Heat coupled Gaussian continuous-wave double-pass type-II second harmonic generation: inclusion of thermally induced phase mismatching and thermal lensing

Sabaeian, Mohammad; Jalil-Abadi, Fatemeh Sedaghat; Rezaee, Mostafa Mohammad; Motazedian, Alireza

doi:10.1364/oe.22.025615

Cited by 12 publications

(7 citation statements)

References 37 publications

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“…As discussed in Ref. [20], the efficiency of pulsed SHG is much higher than CW operation because of its short interaction length. All calculations have been done using a homemade code written in Intel Fortran version 14.04 and were run in Linux operating system.…”

Section: Resultsmentioning

confidence: 99%

“…Recently, this model had been employed to enhance the nonlinear conversion efficiency experimentally [19]. More recently, the double-pass version of this model, including thermal effects, has been reported regenerating experimental data [20].…”

Section: Introductionmentioning

confidence: 99%

“…In nondepleted approximation, it is assumed that the intensity/ amplitude of FW over the crystal length is high enough, and it remains constant so that the SHW equation can be decoupled from two others and solved separately to describe the process of SHG. Although a nondepleted assumption for FW may be fulfilled for CW SHG due to a large interaction length [20], for pulsed SHG in which the peak power of the FW is much higher than that of CW, the smallness of the interaction length makes a complete energy conversion and so does not allow a nondepletion wave model to be valid any longer. Therefore, to solve the coupled equation, we use a numerical method.…”

Section: Introductionmentioning

confidence: 99%

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Pulsed Bessel–Gauss beams: a depleted wave model for type II second-harmonic generation

et al. 2014

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In this work, a three-dimensional and time-dependent nonlinear wave model to describe the generation of pulsed Bessel-Gauss second-harmonic waves (SHWs) is presented. Three coupled equations, two for ordinary and extraordinary fundamental waves and one for extraordinary SHWs, describing type II second-harmonic generation (SHG) in a KTiOPO₄ (KTP) crystal were solved by considering the depletion of fundamental waves (FWs). The results examined the validity of nondepleted wave approximation against the energy of pulses, beam spot size, and interaction length. It was shown that for pulses with spot sizes of ω_f=80 μm and energy of 0.8j, the nonlinear interaction was accomplished over a distance of ∼5 mm. Therefore, for KTP crystals with lengths longer than 5 mm, the nondepleted wave approximation can no longer be valid. To be valid, the crystal must be shorter than the interaction length, i.e., 5 mm.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pulsed Bessel–Gauss beams: a depleted wave model for type II second-harmonic generation

et al. 2014

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“…It is safe to say that, for a CW SHG, due to the shortening of interaction length, longer crystals provide higher efficiencies. However, it should be noted that elongation of the crystal should be continued up to reaching the optimum efficiencies [22]. Unnecessary elongation without any contrivance leads to reduction in SHG efficiency due to optical absorption and converting back the energy of SHW toward the fundamental wave.…”

Section: Resultsmentioning

confidence: 99%

Temperature increase effects on a double-pass cavity type II second-harmonic generation: a model for depleted Gaussian continuous waves

et al. 2015

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In this work, the effect of temperature increase on the efficiency of a double-pass cavity type II second-harmonic generation (SHG) is investigated. To this end, a depleted wave model describing the continuous-wave SHG process with fundamental Gaussian waves was developed. First, six coupled equations were proposed to model a double-pass cavity to generate the second harmonic of a Gaussian fundamental wave in type II configuration. Then, the effect of temperature increase in the nonlinear crystal due to the optical absorption was modeled. To do this, a mismatched phase arising from changes in refractive indices was added to the coupled equations. Although the nondepleted assumption is usually used in such problems, a simultaneous solving of coupled equations with assumption of fundamental beam depletion was performed. The results were obtained by a homemade code written in Intel Fortran, and show how the efficiency of the SHG process decreases when the crystal is warmed up by 5, 10, and 15 K. Dramatic reductions in SHG efficiency were observed due to small changes in temperature. The results show excellent agreement with the experimental data [Opt. Commun.173, 311-314 (2000)].

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“…In their studies, Sabaeian et al investigated the equations of the ideal field in a two-pass cavity for continuous Gaussian beam [18]. They coupled the field equations with the equations of heat and phase mismatch and compared the resulting model with the experimental results [19]. In this work, the SHG equations with heat and phase equations have been coupled.…”

Section: Introductionmentioning

confidence: 99%

A depleted and numerical model for pulsed Gaussian wave type II second harmonic generation

Rezaee¹,

Sabaeian²,

Motazedian³

et al. 2021

Preprint

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This paper presents a three-dimensional (3-D) and spatio-temporal dependent nonlinear wave model to explain the generation of pulsed Gaussian Second Harmonic Waves (SHW). We solve numerically three coupled equations describing the type II Second Harmonic Generation (SHG) in cylindrical KTP crystals under the assumption of fundamental waves depletion, two for ordinary and one for extraordinary Fundamental Waves (FW). The results are attained by a homemade code written in FORTRAN. The results depict the efficiency of the SHG process with the conversion of FW energy to SHW energy, while SHW keeps the same Gaussian profile as FW. Furthermore, the results examine the effect of pulse energy, beam spot size, and therefore interaction length on SHW efficiency.

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Heat coupled Gaussian continuous-wave double-pass type-II second harmonic generation: inclusion of thermally induced phase mismatching and thermal lensing

Cited by 12 publications

References 37 publications

Pulsed Bessel–Gauss beams: a depleted wave model for type II second-harmonic generation

Pulsed Bessel–Gauss beams: a depleted wave model for type II second-harmonic generation

Temperature increase effects on a double-pass cavity type II second-harmonic generation: a model for depleted Gaussian continuous waves

A depleted and numerical model for pulsed Gaussian wave type II second harmonic generation

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