Publications

Kliner, Dahv A.V.

Abstract not provided.

Proceedings of SPIE - The International Society for Optical Engineering

Hoops, Alexandra A.; Farrow, Roger L.; Schulz, Paul; Reichardt, Thomas A.; Bambha, Ray B.; Schmitt, Randal L.; Kliner, Dahv A.V.

Recent EPA regulations targeting mercury (Hg) emissions from utility coal boilers have prompted increased activity in the development of reliable chemical sensors for monitoring Hg emissions with high sensitivity, high specificity, and fast time response. We are developing a portable, laser-based instrument for real-time, stand-off detection of Hg emissions that involves exciting the Hg (6 3P1 ← 6 1S0) transition at 253.7 nm and detecting the resulting resonant emission from Hg (6 3P1). The laser for this approach must be tunable over the Hg absorption line at 253.7 nm, while system performance modeling has indicated a desired output pulse energy ≥0.1 μJ and linewidth ≤5 GHz (full width at half-maximum, FWHM). In addition, the laser must have the requisite physical characteristics for use in coal-fired power plants. To meet these criteria, we are pursing a multistage frequency-conversion scheme involving an optical parametric amplifier (OPA). The OPA is pumped by the frequency-doubled output of a passively Q-switched, monolithic Nd:YAG micro-laser operating at 10-Hz repetition rate and is seeded by a 761-nm, cw distributed-feedback diode laser. The resultant pulse-amplified seed beam is frequency tripled in two nonlinear frequency-conversion steps to generate 253.7-nm light. The laser system is mounted on a 45.7 cm × 30.5 cm breadboard and can be further condensed using custom optical mounts. Based on simulations of the nonlinear frequency-conversion processes and current results, we expect this laser architecture to exceed the desired pulse energy. Moreover, this approach provides a compact, all-solid-state source of tunable, narrow-linewidth visible and ultraviolet radiation, which is required for many chemical sensing applications.

Reichardt, Thomas A.; Headrick, Jeffrey M.; Hoops, Alexandra A.; Koplow, Jeffrey P.; Kliner, Dahv A.V.

Abstract not provided.

Hoops, Alexandra A.; Reichardt, Thomas A.; Farrow, Roger L.; Bambha, Ray B.; Schmitt, Randal L.; Kliner, Dahv A.V.

Abstract not provided.

Optics InfoBase Conference Papers

Hoops, Alexandra A.; Reichardt, Thomas A.; Schulz, P.; Farrow, Roger L.; Bambha, Ray B.; Schmitt, Randal L.; Kliner, Dahv A.V.

A portable laser for real-time, stand-off detection of Hg0 emissions from coal-fired power plants is developed and characterized. The pulse energy of the 254-nm laser is 1.8 μJ, which will enable sub-ppb detection of Hg0. © 2007 Optical Society of America.

Hoops, Alexandra A.; Farrow, Roger L.; Reichardt, Thomas A.; Bambha, Ray B.; Schmitt, Randal L.; Kliner, Dahv A.V.

Abstract not provided.

Headrick, Jeffrey M.; Hoops, Alexandra A.; Koplow, Jeffrey P.; Kliner, Dahv A.V.

Abstract not provided.

Kliner, Dahv A.V.

Abstract not provided.

IEEE Journal of Quantum Electronics

Bambha, Ray B.; Meister, Dorothy C.; Kliner, Dahv A.V.

Abstract not provided.

Kliner, Dahv A.V.

Abstract not provided.

Proceedings of SPIE - The International Society for Optical Engineering

Farrow, Roger L.; Hadley, G.R.; Kliner, Dahv A.V.; Koplow, Jeffrey P.

We have numerically compared the performance of various designs for the core refractive-index (RI) and rare-earth-dopant distributions of large-mode-area fibers for use in bend-loss-filtered, high-power amplifiers. We first established quantitative targets for the key parameters that determine fiber-amplifier performance, including effective LP01 modal area (Aeff, both straight and coiled), bend sensitivity (for handling and packaging), high-order mode discrimination, mode-field displacement upon coiling, and index contrast (manufacturability). We compared design families based on various power-law and hybrid profiles for the RI and evaluated confined rare-earth doping for hybrid profiles. Step-index fibers with straight-fiber Aeff values > 1000 μm2 exhibit large decreases in Aeff and transverse mode-field displacements upon coiling, in agreement with recent calculations of Hadley et al. [Proc. of SPIE, Vol. 6102, 61021S (2006)] and Fini [Opt. Exp. 14, 69 (2006)]. Triangular-profile fibers substantially mitigate these effects, but suffer from excessive bend sensitivity at Aeff values of interest. Square-law (parabolic) profile fibers are free of modal distortion but are hampered by high bend sensitivity (although to a lesser degree than triangular profiles) and exhibit the largest mode displacements. We find that hybrid (combined power-law) profiles provide some decoupling of these tradeoffs and allow all design goals to be achieved simultaneously. We present optimized fiber designs based on this analysis.

Thomes, William J.; Meister, Dorothy C.; Bambha, Ray B.; Kliner, Dahv A.V.

Abstract not provided.

Thomes, William J.; Meister, Dorothy C.; Bambha, Ray B.; Kliner, Dahv A.V.

Abstract not provided.

Reichardt, Thomas A.; Hoops, Alexandra A.; Kliner, Dahv A.V.; Koplow, Jeffrey P.

Abstract not provided.

Proceedings of SPIE - The International Society for Optical Engineering

Farrow, Roger L.; Kliner, Dahv A.V.; Schrader, Paul E.; Hoops, Alexandra A.; Moore, Scan W.; Hadley, G.R.; Schmitt, Randal L.

We report results from Yb-doped fiber amplifiers seeded with two microchip lasers having 0.38-ns and 2.3-ns pulse durations. The shorter duration seed resulted in output pulses with a peak power of > 1.2 MW and pulse energy of 0.67 mJ. Peak power was limited by nonlinear processes that caused breakup and broadening of the pulse envelope as the pump power increased. The 2.3-ns duration seed laser resulted in output pulses with a peak power of >300 kW and pulse energy of > 1.1 mJ. Pulse energies were limited by the onset of stimulated Brillouin scattering and ultimately by internal optical damage (fluences in excess of 400 J/cm 2 were generated). In both experiments, nearly diffraction-limited beam profiles were obtained, with M 2 values of < 1.2. Preliminary results of a pulse-amplification model are in excellent agreement with the experimental results of the amplifiers operating in the low-to-moderate gain-depletion regime.

Kliner, Dahv A.V.; Farrow, Roger L.; Schrader, Paul E.; Hoops, Alexandra A.; Hadley, G.R.; Schmitt, Randal L.

Abstract not provided.

Proceedings of SPIE - The International Society for Optical Engineering

Kliner, Dahv A.V.; Di Teodoro, Fabio; Koplow, Jeffrey P.; Moore, Sean W.; Smith, A.V.

We have generated the second, third, fourth, and fifth harmonics of the output of a Yb-doped fiber amplifier seeded by a passively Q-switched Nd:YAG microchip laser. The fiber amplifier employed multimode fiber (25 μm core diameter, V ≈ 7.4) to provide high-peak-power pulses, but diffraction-limited beam quality was obtained by use of bend-loss-induced mode filtering. The amplifier output had a pulse duration of 0.97 ns and smooth, transform-limited temporal and spectral profiles (∼500 MHz linewidth). We obtained high nonlinear conversion efficiencies using a simple optical arrangement and critically phase-matched crystals. Starting with 320 mW of average power at 1064 nm (86 μJ per pulse at a 3.7 kHz repetition rate), we generated 160 mW at 532 nm, 38 mW at 355 nm, 69 mW at 266 nm, and 18 mW at 213 nm. The experimental results are in excellent agreement with calculations. Significantly higher visible and UV powers will be possible by operating the fiber amplifier at higher repetition rates and pulse energies and by further optimizing the nonlinear conversion scheme.

Optics Communications

Kliner, Dahv A.V.; Di Teodoro, Fabio; Koplow, Jeffrey P.; Moore, Sean W.; Smith, A.V.

We report generation of the second, third, fourth, and fifth harmonics of the output of a Yb-doped fiber amplifier seeded by a passively Q-switched Nd:YAG microchip laser. We obtained high conversion efficiencies using a simple optical arrangement and critically phase-matched nonlinear crystals. Starting with 320 mW of average power at 1064 nm (86 μJ per pulse at a 3.7 kHz repetition rate), we generated 160 mW at 532 nm, 38 mW at 355 nm, 69 mW at 266 nm, and 18 mW at 213 nm. The experimental results are in excellent agreement with calculations. © 2002 Elsevier Science B.V. All rights reserved.