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Boulder, CO, United States

Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 988.75K | Year: 2014

Currently, the most successful approach for table-top soft X-ray and EUV (Extreme Ultra-Violet ) sources is that of High Harmonic Generation (HHG), where high intensity pulses are used to drive frequency conversion from a noble gas. This configuration converts the infrared drive laser to photon energies beyond 1.6keV (x-rays). This approach requires extremely short pulses and typically uses Ti:sapphire lasers. These lasers, however, suffer from reliability and stability issues due in large part to their reliance on complex and unreliable green (532nm) pump lasers. This work will address that problem by proving the viability of direct diode pumping for Ti:sapphire amplifiers. Direct diode pumping is widely recognized for reliability in the larger, industrial markets addressed by Yb-doped laser systems but has not been developed for Ti:sapphire. Recently, KMLabs, along with collaborators at the Colorado School of Mines, was successful in demonstrating the worlds first Kerr lens modelocked ultrafast oscillator using 445nm high power blue diodes and ushering in a new era for Ti:sapphire systems. The promise of direct diode pumping is a 5X-10X reduction in pump laser cost and a corresponding increase in reliability. In this Phase II, we will to take the next step in furthering this research to include an amplifier based on direct diode pumping of Ti:sapphire, with an objective of eventually converting the output to the EUV through HHG for BES applications within the DOE. In phase I of this work, we developed a pump module for an ultrafast Ti:sapphire laser oscillator, and demonstrated direct diode pumping of that laser up to powers & gt;300mW. We showed the feasibility of extending this technology to an ultrafast Ti:sapphire amplifier system. In Phase II of this program, we will investigate the details of further amplifying our direct diode pumped Ti:sapphire oscillator up to levels capable of HHG using direct diode pumping of an amplifier also. We will use our patented cryogenic amplifier technology to run this system at high average powers. Commercial Applications and Other Benefits: Traditional Ti:sapphire markets such as 2-photon microscopy, bio-imaging, and OCT continue to grow, but that expansion could be much larger with cost reductions and reliability improvements. Additionally, industries that have relied on Yb based systems (delivering 300-500fs pulse widths) due to the cost and complexity of Ti:sapphire systems (micromachining, ophthalmology, bio-medical), could benefit from the shorter Ti:sapphire pulses. This program seeks to eliminate the cost and reliability issue while enabling very short pulses (20-30 fs) for existing applications, as well as to open new markets for Ti:sapphire lasers.

Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 994.80K | Year: 2015

Coherent diffraction imaging (CDI) for short-wavelength imaging has proven revolutionary, allowing for the first time imaging with high numerical aperture and simultaneous phase- and amplitude-contrast. This development has created high commercial interest from the semiconductor and bio-medical industry as well as nano-science. Coherent extreme ultraviolet (EUV) and soft X-ray light sources are the front end of this technology and will be key to CDIs wide application. High order harmonic generation (HHG) is the most promising and feasible source for this application. In this proposal, we will develop an HHG based EUV and soft X-ray beamline to accompany an HHG source. . This beamline can be the front end of the future commercial EUV microscope. this phase IIb, we will build upon our current modularized monochromatic and tunable EUV beamline developed in the phase II program. Our approach is to improve the stability and reliability of the EUV source, and upgrade all beamline modules. For the CDI application, we will focus on optimizing a few key modules for the beamline to meet the key specifications. A soft X-ray version of the beamline will also be developed. Finally, both beamlines will be tested using CDI imaging. Commercial Applications and Other Benefits: A tunable monochromatic beamline at EUV or soft X-ray wavelengths itself is a state-of-the-art light source for nano-technology and material science. A premier application where an EUV source plus tunable EUV monochromator can lead to transformative research is in CDI, as mentioned above. CDI using soft X-ray HHG can be a powerful tool to image cells and nanostructures with < 5nm spatial resolution, and to capture the fastest nanoscale dynamics in materials systems with elemental, chemical, and spin sensitivity.

Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 149.60K | Year: 2015

Our approach is to use DUV/VUV laser light to create the metastable Krypton used for dating ground water. The current arc method used leads to contamination of the electrodes, and therefore a lengthy cleaning process before another sample can be analyzed. In this work we propose to use single or multi-photon excitation through DUV/VUV laser systems which eliminated the need for arc discharge, and has the added benefit of efficiently promoting Krypton to its metastable level. In this project, we propose to develop a high repetition rate, DUV/VUV ultrafast source for creating metastable Krypton for dating ground water. Currently, there are no commercial or scientific sources with the combination of high 100kHz 1MHz) repetition rates, and nJ pulse energy in the DUV/VUV, with < 200fs pulses, but there is intense interest in this type of laser to create metastable Krypton through single and multi-photon excitation. This will greatly enhance accurate dating of ground water. This process will increase accuracy and throughput of ground water samples. Other benefits include ARPES Angle Resolved Photoemission Spectroscopy), chemical spectroscopies, as well as semicon fab. Many groups currently using eximer, and Ti:sapphire lasers and amplifiers for generating VUV could benefit greatly from the reduced complexity, reduced cost, and higher power from the laser system we will design. This system will be a large improvement over currently available ultrafast laser sources.

Statement of the problem or situation that is being addressed: In this project, we propose to develop waveguides specific to high harmonic generation, that are more efficient than standard HHG waveguides, can handle pressures in excess of > 30 bar, minimize losses for wavelengths > 1 m, and can be manufactured with ultrafast micromachining. Current waveguides using hollow core fused silica are a great way to engineer the output from ultrafast HHG. However, the transmission of these waveguides depends heavily on Fresnel reflections at the interior surface. This leads to a decrease in transmission which goes as the cube of the diameter, and longer wavelengths will experience massive losses. In addition, at pressures much higher than 30 bar (required for phase matching at longer wavelengths) fused silica may not have the required tensile strength, which can lead to fiber detonation. This impacts laser seed sources for the next generation seeded XFELs (X-Ray Free Electron Laser). Statement of how this Problem or Situation is being addressed: Our approach is to use femtosecond micromachining to cut waveguide structures into harder materials such as metals, sapphire, and diamond for an increase in transmission (this method allows easy interior coatings for the drive laser), safety, and thermal handling. It will also simplify the method of injecting the high pressure gas for the X-Ray generation, and allow differential pumping schemes to avoid absorption of the resultant X-Ray laser beam output. Commercial Applications and Other Benefits: The applications are, specifically, enhancements to high repetition rate X-Ray lasers, Waveguide laser accelerators, semiconductor fab, and seeding of XFEL light sources. Scientific applications would include new table top sources for medical imaging, spectroscopy, and biochemistry. Key Words: X-Ray, Ultrafast, High harmonic Generation, EUV, Laser Summary for Members of Congress: We propose to develop technology critical to next generation table top X-Ray laser sources, which can be used in next generation light sources. These laser systems have applicability in medical imaging, semiconductor fab metrology, and research tools for universities and national laboratories. This work would enhance the capabilities of currently operating light sources, and would allow studies of chemical and biological systems on the molecular level, and would be capable of producing extremely short pulses at X-Ray wavelengths useful for time-resolved spectroscopy and imaging on the nanoscale.

Agency: NSF | Branch: Fixed Price Award | Program: | Phase: ENGINEERING RESEARCH CENTERS | Award Amount: 199.94K | Year: 2014


In this project, KMlabs will work with the currently active ERC in EUV Science and Technology
in an effort to optimize and commercialize a tabletop coherent extreme ultraviolet source
based on high-order harmonic generation (HHG), targeted specifically for 13.5 nm wavelength.
The end goal of this project is to produce a commercial prototype that can produce efficient
13.5 nm light to support EUV lithography tool development. Such a small-scale laser source
can be used for a variety of lithography support applications including optics characterization,
metrology, and mask inspection, which can help to ensure the rapid deployment of this critical
technology, currently planned for ~2015.

Intellectual Merit :
CU-Boulder, as a part of the EUV ERC, has been developing coherent EUV technology for more
than a decade. Their recent work has led to a more comprehensive understanding of how to optimize
the HHG upconversion process to generate EUV or x-ray light at a particular target wavelength.
This for the first time allows us to identify specific approaches that may allow for significant
(up to 3 orders of magnitude) increases in coherent flux capability at 13 nm.
KMlabs has proven track of record for successfully commercializing cutting edge scientific
results?for example the eXtreme Ultraviolet Ultrafast Source (XUUS), introduced in 2009. The
XUUS is a broadband coherent ultrafast EUV source optimized to generate 30 nm light, and >15
XUUS setups have been delivered to research customers worldwide. Optimization of this source
for 13 nm will make it possible to address a much greater range of industry needs. We have
identified three possible approaches for optimizing 13 nm flux. In this project we plan to
perform a direct comparative evaluation of these approaches. Based on our physical understanding,
we believe we can determine the global optimum for HHG conversion to 13 nm.

Broader Impacts :
KMlabs and the EUV ERC will each leverage their technical strengths, and this project will
serve to leverage the impact of EUV ERC technology on the science and technology enterprise.
The rapid advance of microelectronics technology, as described by Moore?s law, has been a
major driver of the global economy. This advance has been driven primarily by progress in
lithography that allows for shrinking feature size. Current visible wavelength tools are straining
against fundamental limits, and the International Technology Roadmap for Semiconductors has
been anticipated a shift to EUV lithography for quite some time. The timeline for EUV had
repeatedly experienced delays because the use of EUV light, which is strongly absorbed by
all materials, is radically more difficult to work with than visible/UV.
Nevertheless, recent progress in 13 nm EUV light sources for lithographic exposure has made
its adoption for the 22 nm node-size in the next generation computer chips a high priority.
EUV lithography remains untested at the systems and large-scale production level, with many
unknowns. Improved capabilities for mask defect detection and characterization, for characterizing
optics degradation with long-term use, and for tasks such as alignment and quality control,
can all benefit from a usable tabletop at-wavelength laser source. An HHG-based coherent 13
nm EUV light source is a relatively low cost, small-scale, contamination-free coherent source
suitable for industrial application, and which has already been proven to enable new capabilities
such as coherent diffractive EUV imaging with near-wavelength resolution, and for materials
characterization. KMlabs plans to build on this proposed work in future with development of
reflectometer/ellipsometer instruments, as well as an inspection microscope for EUV lithography

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