant to the next generation data and energy storage devices, nano-electronics, bioimaging, and future me- ical diagnostics.
Conference on Lasers and Electro-Optics 2012, 2012
ABSTRACT Using a 3.9 μm driving laser focused into a high-pressure gas-filled waveguide, we gener... more ABSTRACT Using a 3.9 μm driving laser focused into a high-pressure gas-filled waveguide, we generate bright, phase matched, fully spatially coherent high harmonic beams in the keV region for the first time.
Conference on Lasers and Electro-Optics 2010, 2010
High-order harmonic generation (HHG) is a unique source of ultrafast, fully spatially coherent, s... more High-order harmonic generation (HHG) is a unique source of ultrafast, fully spatially coherent, soft x-ray beams with applications in ultrafast molecular and materials spectroscopy [1] as well as in high-resolution imaging [2]. Until recently, the useable region of the high ...
Ultrafast Pulse Generation and Spectroscopy, 1993
In this paper, we present results on the generation of 10.9 fs duration pulses directly from a se... more In this paper, we present results on the generation of 10.9 fs duration pulses directly from a self mode-locked Ti:Sapphire laser. Ultrashort-pulse operation of the laser was obtained by optimizing the intracavity dispersion compensation. A short, highly-doped Ti:Sapphire crystal and fused silica prism pair were used to achieve this. We also present preliminary results on frequency doubling of the 800
Short-Pulse High Intensity Lasers and Applications Ii, 1993
By optimizing the intracavity dispersion compensation in a self mode-locked Ti:sapphire laser, we... more By optimizing the intracavity dispersion compensation in a self mode-locked Ti:sapphire laser, we have generated pulses of less than 11 fs in duration. Dispersion within the laser cavity can be reduced by using a short highly-doped Ti:sapphire crystal and a prism glass which reduces third-order dispersion. Amplifier design which reduce third order dispersion have also been tested, and we have
Optics Express, 2004
We demonstrate a general procedure for varying the repetition rate of a modelocked Ti:sapphire la... more We demonstrate a general procedure for varying the repetition rate of a modelocked Ti:sapphire laser using an asymmetric focusing geometry. Using this procedure, we have made an extended length cavity with a repetition rate of 45 MHz, and a reduced length cavity with a repetition rate of 275 MHz, each of which generates sub-20 fs pulses. This procedure allows the repetition rate of the laser to be more precisely tailored for a variety of applications without compromise in performance.
Physical Review Letters, 2007
We present the first experimental demonstration of lensless diffractive imaging using coherent so... more We present the first experimental demonstration of lensless diffractive imaging using coherent soft x rays generated by a tabletop soft-x-ray source. A 29 nm high harmonic beam illuminates an object, and the subsequent diffraction is collected on an x-ray CCD camera. High dynamic range diffraction patterns are obtained by taking multiple exposures while blocking small-angle diffraction using beam blocks of varying size. These patterns reconstruct to images with 214 nm resolution. This work demonstrates a practical tabletop lensless microscope that promises to find applications in materials science, nanoscience, and biology.
We demonstrate a 60MHz, cryogenically cooled, mode-locked Yb:YAG oscillator with up to 12W averag... more We demonstrate a 60MHz, cryogenically cooled, mode-locked Yb:YAG oscillator with up to 12W average output power. Mode-locking is achieved via a SESAM, an intracavity SHG crystal, and an iris near focus for spatial mode filtering. OCIS codes: (140.3615) Lasers, ytterbium; (140.4050) Mode-locked lasers Cryogenically cooled laser media have a number of advantages over room temperature lasers, in particular for high- power operation. For example, Yb:YAG has a significantly higher emission cross section, increased thermal conductivity, and decreased dn/dT (1,2) compared with room temperature operation. Furthermore, while Yb:YAG is a quasi three-level system at room temperature due to thermal population of the lower laser level, below ~100K it becomes a true four-level laser system. The potential for high power pulses on the order of ten picoseconds make Yb:YAG a practical material for many OPCPA pump lasers. However, Yb:YAG is also very susceptible to self Q- switching and Q-switched mode-locking due to its long upper state lifetime (~1ms) (3). Prior to this work, the only reported cryogenically cooled, mode-locked Yb:YAG oscillator was limited to low output powers (pump power 1.2W) and a repetition rate of 21.1MHz (4). Here we demonstrate a cryogenically cooled, cw-modelocked Yb:YAG laser with high output power (up to 12W, limited by damage to the SESAM) running at 60MHz, with the output stabilized against self Q-switching through the use of an intracavity frequency doubling crystal, which forms an effective negative saturable absorber. The layout of the laser is shown in Fig.1.
Advanced Solid State Lasers, 2014
We present a multi-mJ, 1 kHz repetition-rate, mid-IR OPCPA laser, for soft x-ray high harmonic ge... more We present a multi-mJ, 1 kHz repetition-rate, mid-IR OPCPA laser, for soft x-ray high harmonic generation. To date we have demonstrated 2.7mJ at 1.6µm, and 1.1mJ at 3µm, with sufficient bandwidth in each to support <100fs compression.
CLEO: 2014, 2014
ABSTRACT We describe a kHz repetition-rate mid-IR laser system based on OPCPA, optimized for soft... more ABSTRACT We describe a kHz repetition-rate mid-IR laser system based on OPCPA, optimized for soft x-ray high harmonic generation. To date we have demonstrated 1.4mJ at 1.6µm, and 550µJ at 3µm, each with bandwidth compressible to <100fs.
Metrology, Inspection, and Process Control for Microlithography XXIII, 2009
We demonstrate lensless diffractive microscopy using a tabletop source of extreme ultraviolet (EU... more We demonstrate lensless diffractive microscopy using a tabletop source of extreme ultraviolet (EUV) light from high harmonic generation at 29 nm and 13.5 nm. High harmonic generation has been shown to produce fully spatially coherent EUV light when the conversion process is well phase-matched in a hollow-core waveguide. We use this spatial coherence for two related diffractive imaging techniques which circumvent the need for lossy imaging optics in the EUV region of the spectrum. Holography with a reference beam gives sub-100 nm resolution in short exposure times with fast image retrieval. Application of the Guided Hybrid Input-Output phase retrieval algorithm refines the image resolution to 53 nm with 29 nm light. Initial images using the technologically important 13.5 nm wavelength give 92nm resolution in a 10-minute exposure. Straightforward extensions of this work should also allow near-wavelength resolution with the 13.5 nm source. Diffractive imaging techniques provide eased alignment and focusing requirements as compared with zone plate or multilayer mirror imaging systems. The short-pulsed nature of the extreme ultraviolet source will allow pump-probe imaging of materials dynamics with time resolutions down to the pulse duration of the EUV.
Imaging and Applied Optics 2014, 2014
ABSTRACT I will present work on hybrid fiber/bulk systems employing non-linear amplifiers to reac... more ABSTRACT I will present work on hybrid fiber/bulk systems employing non-linear amplifiers to reach near and mid-IR wavelengths to obtain high peak and average powers, with <100 femtosecond pulse durations. These systems have a wide range of uses from biotech imaging techniques, hard X-ray generation, and industrial/medical micromachining. I will illustrate our specific designs for pushing the limits on femtosecond fiber laser technology, mating it with solid state lasers, and extending these systems to meet the needs of cutting edge science.
CLEO: 2013, 2013
ABSTRACT We demonstrate bright high harmonic generation driven by UV lasers with ultra-high conve... more ABSTRACT We demonstrate bright high harmonic generation driven by UV lasers with ultra-high conversion efficiency approaching 10^-3 and ultra-narrow single-harmonic bandwidth of ~0.2%. The enhanced flux results from improved phase-matching combined with a stronger single-atom yield.
Optics and Photonics News, 2006
Optics express, Jan 13, 2012
We extend coherent diffraction imaging (CDI) to a high numerical aperture reflection mode geometr... more We extend coherent diffraction imaging (CDI) to a high numerical aperture reflection mode geometry for the first time. We derive a coordinate transform that allows us to rewrite the recorded far-field scatter pattern from a tilted object as a uniformly spaced Fourier transform. Using this approach, FFTs in standard iterative phase retrieval algorithms can be used to significantly speed up the image reconstruction times. Moreover, we avoid the isolated sample requirement by imaging a pinhole onto the specimen, in a technique termed apertured illumination CDI. By combining the new coordinate transformation with apertured illumination CDI, we demonstrate rapid high numerical aperture imaging of samples illuminated by visible laser light. Finally, we demonstrate future promise for this technique by using high harmonic beams for high numerical aperture reflection mode imaging.
Proceedings of LEOS '93
In conclusion, we have demonstrated a simple and reliable Ti:sapphire laser amplifier capable of ... more In conclusion, we have demonstrated a simple and reliable Ti:sapphire laser amplifier capable of generating pulses of unprecedented short duration. Our results confirm the fact that third-order dispersion is the primary factor limiting pulse duration in these lasers. Also, chirped-pulse amplification designs capable of propagating sub-2O fs pulses have been tested
Optics Express, 2012
We demonstrate a cryogenically cooled Ti:sapphire ultrafast regenerative amplifier laser system p... more We demonstrate a cryogenically cooled Ti:sapphire ultrafast regenerative amplifier laser system producing >20 µJ energies at 50 kHz, >12 µJ at 200 kHz and >3.5 µJ at 1MHz with repetition rates continuously tunable from 50 kHz up to 1.7 MHz in a footprint of only 60x180 cm 2. This laser uses down-chirped pulse amplification employing a grism stretcher and a glass-block compressor, achieving sub-60-fs pulse duration. This laser represents a several-times improvement in repetition-rate and average power over past Ti:sapphire-based ultrafast lasers in this class. We discuss the unique challenges and solutions for this laser system. This laser system has wide applications especially in ultrafast photoemission, nonlinear imaging and spectroscopy, as well as for micro/nano-machining and ultrafast laser therapy and surgery.
2013 Conference on Lasers & Electro-Optics Europe & International Quantum Electronics Conference CLEO EUROPE/IQEC, 2013
ABSTRACT form only given. The past three years in a row marked the 50th anniversaries of three si... more ABSTRACT form only given. The past three years in a row marked the 50th anniversaries of three significant innovations in optics: the invention of the laser; the discovery of the nonlinear upconversion of laser light in a spectral region where laser light has not been available; and the outlining of phase matching of this upconversion process - a recipe that makes the newly generated laser-like light bright and usable for applications. The same revolution that made it possible to create well directed beams in the visible region of the spectrum is only now happening for X-rays. Large-scale X-ray free electron lasers are promising to capture images of ultrafast dynamics in a single shot. An extreme version of nonlinear optics - high harmonic generation (HHG) - can also generate bright, coherent, beams of X-rays, with very short wavelengths <;7.7 angstroms, in a tabletop-scale setup for the first time [1]. This practically realizes a coherent version of the Roentgen X-ray tube in the soft X-ray region. Improved understanding of the microscopic quantum physics and macroscopic nonlinear optics of high harmonic generation [2-5], as well as the development of novel ultrafast mid-IR lasers [6] have lead to this rapid progress in the past few years, essentially solving the phase matching problem of HHG in the X-ray region. In addition, these kiloelectronvolt HHG X-rays have a supercontinuum structure with the broadest coherent bandwidth (>1.3 keV) that any light source, large or small scale, can generate to date. Such an ultrabroad spectral bandwidth can support X-ray pulses as short as 2.5 attoseconds and is scalable towards zeptosecond pulse durations. These unique, ultrafast, laser-like X-ray beams promise revolutionary new capabilities for understanding and controlling how the nanoworld works on its fundamental time and length scales. This understanding is relevant to the next generation data and energy storage devices, nano-electronics, bioimaging, and future me- ical diagnostics.
Conference on Lasers and Electro-Optics 2012, 2012
ABSTRACT Using a 3.9 μm driving laser focused into a high-pressure gas-filled waveguide, we gener... more ABSTRACT Using a 3.9 μm driving laser focused into a high-pressure gas-filled waveguide, we generate bright, phase matched, fully spatially coherent high harmonic beams in the keV region for the first time.
Conference on Lasers and Electro-Optics 2010, 2010
High-order harmonic generation (HHG) is a unique source of ultrafast, fully spatially coherent, s... more High-order harmonic generation (HHG) is a unique source of ultrafast, fully spatially coherent, soft x-ray beams with applications in ultrafast molecular and materials spectroscopy [1] as well as in high-resolution imaging [2]. Until recently, the useable region of the high ...
Ultrafast Pulse Generation and Spectroscopy, 1993
In this paper, we present results on the generation of 10.9 fs duration pulses directly from a se... more In this paper, we present results on the generation of 10.9 fs duration pulses directly from a self mode-locked Ti:Sapphire laser. Ultrashort-pulse operation of the laser was obtained by optimizing the intracavity dispersion compensation. A short, highly-doped Ti:Sapphire crystal and fused silica prism pair were used to achieve this. We also present preliminary results on frequency doubling of the 800
Short-Pulse High Intensity Lasers and Applications Ii, 1993
By optimizing the intracavity dispersion compensation in a self mode-locked Ti:sapphire laser, we... more By optimizing the intracavity dispersion compensation in a self mode-locked Ti:sapphire laser, we have generated pulses of less than 11 fs in duration. Dispersion within the laser cavity can be reduced by using a short highly-doped Ti:sapphire crystal and a prism glass which reduces third-order dispersion. Amplifier design which reduce third order dispersion have also been tested, and we have
Optics Express, 2004
We demonstrate a general procedure for varying the repetition rate of a modelocked Ti:sapphire la... more We demonstrate a general procedure for varying the repetition rate of a modelocked Ti:sapphire laser using an asymmetric focusing geometry. Using this procedure, we have made an extended length cavity with a repetition rate of 45 MHz, and a reduced length cavity with a repetition rate of 275 MHz, each of which generates sub-20 fs pulses. This procedure allows the repetition rate of the laser to be more precisely tailored for a variety of applications without compromise in performance.
Physical Review Letters, 2007
We present the first experimental demonstration of lensless diffractive imaging using coherent so... more We present the first experimental demonstration of lensless diffractive imaging using coherent soft x rays generated by a tabletop soft-x-ray source. A 29 nm high harmonic beam illuminates an object, and the subsequent diffraction is collected on an x-ray CCD camera. High dynamic range diffraction patterns are obtained by taking multiple exposures while blocking small-angle diffraction using beam blocks of varying size. These patterns reconstruct to images with 214 nm resolution. This work demonstrates a practical tabletop lensless microscope that promises to find applications in materials science, nanoscience, and biology.
We demonstrate a 60MHz, cryogenically cooled, mode-locked Yb:YAG oscillator with up to 12W averag... more We demonstrate a 60MHz, cryogenically cooled, mode-locked Yb:YAG oscillator with up to 12W average output power. Mode-locking is achieved via a SESAM, an intracavity SHG crystal, and an iris near focus for spatial mode filtering. OCIS codes: (140.3615) Lasers, ytterbium; (140.4050) Mode-locked lasers Cryogenically cooled laser media have a number of advantages over room temperature lasers, in particular for high- power operation. For example, Yb:YAG has a significantly higher emission cross section, increased thermal conductivity, and decreased dn/dT (1,2) compared with room temperature operation. Furthermore, while Yb:YAG is a quasi three-level system at room temperature due to thermal population of the lower laser level, below ~100K it becomes a true four-level laser system. The potential for high power pulses on the order of ten picoseconds make Yb:YAG a practical material for many OPCPA pump lasers. However, Yb:YAG is also very susceptible to self Q- switching and Q-switched mode-locking due to its long upper state lifetime (~1ms) (3). Prior to this work, the only reported cryogenically cooled, mode-locked Yb:YAG oscillator was limited to low output powers (pump power 1.2W) and a repetition rate of 21.1MHz (4). Here we demonstrate a cryogenically cooled, cw-modelocked Yb:YAG laser with high output power (up to 12W, limited by damage to the SESAM) running at 60MHz, with the output stabilized against self Q-switching through the use of an intracavity frequency doubling crystal, which forms an effective negative saturable absorber. The layout of the laser is shown in Fig.1.
Advanced Solid State Lasers, 2014
We present a multi-mJ, 1 kHz repetition-rate, mid-IR OPCPA laser, for soft x-ray high harmonic ge... more We present a multi-mJ, 1 kHz repetition-rate, mid-IR OPCPA laser, for soft x-ray high harmonic generation. To date we have demonstrated 2.7mJ at 1.6µm, and 1.1mJ at 3µm, with sufficient bandwidth in each to support <100fs compression.
CLEO: 2014, 2014
ABSTRACT We describe a kHz repetition-rate mid-IR laser system based on OPCPA, optimized for soft... more ABSTRACT We describe a kHz repetition-rate mid-IR laser system based on OPCPA, optimized for soft x-ray high harmonic generation. To date we have demonstrated 1.4mJ at 1.6µm, and 550µJ at 3µm, each with bandwidth compressible to <100fs.
Metrology, Inspection, and Process Control for Microlithography XXIII, 2009
We demonstrate lensless diffractive microscopy using a tabletop source of extreme ultraviolet (EU... more We demonstrate lensless diffractive microscopy using a tabletop source of extreme ultraviolet (EUV) light from high harmonic generation at 29 nm and 13.5 nm. High harmonic generation has been shown to produce fully spatially coherent EUV light when the conversion process is well phase-matched in a hollow-core waveguide. We use this spatial coherence for two related diffractive imaging techniques which circumvent the need for lossy imaging optics in the EUV region of the spectrum. Holography with a reference beam gives sub-100 nm resolution in short exposure times with fast image retrieval. Application of the Guided Hybrid Input-Output phase retrieval algorithm refines the image resolution to 53 nm with 29 nm light. Initial images using the technologically important 13.5 nm wavelength give 92nm resolution in a 10-minute exposure. Straightforward extensions of this work should also allow near-wavelength resolution with the 13.5 nm source. Diffractive imaging techniques provide eased alignment and focusing requirements as compared with zone plate or multilayer mirror imaging systems. The short-pulsed nature of the extreme ultraviolet source will allow pump-probe imaging of materials dynamics with time resolutions down to the pulse duration of the EUV.
Imaging and Applied Optics 2014, 2014
ABSTRACT I will present work on hybrid fiber/bulk systems employing non-linear amplifiers to reac... more ABSTRACT I will present work on hybrid fiber/bulk systems employing non-linear amplifiers to reach near and mid-IR wavelengths to obtain high peak and average powers, with <100 femtosecond pulse durations. These systems have a wide range of uses from biotech imaging techniques, hard X-ray generation, and industrial/medical micromachining. I will illustrate our specific designs for pushing the limits on femtosecond fiber laser technology, mating it with solid state lasers, and extending these systems to meet the needs of cutting edge science.
CLEO: 2013, 2013
ABSTRACT We demonstrate bright high harmonic generation driven by UV lasers with ultra-high conve... more ABSTRACT We demonstrate bright high harmonic generation driven by UV lasers with ultra-high conversion efficiency approaching 10^-3 and ultra-narrow single-harmonic bandwidth of ~0.2%. The enhanced flux results from improved phase-matching combined with a stronger single-atom yield.