Theoretical study on SHG conversion efficiency for Gaussian beam and control
          of its decline

Nomura, Kazufumi; Ohmura, Etsuji; Miyamoto, Isamu

doi:10.2351/1.5066165

Cited by 6 publications

(15 citation statements)

References 2 publications

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“…We Influence of crystal temperature change induced by laser absorption on conversion efficiency and output beam profile were analyzed theoretically [1][2][3]. As a result, it was elucidated that output beam profile of second harmonic is distorted and fluctuates as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…This analysis method is the same as our previous studies [1][2][3]. It is assumed that plane wave propagates in the z direction, therefore one-dimensional coordinate system is applied for SHG analysis.…”

Section: Analysis Methods Of Crystal Temperature Changementioning

confidence: 99%

“…The primary horizontal-axis is temperature difference T from the phase matching temperature Tpm, induced by temperature change becomes larger more and more, thus conversion efficiency decreases again. Strictly speaking, refractive index difference caused by incident angle declination is never canceled completely because crystal temperature is not uniform due to laser absorption [3]. But this result suggests a possibility of cancellation of phase mismatching due to angle declination by keeping crystal temperature higher than phase matching temperature.…”

Section: One Pulse Irradiation Under Temperature Phase Matchingmentioning

confidence: 94%

“…We have studied second harmonic generation (SHG) that is basic frequency conversion technique, and reported some analysis results [1][2][3] focusing influence of crystal temperature change induced by laser absorption on SHG. In this paper, influence of incident angle declination of laser from phase matching angle is discussed theoretically first.…”

Section: Introductionmentioning

confidence: 99%

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Theoretical analysis of second harmonic characteristics generated by KTiOPO 4 crystal

Nomura

Ohmura

Horn

et al. 2003

Fourth International Symposium on Laser Precision Microfabrication

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In the harmonic generation using nonlinear optical crystals, phase-matching technique is indispensable for obtaining high conversion efficiency. As the first step of our study, we have investigated crystal temperature variation induced by laser absorption and its influence on conversion efficiency and beam profile in second harmonic generation (SHG) by solving the coupling problem composed of heat conduction equation and complex amplitude equations. In this study, we focused on the declination of irradiation angle of laser from the phase matching angle, which is equivalent to the declination of cut angle of crystal. The influences of angle declination and temperature rise of the crystal on SHG characteristics were examined by supposing KTiOPO4 (KTP) crystal. Main results obtained are as follows: When the angle declination is only 0.1 deg, conversion efficiency easily decreases to half that under perfect phase-matching condition. Significant distortion of output beam profile of second harmonic is also caused by the angle declination. This essential problem on output beam profile should be considered in precision microfabrication. Influences of angle declination and temperature change on phase mismatching are superposed. Our analysis is useful to elucidate such compounded and complicated phenomena in frequency conversion. A possibility of cancellation of phase mismatching due to angle declination by keeping crystal temperature higher than phase matching temperature was suggested through numerical examples.

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Section: Resultsmentioning

confidence: 99%

Section: Analysis Methods Of Crystal Temperature Changementioning

confidence: 99%

Section: One Pulse Irradiation Under Temperature Phase Matchingmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Theoretical analysis of second harmonic characteristics generated by KTiOPO 4 crystal

Nomura

Ohmura

Horn

et al. 2003

Fourth International Symposium on Laser Precision Microfabrication

Self Cite

View full text Add to dashboard Cite

show abstract

“…At the first step, about second harmonic generation (SHG), complex amplitude equations of the electric field in which laser absorption in the nonlinear optical crystal is considered were derived and then coupled analysis of propagation of light waves and heat conduction in the crystal was conducted [1][2][3][4]. Negative uniaxis crystal KH2PO4 (KDP) was supposed and SHG conversion efficiency was investigated when Nd:YAG laser whose spatial intensity is uniform distribution [1] and Gaussian distribution [2] was irradiated.…”

Section: Introductionmentioning

confidence: 99%

Influence of temporal pulse shape on second harmonic generation

Ohmura

Nomura

Miyamoto

2003

Fourth International Symposium on Laser Precision Microfabrication

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Frequency conversion technique using nonlinear optical crystals is indispensable to solid-state laser applications. It is well known that the conversion efficiency is very sensitive to temperature change of crystal, which is caused by laser absorption. We have been analyzing problems of second harmonic generation (SHG) by coupling the electric field to the temperature field. In this study, temporal pulseshape dependence of SHG was investigated theoretically, and Gaussian pulse and rectangular pulse were compared. Main conclusions obtained are as follows: (1) Both conversion efficiencies with Gaussian and rectangular pulses fluctuate with irradiation time, however the former fluctuation is slower and more gentle.(2) Pulse of output second harmonic fluctuates most remarkably at the center, where power density of incident fundamental is highest, in the Gaussian pulse. (3) As a result, pre-pulse and post-pulse are generated at both sides of the main pulse. (4) Such distortion of output pulse shape becomes more remarkable as power density increases.

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Distortion analysis of beam profile and pulse shape of second harmonic due to repetitive irradiation of picosecond pulses

2004

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Frequency conversion technique using nonlinear optical crystals is indispensable to solid-state laser applications. It is well known that the conversion efficiency is very sensitive to temperature change of crystal, which is caused by laser absorption. We have been analyzing problems of second harmonic generation (SHG) by coupling the electric field to the temperature field. In this study, temporal pulse-shape dependence of SHG was investigated theoretically, and Gaussian pulse and rectangular pulse were compared. Main conclusions obtained are as follows: (1) Both conversion efficiencies with Gaussian pulses and rectangular pulses fluctuate with irradiation time, however the former fluctuation is slower and more gentle.(2) Pulse of output second harmonic fluctuates most remarkably at the center, where power density of incident fundamental is highest, in the Gaussian pulse. (3) As a result, pre-pulse and post-pulse are generated before and after the main pulse. (4) Such distortion of output pulse shape becomes more remarkable as power density increases.

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Theoretical study on SHG conversion efficiency for Gaussian beam and control of its decline

Cited by 6 publications

References 2 publications

Theoretical analysis of second harmonic characteristics generated by KTiOPO 4 crystal

Theoretical analysis of second harmonic characteristics generated by KTiOPO 4 crystal

Influence of temporal pulse shape on second harmonic generation

Distortion analysis of beam profile and pulse shape of second harmonic due to repetitive irradiation of picosecond pulses

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