Degradation in long-pulse dye laser emission under fast-flow conditions

Varnado, S.G.

doi:10.1063/1.1662090

Cited by 14 publications

(7 citation statements)

References 5 publications

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“…For this purpose, the dye solution must be flown at sufficiently large velocities across the pump region. This often results in chaos/turbulence and hence degradation of the optical quality of the medium [21,22,27]. The propagation of the spontaneously emitted fluorescent photons is affected by the degraded qualities of the medium.…”

Section: Resultsmentioning

confidence: 99%

“…The value is large, above 80,000 counts in flowing medium. Figure 5 shows the spectral intensity variation of fluorescence [27] has observed degradation of flash lamp pumped dye laser output energy with increasing flow velocity and reported that the degradation is caused by scattering centers present in the dye after flowing. The decreased intensity was, in fact, due to refractive index variation.…”

Section: Resultsmentioning

confidence: 99%

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Spectral Intensity Variation by the Correlation Function of Refractive Index Fluctuations of the Liquid Medium

Singh

2013

International Journal of Optics

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It is proposed that a macroscopic theory of propagation and scattering of light through random media can be functional for the dye liquid flowing media in the microscopic levels too, with modest approximations. Maxwell’s equation for a random refractive index medium is approximated and solved for the electric field. An analytical expression for the spectral intensity of the field scattered by the refractive index fluctuations inside a medium has been derived which was valid within the first Born approximation. Far field spectral intensity variation of the radiation propagating through the liquid medium is a consequence of variation in correlation function of the refractive index inhomogeneities. The strength of radiation scattered in a particular direction depends on the spatial correlation function of the refractive index fluctuations of the medium. An attempt is made to explain some of the experimentally observed spectral intensity variations, particularly dye emission propagation through liquid flowing medium, in the presence of thermal and flow field.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Spectral Intensity Variation by the Correlation Function of Refractive Index Fluctuations of the Liquid Medium

Singh

2013

International Journal of Optics

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“…As a result, stability of the dye laser emission is affected by the flow characteristics of the gain medium [10,11]. The effect of the flowing medium on the performance of dye lasers has been acknowledged through experiments [9][10][11][12][13][14]. In order to understand the mechanism responsible for optical inhomogeneity, a study of the flow characteristics of the dye laser gain medium is needed.…”

Section: Introductionmentioning

confidence: 99%

A study of flow characteristics of a high repetition rate dye laser gain medium

Singh¹,

Kumar²,

Vora³

2014

Laser Phys.

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The gain medium of a high repetition rate liquid dye laser is made to flow at a sufficiently high velocity through the dye cell in order to minimize the thermal inhomogeneity. In this paper, temperature contours as a function of distance from the pump beam entrance dye cell window wall at various flow velocities in the laminar and turbulent region of gain medium flow were evaluated using computational fluid dynamics (CFD). Appreciable temperature gradients subsist at low Reynolds numbers due to inefficient heat transfer from the gain medium. However, at high Reynolds numbers >6000, the substantial effects of local density turbulent fluctuations degrade the optical quality of the gain medium. These computational studies were used to elucidate the characteristics of observed spectral fluctuations of a dye laser as a function of the Reynolds number.

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“…Several dye cell geometries such as converging, diverging, straight, trapezoidal, parallelogram, rectangular and cellular with convex inner surfaces have been extensively used to achieve high flow velocities in the dye active region [8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Roncin and Damay have designed a demountable trapezoidal dye cell to avoid parasitic oscillation [19].…”

Section: Introductionmentioning

confidence: 99%

Design of the dye cell of a dye laser to facilitate repetitive operation in the single longitudinal mode

et al. 2013

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A dye cell was designed and fabricated to facilitate high repetition rate single longitudinal mode (SLM) operation with low viscosity solvents such as ethanol. The flow circulation (vortex) in the dye cell was eliminated by reducing the flow cross section from 10 to 5 mm 2 with optimized flow entry. The physical dimension of dye cell is very important for short cavity SLM lasers in terms of keeping the cavity length small. Flow visualization of various geometries in the dye cell was carried out using commercial computational fluid dynamics (CFD) software. It was found that the slit as well as tubular entry to the dye cell of cross section 1 × 10 mm 2 shows flow circulation (a vortex) near the entry to the dye cell. The SLM was obtained from a 10 mm 2 flow cross section dye cell with a high viscosity solvent such as binary solvent (200 cP) or glycerol (1400 cP) with a higher bandwidth. The pulse to pulse fluctuations in the bandwidth and wavelength are generally associated with dye flow instabilities. These flow related instabilities reduced with higher viscosity solvents, which results in an increased bandwidth of the SLM dye laser (by nearly 40%). A specially designed dye cell was fabricated and used for SLM operation at two different pump lasers having different pulse repetition rates ranging from 20 to 6000 Hz. SLM operation was demonstrated for longitudinal pumping of the dye cell with low viscosity solvents. Time averaged SLM line widths of 400 and 175 MHz were obtained with a copper vapor laser (CVL) and Nd:YAG laser, respectively. A single pulse line width of 315 MHz was obtained with a CVL pumped dye laser.

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Degradation in long-pulse dye laser emission under fast-flow conditions

Cited by 14 publications

References 5 publications

Spectral Intensity Variation by the Correlation Function of Refractive Index Fluctuations of the Liquid Medium

Spectral Intensity Variation by the Correlation Function of Refractive Index Fluctuations of the Liquid Medium

A study of flow characteristics of a high repetition rate dye laser gain medium

Design of the dye cell of a dye laser to facilitate repetitive operation in the single longitudinal mode

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