Friendsville, PA, United States
Friendsville, PA, United States

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In part I of this paper, and to set the foundation for this part II, we derived the resonator equations describing the normalized intensities, output power, gain, and extraction efficiency for a standard resonator incorporating two dielectric mirrors and a gain element. We then generalized the results to include an absorbing region representing a second laser crystal characterized by a small-signal transmission T0. Explicit expressions were found for the output power extracted into absorption by the second laser crystal and the extraction efficiency, and the limits to each were discussed. It was shown that efficient absorption by a thin or dilute second laser crystal can be realized in resonators in which the mirror reflectivities were high and in which the single-pass absorption was low, due to the finite photon lifetime and multi-passing of the absorbing laser element. In this paper, we apply the model derived in part I to thin or dilute laser materials, concentrating on a Yb, Er:glass intracavity pumped by a 946nm Nd:YAG laser, a Yb, Er:glass laser-pumped intracavity by a 977nm diode laser, and an Er:YAG laser-pumped intracavity to a 1530nm diode laser. It is shown that efficient absorption can be obtained in all cases examined. © 2014 Astro Ltd.


Brown D.C.,Snake Creek Lasers, LLC | Singley J.M.,Snake Creek Lasers, LLC | Kowalewski K.,Snake Creek Lasers, LLC | Guelzow J.,Snake Creek Lasers, LLC | Vitali V.,Snake Creek Lasers, LLC
Optics Express | Year: 2010

We report what we believe to be record performance for a high average power Yb:YAG cryogenic laser system with sustained output power. In a CW oscillator-single-pass amplifier configuration, 963 W of output power was measured. In a second configuration, a two amplifier Yb:YAG cryogenic system was driven with a fiber laser picosecond ultrafast oscillator at a 50 MHz repetition rate, double-passed through the first amplifier and single-passed through the second, resulting in 758 W of average power output. Pulses exiting the system have a FWHM pulsewidth of 12.4 ps, an energy/pulse of 15.2 μJ, and a peak power of 1.23 MW. Both systems are force convection-cooled with liquid nitrogen and have been demonstrated to run reliably over long time periods. © 2010 Optical Society of America.


Brown D.C.,Snake Creek Lasers, LLC | Vitali V.A.,Snake Creek Lasers, LLC
IEEE Journal of Quantum Electronics | Year: 2011

We develop a detailed kinetics model for Yb:YAG operating at any temperature and derive expressions for the heat, fluorescence, and lasing power densities and fractions, using a theoretical framework that includes conservation of ions (and power), saturation of the laser and pump beams, and a description of Boltzmann heating and cooling in the upper laser manifold. In addition, we introduce an equation that allows the fluorescence and lasing fractions and power densities to be easily calculated for any value of the extraction efficiency. The model is applied to Yb:YAG lasers operating at 295 and 77 K. We find that the heat fractions at room temperature for no lasing and for complete laser saturation are significantly less than those previously reported, while at 77 K the heat fractions are larger than at room temperature and close to previously reported values. We show, for the first time to our knowledge, that the heat fraction is not constant but varies significantly in the radial direction, leading to a radially dependent phase distortion. © 2010 IEEE.


Brown D.C.,Snake Creek Lasers, LLC | Bruno T.M.,Snake Creek Lasers, LLC | Singley J.M.,Snake Creek Lasers, LLC
Optics Express | Year: 2010

We report the demonstration of a heat-fraction-limited CW Yb:YAG laser operating near 77 K with output at 1029 nm, pumped with a diffraction-limited room-temperature CW Nd:YAG laser operating at 946 nm. With a 50% reflectivity outcoupler, the average threshold absorbed pump power was 18.8 mW and the average slope efficiency 91.9%, close to the heat-fraction limited value of 91.5%. Average optical to optical and photon slope efficiencies are 84% and 100% respectively. To the best of our knowledge this solid-state laser is the first to operate at the heat-fraction-limit and demonstrates record slope, photon slope and optical-optical efficiencies for optically-pumped solid-state lasers. © 2010 Optical Society of America.


Kowalewski K.,Snake Creek Lasers, LLC | Zembek J.,Snake Creek Lasers, LLC | Envid V.,Snake Creek Lasers, LLC | Brown D.C.,Snake Creek Lasers, LLC
Optics Letters | Year: 2012

We have generated 201 W of green (514.5 nm) average power from a frequency-doubled picosecond cryogenic Yb:YAG laser system driven by a 50 MHz, 12.4 ps mode-locked Yb fiber laser producing 430 W of average power at 1029 nm, using direct pulse amplification. The fundamental beam produced was near-diffraction-limited (M2 ≤ 1.3). Second-harmonic-generation is achieved using a 20 mm long noncritically phase-matched Lithium triborate (LiB3O5) crystal; conversion efficiencies as high as 58% have been observed. At 100 W of 514.5 nm output power, the average M2 value was 1.35. To the best of our knowledge, this is the highest average power picosecond green pulsed laser. © 2012 Optical Society of America.


Brown D.C.,Snake Creek Lasers, LLC
IEEE Journal of Quantum Electronics | Year: 2012

This paper is the first of a two-part manuscript whose overall objective is to present a unified mathematical kinetics model of four-level laser systems solidly anchored to known physics, optics, and materials considerations, but ultimately viewed from an engineering systems perspective, and with power conservation obeyed throughout. This paper provides the basis for Part II, which couples this kinetics model with a treatment of solid-state laser amplifiers and oscillators, leading to the presentation of a new laser engineering systems model. © 1965-2012 IEEE.


Brown D.C.,Snake Creek Lasers, LLC
IEEE Journal of Quantum Electronics | Year: 2012

In this paper, the second of a two-part manuscript, we extend the comprehensive kinetics model of Part I to treat four-level solid-state amplifiers and resonators, followed by the presentation of a detailed systems model that preserves power conservation throughout. We believe that this laser systems model is the first to allow an end to end description of the power flow in a solid-state laser while maintaining power conservation, can easily be extended to include quasi-three-level and other laser kinetics schemes, and will provide a very useful tool to physicists and engineers engaged in the design and optimization of solid-state laser systems. © 2012 IEEE.


Assad M.E.H.,Aalto University | Brown D.C.,Advanced Laser Systems | Brown D.C.,Snake Creek Lasers, LLC
IEEE Journal of Quantum Electronics | Year: 2013

In this paper, the temperature distribution is derived analytically within a fiber laser end pumped by a top-hat beam subjected to an external convection at the cladding surface. The temperature distribution is obtained through considering the radial heat conduction and neglecting the axial heat conduction due to large aspect ratio. An expression for the volumetric entropy generation rate within the fiber laser is also derived, which is directly proportional to the temperature gradients and inversely proportional to the temperature. Based on the temperature distribution, the maximum pump power is obtained just before the thermal damage. The temperature distribution is compared with 2-D temperature distribution and the results are in good agreement. The effect of laser absorption coefficient and Biot number on the temperature and volumetric entropy generation rate are presented graphically. The results show that volumetric entropy generation rate decreases as the Biot number decreases because of lower temperature gradients at the cladding surface. The volumetric rate is always maximum at the fiber core and cladding interface. The results are presented in dimensionless form, so that they can be applied to any end-pumped laser rod, crystalline or glassy. © 2012 IEEE.


Grant
Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 150.00K | Year: 2011

This Proposal addresses the need for high average power (HAP), near-diffraction-limited laser sources for laser stripping applications, an important process for going forward with plans to build an 8 GeV H- to proton injector source for driving upgraded Fermi National Accelerator Laboratory proton accelerators. The overall objective of the proposed program is to apply high average power ultrafast cryogenic laser technology developed by Snake Creek Lasers to demonstrate efficient high average power laser sources with excellent beam-quality for laser stripping applications. Commercial Applications and Other Benefits: Laser technology developed under this proposed program will have applications in national laboratories for laser stripping and photocathode illumination, and in the commercial sector for laser texturing, selective ablation, wrap-through, and other micromachining applications to the photovoltaic and semiconductor industries. The high efficiency and average power available from cryogenic lasers will significantly increase process throughput and reduce carbon emissions


Grant
Agency: Department of Defense | Branch: Office for Chemical and Biological Defense | Program: SBIR | Phase: Phase I | Award Amount: 100.00K | Year: 2011

This topic addresses the need for compact efficient solid-state deep ultraviolet (UV) lasers operating in the wavelength range of 220-250 nm, for use in Raman systems for chemical and biological detection. The laser to be developed would also be very useful in the detection of explosives. We propose to develop an efficient 946 Q-switched nm laser system that is efficiently quadrupled to 236.5 nm. The laser system will produce excellent beam-quality and high pulse energy. It will operate single longitudinal and transverse mode. During Phase I we will generate a detailed design for the compact deep UV laser, complete experimental testing of candidate nonlinear crystals to be used for deep UV generation using existing high power lasers, generate detailed engineering device drawings for a Phase II demonstration, and develop a technology roadmap leading to a compact, efficient deep UV laser system with a volume of<1800 in3 and a weight<25 pounds. In the Phase I option we propose to demonstrate an integrated long-pulse Q-switched Nd:YAG laser that operates in both single longitudinal and transverse modes.

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